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# Copyright (C) 2005 by Canonical Ltd
#
# Distributed under the GNU General Public Licence v2
#
# \subsection{\emph{rio} - simple text metaformat}
#
# \emph{r} stands for `restricted', `reproducible', or `rfc822-like'.
#
# The stored data consists of a series of \emph{stanzas}, each of which contains
# \emph{fields} identified by an ascii name, with Unicode or string contents.
# The field tag is constrained to alphanumeric characters.
# There may be more than one field in a stanza with the same name.
#
# The format itself does not deal with character encoding issues, though
# the result will normally be written in Unicode.
#
# The format is intended to be simple enough that there is exactly one character
# stream representation of an object and vice versa, and that this relation
# will continue to hold for future versions of bzr.
# In comments, $\min(1,10)$
min(1,10)
import re
# XXX: some redundancy is allowing to write stanzas in isolation as well as
# through a writer object.
class RioWriter(object):
def __init__(self, to_file):
self._soft_nl = False
self._to_file = to_file
def write_stanza(self, stanza):
if self._soft_nl:
print >>self._to_file
stanza.write(self._to_file)
self._soft_nl = True
class RioReader(object):
"""Read stanzas from a file as a sequence
to_file can be anything that can be enumerated as a sequence of
lines (with newlines.)
"""
def __init__(self, from_file):
self._from_file = from_file
def __iter__(self):
while True:
s = read_stanza(self._from_file)
if s is None:
break
else:
yield s
def read_stanzas(from_file):
while True:
s = read_stanza(from_file)
if s is None:
break
else:
yield s
class Stanza(object):
"""One stanza for rio.
Each stanza contains a set of named fields.
Names must be non-empty ascii alphanumeric plus _. Names can be repeated
within a stanza. Names are case-sensitive. The ordering of fields is
preserved.
Each field value must be either an int or a string.
"""
__slots__ = ['items']
def __init__(self, **kwargs):
"""Construct a new Stanza.
The keyword arguments, if any, are added in sorted order to the stanza.
"""
self.items = []
if kwargs:
for tag, value in sorted(kwargs.items()):
self.add(tag, value)
def add(self, tag, value):
"""Append a name and value to the stanza."""
assert valid_tag(tag), \
("invalid tag %r" % tag)
if isinstance(value, (str, unicode)):
pass
## elif isinstance(value, (int, long)):
## value = str(value) # XXX: python2.4 without L-suffix
else:
raise ValueError("invalid value %r" % value)
self.items.append((tag, value))
def __contains__(self, find_tag):
"""True if there is any field in this stanza with the given tag."""
for tag, value in self.items:
if tag == find_tag:
return True
return False
def __len__(self):
"""Return number of pairs in the stanza."""
return len(self.items)
def __eq__(self, other):
if not isinstance(other, Stanza):
return False
return self.items == other.items
def __ne__(self, other):
return not self.__eq__(other)
def __repr__(self):
return "Stanza(%r)" % self.items
def iter_pairs(self):
"""Return iterator of tag, value pairs."""
return iter(self.items)
def to_lines(self):
"""Generate sequence of lines for external version of this file."""
if not self.items:
# max() complains if sequence is empty
return []
result = []
for tag, value in self.items:
assert isinstance(value, (str, unicode))
if value == '':
result.append(tag + ': \n')
elif '\n' in value:
# don't want splitlines behaviour on empty lines
val_lines = value.split('\n')
result.append(tag + ': ' + val_lines[0] + '\n')
for line in val_lines[1:]:
result.append('\t' + line + '\n')
else:
result.append(tag + ': ' + value + '\n')
return result
def to_string(self):
"""Return stanza as a single string"""
return ''.join(self.to_lines())
def write(self, to_file):
"""Write stanza to a file"""
to_file.writelines(self.to_lines())
def get(self, tag):
"""Return the value for a field wih given tag.
If there is more than one value, only the first is returned. If the
tag is not present, KeyError is raised.
"""
for t, v in self.items:
if t == tag:
return v
else:
raise KeyError(tag)
__getitem__ = get
def get_all(self, tag):
r = []
for t, v in self.items:
if t == tag:
r.append(v)
return r
_tag_re = re.compile(r'^[-a-zA-Z0-9_]+$')
def valid_tag(tag):
return bool(_tag_re.match(tag))
def read_stanza(line_iter):
"""Return new Stanza read from list of lines or a file
Returns one Stanza that was read, or returns None at end of file. If a
blank line follows the stanza, it is consumed. It's not an error for
there to be no blank at end of file. If there is a blank file at the
start of the input this is really an empty stanza and that is returned.
Only the stanza lines and the trailing blank (if any) are consumed
from the line_iter.
"""
items = []
stanza = Stanza()
tag = None
accum_value = None
for line in line_iter:
if line == None or line == '':
break # end of file
if line == '\n':
break # end of stanza
assert line[-1] == '\n'
real_l = line
if line[0] == '\t': # continues previous value
if tag is None:
raise ValueError('invalid continuation line %r' % real_l)
accum_value += '\n' + line[1:-1]
else: # new tag:value line
if tag is not None:
stanza.add(tag, accum_value)
try:
colon_index = line.index(': ')
except ValueError:
raise ValueError('tag/value separator not found in line %r' % real_l)
tag = line[:colon_index]
assert valid_tag(tag), \
"invalid rio tag %r" % tag
accum_value = line[colon_index+2:-1]
if tag is not None: # add last tag-value
stanza.add(tag, accum_value)
return stanza
else: # didn't see any content
return None
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