~bzr-pqm/bzr/bzr.dev

# Copyright (C) 2005 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


import os
import tempfile
import shutil
import errno

import bzrlib.osutils
import bzrlib.revision
from bzrlib.merge_core import merge_flex, ApplyMerge3, BackupBeforeChange
from bzrlib.changeset import generate_changeset, ExceptionConflictHandler
from bzrlib.changeset import Inventory, Diff3Merge, ReplaceContents
from bzrlib.branch import Branch
from bzrlib.errors import BzrCommandError, UnrelatedBranches, NoCommonAncestor
from bzrlib.errors import NoCommits
from bzrlib.delta import compare_trees
from bzrlib.trace import mutter, warning, note
from bzrlib.fetch import greedy_fetch, fetch
from bzrlib.revision import is_ancestor
from bzrlib.osutils import rename
from bzrlib.revision import common_ancestor, MultipleRevisionSources
from bzrlib.errors import NoSuchRevision

# TODO: build_working_dir can be built on something simpler than merge()

# FIXME: merge() parameters seem oriented towards the command line
# NOTABUG: merge is a helper for commandline functions.  merge_inner is the
#          the core functionality.

# comments from abentley on irc: merge happens in two stages, each
# of which generates a changeset object

# stage 1: generate OLD->OTHER,
# stage 2: use MINE and OLD->OTHER to generate MINE -> RESULT

class MergeConflictHandler(ExceptionConflictHandler):
    """Handle conflicts encountered while merging.

    This subclasses ExceptionConflictHandler, so that any types of
    conflict that are not explicitly handled cause an exception and
    terminate the merge.
    """
    def __init__(self, this_tree, base_tree, other_tree, ignore_zero=False):
        ExceptionConflictHandler.__init__(self)
        self.conflicts = 0
        self.ignore_zero = ignore_zero
        self.this_tree = this_tree
        self.base_tree = base_tree
        self.other_tree = other_tree

    def copy(self, source, dest):
        """Copy the text and mode of a file
        :param source: The path of the file to copy
        :param dest: The distination file to create
        """
        s_file = file(source, "rb")
        d_file = file(dest, "wb")
        for line in s_file:
            d_file.write(line)
        os.chmod(dest, 0777 & os.stat(source).st_mode)

    def dump(self, lines, dest):
        """Copy the text and mode of a file
        :param source: The path of the file to copy
        :param dest: The distination file to create
        """
        d_file = file(dest, "wb")
        for line in lines:
            d_file.write(line)

    def add_suffix(self, name, suffix, last_new_name=None):
        """Rename a file to append a suffix.  If the new name exists, the
        suffix is added repeatedly until a non-existant name is found

        :param name: The path of the file
        :param suffix: The suffix to append
        :param last_new_name: (used for recursive calls) the last name tried
        """
        if last_new_name is None:
            last_new_name = name
        new_name = last_new_name+suffix
        try:
            rename(name, new_name)
            return new_name
        except OSError, e:
            if e.errno != errno.EEXIST and e.errno != errno.ENOTEMPTY:
                raise
            return self.add_suffix(name, suffix, last_new_name=new_name)

    def conflict(self, text):
        warning(text)
        self.conflicts += 1
        

    def merge_conflict(self, new_file, this_path, base_lines, other_lines):
        """
        Handle diff3 conflicts by producing a .THIS, .BASE and .OTHER.  The
        main file will be a version with diff3 conflicts.
        :param new_file: Path to the output file with diff3 markers
        :param this_path: Path to the file text for the THIS tree
        :param base_path: Path to the file text for the BASE tree
        :param other_path: Path to the file text for the OTHER tree
        """
        self.add_suffix(this_path, ".THIS")
        self.dump(base_lines, this_path+".BASE")
        self.dump(other_lines, this_path+".OTHER")
        rename(new_file, this_path)
        self.conflict("Diff3 conflict encountered in %s" % this_path)

    def new_contents_conflict(self, filename, other_contents):
        """Conflicting contents for newly added file."""
        other.contents.apply(filename + ".OTHER")
        self.conflict("Conflict in newly added file %s" % filename)
    

    def target_exists(self, entry, target, old_path):
        """Handle the case when the target file or dir exists"""
        moved_path = self.add_suffix(target, ".moved")
        self.conflict("Moved existing %s to %s" % (target, moved_path))

    def rmdir_non_empty(self, filename):
        """Handle the case where the dir to be removed still has contents"""
        self.conflict("Directory %s not removed because it is not empty"\
            % filename)
        return "skip"

    def rem_contents_conflict(self, filename, this_contents, base_contents):
        base_contents(filename+".BASE", self, False)
        this_contents(filename+".THIS", self, False)
        return ReplaceContents(this_contents, None)

    def rem_contents_conflict(self, filename, this_contents, base_contents):
        base_contents(filename+".BASE", self, False)
        this_contents(filename+".THIS", self, False)
        self.conflict("Other branch deleted locally modified file %s" %
                      filename)
        return ReplaceContents(this_contents, None)

    def abs_this_path(self, file_id):
        """Return the absolute path for a file_id in the this tree."""
        return self.this_tree.id2abspath(file_id)

    def add_missing_parents(self, file_id, tree):
        """If some of the parents for file_id are missing, add them."""
        entry = tree.inventory[file_id]
        if entry.parent_id not in self.this_tree:
            return self.create_all_missing(entry.parent_id, tree)
        else:
            return self.abs_this_path(entry.parent_id)

    def create_all_missing(self, file_id, tree):
        """Add contents for a file_id and all its parents to a tree."""
        entry = tree.inventory[file_id]
        if entry.parent_id is not None and entry.parent_id not in self.this_tree:
            abspath = self.create_all_missing(entry.parent_id, tree)
        else:
            abspath = self.abs_this_path(entry.parent_id)
        entry_path = os.path.join(abspath, entry.name)
        if not os.path.isdir(entry_path):
            self.create(file_id, entry_path, tree)
        return entry_path

    def create(self, file_id, path, tree, reverse=False):
        """Uses tree data to create a filesystem object for the file_id"""
        from changeset import get_contents
        get_contents(tree, file_id)(path, self, reverse)

    def missing_for_merge(self, file_id, other_path):
        """The file_id doesn't exist in THIS, but does in OTHER and BASE"""
        self.conflict("Other branch modified locally deleted file %s" %
                      other_path)
        parent_dir = self.add_missing_parents(file_id, self.other_tree)
        stem = os.path.join(parent_dir, os.path.basename(other_path))
        self.create(file_id, stem+".OTHER", self.other_tree)
        self.create(file_id, stem+".BASE", self.base_tree)

    def threeway_contents_conflict(filename, this_contents, base_contents,
                                   other_contents):
        self.conflict("Three-way conflict merging %s" % filename)

    def finalize(self):
        if not self.ignore_zero:
            note("%d conflicts encountered.\n" % self.conflicts)
            
def get_tree(treespec, local_branch=None):
    location, revno = treespec
    branch = Branch.open_containing(location)[0]
    if revno is None:
        revision = None
    elif revno == -1:
        revision = branch.last_revision()
    else:
        revision = branch.get_rev_id(revno)
    return branch, get_revid_tree(branch, revision, local_branch)

def get_revid_tree(branch, revision, local_branch):
    if revision is None:
        base_tree = branch.working_tree()
    else:
        if local_branch is not None:
            greedy_fetch(local_branch, branch, revision)
            base_tree = local_branch.revision_tree(revision)
        else:
            base_tree = branch.revision_tree(revision)
    return base_tree


def file_exists(tree, file_id):
    return tree.has_filename(tree.id2path(file_id))
    

def build_working_dir(to_dir):
    """Build a working directory in an empty directory.

    to_dir is a directory containing branch metadata but no working files,
    typically constructed by cloning an existing branch. 

    This is split out as a special idiomatic case of merge.  It could
    eventually be done by just building the tree directly calling into 
    lower-level code (e.g. constructing a changeset).
    """
    # RBC 20051019 is this not just 'export' ?
    merge((to_dir, -1), (to_dir, 0), this_dir=to_dir,
          check_clean=False, ignore_zero=True)


def merge(other_revision, base_revision,
          check_clean=True, ignore_zero=False,
          this_dir=None, backup_files=False, merge_type=ApplyMerge3,
          file_list=None):
    """Merge changes into a tree.

    base_revision
        tuple(path, revision) Base for three-way merge.
    other_revision
        tuple(path, revision) Other revision for three-way merge.
    this_dir
        Directory to merge changes into; '.' by default.
    check_clean
        If true, this_dir must have no uncommitted changes before the
        merge begins.
    ignore_zero - If true, suppress the "zero conflicts" message when 
        there are no conflicts; should be set when doing something we expect
        to complete perfectly.

    All available ancestors of other_revision and base_revision are
    automatically pulled into the branch.
    """
    if this_dir is None:
        this_dir = '.'
    this_branch = Branch.open_containing(this_dir)[0]
    this_rev_id = this_branch.last_revision()
    if this_rev_id is None:
        raise BzrCommandError("This branch has no commits")
    if check_clean:
        changes = compare_trees(this_branch.working_tree(), 
                                this_branch.basis_tree(), False)
        if changes.has_changed():
            raise BzrCommandError("Working tree has uncommitted changes.")
    other_branch, other_tree = get_tree(other_revision, this_branch)
    if other_revision[1] == -1:
        other_rev_id = other_branch.last_revision()
        if other_rev_id is None:
            raise NoCommits(other_branch)
        other_basis = other_rev_id
    elif other_revision[1] is not None:
        other_rev_id = other_branch.get_rev_id(other_revision[1])
        other_basis = other_rev_id
    else:
        other_rev_id = None
        other_basis = other_branch.last_revision()
        if other_basis is None:
            raise NoCommits(other_branch)
    if base_revision == [None, None]:
        try:
            base_rev_id = common_ancestor(this_rev_id, other_basis, 
                                          this_branch)
        except NoCommonAncestor:
            raise UnrelatedBranches()
        base_tree = get_revid_tree(this_branch, base_rev_id, None)
        base_is_ancestor = True
    else:
        base_branch, base_tree = get_tree(base_revision)
        if base_revision[1] == -1:
            base_rev_id = base_branch.last_revision()
        elif base_revision[1] is None:
            base_rev_id = None
        else:
            base_rev_id = base_branch.get_rev_id(base_revision[1])
        fetch(from_branch=base_branch, to_branch=this_branch)
        base_is_ancestor = is_ancestor(this_rev_id, base_rev_id,
                                       this_branch)
    if file_list is None:
        interesting_ids = None
    else:
        interesting_ids = set()
        this_tree = this_branch.working_tree()
        for fname in file_list:
            path = this_tree.relpath(fname)
            found_id = False
            for tree in (this_tree, base_tree, other_tree):
                file_id = tree.inventory.path2id(path)
                if file_id is not None:
                    interesting_ids.add(file_id)
                    found_id = True
            if not found_id:
                raise BzrCommandError("%s is not a source file in any"
                                      " tree." % fname)
    merge_inner(this_branch, other_tree, base_tree, tempdir=None, 
                ignore_zero=ignore_zero, backup_files=backup_files, 
                merge_type=merge_type, interesting_ids=interesting_ids)
    if base_is_ancestor and other_rev_id is not None\
        and other_rev_id not in this_branch.revision_history():
        this_branch.add_pending_merge(other_rev_id)


def set_interesting(inventory_a, inventory_b, interesting_ids):
    """Mark files whose ids are in interesting_ids as interesting
    """
    for inventory in (inventory_a, inventory_b):
        for path, source_file in inventory.iteritems():
             source_file.interesting = source_file.id in interesting_ids


def merge_inner(this_branch, other_tree, base_tree, tempdir=None, 
                ignore_zero=False, merge_type=ApplyMerge3, backup_files=False,
                interesting_ids=None):
    """Primary interface for merging. 

    typical use is probably 
    'merge_inner(branch, branch.get_revision_tree(other_revision),
                 branch.get_revision_tree(base_revision))'
    """
    if tempdir is None:
        _tempdir = tempfile.mkdtemp(prefix="bzr-")
    else:
        _tempdir = tempdir
    try:
        _merge_inner(this_branch, other_tree, base_tree, _tempdir,
                     ignore_zero, merge_type, backup_files, interesting_ids)
    finally:
        if tempdir is None:
            shutil.rmtree(_tempdir)


def _merge_inner(this_branch, other_tree, base_tree, user_tempdir, 
                ignore_zero=False, merge_type=ApplyMerge3, backup_files=False,
                interesting_ids=None):
    def merge_factory(file_id, base, other):
        contents_change = merge_type(file_id, base, other)
        if backup_files:
            contents_change = BackupBeforeChange(contents_change)
        return contents_change

    this_tree = get_tree((this_branch.base, None))[1]

    def get_inventory(tree):
        return tree.inventory

    inv_changes = merge_flex(this_tree, base_tree, other_tree,
                             generate_changeset, get_inventory,
                             MergeConflictHandler(this_tree, base_tree,
                             other_tree, ignore_zero=ignore_zero),
                             merge_factory=merge_factory, 
                             interesting_ids=interesting_ids)

    adjust_ids = []
    for id, path in inv_changes.iteritems():
        if path is not None:
            if path == '.':
                path = ''
            else:
                assert path.startswith('.' + os.sep), "path is %s" % path
            path = path[2:]
        adjust_ids.append((path, id))
    if len(adjust_ids) > 0:
        this_branch.set_inventory(regen_inventory(this_branch, 
                                                  this_tree.basedir,
                                                  adjust_ids))


def regen_inventory(this_branch, root, new_entries):
    old_entries = this_branch.read_working_inventory()
    new_inventory = {}
    by_path = {}
    new_entries_map = {} 
    for path, file_id in new_entries:
        if path is None:
            continue
        new_entries_map[file_id] = path

    def id2path(file_id):
        path = new_entries_map.get(file_id)
        if path is not None:
            return path
        entry = old_entries[file_id]
        if entry.parent_id is None:
            return entry.name
        return os.path.join(id2path(entry.parent_id), entry.name)
        
    for file_id in old_entries:
        entry = old_entries[file_id]
        path = id2path(file_id)
        new_inventory[file_id] = (path, file_id, entry.parent_id, entry.kind)
        by_path[path] = file_id
    
    deletions = 0
    insertions = 0
    new_path_list = []
    for path, file_id in new_entries:
        if path is None:
            del new_inventory[file_id]
            deletions += 1
        else:
            new_path_list.append((path, file_id))
            if file_id not in old_entries:
                insertions += 1
    # Ensure no file is added before its parent
    new_path_list.sort()
    for path, file_id in new_path_list:
        if path == '':
            parent = None
        else:
            parent = by_path[os.path.dirname(path)]
        kind = bzrlib.osutils.file_kind(os.path.join(root, path))
        new_inventory[file_id] = (path, file_id, parent, kind)
        by_path[path] = file_id 

    # Get a list in insertion order
    new_inventory_list = new_inventory.values()
    mutter ("""Inventory regeneration:
old length: %i insertions: %i deletions: %i new_length: %i"""\
        % (len(old_entries), insertions, deletions, len(new_inventory_list)))
    assert len(new_inventory_list) == len(old_entries) + insertions - deletions
    new_inventory_list.sort()
    return new_inventory_list

merge_types = {     "merge3": (ApplyMerge3, "Native diff3-style merge"), 
                     "diff3": (Diff3Merge,  "Merge using external diff3")
              }