Teach new infrastructure to diff two trees

[stgit] / stgit / lib / git.py

import os, os.path, re
from stgit import exception, run, utils
from stgit.config import config

class RepositoryException(exception.StgException):
    pass

class DetachedHeadException(RepositoryException):
    def __init__(self):
        RepositoryException.__init__(self, 'Not on any branch')

class Repr(object):
    def __repr__(self):
        return str(self)

class NoValue(object):
    pass

def make_defaults(defaults):
    def d(val, attr):
        if val != NoValue:
            return val
        elif defaults != NoValue:
            return getattr(defaults, attr)
        else:
            return None
    return d

class Person(Repr):
    """Immutable."""
    def __init__(self, name = NoValue, email = NoValue,
                 date = NoValue, defaults = NoValue):
        d = make_defaults(defaults)
        self.__name = d(name, 'name')
        self.__email = d(email, 'email')
        self.__date = d(date, 'date')
    name = property(lambda self: self.__name)
    email = property(lambda self: self.__email)
    date = property(lambda self: self.__date)
    def set_name(self, name):
        return type(self)(name = name, defaults = self)
    def set_email(self, email):
        return type(self)(email = email, defaults = self)
    def set_date(self, date):
        return type(self)(date = date, defaults = self)
    def __str__(self):
        return '%s <%s> %s' % (self.name, self.email, self.date)
    @classmethod
    def parse(cls, s):
        m = re.match(r'^([^<]*)<([^>]*)>\s+(\d+\s+[+-]\d{4})$', s)
        assert m
        name = m.group(1).strip()
        email = m.group(2)
        date = m.group(3)
        return cls(name, email, date)
    @classmethod
    def user(cls):
        if not hasattr(cls, '__user'):
            cls.__user = cls(name = config.get('user.name'),
                             email = config.get('user.email'))
        return cls.__user
    @classmethod
    def author(cls):
        if not hasattr(cls, '__author'):
            cls.__author = cls(
                name = os.environ.get('GIT_AUTHOR_NAME', NoValue),
                email = os.environ.get('GIT_AUTHOR_EMAIL', NoValue),
                date = os.environ.get('GIT_AUTHOR_DATE', NoValue),
                defaults = cls.user())
        return cls.__author
    @classmethod
    def committer(cls):
        if not hasattr(cls, '__committer'):
            cls.__committer = cls(
                name = os.environ.get('GIT_COMMITTER_NAME', NoValue),
                email = os.environ.get('GIT_COMMITTER_EMAIL', NoValue),
                date = os.environ.get('GIT_COMMITTER_DATE', NoValue),
                defaults = cls.user())
        return cls.__committer

class Tree(Repr):
    """Immutable."""
    def __init__(self, sha1):
        self.__sha1 = sha1
    sha1 = property(lambda self: self.__sha1)
    def __str__(self):
        return 'Tree<%s>' % self.sha1

class Commitdata(Repr):
    """Immutable."""
    def __init__(self, tree = NoValue, parents = NoValue, author = NoValue,
                 committer = NoValue, message = NoValue, defaults = NoValue):
        d = make_defaults(defaults)
        self.__tree = d(tree, 'tree')
        self.__parents = d(parents, 'parents')
        self.__author = d(author, 'author')
        self.__committer = d(committer, 'committer')
        self.__message = d(message, 'message')
    tree = property(lambda self: self.__tree)
    parents = property(lambda self: self.__parents)
    @property
    def parent(self):
        assert len(self.__parents) == 1
        return self.__parents[0]
    author = property(lambda self: self.__author)
    committer = property(lambda self: self.__committer)
    message = property(lambda self: self.__message)
    def set_tree(self, tree):
        return type(self)(tree = tree, defaults = self)
    def set_parents(self, parents):
        return type(self)(parents = parents, defaults = self)
    def add_parent(self, parent):
        return type(self)(parents = list(self.parents or []) + [parent],
                          defaults = self)
    def set_parent(self, parent):
        return self.set_parents([parent])
    def set_author(self, author):
        return type(self)(author = author, defaults = self)
    def set_committer(self, committer):
        return type(self)(committer = committer, defaults = self)
    def set_message(self, message):
        return type(self)(message = message, defaults = self)
    def is_nochange(self):
        return len(self.parents) == 1 and self.tree == self.parent.data.tree
    def __str__(self):
        if self.tree == None:
            tree = None
        else:
            tree = self.tree.sha1
        if self.parents == None:
            parents = None
        else:
            parents = [p.sha1 for p in self.parents]
        return ('Commitdata<tree: %s, parents: %s, author: %s,'
                ' committer: %s, message: "%s">'
                ) % (tree, parents, self.author, self.committer, self.message)
    @classmethod
    def parse(cls, repository, s):
        cd = cls()
        lines = list(s.splitlines(True))
        for i in xrange(len(lines)):
            line = lines[i].strip()
            if not line:
                return cd.set_message(''.join(lines[i+1:]))
            key, value = line.split(None, 1)
            if key == 'tree':
                cd = cd.set_tree(repository.get_tree(value))
            elif key == 'parent':
                cd = cd.add_parent(repository.get_commit(value))
            elif key == 'author':
                cd = cd.set_author(Person.parse(value))
            elif key == 'committer':
                cd = cd.set_committer(Person.parse(value))
            else:
                assert False
        assert False

class Commit(Repr):
    """Immutable."""
    def __init__(self, repository, sha1):
        self.__sha1 = sha1
        self.__repository = repository
        self.__data = None
    sha1 = property(lambda self: self.__sha1)
    @property
    def data(self):
        if self.__data == None:
            self.__data = Commitdata.parse(
                self.__repository,
                self.__repository.cat_object(self.sha1))
        return self.__data
    def __str__(self):
        return 'Commit<sha1: %s, data: %s>' % (self.sha1, self.__data)

class Refs(object):
    def __init__(self, repository):
        self.__repository = repository
        self.__refs = None
    def __cache_refs(self):
        self.__refs = {}
        for line in self.__repository.run(['git', 'show-ref']).output_lines():
            m = re.match(r'^([0-9a-f]{40})\s+(\S+)$', line)
            sha1, ref = m.groups()
            self.__refs[ref] = sha1
    def get(self, ref):
        """Throws KeyError if ref doesn't exist."""
        if self.__refs == None:
            self.__cache_refs()
        return self.__repository.get_commit(self.__refs[ref])
    def exists(self, ref):
        try:
            self.get(ref)
        except KeyError:
            return False
        else:
            return True
    def set(self, ref, commit, msg):
        if self.__refs == None:
            self.__cache_refs()
        old_sha1 = self.__refs.get(ref, '0'*40)
        new_sha1 = commit.sha1
        if old_sha1 != new_sha1:
            self.__repository.run(['git', 'update-ref', '-m', msg,
                                   ref, new_sha1, old_sha1]).no_output()
            self.__refs[ref] = new_sha1
    def delete(self, ref):
        if self.__refs == None:
            self.__cache_refs()
        self.__repository.run(['git', 'update-ref',
                               '-d', ref, self.__refs[ref]]).no_output()
        del self.__refs[ref]

class ObjectCache(object):
    """Cache for Python objects, for making sure that we create only one
    Python object per git object."""
    def __init__(self, create):
        self.__objects = {}
        self.__create = create
    def __getitem__(self, name):
        if not name in self.__objects:
            self.__objects[name] = self.__create(name)
        return self.__objects[name]
    def __contains__(self, name):
        return name in self.__objects
    def __setitem__(self, name, val):
        assert not name in self.__objects
        self.__objects[name] = val

class RunWithEnv(object):
    def run(self, args, env = {}):
        return run.Run(*args).env(utils.add_dict(self.env, env))

class Repository(RunWithEnv):
    def __init__(self, directory):
        self.__git_dir = directory
        self.__refs = Refs(self)
        self.__trees = ObjectCache(lambda sha1: Tree(sha1))
        self.__commits = ObjectCache(lambda sha1: Commit(self, sha1))
        self.__default_index = None
        self.__default_worktree = None
        self.__default_iw = None
    env = property(lambda self: { 'GIT_DIR': self.__git_dir })
    @classmethod
    def default(cls):
        """Return the default repository."""
        try:
            return cls(run.Run('git', 'rev-parse', '--git-dir'
                               ).output_one_line())
        except run.RunException:
            raise RepositoryException('Cannot find git repository')
    @property
    def default_index(self):
        if self.__default_index == None:
            self.__default_index = Index(
                self, (os.environ.get('GIT_INDEX_FILE', None)
                       or os.path.join(self.__git_dir, 'index')))
        return self.__default_index
    def temp_index(self):
        return Index(self, self.__git_dir)
    @property
    def default_worktree(self):
        if self.__default_worktree == None:
            path = os.environ.get('GIT_WORK_TREE', None)
            if not path:
                o = run.Run('git', 'rev-parse', '--show-cdup').output_lines()
                o = o or ['.']
                assert len(o) == 1
                path = o[0]
            self.__default_worktree = Worktree(path)
        return self.__default_worktree
    @property
    def default_iw(self):
        if self.__default_iw == None:
            self.__default_iw = IndexAndWorktree(self.default_index,
                                                 self.default_worktree)
        return self.__default_iw
    directory = property(lambda self: self.__git_dir)
    refs = property(lambda self: self.__refs)
    def cat_object(self, sha1):
        return self.run(['git', 'cat-file', '-p', sha1]).raw_output()
    def rev_parse(self, rev):
        try:
            return self.get_commit(self.run(
                    ['git', 'rev-parse', '%s^{commit}' % rev]
                    ).output_one_line())
        except run.RunException:
            raise RepositoryException('%s: No such revision' % rev)
    def get_tree(self, sha1):
        return self.__trees[sha1]
    def get_commit(self, sha1):
        return self.__commits[sha1]
    def commit(self, commitdata):
        c = ['git', 'commit-tree', commitdata.tree.sha1]
        for p in commitdata.parents:
            c.append('-p')
            c.append(p.sha1)
        env = {}
        for p, v1 in ((commitdata.author, 'AUTHOR'),
                       (commitdata.committer, 'COMMITTER')):
            if p != None:
                for attr, v2 in (('name', 'NAME'), ('email', 'EMAIL'),
                                 ('date', 'DATE')):
                    if getattr(p, attr) != None:
                        env['GIT_%s_%s' % (v1, v2)] = getattr(p, attr)
        sha1 = self.run(c, env = env).raw_input(commitdata.message
                                                ).output_one_line()
        return self.get_commit(sha1)
    @property
    def head(self):
        try:
            return self.run(['git', 'symbolic-ref', '-q', 'HEAD']
                            ).output_one_line()
        except run.RunException:
            raise DetachedHeadException()
    def set_head(self, ref, msg):
        self.run(['git', 'symbolic-ref', '-m', msg, 'HEAD', ref]).no_output()
    def simple_merge(self, base, ours, theirs):
        """Given three trees, tries to do an in-index merge in a temporary
        index with a temporary index. Returns the result tree, or None if
        the merge failed (due to conflicts)."""
        assert isinstance(base, Tree)
        assert isinstance(ours, Tree)
        assert isinstance(theirs, Tree)

        # Take care of the really trivial cases.
        if base == ours:
            return theirs
        if base == theirs:
            return ours
        if ours == theirs:
            return ours

        index = self.temp_index()
        try:
            index.merge(base, ours, theirs)
            try:
                return index.write_tree()
            except MergeException:
                return None
        finally:
            index.delete()
    def apply(self, tree, patch_text):
        """Given a tree and a patch, will either return the new tree that
        results when the patch is applied, or None if the patch
        couldn't be applied."""
        assert isinstance(tree, Tree)
        if not patch_text:
            return tree
        index = self.temp_index()
        try:
            index.read_tree(tree)
            try:
                index.apply(patch_text)
                return index.write_tree()
            except MergeException:
                return None
        finally:
            index.delete()
    def diff_tree(self, t1, t2, diff_opts):
        assert isinstance(t1, Tree)
        assert isinstance(t2, Tree)
        return self.run(['git', 'diff-tree', '-p'] + list(diff_opts)
                        + [t1.sha1, t2.sha1]).raw_output()

class MergeException(exception.StgException):
    pass

class Index(RunWithEnv):
    def __init__(self, repository, filename):
        self.__repository = repository
        if os.path.isdir(filename):
            # Create a temp index in the given directory.
            self.__filename = os.path.join(
                filename, 'index.temp-%d-%x' % (os.getpid(), id(self)))
            self.delete()
        else:
            self.__filename = filename
    env = property(lambda self: utils.add_dict(
            self.__repository.env, { 'GIT_INDEX_FILE': self.__filename }))
    def read_tree(self, tree):
        self.run(['git', 'read-tree', tree.sha1]).no_output()
    def write_tree(self):
        try:
            return self.__repository.get_tree(
                self.run(['git', 'write-tree']).discard_stderr(
                    ).output_one_line())
        except run.RunException:
            raise MergeException('Conflicting merge')
    def is_clean(self):
        try:
            self.run(['git', 'update-index', '--refresh']).discard_output()
        except run.RunException:
            return False
        else:
            return True
    def merge(self, base, ours, theirs):
        """In-index merge, no worktree involved."""
        self.run(['git', 'read-tree', '-m', '-i', '--aggressive',
                  base.sha1, ours.sha1, theirs.sha1]).no_output()
    def apply(self, patch_text):
        """In-index patch application, no worktree involved."""
        try:
            self.run(['git', 'apply', '--cached']
                     ).raw_input(patch_text).no_output()
        except run.RunException:
            raise MergeException('Patch does not apply cleanly')
    def delete(self):
        if os.path.isfile(self.__filename):
            os.remove(self.__filename)
    def conflicts(self):
        """The set of conflicting paths."""
        paths = set()
        for line in self.run(['git', 'ls-files', '-z', '--unmerged']
                             ).raw_output().split('\0')[:-1]:
            stat, path = line.split('\t', 1)
            paths.add(path)
        return paths

class Worktree(object):
    def __init__(self, directory):
        self.__directory = directory
    env = property(lambda self: { 'GIT_WORK_TREE': self.__directory })
    directory = property(lambda self: self.__directory)

class CheckoutException(exception.StgException):
    pass

class IndexAndWorktree(RunWithEnv):
    def __init__(self, index, worktree):
        self.__index = index
        self.__worktree = worktree
    index = property(lambda self: self.__index)
    env = property(lambda self: utils.add_dict(self.__index.env,
                                               self.__worktree.env))
    def checkout(self, old_tree, new_tree):
        # TODO: Optionally do a 3-way instead of doing nothing when we
        # have a problem. Or maybe we should stash changes in a patch?
        assert isinstance(old_tree, Tree)
        assert isinstance(new_tree, Tree)
        try:
            self.run(['git', 'read-tree', '-u', '-m',
                      '--exclude-per-directory=.gitignore',
                      old_tree.sha1, new_tree.sha1]
                     ).cwd(self.__worktree.directory).discard_output()
        except run.RunException:
            raise CheckoutException('Index/workdir dirty')
    def merge(self, base, ours, theirs):
        assert isinstance(base, Tree)
        assert isinstance(ours, Tree)
        assert isinstance(theirs, Tree)
        try:
            self.run(['git', 'merge-recursive', base.sha1, '--', ours.sha1,
                      theirs.sha1],
                     env = { 'GITHEAD_%s' % base.sha1: 'ancestor',
                             'GITHEAD_%s' % ours.sha1: 'current',
                             'GITHEAD_%s' % theirs.sha1: 'patched'}
                     ).cwd(self.__worktree.directory).discard_output()
        except run.RunException, e:
            raise MergeException('Index/worktree dirty')
    def changed_files(self):
        return self.run(['git', 'diff-files', '--name-only']).output_lines()
    def update_index(self, files):
        self.run(['git', 'update-index', '--remove', '-z', '--stdin']
                 ).input_nulterm(files).discard_output()