~bzr-pqm/bzr/bzr.dev

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
2662
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
2721
2722
2723
2724
2725
2726
2727
2728
2729
2730
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
2753
2754
2755
2756
2757
2758
2759
2760
2761
2762
2763
2764
2765
2766
2767
2768
2769
2770
2771
2772
2773
2774
2775
2776
2777
2778
2779
2780
2781
2782
2783
2784
2785
2786
2787
2788
2789
2790
2791
2792
2793
2794
2795
2796
2797
2798
2799
2800
2801
2802
2803
2804
2805
2806
2807
2808
2809
2810
2811
2812
2813
2814
2815
2816
2817
2818
2819
2820
2821
2822
2823
2824
2825
2826
2827
2828
2829
2830
2831
2832
2833
2834
2835
2836
2837
2838
2839
2840
2841
2842
2843
2844
2845
2846
2847
2848
2849
2850
2851
2852
2853
2854
2855
2856
2857
2858
2859
2860
2861
2862
2863
2864
2865
2866
2867
2868
2869
2870
2871
2872
2873
2874
2875
2876
2877
2878
2879
2880
2881
2882
2883
2884
2885
2886
2887
2888
2889
2890
2891
2892
2893
2894
2895
2896
2897
2898
2899
2900
2901
2902
2903
2904
2905
2906
2907
2908
2909
2910
2911
2912
2913
2914
2915
2916
2917
2918
2919
2920
2921
2922
2923
2924
2925
2926
2927
2928
2929
2930
2931
2932
2933
2934
2935
2936
2937
2938
2939
2940
2941
2942
2943
2944
2945
2946
2947
2948
2949
2950
2951
2952
2953
2954
2955
2956
2957
2958
2959
2960
2961
2962
2963
2964
2965
2966
2967
2968
2969
2970
2971
2972
2973
2974
2975
2976
2977
2978
2979
2980
2981
2982
2983
2984
2985
2986
2987
2988
2989
2990
2991
2992
2993
2994
2995
2996
2997
2998
2999
3000
3001
3002
3003
3004
3005
3006
3007
3008
3009
3010
3011
3012
3013
3014
3015
3016
3017
3018
3019
3020
3021
3022
3023
3024
3025
3026
3027
3028
3029
3030
3031
3032
3033
3034
3035
3036
3037
3038
3039
3040
3041
3042
3043
3044
3045
3046
3047
3048
3049
3050
3051
3052
3053
3054
3055
3056
3057
3058
3059
3060
3061
3062
3063
3064
3065
3066
3067
3068
3069
3070
3071
3072
3073
3074
3075
3076
3077
3078
3079
3080
3081
3082
3083
3084
3085
3086
3087
3088
3089
3090
3091
3092
3093
3094
3095
3096
3097
3098
3099
3100
3101
3102
3103
3104
3105
3106
3107
3108
3109
3110
3111
3112
3113
3114
3115
3116
3117
3118
3119
3120
3121
3122
3123
3124
3125
3126
3127
3128
3129
3130
3131
3132
3133
3134
3135
3136
3137
3138
3139
3140
3141
3142
3143
3144
3145
3146
3147
3148
3149
3150
3151
3152
3153
3154
3155
3156
3157
3158
3159
3160
3161
3162
3163
3164
3165
3166
3167
3168
3169
3170
3171
3172
3173
3174
3175
3176
3177
3178
3179
3180
3181
3182
3183
3184
3185
3186
3187
3188
3189
3190
3191
3192
# Copyright (C) 2005, 2006, 2007, 2008 Canonical Ltd
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

from cStringIO import StringIO

from bzrlib.lazy_import import lazy_import
lazy_import(globals(), """
import re
import time

from bzrlib import (
    bzrdir,
    check,
    debug,
    errors,
    generate_ids,
    gpg,
    graph,
    lazy_regex,
    lockable_files,
    lockdir,
    lru_cache,
    osutils,
    registry,
    remote,
    revision as _mod_revision,
    symbol_versioning,
    transactions,
    tsort,
    ui,
    )
from bzrlib.bundle import serializer
from bzrlib.revisiontree import RevisionTree
from bzrlib.store.versioned import VersionedFileStore
from bzrlib.store.text import TextStore
from bzrlib.testament import Testament
from bzrlib.util import bencode
""")

from bzrlib.decorators import needs_read_lock, needs_write_lock
from bzrlib.inter import InterObject
from bzrlib.inventory import Inventory, InventoryDirectory, ROOT_ID
from bzrlib.symbol_versioning import (
        deprecated_method,
        one_one,
        one_two,
        one_three,
        one_six,
        )
from bzrlib.trace import mutter, mutter_callsite, note, warning


# Old formats display a warning, but only once
_deprecation_warning_done = False


class CommitBuilder(object):
    """Provides an interface to build up a commit.

    This allows describing a tree to be committed without needing to 
    know the internals of the format of the repository.
    """
    
    # all clients should supply tree roots.
    record_root_entry = True
    # the default CommitBuilder does not manage trees whose root is versioned.
    _versioned_root = False

    def __init__(self, repository, parents, config, timestamp=None,
                 timezone=None, committer=None, revprops=None,
                 revision_id=None):
        """Initiate a CommitBuilder.

        :param repository: Repository to commit to.
        :param parents: Revision ids of the parents of the new revision.
        :param config: Configuration to use.
        :param timestamp: Optional timestamp recorded for commit.
        :param timezone: Optional timezone for timestamp.
        :param committer: Optional committer to set for commit.
        :param revprops: Optional dictionary of revision properties.
        :param revision_id: Optional revision id.
        """
        self._config = config

        if committer is None:
            self._committer = self._config.username()
        else:
            self._committer = committer

        self.new_inventory = Inventory(None)
        self._new_revision_id = revision_id
        self.parents = parents
        self.repository = repository

        self._revprops = {}
        if revprops is not None:
            self._revprops.update(revprops)

        if timestamp is None:
            timestamp = time.time()
        # Restrict resolution to 1ms
        self._timestamp = round(timestamp, 3)

        if timezone is None:
            self._timezone = osutils.local_time_offset()
        else:
            self._timezone = int(timezone)

        self._generate_revision_if_needed()
        self.__heads = graph.HeadsCache(repository.get_graph()).heads

    def commit(self, message):
        """Make the actual commit.

        :return: The revision id of the recorded revision.
        """
        rev = _mod_revision.Revision(
                       timestamp=self._timestamp,
                       timezone=self._timezone,
                       committer=self._committer,
                       message=message,
                       inventory_sha1=self.inv_sha1,
                       revision_id=self._new_revision_id,
                       properties=self._revprops)
        rev.parent_ids = self.parents
        self.repository.add_revision(self._new_revision_id, rev,
            self.new_inventory, self._config)
        self.repository.commit_write_group()
        return self._new_revision_id

    def abort(self):
        """Abort the commit that is being built.
        """
        self.repository.abort_write_group()

    def revision_tree(self):
        """Return the tree that was just committed.

        After calling commit() this can be called to get a RevisionTree
        representing the newly committed tree. This is preferred to
        calling Repository.revision_tree() because that may require
        deserializing the inventory, while we already have a copy in
        memory.
        """
        return RevisionTree(self.repository, self.new_inventory,
                            self._new_revision_id)

    def finish_inventory(self):
        """Tell the builder that the inventory is finished."""
        if self.new_inventory.root is None:
            raise AssertionError('Root entry should be supplied to'
                ' record_entry_contents, as of bzr 0.10.')
            self.new_inventory.add(InventoryDirectory(ROOT_ID, '', None))
        self.new_inventory.revision_id = self._new_revision_id
        self.inv_sha1 = self.repository.add_inventory(
            self._new_revision_id,
            self.new_inventory,
            self.parents
            )

    def _gen_revision_id(self):
        """Return new revision-id."""
        return generate_ids.gen_revision_id(self._config.username(),
                                            self._timestamp)

    def _generate_revision_if_needed(self):
        """Create a revision id if None was supplied.
        
        If the repository can not support user-specified revision ids
        they should override this function and raise CannotSetRevisionId
        if _new_revision_id is not None.

        :raises: CannotSetRevisionId
        """
        if self._new_revision_id is None:
            self._new_revision_id = self._gen_revision_id()
            self.random_revid = True
        else:
            self.random_revid = False

    def _heads(self, file_id, revision_ids):
        """Calculate the graph heads for revision_ids in the graph of file_id.

        This can use either a per-file graph or a global revision graph as we
        have an identity relationship between the two graphs.
        """
        return self.__heads(revision_ids)

    def _check_root(self, ie, parent_invs, tree):
        """Helper for record_entry_contents.

        :param ie: An entry being added.
        :param parent_invs: The inventories of the parent revisions of the
            commit.
        :param tree: The tree that is being committed.
        """
        # In this revision format, root entries have no knit or weave When
        # serializing out to disk and back in root.revision is always
        # _new_revision_id
        ie.revision = self._new_revision_id

    def _get_delta(self, ie, basis_inv, path):
        """Get a delta against the basis inventory for ie."""
        if ie.file_id not in basis_inv:
            # add
            return (None, path, ie.file_id, ie)
        elif ie != basis_inv[ie.file_id]:
            # common but altered
            # TODO: avoid tis id2path call.
            return (basis_inv.id2path(ie.file_id), path, ie.file_id, ie)
        else:
            # common, unaltered
            return None

    def record_entry_contents(self, ie, parent_invs, path, tree,
        content_summary):
        """Record the content of ie from tree into the commit if needed.

        Side effect: sets ie.revision when unchanged

        :param ie: An inventory entry present in the commit.
        :param parent_invs: The inventories of the parent revisions of the
            commit.
        :param path: The path the entry is at in the tree.
        :param tree: The tree which contains this entry and should be used to 
            obtain content.
        :param content_summary: Summary data from the tree about the paths
            content - stat, length, exec, sha/link target. This is only
            accessed when the entry has a revision of None - that is when it is
            a candidate to commit.
        :return: A tuple (change_delta, version_recorded). change_delta is 
            an inventory_delta change for this entry against the basis tree of
            the commit, or None if no change occured against the basis tree.
            version_recorded is True if a new version of the entry has been
            recorded. For instance, committing a merge where a file was only
            changed on the other side will return (delta, False).
        """
        if self.new_inventory.root is None:
            if ie.parent_id is not None:
                raise errors.RootMissing()
            self._check_root(ie, parent_invs, tree)
        if ie.revision is None:
            kind = content_summary[0]
        else:
            # ie is carried over from a prior commit
            kind = ie.kind
        # XXX: repository specific check for nested tree support goes here - if
        # the repo doesn't want nested trees we skip it ?
        if (kind == 'tree-reference' and
            not self.repository._format.supports_tree_reference):
            # mismatch between commit builder logic and repository:
            # this needs the entry creation pushed down into the builder.
            raise NotImplementedError('Missing repository subtree support.')
        self.new_inventory.add(ie)

        # TODO: slow, take it out of the inner loop.
        try:
            basis_inv = parent_invs[0]
        except IndexError:
            basis_inv = Inventory(root_id=None)

        # ie.revision is always None if the InventoryEntry is considered
        # for committing. We may record the previous parents revision if the
        # content is actually unchanged against a sole head.
        if ie.revision is not None:
            if not self._versioned_root and path == '':
                # repositories that do not version the root set the root's
                # revision to the new commit even when no change occurs, and
                # this masks when a change may have occurred against the basis,
                # so calculate if one happened.
                if ie.file_id in basis_inv:
                    delta = (basis_inv.id2path(ie.file_id), path,
                        ie.file_id, ie)
                else:
                    # add
                    delta = (None, path, ie.file_id, ie)
                return delta, False
            else:
                # we don't need to commit this, because the caller already
                # determined that an existing revision of this file is
                # appropriate.
                return None, (ie.revision == self._new_revision_id)
        # XXX: Friction: parent_candidates should return a list not a dict
        #      so that we don't have to walk the inventories again.
        parent_candiate_entries = ie.parent_candidates(parent_invs)
        head_set = self._heads(ie.file_id, parent_candiate_entries.keys())
        heads = []
        for inv in parent_invs:
            if ie.file_id in inv:
                old_rev = inv[ie.file_id].revision
                if old_rev in head_set:
                    heads.append(inv[ie.file_id].revision)
                    head_set.remove(inv[ie.file_id].revision)

        store = False
        # now we check to see if we need to write a new record to the
        # file-graph.
        # We write a new entry unless there is one head to the ancestors, and
        # the kind-derived content is unchanged.

        # Cheapest check first: no ancestors, or more the one head in the
        # ancestors, we write a new node.
        if len(heads) != 1:
            store = True
        if not store:
            # There is a single head, look it up for comparison
            parent_entry = parent_candiate_entries[heads[0]]
            # if the non-content specific data has changed, we'll be writing a
            # node:
            if (parent_entry.parent_id != ie.parent_id or
                parent_entry.name != ie.name):
                store = True
        # now we need to do content specific checks:
        if not store:
            # if the kind changed the content obviously has
            if kind != parent_entry.kind:
                store = True
        if kind == 'file':
            if content_summary[2] is None:
                raise ValueError("Files must not have executable = None")
            if not store:
                if (# if the file length changed we have to store:
                    parent_entry.text_size != content_summary[1] or
                    # if the exec bit has changed we have to store:
                    parent_entry.executable != content_summary[2]):
                    store = True
                elif parent_entry.text_sha1 == content_summary[3]:
                    # all meta and content is unchanged (using a hash cache
                    # hit to check the sha)
                    ie.revision = parent_entry.revision
                    ie.text_size = parent_entry.text_size
                    ie.text_sha1 = parent_entry.text_sha1
                    ie.executable = parent_entry.executable
                    return self._get_delta(ie, basis_inv, path), False
                else:
                    # Either there is only a hash change(no hash cache entry,
                    # or same size content change), or there is no change on
                    # this file at all.
                    # Provide the parent's hash to the store layer, so that the
                    # content is unchanged we will not store a new node.
                    nostore_sha = parent_entry.text_sha1
            if store:
                # We want to record a new node regardless of the presence or
                # absence of a content change in the file.
                nostore_sha = None
            ie.executable = content_summary[2]
            lines = tree.get_file(ie.file_id, path).readlines()
            try:
                ie.text_sha1, ie.text_size = self._add_text_to_weave(
                    ie.file_id, lines, heads, nostore_sha)
            except errors.ExistingContent:
                # Turns out that the file content was unchanged, and we were
                # only going to store a new node if it was changed. Carry over
                # the entry.
                ie.revision = parent_entry.revision
                ie.text_size = parent_entry.text_size
                ie.text_sha1 = parent_entry.text_sha1
                ie.executable = parent_entry.executable
                return self._get_delta(ie, basis_inv, path), False
        elif kind == 'directory':
            if not store:
                # all data is meta here, nothing specific to directory, so
                # carry over:
                ie.revision = parent_entry.revision
                return self._get_delta(ie, basis_inv, path), False
            lines = []
            self._add_text_to_weave(ie.file_id, lines, heads, None)
        elif kind == 'symlink':
            current_link_target = content_summary[3]
            if not store:
                # symlink target is not generic metadata, check if it has
                # changed.
                if current_link_target != parent_entry.symlink_target:
                    store = True
            if not store:
                # unchanged, carry over.
                ie.revision = parent_entry.revision
                ie.symlink_target = parent_entry.symlink_target
                return self._get_delta(ie, basis_inv, path), False
            ie.symlink_target = current_link_target
            lines = []
            self._add_text_to_weave(ie.file_id, lines, heads, None)
        elif kind == 'tree-reference':
            if not store:
                if content_summary[3] != parent_entry.reference_revision:
                    store = True
            if not store:
                # unchanged, carry over.
                ie.reference_revision = parent_entry.reference_revision
                ie.revision = parent_entry.revision
                return self._get_delta(ie, basis_inv, path), False
            ie.reference_revision = content_summary[3]
            lines = []
            self._add_text_to_weave(ie.file_id, lines, heads, None)
        else:
            raise NotImplementedError('unknown kind')
        ie.revision = self._new_revision_id
        return self._get_delta(ie, basis_inv, path), True

    def _add_text_to_weave(self, file_id, new_lines, parents, nostore_sha):
        # Note: as we read the content directly from the tree, we know its not
        # been turned into unicode or badly split - but a broken tree
        # implementation could give us bad output from readlines() so this is
        # not a guarantee of safety. What would be better is always checking
        # the content during test suite execution. RBC 20070912
        parent_keys = tuple((file_id, parent) for parent in parents)
        return self.repository.texts.add_lines(
            (file_id, self._new_revision_id), parent_keys, new_lines,
            nostore_sha=nostore_sha, random_id=self.random_revid,
            check_content=False)[0:2]


class RootCommitBuilder(CommitBuilder):
    """This commitbuilder actually records the root id"""
    
    # the root entry gets versioned properly by this builder.
    _versioned_root = True

    def _check_root(self, ie, parent_invs, tree):
        """Helper for record_entry_contents.

        :param ie: An entry being added.
        :param parent_invs: The inventories of the parent revisions of the
            commit.
        :param tree: The tree that is being committed.
        """


######################################################################
# Repositories

class Repository(object):
    """Repository holding history for one or more branches.

    The repository holds and retrieves historical information including
    revisions and file history.  It's normally accessed only by the Branch,
    which views a particular line of development through that history.

    The Repository builds on top of some byte storage facilies (the revisions,
    signatures, inventories and texts attributes) and a Transport, which
    respectively provide byte storage and a means to access the (possibly
    remote) disk.

    The byte storage facilities are addressed via tuples, which we refer to
    as 'keys' throughout the code base. Revision_keys, inventory_keys and
    signature_keys are all 1-tuples: (revision_id,). text_keys are two-tuples:
    (file_id, revision_id). We use this interface because it allows low
    friction with the underlying code that implements disk indices, network
    encoding and other parts of bzrlib.

    :ivar revisions: A bzrlib.versionedfile.VersionedFiles instance containing
        the serialised revisions for the repository. This can be used to obtain
        revision graph information or to access raw serialised revisions.
        The result of trying to insert data into the repository via this store
        is undefined: it should be considered read-only except for implementors
        of repositories.
    :ivar signatures: A bzrlib.versionedfile.VersionedFiles instance containing
        the serialised signatures for the repository. This can be used to
        obtain access to raw serialised signatures.  The result of trying to
        insert data into the repository via this store is undefined: it should
        be considered read-only except for implementors of repositories.
    :ivar inventories: A bzrlib.versionedfile.VersionedFiles instance containing
        the serialised inventories for the repository. This can be used to
        obtain unserialised inventories.  The result of trying to insert data
        into the repository via this store is undefined: it should be
        considered read-only except for implementors of repositories.
    :ivar texts: A bzrlib.versionedfile.VersionedFiles instance containing the
        texts of files and directories for the repository. This can be used to
        obtain file texts or file graphs. Note that Repository.iter_file_bytes
        is usually a better interface for accessing file texts.
        The result of trying to insert data into the repository via this store
        is undefined: it should be considered read-only except for implementors
        of repositories.
    :ivar _transport: Transport for file access to repository, typically
        pointing to .bzr/repository.
    """

    # What class to use for a CommitBuilder. Often its simpler to change this
    # in a Repository class subclass rather than to override
    # get_commit_builder.
    _commit_builder_class = CommitBuilder
    # The search regex used by xml based repositories to determine what things
    # where changed in a single commit.
    _file_ids_altered_regex = lazy_regex.lazy_compile(
        r'file_id="(?P<file_id>[^"]+)"'
        r'.* revision="(?P<revision_id>[^"]+)"'
        )

    def abort_write_group(self):
        """Commit the contents accrued within the current write group.

        :seealso: start_write_group.
        """
        if self._write_group is not self.get_transaction():
            # has an unlock or relock occured ?
            raise errors.BzrError('mismatched lock context and write group.')
        self._abort_write_group()
        self._write_group = None

    def _abort_write_group(self):
        """Template method for per-repository write group cleanup.
        
        This is called during abort before the write group is considered to be 
        finished and should cleanup any internal state accrued during the write
        group. There is no requirement that data handed to the repository be
        *not* made available - this is not a rollback - but neither should any
        attempt be made to ensure that data added is fully commited. Abort is
        invoked when an error has occured so futher disk or network operations
        may not be possible or may error and if possible should not be
        attempted.
        """

    def add_fallback_repository(self, repository):
        """Add a repository to use for looking up data not held locally.
        
        :param repository: A repository.
        """
        if not self._format.supports_external_lookups:
            raise errors.UnstackableRepositoryFormat(self._format, self.base)
        if not self._add_fallback_repository_check(repository):
            raise errors.IncompatibleRepositories(self, repository)
        self._fallback_repositories.append(repository)
        self.texts.add_fallback_versioned_files(repository.texts)
        self.inventories.add_fallback_versioned_files(repository.inventories)
        self.revisions.add_fallback_versioned_files(repository.revisions)
        self.signatures.add_fallback_versioned_files(repository.signatures)

    def _add_fallback_repository_check(self, repository):
        """Check that this repository can fallback to repository safely.
        
        :param repository: A repository to fallback to.
        :return: True if the repositories can stack ok.
        """
        return InterRepository._same_model(self, repository)

    def add_inventory(self, revision_id, inv, parents):
        """Add the inventory inv to the repository as revision_id.
        
        :param parents: The revision ids of the parents that revision_id
                        is known to have and are in the repository already.

        :returns: The validator(which is a sha1 digest, though what is sha'd is
            repository format specific) of the serialized inventory.
        """
        if not self.is_in_write_group():
            raise AssertionError("%r not in write group" % (self,))
        _mod_revision.check_not_reserved_id(revision_id)
        if not (inv.revision_id is None or inv.revision_id == revision_id):
            raise AssertionError(
                "Mismatch between inventory revision"
                " id and insertion revid (%r, %r)"
                % (inv.revision_id, revision_id))
        if inv.root is None:
            raise AssertionError()
        inv_lines = self._serialise_inventory_to_lines(inv)
        return self._inventory_add_lines(revision_id, parents,
            inv_lines, check_content=False)

    def _inventory_add_lines(self, revision_id, parents, lines,
        check_content=True):
        """Store lines in inv_vf and return the sha1 of the inventory."""
        parents = [(parent,) for parent in parents]
        return self.inventories.add_lines((revision_id,), parents, lines,
            check_content=check_content)[0]

    def add_revision(self, revision_id, rev, inv=None, config=None):
        """Add rev to the revision store as revision_id.

        :param revision_id: the revision id to use.
        :param rev: The revision object.
        :param inv: The inventory for the revision. if None, it will be looked
                    up in the inventory storer
        :param config: If None no digital signature will be created.
                       If supplied its signature_needed method will be used
                       to determine if a signature should be made.
        """
        # TODO: jam 20070210 Shouldn't we check rev.revision_id and
        #       rev.parent_ids?
        _mod_revision.check_not_reserved_id(revision_id)
        if config is not None and config.signature_needed():
            if inv is None:
                inv = self.get_inventory(revision_id)
            plaintext = Testament(rev, inv).as_short_text()
            self.store_revision_signature(
                gpg.GPGStrategy(config), plaintext, revision_id)
        # check inventory present
        if not self.inventories.get_parent_map([(revision_id,)]):
            if inv is None:
                raise errors.WeaveRevisionNotPresent(revision_id,
                                                     self.inventories)
            else:
                # yes, this is not suitable for adding with ghosts.
                rev.inventory_sha1 = self.add_inventory(revision_id, inv,
                                                        rev.parent_ids)
        else:
            key = (revision_id,)
            rev.inventory_sha1 = self.inventories.get_sha1s([key])[key]
        self._add_revision(rev)

    def _add_revision(self, revision):
        text = self._serializer.write_revision_to_string(revision)
        key = (revision.revision_id,)
        parents = tuple((parent,) for parent in revision.parent_ids)
        self.revisions.add_lines(key, parents, osutils.split_lines(text))

    def all_revision_ids(self):
        """Returns a list of all the revision ids in the repository. 

        This is conceptually deprecated because code should generally work on
        the graph reachable from a particular revision, and ignore any other
        revisions that might be present.  There is no direct replacement
        method.
        """
        if 'evil' in debug.debug_flags:
            mutter_callsite(2, "all_revision_ids is linear with history.")
        return self._all_revision_ids()

    def _all_revision_ids(self):
        """Returns a list of all the revision ids in the repository. 

        These are in as much topological order as the underlying store can 
        present.
        """
        raise NotImplementedError(self._all_revision_ids)

    def break_lock(self):
        """Break a lock if one is present from another instance.

        Uses the ui factory to ask for confirmation if the lock may be from
        an active process.
        """
        self.control_files.break_lock()

    @needs_read_lock
    def _eliminate_revisions_not_present(self, revision_ids):
        """Check every revision id in revision_ids to see if we have it.

        Returns a set of the present revisions.
        """
        result = []
        graph = self.get_graph()
        parent_map = graph.get_parent_map(revision_ids)
        # The old API returned a list, should this actually be a set?
        return parent_map.keys()

    @staticmethod
    def create(a_bzrdir):
        """Construct the current default format repository in a_bzrdir."""
        return RepositoryFormat.get_default_format().initialize(a_bzrdir)

    def __init__(self, _format, a_bzrdir, control_files):
        """instantiate a Repository.

        :param _format: The format of the repository on disk.
        :param a_bzrdir: The BzrDir of the repository.

        In the future we will have a single api for all stores for
        getting file texts, inventories and revisions, then
        this construct will accept instances of those things.
        """
        super(Repository, self).__init__()
        self._format = _format
        # the following are part of the public API for Repository:
        self.bzrdir = a_bzrdir
        self.control_files = control_files
        self._transport = control_files._transport
        self.base = self._transport.base
        # for tests
        self._reconcile_does_inventory_gc = True
        self._reconcile_fixes_text_parents = False
        self._reconcile_backsup_inventory = True
        # not right yet - should be more semantically clear ? 
        # 
        # TODO: make sure to construct the right store classes, etc, depending
        # on whether escaping is required.
        self._warn_if_deprecated()
        self._write_group = None
        # Additional places to query for data.
        self._fallback_repositories = []

    def __repr__(self):
        return '%s(%r)' % (self.__class__.__name__,
                           self.base)

    def has_same_location(self, other):
        """Returns a boolean indicating if this repository is at the same
        location as another repository.

        This might return False even when two repository objects are accessing
        the same physical repository via different URLs.
        """
        if self.__class__ is not other.__class__:
            return False
        return (self._transport.base == other._transport.base)

    def is_in_write_group(self):
        """Return True if there is an open write group.

        :seealso: start_write_group.
        """
        return self._write_group is not None

    def is_locked(self):
        return self.control_files.is_locked()

    def is_write_locked(self):
        """Return True if this object is write locked."""
        return self.is_locked() and self.control_files._lock_mode == 'w'

    def lock_write(self, token=None):
        """Lock this repository for writing.

        This causes caching within the repository obejct to start accumlating
        data during reads, and allows a 'write_group' to be obtained. Write
        groups must be used for actual data insertion.
        
        :param token: if this is already locked, then lock_write will fail
            unless the token matches the existing lock.
        :returns: a token if this instance supports tokens, otherwise None.
        :raises TokenLockingNotSupported: when a token is given but this
            instance doesn't support using token locks.
        :raises MismatchedToken: if the specified token doesn't match the token
            of the existing lock.
        :seealso: start_write_group.

        A token should be passed in if you know that you have locked the object
        some other way, and need to synchronise this object's state with that
        fact.

        XXX: this docstring is duplicated in many places, e.g. lockable_files.py
        """
        result = self.control_files.lock_write(token=token)
        for repo in self._fallback_repositories:
            # Writes don't affect fallback repos
            repo.lock_read()
        self._refresh_data()
        return result

    def lock_read(self):
        self.control_files.lock_read()
        for repo in self._fallback_repositories:
            repo.lock_read()
        self._refresh_data()

    def get_physical_lock_status(self):
        return self.control_files.get_physical_lock_status()

    def leave_lock_in_place(self):
        """Tell this repository not to release the physical lock when this
        object is unlocked.
        
        If lock_write doesn't return a token, then this method is not supported.
        """
        self.control_files.leave_in_place()

    def dont_leave_lock_in_place(self):
        """Tell this repository to release the physical lock when this
        object is unlocked, even if it didn't originally acquire it.

        If lock_write doesn't return a token, then this method is not supported.
        """
        self.control_files.dont_leave_in_place()

    @needs_read_lock
    def gather_stats(self, revid=None, committers=None):
        """Gather statistics from a revision id.

        :param revid: The revision id to gather statistics from, if None, then
            no revision specific statistics are gathered.
        :param committers: Optional parameter controlling whether to grab
            a count of committers from the revision specific statistics.
        :return: A dictionary of statistics. Currently this contains:
            committers: The number of committers if requested.
            firstrev: A tuple with timestamp, timezone for the penultimate left
                most ancestor of revid, if revid is not the NULL_REVISION.
            latestrev: A tuple with timestamp, timezone for revid, if revid is
                not the NULL_REVISION.
            revisions: The total revision count in the repository.
            size: An estimate disk size of the repository in bytes.
        """
        result = {}
        if revid and committers:
            result['committers'] = 0
        if revid and revid != _mod_revision.NULL_REVISION:
            if committers:
                all_committers = set()
            revisions = self.get_ancestry(revid)
            # pop the leading None
            revisions.pop(0)
            first_revision = None
            if not committers:
                # ignore the revisions in the middle - just grab first and last
                revisions = revisions[0], revisions[-1]
            for revision in self.get_revisions(revisions):
                if not first_revision:
                    first_revision = revision
                if committers:
                    all_committers.add(revision.committer)
            last_revision = revision
            if committers:
                result['committers'] = len(all_committers)
            result['firstrev'] = (first_revision.timestamp,
                first_revision.timezone)
            result['latestrev'] = (last_revision.timestamp,
                last_revision.timezone)

        # now gather global repository information
        # XXX: This is available for many repos regardless of listability.
        if self.bzrdir.root_transport.listable():
            # XXX: do we want to __define len__() ?
            # Maybe the versionedfiles object should provide a different
            # method to get the number of keys.
            result['revisions'] = len(self.revisions.keys())
            # result['size'] = t
        return result

    def find_branches(self, using=False):
        """Find branches underneath this repository.

        This will include branches inside other branches.

        :param using: If True, list only branches using this repository.
        """
        if using and not self.is_shared():
            try:
                return [self.bzrdir.open_branch()]
            except errors.NotBranchError:
                return []
        class Evaluator(object):

            def __init__(self):
                self.first_call = True

            def __call__(self, bzrdir):
                # On the first call, the parameter is always the bzrdir
                # containing the current repo.
                if not self.first_call:
                    try:
                        repository = bzrdir.open_repository()
                    except errors.NoRepositoryPresent:
                        pass
                    else:
                        return False, (None, repository)
                self.first_call = False
                try:
                    value = (bzrdir.open_branch(), None)
                except errors.NotBranchError:
                    value = (None, None)
                return True, value

        branches = []
        for branch, repository in bzrdir.BzrDir.find_bzrdirs(
                self.bzrdir.root_transport, evaluate=Evaluator()):
            if branch is not None:
                branches.append(branch)
            if not using and repository is not None:
                branches.extend(repository.find_branches())
        return branches

    @needs_read_lock
    def search_missing_revision_ids(self, other, revision_id=None, find_ghosts=True):
        """Return the revision ids that other has that this does not.
        
        These are returned in topological order.

        revision_id: only return revision ids included by revision_id.
        """
        return InterRepository.get(other, self).search_missing_revision_ids(
            revision_id, find_ghosts)

    @deprecated_method(one_two)
    @needs_read_lock
    def missing_revision_ids(self, other, revision_id=None, find_ghosts=True):
        """Return the revision ids that other has that this does not.
        
        These are returned in topological order.

        revision_id: only return revision ids included by revision_id.
        """
        keys =  self.search_missing_revision_ids(
            other, revision_id, find_ghosts).get_keys()
        other.lock_read()
        try:
            parents = other.get_graph().get_parent_map(keys)
        finally:
            other.unlock()
        return tsort.topo_sort(parents)

    @staticmethod
    def open(base):
        """Open the repository rooted at base.

        For instance, if the repository is at URL/.bzr/repository,
        Repository.open(URL) -> a Repository instance.
        """
        control = bzrdir.BzrDir.open(base)
        return control.open_repository()

    def copy_content_into(self, destination, revision_id=None):
        """Make a complete copy of the content in self into destination.
        
        This is a destructive operation! Do not use it on existing 
        repositories.
        """
        return InterRepository.get(self, destination).copy_content(revision_id)

    def commit_write_group(self):
        """Commit the contents accrued within the current write group.

        :seealso: start_write_group.
        """
        if self._write_group is not self.get_transaction():
            # has an unlock or relock occured ?
            raise errors.BzrError('mismatched lock context %r and '
                'write group %r.' %
                (self.get_transaction(), self._write_group))
        self._commit_write_group()
        self._write_group = None

    def _commit_write_group(self):
        """Template method for per-repository write group cleanup.
        
        This is called before the write group is considered to be 
        finished and should ensure that all data handed to the repository
        for writing during the write group is safely committed (to the 
        extent possible considering file system caching etc).
        """

    def fetch(self, source, revision_id=None, pb=None, find_ghosts=False):
        """Fetch the content required to construct revision_id from source.

        If revision_id is None all content is copied.
        :param find_ghosts: Find and copy revisions in the source that are
            ghosts in the target (and not reachable directly by walking out to
            the first-present revision in target from revision_id).
        """
        # fast path same-url fetch operations
        if self.has_same_location(source):
            # check that last_revision is in 'from' and then return a
            # no-operation.
            if (revision_id is not None and
                not _mod_revision.is_null(revision_id)):
                self.get_revision(revision_id)
            return 0, []
        inter = InterRepository.get(source, self)
        try:
            return inter.fetch(revision_id=revision_id, pb=pb, find_ghosts=find_ghosts)
        except NotImplementedError:
            raise errors.IncompatibleRepositories(source, self)

    def create_bundle(self, target, base, fileobj, format=None):
        return serializer.write_bundle(self, target, base, fileobj, format)

    def get_commit_builder(self, branch, parents, config, timestamp=None,
                           timezone=None, committer=None, revprops=None,
                           revision_id=None):
        """Obtain a CommitBuilder for this repository.
        
        :param branch: Branch to commit to.
        :param parents: Revision ids of the parents of the new revision.
        :param config: Configuration to use.
        :param timestamp: Optional timestamp recorded for commit.
        :param timezone: Optional timezone for timestamp.
        :param committer: Optional committer to set for commit.
        :param revprops: Optional dictionary of revision properties.
        :param revision_id: Optional revision id.
        """
        result = self._commit_builder_class(self, parents, config,
            timestamp, timezone, committer, revprops, revision_id)
        self.start_write_group()
        return result

    def unlock(self):
        if (self.control_files._lock_count == 1 and
            self.control_files._lock_mode == 'w'):
            if self._write_group is not None:
                self.abort_write_group()
                self.control_files.unlock()
                raise errors.BzrError(
                    'Must end write groups before releasing write locks.')
        self.control_files.unlock()
        for repo in self._fallback_repositories:
            repo.unlock()

    @needs_read_lock
    def clone(self, a_bzrdir, revision_id=None):
        """Clone this repository into a_bzrdir using the current format.

        Currently no check is made that the format of this repository and
        the bzrdir format are compatible. FIXME RBC 20060201.

        :return: The newly created destination repository.
        """
        # TODO: deprecate after 0.16; cloning this with all its settings is
        # probably not very useful -- mbp 20070423
        dest_repo = self._create_sprouting_repo(a_bzrdir, shared=self.is_shared())
        self.copy_content_into(dest_repo, revision_id)
        return dest_repo

    def start_write_group(self):
        """Start a write group in the repository.

        Write groups are used by repositories which do not have a 1:1 mapping
        between file ids and backend store to manage the insertion of data from
        both fetch and commit operations.

        A write lock is required around the start_write_group/commit_write_group
        for the support of lock-requiring repository formats.

        One can only insert data into a repository inside a write group.

        :return: None.
        """
        if not self.is_write_locked():
            raise errors.NotWriteLocked(self)
        if self._write_group:
            raise errors.BzrError('already in a write group')
        self._start_write_group()
        # so we can detect unlock/relock - the write group is now entered.
        self._write_group = self.get_transaction()

    def _start_write_group(self):
        """Template method for per-repository write group startup.
        
        This is called before the write group is considered to be 
        entered.
        """

    @needs_read_lock
    def sprout(self, to_bzrdir, revision_id=None):
        """Create a descendent repository for new development.

        Unlike clone, this does not copy the settings of the repository.
        """
        dest_repo = self._create_sprouting_repo(to_bzrdir, shared=False)
        dest_repo.fetch(self, revision_id=revision_id)
        return dest_repo

    def _create_sprouting_repo(self, a_bzrdir, shared):
        if not isinstance(a_bzrdir._format, self.bzrdir._format.__class__):
            # use target default format.
            dest_repo = a_bzrdir.create_repository()
        else:
            # Most control formats need the repository to be specifically
            # created, but on some old all-in-one formats it's not needed
            try:
                dest_repo = self._format.initialize(a_bzrdir, shared=shared)
            except errors.UninitializableFormat:
                dest_repo = a_bzrdir.open_repository()
        return dest_repo

    @needs_read_lock
    def has_revision(self, revision_id):
        """True if this repository has a copy of the revision."""
        return revision_id in self.has_revisions((revision_id,))

    @needs_read_lock
    def has_revisions(self, revision_ids):
        """Probe to find out the presence of multiple revisions.

        :param revision_ids: An iterable of revision_ids.
        :return: A set of the revision_ids that were present.
        """
        parent_map = self.revisions.get_parent_map(
            [(rev_id,) for rev_id in revision_ids])
        result = set()
        if _mod_revision.NULL_REVISION in revision_ids:
            result.add(_mod_revision.NULL_REVISION)
        result.update([key[0] for key in parent_map])
        return result

    @needs_read_lock
    def get_revision(self, revision_id):
        """Return the Revision object for a named revision."""
        return self.get_revisions([revision_id])[0]

    @needs_read_lock
    def get_revision_reconcile(self, revision_id):
        """'reconcile' helper routine that allows access to a revision always.
        
        This variant of get_revision does not cross check the weave graph
        against the revision one as get_revision does: but it should only
        be used by reconcile, or reconcile-alike commands that are correcting
        or testing the revision graph.
        """
        return self._get_revisions([revision_id])[0]

    @needs_read_lock
    def get_revisions(self, revision_ids):
        """Get many revisions at once."""
        return self._get_revisions(revision_ids)

    @needs_read_lock
    def _get_revisions(self, revision_ids):
        """Core work logic to get many revisions without sanity checks."""
        for rev_id in revision_ids:
            if not rev_id or not isinstance(rev_id, basestring):
                raise errors.InvalidRevisionId(revision_id=rev_id, branch=self)
        keys = [(key,) for key in revision_ids]
        stream = self.revisions.get_record_stream(keys, 'unordered', True)
        revs = {}
        for record in stream:
            if record.storage_kind == 'absent':
                raise errors.NoSuchRevision(self, record.key[0])
            text = record.get_bytes_as('fulltext')
            rev = self._serializer.read_revision_from_string(text)
            revs[record.key[0]] = rev
        return [revs[revid] for revid in revision_ids]

    @needs_read_lock
    def get_revision_xml(self, revision_id):
        # TODO: jam 20070210 This shouldn't be necessary since get_revision
        #       would have already do it.
        # TODO: jam 20070210 Just use _serializer.write_revision_to_string()
        rev = self.get_revision(revision_id)
        rev_tmp = StringIO()
        # the current serializer..
        self._serializer.write_revision(rev, rev_tmp)
        rev_tmp.seek(0)
        return rev_tmp.getvalue()

    def get_deltas_for_revisions(self, revisions):
        """Produce a generator of revision deltas.
        
        Note that the input is a sequence of REVISIONS, not revision_ids.
        Trees will be held in memory until the generator exits.
        Each delta is relative to the revision's lefthand predecessor.
        """
        required_trees = set()
        for revision in revisions:
            required_trees.add(revision.revision_id)
            required_trees.update(revision.parent_ids[:1])
        trees = dict((t.get_revision_id(), t) for 
                     t in self.revision_trees(required_trees))
        for revision in revisions:
            if not revision.parent_ids:
                old_tree = self.revision_tree(None)
            else:
                old_tree = trees[revision.parent_ids[0]]
            yield trees[revision.revision_id].changes_from(old_tree)

    @needs_read_lock
    def get_revision_delta(self, revision_id):
        """Return the delta for one revision.

        The delta is relative to the left-hand predecessor of the
        revision.
        """
        r = self.get_revision(revision_id)
        return list(self.get_deltas_for_revisions([r]))[0]

    @needs_write_lock
    def store_revision_signature(self, gpg_strategy, plaintext, revision_id):
        signature = gpg_strategy.sign(plaintext)
        self.add_signature_text(revision_id, signature)

    @needs_write_lock
    def add_signature_text(self, revision_id, signature):
        self.signatures.add_lines((revision_id,), (),
            osutils.split_lines(signature))

    def find_text_key_references(self):
        """Find the text key references within the repository.

        :return: a dictionary mapping (file_id, revision_id) tuples to altered file-ids to an iterable of
        revision_ids. Each altered file-ids has the exact revision_ids that
        altered it listed explicitly.
        :return: A dictionary mapping text keys ((fileid, revision_id) tuples)
            to whether they were referred to by the inventory of the
            revision_id that they contain. The inventory texts from all present
            revision ids are assessed to generate this report.
        """
        revision_keys = self.revisions.keys()
        w = self.inventories
        pb = ui.ui_factory.nested_progress_bar()
        try:
            return self._find_text_key_references_from_xml_inventory_lines(
                w.iter_lines_added_or_present_in_keys(revision_keys, pb=pb))
        finally:
            pb.finished()

    def _find_text_key_references_from_xml_inventory_lines(self,
        line_iterator):
        """Core routine for extracting references to texts from inventories.

        This performs the translation of xml lines to revision ids.

        :param line_iterator: An iterator of lines, origin_version_id
        :return: A dictionary mapping text keys ((fileid, revision_id) tuples)
            to whether they were referred to by the inventory of the
            revision_id that they contain. Note that if that revision_id was
            not part of the line_iterator's output then False will be given -
            even though it may actually refer to that key.
        """
        if not self._serializer.support_altered_by_hack:
            raise AssertionError(
                "_find_text_key_references_from_xml_inventory_lines only "
                "supported for branches which store inventory as unnested xml"
                ", not on %r" % self)
        result = {}

        # this code needs to read every new line in every inventory for the
        # inventories [revision_ids]. Seeing a line twice is ok. Seeing a line
        # not present in one of those inventories is unnecessary but not 
        # harmful because we are filtering by the revision id marker in the
        # inventory lines : we only select file ids altered in one of those  
        # revisions. We don't need to see all lines in the inventory because
        # only those added in an inventory in rev X can contain a revision=X
        # line.
        unescape_revid_cache = {}
        unescape_fileid_cache = {}

        # jam 20061218 In a big fetch, this handles hundreds of thousands
        # of lines, so it has had a lot of inlining and optimizing done.
        # Sorry that it is a little bit messy.
        # Move several functions to be local variables, since this is a long
        # running loop.
        search = self._file_ids_altered_regex.search
        unescape = _unescape_xml
        setdefault = result.setdefault
        for line, line_key in line_iterator:
            match = search(line)
            if match is None:
                continue
            # One call to match.group() returning multiple items is quite a
            # bit faster than 2 calls to match.group() each returning 1
            file_id, revision_id = match.group('file_id', 'revision_id')

            # Inlining the cache lookups helps a lot when you make 170,000
            # lines and 350k ids, versus 8.4 unique ids.
            # Using a cache helps in 2 ways:
            #   1) Avoids unnecessary decoding calls
            #   2) Re-uses cached strings, which helps in future set and
            #      equality checks.
            # (2) is enough that removing encoding entirely along with
            # the cache (so we are using plain strings) results in no
            # performance improvement.
            try:
                revision_id = unescape_revid_cache[revision_id]
            except KeyError:
                unescaped = unescape(revision_id)
                unescape_revid_cache[revision_id] = unescaped
                revision_id = unescaped

            # Note that unconditionally unescaping means that we deserialise
            # every fileid, which for general 'pull' is not great, but we don't
            # really want to have some many fulltexts that this matters anyway.
            # RBC 20071114.
            try:
                file_id = unescape_fileid_cache[file_id]
            except KeyError:
                unescaped = unescape(file_id)
                unescape_fileid_cache[file_id] = unescaped
                file_id = unescaped

            key = (file_id, revision_id)
            setdefault(key, False)
            if revision_id == line_key[-1]:
                result[key] = True
        return result

    def _find_file_ids_from_xml_inventory_lines(self, line_iterator,
        revision_ids):
        """Helper routine for fileids_altered_by_revision_ids.

        This performs the translation of xml lines to revision ids.

        :param line_iterator: An iterator of lines, origin_version_id
        :param revision_ids: The revision ids to filter for. This should be a
            set or other type which supports efficient __contains__ lookups, as
            the revision id from each parsed line will be looked up in the
            revision_ids filter.
        :return: a dictionary mapping altered file-ids to an iterable of
        revision_ids. Each altered file-ids has the exact revision_ids that
        altered it listed explicitly.
        """
        result = {}
        setdefault = result.setdefault
        for key in \
            self._find_text_key_references_from_xml_inventory_lines(
                line_iterator).iterkeys():
            # once data is all ensured-consistent; then this is
            # if revision_id == version_id
            if key[-1:] in revision_ids:
                setdefault(key[0], set()).add(key[-1])
        return result

    def fileids_altered_by_revision_ids(self, revision_ids, _inv_weave=None):
        """Find the file ids and versions affected by revisions.

        :param revisions: an iterable containing revision ids.
        :param _inv_weave: The inventory weave from this repository or None.
            If None, the inventory weave will be opened automatically.
        :return: a dictionary mapping altered file-ids to an iterable of
        revision_ids. Each altered file-ids has the exact revision_ids that
        altered it listed explicitly.
        """
        selected_keys = set((revid,) for revid in revision_ids)
        w = _inv_weave or self.inventories
        pb = ui.ui_factory.nested_progress_bar()
        try:
            return self._find_file_ids_from_xml_inventory_lines(
                w.iter_lines_added_or_present_in_keys(
                    selected_keys, pb=pb),
                selected_keys)
        finally:
            pb.finished()

    def iter_files_bytes(self, desired_files):
        """Iterate through file versions.

        Files will not necessarily be returned in the order they occur in
        desired_files.  No specific order is guaranteed.

        Yields pairs of identifier, bytes_iterator.  identifier is an opaque
        value supplied by the caller as part of desired_files.  It should
        uniquely identify the file version in the caller's context.  (Examples:
        an index number or a TreeTransform trans_id.)

        bytes_iterator is an iterable of bytestrings for the file.  The
        kind of iterable and length of the bytestrings are unspecified, but for
        this implementation, it is a list of bytes produced by
        VersionedFile.get_record_stream().

        :param desired_files: a list of (file_id, revision_id, identifier)
            triples
        """
        transaction = self.get_transaction()
        text_keys = {}
        for file_id, revision_id, callable_data in desired_files:
            text_keys[(file_id, revision_id)] = callable_data
        for record in self.texts.get_record_stream(text_keys, 'unordered', True):
            if record.storage_kind == 'absent':
                raise errors.RevisionNotPresent(record.key, self)
            yield text_keys[record.key], record.get_bytes_as('fulltext')

    def _generate_text_key_index(self, text_key_references=None,
        ancestors=None):
        """Generate a new text key index for the repository.

        This is an expensive function that will take considerable time to run.

        :return: A dict mapping text keys ((file_id, revision_id) tuples) to a
            list of parents, also text keys. When a given key has no parents,
            the parents list will be [NULL_REVISION].
        """
        # All revisions, to find inventory parents.
        if ancestors is None:
            graph = self.get_graph()
            ancestors = graph.get_parent_map(self.all_revision_ids())
        if text_key_references is None:
            text_key_references = self.find_text_key_references()
        pb = ui.ui_factory.nested_progress_bar()
        try:
            return self._do_generate_text_key_index(ancestors,
                text_key_references, pb)
        finally:
            pb.finished()

    def _do_generate_text_key_index(self, ancestors, text_key_references, pb):
        """Helper for _generate_text_key_index to avoid deep nesting."""
        revision_order = tsort.topo_sort(ancestors)
        invalid_keys = set()
        revision_keys = {}
        for revision_id in revision_order:
            revision_keys[revision_id] = set()
        text_count = len(text_key_references)
        # a cache of the text keys to allow reuse; costs a dict of all the
        # keys, but saves a 2-tuple for every child of a given key.
        text_key_cache = {}
        for text_key, valid in text_key_references.iteritems():
            if not valid:
                invalid_keys.add(text_key)
            else:
                revision_keys[text_key[1]].add(text_key)
            text_key_cache[text_key] = text_key
        del text_key_references
        text_index = {}
        text_graph = graph.Graph(graph.DictParentsProvider(text_index))
        NULL_REVISION = _mod_revision.NULL_REVISION
        # Set a cache with a size of 10 - this suffices for bzr.dev but may be
        # too small for large or very branchy trees. However, for 55K path
        # trees, it would be easy to use too much memory trivially. Ideally we
        # could gauge this by looking at available real memory etc, but this is
        # always a tricky proposition.
        inventory_cache = lru_cache.LRUCache(10)
        batch_size = 10 # should be ~150MB on a 55K path tree
        batch_count = len(revision_order) / batch_size + 1
        processed_texts = 0
        pb.update("Calculating text parents.", processed_texts, text_count)
        for offset in xrange(batch_count):
            to_query = revision_order[offset * batch_size:(offset + 1) *
                batch_size]
            if not to_query:
                break
            for rev_tree in self.revision_trees(to_query):
                revision_id = rev_tree.get_revision_id()
                parent_ids = ancestors[revision_id]
                for text_key in revision_keys[revision_id]:
                    pb.update("Calculating text parents.", processed_texts)
                    processed_texts += 1
                    candidate_parents = []
                    for parent_id in parent_ids:
                        parent_text_key = (text_key[0], parent_id)
                        try:
                            check_parent = parent_text_key not in \
                                revision_keys[parent_id]
                        except KeyError:
                            # the parent parent_id is a ghost:
                            check_parent = False
                            # truncate the derived graph against this ghost.
                            parent_text_key = None
                        if check_parent:
                            # look at the parent commit details inventories to
                            # determine possible candidates in the per file graph.
                            # TODO: cache here.
                            try:
                                inv = inventory_cache[parent_id]
                            except KeyError:
                                inv = self.revision_tree(parent_id).inventory
                                inventory_cache[parent_id] = inv
                            parent_entry = inv._byid.get(text_key[0], None)
                            if parent_entry is not None:
                                parent_text_key = (
                                    text_key[0], parent_entry.revision)
                            else:
                                parent_text_key = None
                        if parent_text_key is not None:
                            candidate_parents.append(
                                text_key_cache[parent_text_key])
                    parent_heads = text_graph.heads(candidate_parents)
                    new_parents = list(parent_heads)
                    new_parents.sort(key=lambda x:candidate_parents.index(x))
                    if new_parents == []:
                        new_parents = [NULL_REVISION]
                    text_index[text_key] = new_parents

        for text_key in invalid_keys:
            text_index[text_key] = [NULL_REVISION]
        return text_index

    def item_keys_introduced_by(self, revision_ids, _files_pb=None):
        """Get an iterable listing the keys of all the data introduced by a set
        of revision IDs.

        The keys will be ordered so that the corresponding items can be safely
        fetched and inserted in that order.

        :returns: An iterable producing tuples of (knit-kind, file-id,
            versions).  knit-kind is one of 'file', 'inventory', 'signatures',
            'revisions'.  file-id is None unless knit-kind is 'file'.
        """
        # XXX: it's a bit weird to control the inventory weave caching in this
        # generator.  Ideally the caching would be done in fetch.py I think.  Or
        # maybe this generator should explicitly have the contract that it
        # should not be iterated until the previously yielded item has been
        # processed?
        inv_w = self.inventories

        # file ids that changed
        file_ids = self.fileids_altered_by_revision_ids(revision_ids, inv_w)
        count = 0
        num_file_ids = len(file_ids)
        for file_id, altered_versions in file_ids.iteritems():
            if _files_pb is not None:
                _files_pb.update("fetch texts", count, num_file_ids)
            count += 1
            yield ("file", file_id, altered_versions)
        # We're done with the files_pb.  Note that it finished by the caller,
        # just as it was created by the caller.
        del _files_pb

        # inventory
        yield ("inventory", None, revision_ids)

        # signatures
        revisions_with_signatures = set()
        for rev_id in revision_ids:
            try:
                self.get_signature_text(rev_id)
            except errors.NoSuchRevision:
                # not signed.
                pass
            else:
                revisions_with_signatures.add(rev_id)
        yield ("signatures", None, revisions_with_signatures)

        # revisions
        yield ("revisions", None, revision_ids)

    @needs_read_lock
    def get_inventory(self, revision_id):
        """Get Inventory object by revision id."""
        return self.iter_inventories([revision_id]).next()

    def iter_inventories(self, revision_ids):
        """Get many inventories by revision_ids.

        This will buffer some or all of the texts used in constructing the
        inventories in memory, but will only parse a single inventory at a
        time.

        :return: An iterator of inventories.
        """
        if ((None in revision_ids)
            or (_mod_revision.NULL_REVISION in revision_ids)):
            raise ValueError('cannot get null revision inventory')
        return self._iter_inventories(revision_ids)

    def _iter_inventories(self, revision_ids):
        """single-document based inventory iteration."""
        for text, revision_id in self._iter_inventory_xmls(revision_ids):
            yield self.deserialise_inventory(revision_id, text)

    def _iter_inventory_xmls(self, revision_ids):
        keys = [(revision_id,) for revision_id in revision_ids]
        stream = self.inventories.get_record_stream(keys, 'unordered', True)
        texts = {}
        for record in stream:
            if record.storage_kind != 'absent':
                texts[record.key] = record.get_bytes_as('fulltext')
            else:
                raise errors.NoSuchRevision(self, record.key)
        for key in keys:
            yield texts[key], key[-1]

    def deserialise_inventory(self, revision_id, xml):
        """Transform the xml into an inventory object. 

        :param revision_id: The expected revision id of the inventory.
        :param xml: A serialised inventory.
        """
        result = self._serializer.read_inventory_from_string(xml, revision_id)
        if result.revision_id != revision_id:
            raise AssertionError('revision id mismatch %s != %s' % (
                result.revision_id, revision_id))
        return result

    def serialise_inventory(self, inv):
        return self._serializer.write_inventory_to_string(inv)

    def _serialise_inventory_to_lines(self, inv):
        return self._serializer.write_inventory_to_lines(inv)

    def get_serializer_format(self):
        return self._serializer.format_num

    @needs_read_lock
    def get_inventory_xml(self, revision_id):
        """Get inventory XML as a file object."""
        texts = self._iter_inventory_xmls([revision_id])
        try:
            text, revision_id = texts.next()
        except StopIteration:
            raise errors.HistoryMissing(self, 'inventory', revision_id)
        return text

    @needs_read_lock
    def get_inventory_sha1(self, revision_id):
        """Return the sha1 hash of the inventory entry
        """
        return self.get_revision(revision_id).inventory_sha1

    def iter_reverse_revision_history(self, revision_id):
        """Iterate backwards through revision ids in the lefthand history

        :param revision_id: The revision id to start with.  All its lefthand
            ancestors will be traversed.
        """
        graph = self.get_graph()
        next_id = revision_id
        while True:
            if next_id in (None, _mod_revision.NULL_REVISION):
                return
            yield next_id
            # Note: The following line may raise KeyError in the event of
            # truncated history. We decided not to have a try:except:raise
            # RevisionNotPresent here until we see a use for it, because of the
            # cost in an inner loop that is by its very nature O(history).
            # Robert Collins 20080326
            parents = graph.get_parent_map([next_id])[next_id]
            if len(parents) == 0:
                return
            else:
                next_id = parents[0]

    @needs_read_lock
    def get_revision_inventory(self, revision_id):
        """Return inventory of a past revision."""
        # TODO: Unify this with get_inventory()
        # bzr 0.0.6 and later imposes the constraint that the inventory_id
        # must be the same as its revision, so this is trivial.
        if revision_id is None:
            # This does not make sense: if there is no revision,
            # then it is the current tree inventory surely ?!
            # and thus get_root_id() is something that looks at the last
            # commit on the branch, and the get_root_id is an inventory check.
            raise NotImplementedError
            # return Inventory(self.get_root_id())
        else:
            return self.get_inventory(revision_id)

    @needs_read_lock
    def is_shared(self):
        """Return True if this repository is flagged as a shared repository."""
        raise NotImplementedError(self.is_shared)

    @needs_write_lock
    def reconcile(self, other=None, thorough=False):
        """Reconcile this repository."""
        from bzrlib.reconcile import RepoReconciler
        reconciler = RepoReconciler(self, thorough=thorough)
        reconciler.reconcile()
        return reconciler

    def _refresh_data(self):
        """Helper called from lock_* to ensure coherency with disk.

        The default implementation does nothing; it is however possible
        for repositories to maintain loaded indices across multiple locks
        by checking inside their implementation of this method to see
        whether their indices are still valid. This depends of course on
        the disk format being validatable in this manner.
        """

    @needs_read_lock
    def revision_tree(self, revision_id):
        """Return Tree for a revision on this branch.

        `revision_id` may be None for the empty tree revision.
        """
        # TODO: refactor this to use an existing revision object
        # so we don't need to read it in twice.
        if revision_id is None or revision_id == _mod_revision.NULL_REVISION:
            return RevisionTree(self, Inventory(root_id=None), 
                                _mod_revision.NULL_REVISION)
        else:
            inv = self.get_revision_inventory(revision_id)
            return RevisionTree(self, inv, revision_id)

    def revision_trees(self, revision_ids):
        """Return Tree for a revision on this branch.

        `revision_id` may not be None or 'null:'"""
        inventories = self.iter_inventories(revision_ids)
        for inv in inventories:
            yield RevisionTree(self, inv, inv.revision_id)

    @needs_read_lock
    def get_ancestry(self, revision_id, topo_sorted=True):
        """Return a list of revision-ids integrated by a revision.

        The first element of the list is always None, indicating the origin 
        revision.  This might change when we have history horizons, or 
        perhaps we should have a new API.
        
        This is topologically sorted.
        """
        if _mod_revision.is_null(revision_id):
            return [None]
        if not self.has_revision(revision_id):
            raise errors.NoSuchRevision(self, revision_id)
        graph = self.get_graph()
        keys = set()
        search = graph._make_breadth_first_searcher([revision_id])
        while True:
            try:
                found, ghosts = search.next_with_ghosts()
            except StopIteration:
                break
            keys.update(found)
        if _mod_revision.NULL_REVISION in keys:
            keys.remove(_mod_revision.NULL_REVISION)
        if topo_sorted:
            parent_map = graph.get_parent_map(keys)
            keys = tsort.topo_sort(parent_map)
        return [None] + list(keys)

    def pack(self):
        """Compress the data within the repository.

        This operation only makes sense for some repository types. For other
        types it should be a no-op that just returns.

        This stub method does not require a lock, but subclasses should use
        @needs_write_lock as this is a long running call its reasonable to 
        implicitly lock for the user.
        """

    @needs_read_lock
    @deprecated_method(one_six)
    def print_file(self, file, revision_id):
        """Print `file` to stdout.
        
        FIXME RBC 20060125 as John Meinel points out this is a bad api
        - it writes to stdout, it assumes that that is valid etc. Fix
        by creating a new more flexible convenience function.
        """
        tree = self.revision_tree(revision_id)
        # use inventory as it was in that revision
        file_id = tree.inventory.path2id(file)
        if not file_id:
            # TODO: jam 20060427 Write a test for this code path
            #       it had a bug in it, and was raising the wrong
            #       exception.
            raise errors.BzrError("%r is not present in revision %s" % (file, revision_id))
        tree.print_file(file_id)

    def get_transaction(self):
        return self.control_files.get_transaction()

    @deprecated_method(one_one)
    def get_parents(self, revision_ids):
        """See StackedParentsProvider.get_parents"""
        parent_map = self.get_parent_map(revision_ids)
        return [parent_map.get(r, None) for r in revision_ids]

    def get_parent_map(self, revision_ids):
        """See graph._StackedParentsProvider.get_parent_map"""
        # revisions index works in keys; this just works in revisions
        # therefore wrap and unwrap
        query_keys = []
        result = {}
        for revision_id in revision_ids:
            if revision_id == _mod_revision.NULL_REVISION:
                result[revision_id] = ()
            elif revision_id is None:
                raise ValueError('get_parent_map(None) is not valid')
            else:
                query_keys.append((revision_id ,))
        for ((revision_id,), parent_keys) in \
                self.revisions.get_parent_map(query_keys).iteritems():
            if parent_keys:
                result[revision_id] = tuple(parent_revid
                    for (parent_revid,) in parent_keys)
            else:
                result[revision_id] = (_mod_revision.NULL_REVISION,)
        return result

    def _make_parents_provider(self):
        return self

    def get_graph(self, other_repository=None):
        """Return the graph walker for this repository format"""
        parents_provider = self._make_parents_provider()
        if (other_repository is not None and
            not self.has_same_location(other_repository)):
            parents_provider = graph._StackedParentsProvider(
                [parents_provider, other_repository._make_parents_provider()])
        return graph.Graph(parents_provider)

    def _get_versioned_file_checker(self):
        """Return an object suitable for checking versioned files."""
        return _VersionedFileChecker(self)

    def revision_ids_to_search_result(self, result_set):
        """Convert a set of revision ids to a graph SearchResult."""
        result_parents = set()
        for parents in self.get_graph().get_parent_map(
            result_set).itervalues():
            result_parents.update(parents)
        included_keys = result_set.intersection(result_parents)
        start_keys = result_set.difference(included_keys)
        exclude_keys = result_parents.difference(result_set)
        result = graph.SearchResult(start_keys, exclude_keys,
            len(result_set), result_set)
        return result

    @needs_write_lock
    def set_make_working_trees(self, new_value):
        """Set the policy flag for making working trees when creating branches.

        This only applies to branches that use this repository.

        The default is 'True'.
        :param new_value: True to restore the default, False to disable making
                          working trees.
        """
        raise NotImplementedError(self.set_make_working_trees)
    
    def make_working_trees(self):
        """Returns the policy for making working trees on new branches."""
        raise NotImplementedError(self.make_working_trees)

    @needs_write_lock
    def sign_revision(self, revision_id, gpg_strategy):
        plaintext = Testament.from_revision(self, revision_id).as_short_text()
        self.store_revision_signature(gpg_strategy, plaintext, revision_id)

    @needs_read_lock
    def has_signature_for_revision_id(self, revision_id):
        """Query for a revision signature for revision_id in the repository."""
        if not self.has_revision(revision_id):
            raise errors.NoSuchRevision(self, revision_id)
        sig_present = (1 == len(
            self.signatures.get_parent_map([(revision_id,)])))
        return sig_present

    @needs_read_lock
    def get_signature_text(self, revision_id):
        """Return the text for a signature."""
        stream = self.signatures.get_record_stream([(revision_id,)],
            'unordered', True)
        record = stream.next()
        if record.storage_kind == 'absent':
            raise errors.NoSuchRevision(self, revision_id)
        return record.get_bytes_as('fulltext')

    @needs_read_lock
    def check(self, revision_ids=None):
        """Check consistency of all history of given revision_ids.

        Different repository implementations should override _check().

        :param revision_ids: A non-empty list of revision_ids whose ancestry
             will be checked.  Typically the last revision_id of a branch.
        """
        return self._check(revision_ids)

    def _check(self, revision_ids):
        result = check.Check(self)
        result.check()
        return result

    def _warn_if_deprecated(self):
        global _deprecation_warning_done
        if _deprecation_warning_done:
            return
        _deprecation_warning_done = True
        warning("Format %s for %s is deprecated - please use 'bzr upgrade' to get better performance"
                % (self._format, self.bzrdir.transport.base))

    def supports_rich_root(self):
        return self._format.rich_root_data

    def _check_ascii_revisionid(self, revision_id, method):
        """Private helper for ascii-only repositories."""
        # weave repositories refuse to store revisionids that are non-ascii.
        if revision_id is not None:
            # weaves require ascii revision ids.
            if isinstance(revision_id, unicode):
                try:
                    revision_id.encode('ascii')
                except UnicodeEncodeError:
                    raise errors.NonAsciiRevisionId(method, self)
            else:
                try:
                    revision_id.decode('ascii')
                except UnicodeDecodeError:
                    raise errors.NonAsciiRevisionId(method, self)
    
    def revision_graph_can_have_wrong_parents(self):
        """Is it possible for this repository to have a revision graph with
        incorrect parents?

        If True, then this repository must also implement
        _find_inconsistent_revision_parents so that check and reconcile can
        check for inconsistencies before proceeding with other checks that may
        depend on the revision index being consistent.
        """
        raise NotImplementedError(self.revision_graph_can_have_wrong_parents)


# remove these delegates a while after bzr 0.15
def __make_delegated(name, from_module):
    def _deprecated_repository_forwarder():
        symbol_versioning.warn('%s moved to %s in bzr 0.15'
            % (name, from_module),
            DeprecationWarning,
            stacklevel=2)
        m = __import__(from_module, globals(), locals(), [name])
        try:
            return getattr(m, name)
        except AttributeError:
            raise AttributeError('module %s has no name %s'
                    % (m, name))
    globals()[name] = _deprecated_repository_forwarder

for _name in [
        'AllInOneRepository',
        'WeaveMetaDirRepository',
        'PreSplitOutRepositoryFormat',
        'RepositoryFormat4',
        'RepositoryFormat5',
        'RepositoryFormat6',
        'RepositoryFormat7',
        ]:
    __make_delegated(_name, 'bzrlib.repofmt.weaverepo')

for _name in [
        'KnitRepository',
        'RepositoryFormatKnit',
        'RepositoryFormatKnit1',
        ]:
    __make_delegated(_name, 'bzrlib.repofmt.knitrepo')


def install_revision(repository, rev, revision_tree):
    """Install all revision data into a repository."""
    install_revisions(repository, [(rev, revision_tree, None)])


def install_revisions(repository, iterable, num_revisions=None, pb=None):
    """Install all revision data into a repository.

    Accepts an iterable of revision, tree, signature tuples.  The signature
    may be None.
    """
    repository.start_write_group()
    try:
        for n, (revision, revision_tree, signature) in enumerate(iterable):
            _install_revision(repository, revision, revision_tree, signature)
            if pb is not None:
                pb.update('Transferring revisions', n + 1, num_revisions)
    except:
        repository.abort_write_group()
        raise
    else:
        repository.commit_write_group()


def _install_revision(repository, rev, revision_tree, signature):
    """Install all revision data into a repository."""
    present_parents = []
    parent_trees = {}
    for p_id in rev.parent_ids:
        if repository.has_revision(p_id):
            present_parents.append(p_id)
            parent_trees[p_id] = repository.revision_tree(p_id)
        else:
            parent_trees[p_id] = repository.revision_tree(None)

    inv = revision_tree.inventory
    entries = inv.iter_entries()
    # backwards compatibility hack: skip the root id.
    if not repository.supports_rich_root():
        path, root = entries.next()
        if root.revision != rev.revision_id:
            raise errors.IncompatibleRevision(repr(repository))
    text_keys = {}
    for path, ie in entries:
        text_keys[(ie.file_id, ie.revision)] = ie
    text_parent_map = repository.texts.get_parent_map(text_keys)
    missing_texts = set(text_keys) - set(text_parent_map)
    # Add the texts that are not already present
    for text_key in missing_texts:
        ie = text_keys[text_key]
        text_parents = []
        # FIXME: TODO: The following loop overlaps/duplicates that done by
        # commit to determine parents. There is a latent/real bug here where
        # the parents inserted are not those commit would do - in particular
        # they are not filtered by heads(). RBC, AB
        for revision, tree in parent_trees.iteritems():
            if ie.file_id not in tree:
                continue
            parent_id = tree.inventory[ie.file_id].revision
            if parent_id in text_parents:
                continue
            text_parents.append((ie.file_id, parent_id))
        lines = revision_tree.get_file(ie.file_id).readlines()
        repository.texts.add_lines(text_key, text_parents, lines)
    try:
        # install the inventory
        repository.add_inventory(rev.revision_id, inv, present_parents)
    except errors.RevisionAlreadyPresent:
        pass
    if signature is not None:
        repository.add_signature_text(rev.revision_id, signature)
    repository.add_revision(rev.revision_id, rev, inv)


class MetaDirRepository(Repository):
    """Repositories in the new meta-dir layout.
    
    :ivar _transport: Transport for access to repository control files,
        typically pointing to .bzr/repository.
    """

    def __init__(self, _format, a_bzrdir, control_files):
        super(MetaDirRepository, self).__init__(_format, a_bzrdir, control_files)
        self._transport = control_files._transport

    @needs_read_lock
    def is_shared(self):
        """Return True if this repository is flagged as a shared repository."""
        return self._transport.has('shared-storage')

    @needs_write_lock
    def set_make_working_trees(self, new_value):
        """Set the policy flag for making working trees when creating branches.

        This only applies to branches that use this repository.

        The default is 'True'.
        :param new_value: True to restore the default, False to disable making
                          working trees.
        """
        if new_value:
            try:
                self._transport.delete('no-working-trees')
            except errors.NoSuchFile:
                pass
        else:
            self._transport.put_bytes('no-working-trees', '',
                mode=self.bzrdir._get_file_mode())
    
    def make_working_trees(self):
        """Returns the policy for making working trees on new branches."""
        return not self._transport.has('no-working-trees')


class MetaDirVersionedFileRepository(MetaDirRepository):
    """Repositories in a meta-dir, that work via versioned file objects."""

    def __init__(self, _format, a_bzrdir, control_files):
        super(MetaDirVersionedFileRepository, self).__init__(_format, a_bzrdir,
            control_files)


class RepositoryFormatRegistry(registry.Registry):
    """Registry of RepositoryFormats."""

    def get(self, format_string):
        r = registry.Registry.get(self, format_string)
        if callable(r):
            r = r()
        return r
    

format_registry = RepositoryFormatRegistry()
"""Registry of formats, indexed by their identifying format string.

This can contain either format instances themselves, or classes/factories that
can be called to obtain one.
"""


#####################################################################
# Repository Formats

class RepositoryFormat(object):
    """A repository format.

    Formats provide three things:
     * An initialization routine to construct repository data on disk.
     * a format string which is used when the BzrDir supports versioned
       children.
     * an open routine which returns a Repository instance.

    There is one and only one Format subclass for each on-disk format. But
    there can be one Repository subclass that is used for several different
    formats. The _format attribute on a Repository instance can be used to
    determine the disk format.

    Formats are placed in an dict by their format string for reference 
    during opening. These should be subclasses of RepositoryFormat
    for consistency.

    Once a format is deprecated, just deprecate the initialize and open
    methods on the format class. Do not deprecate the object, as the 
    object will be created every system load.

    Common instance attributes:
    _matchingbzrdir - the bzrdir format that the repository format was
    originally written to work with. This can be used if manually
    constructing a bzrdir and repository, or more commonly for test suite
    parameterization.
    """

    # Set to True or False in derived classes. True indicates that the format
    # supports ghosts gracefully.
    supports_ghosts = None
    # Can this repository be given external locations to lookup additional
    # data. Set to True or False in derived classes.
    supports_external_lookups = None

    def __str__(self):
        return "<%s>" % self.__class__.__name__

    def __eq__(self, other):
        # format objects are generally stateless
        return isinstance(other, self.__class__)

    def __ne__(self, other):
        return not self == other

    @classmethod
    def find_format(klass, a_bzrdir):
        """Return the format for the repository object in a_bzrdir.
        
        This is used by bzr native formats that have a "format" file in
        the repository.  Other methods may be used by different types of 
        control directory.
        """
        try:
            transport = a_bzrdir.get_repository_transport(None)
            format_string = transport.get("format").read()
            return format_registry.get(format_string)
        except errors.NoSuchFile:
            raise errors.NoRepositoryPresent(a_bzrdir)
        except KeyError:
            raise errors.UnknownFormatError(format=format_string,
                                            kind='repository')

    @classmethod
    def register_format(klass, format):
        format_registry.register(format.get_format_string(), format)

    @classmethod
    def unregister_format(klass, format):
        format_registry.remove(format.get_format_string())
    
    @classmethod
    def get_default_format(klass):
        """Return the current default format."""
        from bzrlib import bzrdir
        return bzrdir.format_registry.make_bzrdir('default').repository_format

    def get_format_string(self):
        """Return the ASCII format string that identifies this format.
        
        Note that in pre format ?? repositories the format string is 
        not permitted nor written to disk.
        """
        raise NotImplementedError(self.get_format_string)

    def get_format_description(self):
        """Return the short description for this format."""
        raise NotImplementedError(self.get_format_description)

    # TODO: this shouldn't be in the base class, it's specific to things that
    # use weaves or knits -- mbp 20070207
    def _get_versioned_file_store(self,
                                  name,
                                  transport,
                                  control_files,
                                  prefixed=True,
                                  versionedfile_class=None,
                                  versionedfile_kwargs={},
                                  escaped=False):
        if versionedfile_class is None:
            versionedfile_class = self._versionedfile_class
        weave_transport = control_files._transport.clone(name)
        dir_mode = control_files._dir_mode
        file_mode = control_files._file_mode
        return VersionedFileStore(weave_transport, prefixed=prefixed,
                                  dir_mode=dir_mode,
                                  file_mode=file_mode,
                                  versionedfile_class=versionedfile_class,
                                  versionedfile_kwargs=versionedfile_kwargs,
                                  escaped=escaped)

    def initialize(self, a_bzrdir, shared=False):
        """Initialize a repository of this format in a_bzrdir.

        :param a_bzrdir: The bzrdir to put the new repository in it.
        :param shared: The repository should be initialized as a sharable one.
        :returns: The new repository object.
        
        This may raise UninitializableFormat if shared repository are not
        compatible the a_bzrdir.
        """
        raise NotImplementedError(self.initialize)

    def is_supported(self):
        """Is this format supported?

        Supported formats must be initializable and openable.
        Unsupported formats may not support initialization or committing or 
        some other features depending on the reason for not being supported.
        """
        return True

    def check_conversion_target(self, target_format):
        raise NotImplementedError(self.check_conversion_target)

    def open(self, a_bzrdir, _found=False):
        """Return an instance of this format for the bzrdir a_bzrdir.
        
        _found is a private parameter, do not use it.
        """
        raise NotImplementedError(self.open)


class MetaDirRepositoryFormat(RepositoryFormat):
    """Common base class for the new repositories using the metadir layout."""

    rich_root_data = False
    supports_tree_reference = False
    supports_external_lookups = False
    _matchingbzrdir = bzrdir.BzrDirMetaFormat1()

    def __init__(self):
        super(MetaDirRepositoryFormat, self).__init__()

    def _create_control_files(self, a_bzrdir):
        """Create the required files and the initial control_files object."""
        # FIXME: RBC 20060125 don't peek under the covers
        # NB: no need to escape relative paths that are url safe.
        repository_transport = a_bzrdir.get_repository_transport(self)
        control_files = lockable_files.LockableFiles(repository_transport,
                                'lock', lockdir.LockDir)
        control_files.create_lock()
        return control_files

    def _upload_blank_content(self, a_bzrdir, dirs, files, utf8_files, shared):
        """Upload the initial blank content."""
        control_files = self._create_control_files(a_bzrdir)
        control_files.lock_write()
        transport = control_files._transport
        if shared == True:
            utf8_files += [('shared-storage', '')]
        try:
            transport.mkdir_multi(dirs, mode=a_bzrdir._get_dir_mode())
            for (filename, content_stream) in files:
                transport.put_file(filename, content_stream,
                    mode=a_bzrdir._get_file_mode())
            for (filename, content_bytes) in utf8_files:
                transport.put_bytes_non_atomic(filename, content_bytes,
                    mode=a_bzrdir._get_file_mode())
        finally:
            control_files.unlock()


# formats which have no format string are not discoverable
# and not independently creatable, so are not registered.  They're 
# all in bzrlib.repofmt.weaverepo now.  When an instance of one of these is
# needed, it's constructed directly by the BzrDir.  Non-native formats where
# the repository is not separately opened are similar.

format_registry.register_lazy(
    'Bazaar-NG Repository format 7',
    'bzrlib.repofmt.weaverepo',
    'RepositoryFormat7'
    )

format_registry.register_lazy(
    'Bazaar-NG Knit Repository Format 1',
    'bzrlib.repofmt.knitrepo',
    'RepositoryFormatKnit1',
    )

format_registry.register_lazy(
    'Bazaar Knit Repository Format 3 (bzr 0.15)\n',
    'bzrlib.repofmt.knitrepo',
    'RepositoryFormatKnit3',
    )

format_registry.register_lazy(
    'Bazaar Knit Repository Format 4 (bzr 1.0)\n',
    'bzrlib.repofmt.knitrepo',
    'RepositoryFormatKnit4',
    )

# Pack-based formats. There is one format for pre-subtrees, and one for
# post-subtrees to allow ease of testing.
# NOTE: These are experimental in 0.92. Stable in 1.0 and above
format_registry.register_lazy(
    'Bazaar pack repository format 1 (needs bzr 0.92)\n',
    'bzrlib.repofmt.pack_repo',
    'RepositoryFormatKnitPack1',
    )
format_registry.register_lazy(
    'Bazaar pack repository format 1 with subtree support (needs bzr 0.92)\n',
    'bzrlib.repofmt.pack_repo',
    'RepositoryFormatKnitPack3',
    )
format_registry.register_lazy(
    'Bazaar pack repository format 1 with rich root (needs bzr 1.0)\n',
    'bzrlib.repofmt.pack_repo',
    'RepositoryFormatKnitPack4',
    )
format_registry.register_lazy(
    'Bazaar RepositoryFormatKnitPack5 (bzr 1.6)\n',
    'bzrlib.repofmt.pack_repo',
    'RepositoryFormatKnitPack5',
    )
format_registry.register_lazy(
    'Bazaar RepositoryFormatKnitPack5RichRoot (bzr 1.6)\n',
    'bzrlib.repofmt.pack_repo',
    'RepositoryFormatKnitPack5RichRoot',
    )

# Development formats. 
# 1.2->1.3
# development 0 - stub to introduce development versioning scheme.
format_registry.register_lazy(
    "Bazaar development format 0 (needs bzr.dev from before 1.3)\n",
    'bzrlib.repofmt.pack_repo',
    'RepositoryFormatPackDevelopment0',
    )
format_registry.register_lazy(
    ("Bazaar development format 0 with subtree support "
        "(needs bzr.dev from before 1.3)\n"),
    'bzrlib.repofmt.pack_repo',
    'RepositoryFormatPackDevelopment0Subtree',
    )
format_registry.register_lazy(
    "Bazaar development format 1 (needs bzr.dev from before 1.6)\n",
    'bzrlib.repofmt.pack_repo',
    'RepositoryFormatPackDevelopment1',
    )
format_registry.register_lazy(
    ("Bazaar development format 1 with subtree support "
        "(needs bzr.dev from before 1.6)\n"),
    'bzrlib.repofmt.pack_repo',
    'RepositoryFormatPackDevelopment1Subtree',
    )
# 1.3->1.4 go below here


class InterRepository(InterObject):
    """This class represents operations taking place between two repositories.

    Its instances have methods like copy_content and fetch, and contain
    references to the source and target repositories these operations can be 
    carried out on.

    Often we will provide convenience methods on 'repository' which carry out
    operations with another repository - they will always forward to
    InterRepository.get(other).method_name(parameters).
    """

    _optimisers = []
    """The available optimised InterRepository types."""

    def copy_content(self, revision_id=None):
        raise NotImplementedError(self.copy_content)

    def fetch(self, revision_id=None, pb=None, find_ghosts=False):
        """Fetch the content required to construct revision_id.

        The content is copied from self.source to self.target.

        :param revision_id: if None all content is copied, if NULL_REVISION no
                            content is copied.
        :param pb: optional progress bar to use for progress reports. If not
                   provided a default one will be created.

        Returns the copied revision count and the failed revisions in a tuple:
        (copied, failures).
        """
        raise NotImplementedError(self.fetch)

    def _walk_to_common_revisions(self, revision_ids):
        """Walk out from revision_ids in source to revisions target has.

        :param revision_ids: The start point for the search.
        :return: A set of revision ids.
        """
        target_graph = self.target.get_graph()
        revision_ids = frozenset(revision_ids)
        if set(target_graph.get_parent_map(revision_ids)) == revision_ids:
            return graph.SearchResult(revision_ids, set(), 0, set())
        missing_revs = set()
        source_graph = self.source.get_graph()
        # ensure we don't pay silly lookup costs.
        searcher = source_graph._make_breadth_first_searcher(revision_ids)
        null_set = frozenset([_mod_revision.NULL_REVISION])
        while True:
            try:
                next_revs, ghosts = searcher.next_with_ghosts()
            except StopIteration:
                break
            if revision_ids.intersection(ghosts):
                absent_ids = set(revision_ids.intersection(ghosts))
                # If all absent_ids are present in target, no error is needed.
                absent_ids.difference_update(
                    set(target_graph.get_parent_map(absent_ids)))
                if absent_ids:
                    raise errors.NoSuchRevision(self.source, absent_ids.pop())
            # we don't care about other ghosts as we can't fetch them and
            # haven't been asked to.
            next_revs = set(next_revs)
            # we always have NULL_REVISION present.
            have_revs = set(target_graph.get_parent_map(next_revs)).union(null_set)
            missing_revs.update(next_revs - have_revs)
            searcher.stop_searching_any(have_revs)
        return searcher.get_result()
   
    @deprecated_method(one_two)
    @needs_read_lock
    def missing_revision_ids(self, revision_id=None, find_ghosts=True):
        """Return the revision ids that source has that target does not.
        
        These are returned in topological order.

        :param revision_id: only return revision ids included by this
                            revision_id.
        :param find_ghosts: If True find missing revisions in deep history
            rather than just finding the surface difference.
        """
        return list(self.search_missing_revision_ids(
            revision_id, find_ghosts).get_keys())

    @needs_read_lock
    def search_missing_revision_ids(self, revision_id=None, find_ghosts=True):
        """Return the revision ids that source has that target does not.
        
        :param revision_id: only return revision ids included by this
                            revision_id.
        :param find_ghosts: If True find missing revisions in deep history
            rather than just finding the surface difference.
        :return: A bzrlib.graph.SearchResult.
        """
        # stop searching at found target revisions.
        if not find_ghosts and revision_id is not None:
            return self._walk_to_common_revisions([revision_id])
        # generic, possibly worst case, slow code path.
        target_ids = set(self.target.all_revision_ids())
        if revision_id is not None:
            source_ids = self.source.get_ancestry(revision_id)
            if source_ids[0] is not None:
                raise AssertionError()
            source_ids.pop(0)
        else:
            source_ids = self.source.all_revision_ids()
        result_set = set(source_ids).difference(target_ids)
        return self.source.revision_ids_to_search_result(result_set)

    @staticmethod
    def _same_model(source, target):
        """True if source and target have the same data representation."""
        if source.supports_rich_root() != target.supports_rich_root():
            return False
        if source._serializer != target._serializer:
            return False
        return True


class InterSameDataRepository(InterRepository):
    """Code for converting between repositories that represent the same data.
    
    Data format and model must match for this to work.
    """

    @classmethod
    def _get_repo_format_to_test(self):
        """Repository format for testing with.
        
        InterSameData can pull from subtree to subtree and from non-subtree to
        non-subtree, so we test this with the richest repository format.
        """
        from bzrlib.repofmt import knitrepo
        return knitrepo.RepositoryFormatKnit3()

    @staticmethod
    def is_compatible(source, target):
        return InterRepository._same_model(source, target)

    @needs_write_lock
    def copy_content(self, revision_id=None):
        """Make a complete copy of the content in self into destination.

        This copies both the repository's revision data, and configuration information
        such as the make_working_trees setting.
        
        This is a destructive operation! Do not use it on existing 
        repositories.

        :param revision_id: Only copy the content needed to construct
                            revision_id and its parents.
        """
        try:
            self.target.set_make_working_trees(self.source.make_working_trees())
        except NotImplementedError:
            pass
        # but don't bother fetching if we have the needed data now.
        if (revision_id not in (None, _mod_revision.NULL_REVISION) and 
            self.target.has_revision(revision_id)):
            return
        self.target.fetch(self.source, revision_id=revision_id)

    @needs_write_lock
    def fetch(self, revision_id=None, pb=None, find_ghosts=False):
        """See InterRepository.fetch()."""
        from bzrlib.fetch import GenericRepoFetcher
        mutter("Using fetch logic to copy between %s(%s) and %s(%s)",
               self.source, self.source._format, self.target,
               self.target._format)
        f = GenericRepoFetcher(to_repository=self.target,
                               from_repository=self.source,
                               last_revision=revision_id,
                               pb=pb, find_ghosts=find_ghosts)
        return f.count_copied, f.failed_revisions


class InterWeaveRepo(InterSameDataRepository):
    """Optimised code paths between Weave based repositories.
    
    This should be in bzrlib/repofmt/weaverepo.py but we have not yet
    implemented lazy inter-object optimisation.
    """

    @classmethod
    def _get_repo_format_to_test(self):
        from bzrlib.repofmt import weaverepo
        return weaverepo.RepositoryFormat7()

    @staticmethod
    def is_compatible(source, target):
        """Be compatible with known Weave formats.
        
        We don't test for the stores being of specific types because that
        could lead to confusing results, and there is no need to be 
        overly general.
        """
        from bzrlib.repofmt.weaverepo import (
                RepositoryFormat5,
                RepositoryFormat6,
                RepositoryFormat7,
                )
        try:
            return (isinstance(source._format, (RepositoryFormat5,
                                                RepositoryFormat6,
                                                RepositoryFormat7)) and
                    isinstance(target._format, (RepositoryFormat5,
                                                RepositoryFormat6,
                                                RepositoryFormat7)))
        except AttributeError:
            return False
    
    @needs_write_lock
    def copy_content(self, revision_id=None):
        """See InterRepository.copy_content()."""
        # weave specific optimised path:
        try:
            self.target.set_make_working_trees(self.source.make_working_trees())
        except (errors.RepositoryUpgradeRequired, NotImplemented):
            pass
        # FIXME do not peek!
        if self.source._transport.listable():
            pb = ui.ui_factory.nested_progress_bar()
            try:
                self.target.texts.insert_record_stream(
                    self.source.texts.get_record_stream(
                        self.source.texts.keys(), 'topological', False))
                pb.update('copying inventory', 0, 1)
                self.target.inventories.insert_record_stream(
                    self.source.inventories.get_record_stream(
                        self.source.inventories.keys(), 'topological', False))
                self.target.signatures.insert_record_stream(
                    self.source.signatures.get_record_stream(
                        self.source.signatures.keys(),
                        'unordered', True))
                self.target.revisions.insert_record_stream(
                    self.source.revisions.get_record_stream(
                        self.source.revisions.keys(),
                        'topological', True))
            finally:
                pb.finished()
        else:
            self.target.fetch(self.source, revision_id=revision_id)

    @needs_write_lock
    def fetch(self, revision_id=None, pb=None, find_ghosts=False):
        """See InterRepository.fetch()."""
        from bzrlib.fetch import GenericRepoFetcher
        mutter("Using fetch logic to copy between %s(%s) and %s(%s)",
               self.source, self.source._format, self.target, self.target._format)
        f = GenericRepoFetcher(to_repository=self.target,
                               from_repository=self.source,
                               last_revision=revision_id,
                               pb=pb, find_ghosts=find_ghosts)
        return f.count_copied, f.failed_revisions

    @needs_read_lock
    def search_missing_revision_ids(self, revision_id=None, find_ghosts=True):
        """See InterRepository.missing_revision_ids()."""
        # we want all revisions to satisfy revision_id in source.
        # but we don't want to stat every file here and there.
        # we want then, all revisions other needs to satisfy revision_id 
        # checked, but not those that we have locally.
        # so the first thing is to get a subset of the revisions to 
        # satisfy revision_id in source, and then eliminate those that
        # we do already have. 
        # this is slow on high latency connection to self, but as as this
        # disk format scales terribly for push anyway due to rewriting 
        # inventory.weave, this is considered acceptable.
        # - RBC 20060209
        if revision_id is not None:
            source_ids = self.source.get_ancestry(revision_id)
            if source_ids[0] is not None:
                raise AssertionError()
            source_ids.pop(0)
        else:
            source_ids = self.source._all_possible_ids()
        source_ids_set = set(source_ids)
        # source_ids is the worst possible case we may need to pull.
        # now we want to filter source_ids against what we actually
        # have in target, but don't try to check for existence where we know
        # we do not have a revision as that would be pointless.
        target_ids = set(self.target._all_possible_ids())
        possibly_present_revisions = target_ids.intersection(source_ids_set)
        actually_present_revisions = set(
            self.target._eliminate_revisions_not_present(possibly_present_revisions))
        required_revisions = source_ids_set.difference(actually_present_revisions)
        if revision_id is not None:
            # we used get_ancestry to determine source_ids then we are assured all
            # revisions referenced are present as they are installed in topological order.
            # and the tip revision was validated by get_ancestry.
            result_set = required_revisions
        else:
            # if we just grabbed the possibly available ids, then 
            # we only have an estimate of whats available and need to validate
            # that against the revision records.
            result_set = set(
                self.source._eliminate_revisions_not_present(required_revisions))
        return self.source.revision_ids_to_search_result(result_set)


class InterKnitRepo(InterSameDataRepository):
    """Optimised code paths between Knit based repositories."""

    @classmethod
    def _get_repo_format_to_test(self):
        from bzrlib.repofmt import knitrepo
        return knitrepo.RepositoryFormatKnit1()

    @staticmethod
    def is_compatible(source, target):
        """Be compatible with known Knit formats.
        
        We don't test for the stores being of specific types because that
        could lead to confusing results, and there is no need to be 
        overly general.
        """
        from bzrlib.repofmt.knitrepo import RepositoryFormatKnit
        try:
            are_knits = (isinstance(source._format, RepositoryFormatKnit) and
                isinstance(target._format, RepositoryFormatKnit))
        except AttributeError:
            return False
        return are_knits and InterRepository._same_model(source, target)

    @needs_write_lock
    def fetch(self, revision_id=None, pb=None, find_ghosts=False):
        """See InterRepository.fetch()."""
        from bzrlib.fetch import KnitRepoFetcher
        mutter("Using fetch logic to copy between %s(%s) and %s(%s)",
               self.source, self.source._format, self.target, self.target._format)
        f = KnitRepoFetcher(to_repository=self.target,
                            from_repository=self.source,
                            last_revision=revision_id,
                            pb=pb, find_ghosts=find_ghosts)
        return f.count_copied, f.failed_revisions

    @needs_read_lock
    def search_missing_revision_ids(self, revision_id=None, find_ghosts=True):
        """See InterRepository.missing_revision_ids()."""
        if revision_id is not None:
            source_ids = self.source.get_ancestry(revision_id)
            if source_ids[0] is not None:
                raise AssertionError()
            source_ids.pop(0)
        else:
            source_ids = self.source.all_revision_ids()
        source_ids_set = set(source_ids)
        # source_ids is the worst possible case we may need to pull.
        # now we want to filter source_ids against what we actually
        # have in target, but don't try to check for existence where we know
        # we do not have a revision as that would be pointless.
        target_ids = set(self.target.all_revision_ids())
        possibly_present_revisions = target_ids.intersection(source_ids_set)
        actually_present_revisions = set(
            self.target._eliminate_revisions_not_present(possibly_present_revisions))
        required_revisions = source_ids_set.difference(actually_present_revisions)
        if revision_id is not None:
            # we used get_ancestry to determine source_ids then we are assured all
            # revisions referenced are present as they are installed in topological order.
            # and the tip revision was validated by get_ancestry.
            result_set = required_revisions
        else:
            # if we just grabbed the possibly available ids, then 
            # we only have an estimate of whats available and need to validate
            # that against the revision records.
            result_set = set(
                self.source._eliminate_revisions_not_present(required_revisions))
        return self.source.revision_ids_to_search_result(result_set)


class InterPackRepo(InterSameDataRepository):
    """Optimised code paths between Pack based repositories."""

    @classmethod
    def _get_repo_format_to_test(self):
        from bzrlib.repofmt import pack_repo
        return pack_repo.RepositoryFormatKnitPack1()

    @staticmethod
    def is_compatible(source, target):
        """Be compatible with known Pack formats.
        
        We don't test for the stores being of specific types because that
        could lead to confusing results, and there is no need to be 
        overly general.
        """
        from bzrlib.repofmt.pack_repo import RepositoryFormatPack
        try:
            are_packs = (isinstance(source._format, RepositoryFormatPack) and
                isinstance(target._format, RepositoryFormatPack))
        except AttributeError:
            return False
        return are_packs and InterRepository._same_model(source, target)

    @needs_write_lock
    def fetch(self, revision_id=None, pb=None, find_ghosts=False):
        """See InterRepository.fetch()."""
        if len(self.source._fallback_repositories) > 0:
            from bzrlib.fetch import KnitRepoFetcher
            fetcher = KnitRepoFetcher(self.target, self.source, revision_id,
                                      pb, find_ghosts)
            return fetcher.count_copied, fetcher.failed_revisions
        from bzrlib.repofmt.pack_repo import Packer
        mutter("Using fetch logic to copy between %s(%s) and %s(%s)",
               self.source, self.source._format, self.target, self.target._format)
        self.count_copied = 0
        if revision_id is None:
            # TODO:
            # everything to do - use pack logic
            # to fetch from all packs to one without
            # inventory parsing etc, IFF nothing to be copied is in the target.
            # till then:
            source_revision_ids = frozenset(self.source.all_revision_ids())
            revision_ids = source_revision_ids - \
                frozenset(self.target.get_parent_map(source_revision_ids))
            revision_keys = [(revid,) for revid in revision_ids]
            index = self.target._pack_collection.revision_index.combined_index
            present_revision_ids = set(item[1][0] for item in
                index.iter_entries(revision_keys))
            revision_ids = set(revision_ids) - present_revision_ids
            # implementing the TODO will involve:
            # - detecting when all of a pack is selected
            # - avoiding as much as possible pre-selection, so the
            # more-core routines such as create_pack_from_packs can filter in
            # a just-in-time fashion. (though having a HEADS list on a
            # repository might make this a lot easier, because we could
            # sensibly detect 'new revisions' without doing a full index scan.
        elif _mod_revision.is_null(revision_id):
            # nothing to do:
            return (0, [])
        else:
            try:
                revision_ids = self.search_missing_revision_ids(revision_id,
                    find_ghosts=find_ghosts).get_keys()
            except errors.NoSuchRevision:
                raise errors.InstallFailed([revision_id])
            if len(revision_ids) == 0:
                return (0, [])
        packs = self.source._pack_collection.all_packs()
        pack = Packer(self.target._pack_collection, packs, '.fetch',
            revision_ids).pack()
        if pack is not None:
            self.target._pack_collection._save_pack_names()
            # Trigger an autopack. This may duplicate effort as we've just done
            # a pack creation, but for now it is simpler to think about as
            # 'upload data, then repack if needed'.
            self.target._pack_collection.autopack()
            return (pack.get_revision_count(), [])
        else:
            return (0, [])

    @needs_read_lock
    def search_missing_revision_ids(self, revision_id=None, find_ghosts=True):
        """See InterRepository.missing_revision_ids().
        
        :param find_ghosts: Find ghosts throughout the ancestry of
            revision_id.
        """
        if not find_ghosts and revision_id is not None:
            return self._walk_to_common_revisions([revision_id])
        elif revision_id is not None:
            # Find ghosts: search for revisions pointing from one repository to
            # the other, and vice versa, anywhere in the history of revision_id.
            graph = self.target.get_graph(other_repository=self.source)
            searcher = graph._make_breadth_first_searcher([revision_id])
            found_ids = set()
            while True:
                try:
                    next_revs, ghosts = searcher.next_with_ghosts()
                except StopIteration:
                    break
                if revision_id in ghosts:
                    raise errors.NoSuchRevision(self.source, revision_id)
                found_ids.update(next_revs)
                found_ids.update(ghosts)
            found_ids = frozenset(found_ids)
            # Double query here: should be able to avoid this by changing the
            # graph api further.
            result_set = found_ids - frozenset(
                self.target.get_parent_map(found_ids))
        else:
            source_ids = self.source.all_revision_ids()
            # source_ids is the worst possible case we may need to pull.
            # now we want to filter source_ids against what we actually
            # have in target, but don't try to check for existence where we know
            # we do not have a revision as that would be pointless.
            target_ids = set(self.target.all_revision_ids())
            result_set = set(source_ids).difference(target_ids)
        return self.source.revision_ids_to_search_result(result_set)


class InterModel1and2(InterRepository):

    @classmethod
    def _get_repo_format_to_test(self):
        return None

    @staticmethod
    def is_compatible(source, target):
        if not source.supports_rich_root() and target.supports_rich_root():
            return True
        else:
            return False

    @needs_write_lock
    def fetch(self, revision_id=None, pb=None, find_ghosts=False):
        """See InterRepository.fetch()."""
        from bzrlib.fetch import Model1toKnit2Fetcher
        f = Model1toKnit2Fetcher(to_repository=self.target,
                                 from_repository=self.source,
                                 last_revision=revision_id,
                                 pb=pb, find_ghosts=find_ghosts)
        return f.count_copied, f.failed_revisions

    @needs_write_lock
    def copy_content(self, revision_id=None):
        """Make a complete copy of the content in self into destination.
        
        This is a destructive operation! Do not use it on existing 
        repositories.

        :param revision_id: Only copy the content needed to construct
                            revision_id and its parents.
        """
        try:
            self.target.set_make_working_trees(self.source.make_working_trees())
        except NotImplementedError:
            pass
        # but don't bother fetching if we have the needed data now.
        if (revision_id not in (None, _mod_revision.NULL_REVISION) and 
            self.target.has_revision(revision_id)):
            return
        self.target.fetch(self.source, revision_id=revision_id)


class InterKnit1and2(InterKnitRepo):

    @classmethod
    def _get_repo_format_to_test(self):
        return None

    @staticmethod
    def is_compatible(source, target):
        """Be compatible with Knit1 source and Knit3 target"""
        from bzrlib.repofmt.knitrepo import RepositoryFormatKnit3
        try:
            from bzrlib.repofmt.knitrepo import (RepositoryFormatKnit1,
                RepositoryFormatKnit3)
            from bzrlib.repofmt.pack_repo import (
                RepositoryFormatKnitPack1,
                RepositoryFormatKnitPack3,
                RepositoryFormatPackDevelopment0,
                RepositoryFormatPackDevelopment0Subtree,
                )
            nosubtrees = (
                RepositoryFormatKnit1,
                RepositoryFormatKnitPack1,
                RepositoryFormatPackDevelopment0,
                )
            subtrees = (
                RepositoryFormatKnit3,
                RepositoryFormatKnitPack3,
                RepositoryFormatPackDevelopment0Subtree,
                )
            return (isinstance(source._format, nosubtrees) and
                isinstance(target._format, subtrees))
        except AttributeError:
            return False

    @needs_write_lock
    def fetch(self, revision_id=None, pb=None, find_ghosts=False):
        """See InterRepository.fetch()."""
        from bzrlib.fetch import Knit1to2Fetcher
        mutter("Using fetch logic to copy between %s(%s) and %s(%s)",
               self.source, self.source._format, self.target, 
               self.target._format)
        f = Knit1to2Fetcher(to_repository=self.target,
                            from_repository=self.source,
                            last_revision=revision_id,
                            pb=pb, find_ghosts=find_ghosts)
        return f.count_copied, f.failed_revisions


class InterDifferingSerializer(InterKnitRepo):

    @classmethod
    def _get_repo_format_to_test(self):
        return None

    @staticmethod
    def is_compatible(source, target):
        """Be compatible with Knit2 source and Knit3 target"""
        if source.supports_rich_root() != target.supports_rich_root():
            return False
        # Ideally, we'd support fetching if the source had no tree references
        # even if it supported them...
        if (getattr(source, '_format.supports_tree_reference', False) and
            not getattr(target, '_format.supports_tree_reference', False)):
            return False
        return True

    @needs_write_lock
    def fetch(self, revision_id=None, pb=None, find_ghosts=False):
        """See InterRepository.fetch()."""
        revision_ids = self.target.search_missing_revision_ids(self.source,
            revision_id, find_ghosts=find_ghosts).get_keys()
        revision_ids = tsort.topo_sort(
            self.source.get_graph().get_parent_map(revision_ids))
        def revisions_iterator():
            for current_revision_id in revision_ids:
                revision = self.source.get_revision(current_revision_id)
                tree = self.source.revision_tree(current_revision_id)
                try:
                    signature = self.source.get_signature_text(
                        current_revision_id)
                except errors.NoSuchRevision:
                    signature = None
                yield revision, tree, signature
        if pb is None:
            my_pb = ui.ui_factory.nested_progress_bar()
            pb = my_pb
        else:
            my_pb = None
        try:
            install_revisions(self.target, revisions_iterator(),
                              len(revision_ids), pb)
        finally:
            if my_pb is not None:
                my_pb.finished()
        return len(revision_ids), 0


class InterOtherToRemote(InterRepository):

    def __init__(self, source, target):
        InterRepository.__init__(self, source, target)
        self._real_inter = None

    @staticmethod
    def is_compatible(source, target):
        if isinstance(target, remote.RemoteRepository):
            return True
        return False

    def _ensure_real_inter(self):
        if self._real_inter is None:
            self.target._ensure_real()
            real_target = self.target._real_repository
            self._real_inter = InterRepository.get(self.source, real_target)
    
    def copy_content(self, revision_id=None):
        self._ensure_real_inter()
        self._real_inter.copy_content(revision_id=revision_id)

    def fetch(self, revision_id=None, pb=None, find_ghosts=False):
        self._ensure_real_inter()
        return self._real_inter.fetch(revision_id=revision_id, pb=pb,
            find_ghosts=find_ghosts)

    @classmethod
    def _get_repo_format_to_test(self):
        return None


class InterRemoteToOther(InterRepository):

    def __init__(self, source, target):
        InterRepository.__init__(self, source, target)
        self._real_inter = None

    @staticmethod
    def is_compatible(source, target):
        if not isinstance(source, remote.RemoteRepository):
            return False
        # Is source's model compatible with target's model?
        source._ensure_real()
        real_source = source._real_repository
        if isinstance(real_source, remote.RemoteRepository):
            raise NotImplementedError(
                "We don't support remote repos backed by remote repos yet.")
        return InterRepository._same_model(real_source, target)

    def _ensure_real_inter(self):
        if self._real_inter is None:
            self.source._ensure_real()
            real_source = self.source._real_repository
            self._real_inter = InterRepository.get(real_source, self.target)
    
    def fetch(self, revision_id=None, pb=None, find_ghosts=False):
        self._ensure_real_inter()
        return self._real_inter.fetch(revision_id=revision_id, pb=pb,
            find_ghosts=find_ghosts)

    def copy_content(self, revision_id=None):
        self._ensure_real_inter()
        self._real_inter.copy_content(revision_id=revision_id)

    @classmethod
    def _get_repo_format_to_test(self):
        return None



InterRepository.register_optimiser(InterDifferingSerializer)
InterRepository.register_optimiser(InterSameDataRepository)
InterRepository.register_optimiser(InterWeaveRepo)
InterRepository.register_optimiser(InterKnitRepo)
InterRepository.register_optimiser(InterModel1and2)
InterRepository.register_optimiser(InterKnit1and2)
InterRepository.register_optimiser(InterPackRepo)
InterRepository.register_optimiser(InterOtherToRemote)
InterRepository.register_optimiser(InterRemoteToOther)


class CopyConverter(object):
    """A repository conversion tool which just performs a copy of the content.
    
    This is slow but quite reliable.
    """

    def __init__(self, target_format):
        """Create a CopyConverter.

        :param target_format: The format the resulting repository should be.
        """
        self.target_format = target_format
        
    def convert(self, repo, pb):
        """Perform the conversion of to_convert, giving feedback via pb.

        :param to_convert: The disk object to convert.
        :param pb: a progress bar to use for progress information.
        """
        self.pb = pb
        self.count = 0
        self.total = 4
        # this is only useful with metadir layouts - separated repo content.
        # trigger an assertion if not such
        repo._format.get_format_string()
        self.repo_dir = repo.bzrdir
        self.step('Moving repository to repository.backup')
        self.repo_dir.transport.move('repository', 'repository.backup')
        backup_transport =  self.repo_dir.transport.clone('repository.backup')
        repo._format.check_conversion_target(self.target_format)
        self.source_repo = repo._format.open(self.repo_dir,
            _found=True,
            _override_transport=backup_transport)
        self.step('Creating new repository')
        converted = self.target_format.initialize(self.repo_dir,
                                                  self.source_repo.is_shared())
        converted.lock_write()
        try:
            self.step('Copying content into repository.')
            self.source_repo.copy_content_into(converted)
        finally:
            converted.unlock()
        self.step('Deleting old repository content.')
        self.repo_dir.transport.delete_tree('repository.backup')
        self.pb.note('repository converted')

    def step(self, message):
        """Update the pb by a step."""
        self.count +=1
        self.pb.update(message, self.count, self.total)


_unescape_map = {
    'apos':"'",
    'quot':'"',
    'amp':'&',
    'lt':'<',
    'gt':'>'
}


def _unescaper(match, _map=_unescape_map):
    code = match.group(1)
    try:
        return _map[code]
    except KeyError:
        if not code.startswith('#'):
            raise
        return unichr(int(code[1:])).encode('utf8')


_unescape_re = None


def _unescape_xml(data):
    """Unescape predefined XML entities in a string of data."""
    global _unescape_re
    if _unescape_re is None:
        _unescape_re = re.compile('\&([^;]*);')
    return _unescape_re.sub(_unescaper, data)


class _VersionedFileChecker(object):

    def __init__(self, repository):
        self.repository = repository
        self.text_index = self.repository._generate_text_key_index()
    
    def calculate_file_version_parents(self, text_key):
        """Calculate the correct parents for a file version according to
        the inventories.
        """
        parent_keys = self.text_index[text_key]
        if parent_keys == [_mod_revision.NULL_REVISION]:
            return ()
        return tuple(parent_keys)

    def check_file_version_parents(self, texts, progress_bar=None):
        """Check the parents stored in a versioned file are correct.

        It also detects file versions that are not referenced by their
        corresponding revision's inventory.

        :returns: A tuple of (wrong_parents, dangling_file_versions).
            wrong_parents is a dict mapping {revision_id: (stored_parents,
            correct_parents)} for each revision_id where the stored parents
            are not correct.  dangling_file_versions is a set of (file_id,
            revision_id) tuples for versions that are present in this versioned
            file, but not used by the corresponding inventory.
        """
        wrong_parents = {}
        self.file_ids = set([file_id for file_id, _ in
            self.text_index.iterkeys()])
        # text keys is now grouped by file_id
        n_weaves = len(self.file_ids)
        files_in_revisions = {}
        revisions_of_files = {}
        n_versions = len(self.text_index)
        progress_bar.update('loading text store', 0, n_versions)
        parent_map = self.repository.texts.get_parent_map(self.text_index)
        # On unlistable transports this could well be empty/error...
        text_keys = self.repository.texts.keys()
        unused_keys = frozenset(text_keys) - set(self.text_index)
        for num, key in enumerate(self.text_index.iterkeys()):
            if progress_bar is not None:
                progress_bar.update('checking text graph', num, n_versions)
            correct_parents = self.calculate_file_version_parents(key)
            try:
                knit_parents = parent_map[key]
            except errors.RevisionNotPresent:
                # Missing text!
                knit_parents = None
            if correct_parents != knit_parents:
                wrong_parents[key] = (knit_parents, correct_parents)
        return wrong_parents, unused_keys


def _old_get_graph(repository, revision_id):
    """DO NOT USE. That is all. I'm serious."""
    graph = repository.get_graph()
    revision_graph = dict(((key, value) for key, value in
        graph.iter_ancestry([revision_id]) if value is not None))
    return _strip_NULL_ghosts(revision_graph)


def _strip_NULL_ghosts(revision_graph):
    """Also don't use this. more compatibility code for unmigrated clients."""
    # Filter ghosts, and null:
    if _mod_revision.NULL_REVISION in revision_graph:
        del revision_graph[_mod_revision.NULL_REVISION]
    for key, parents in revision_graph.items():
        revision_graph[key] = tuple(parent for parent in parents if parent
            in revision_graph)
    return revision_graph