path: root/git/db/py/resolve.py

"""Module with an implementation for refspec parsing. It is the pure-python
version assuming compatible interface for reference and object types"""

from git.db.interface import ReferencesMixin
from git.exc import BadObject
from git.refs import (
    SymbolicReference,
    Reference,
    HEAD,
    Head,
    TagReference
)
from git.refs.head import HEAD
from git.refs.headref import Head
from git.refs.tag import TagReference

from git.objects.base import Object
from git.objects.commit import Commit
from git.util import (
    join,
    isdir,
    isfile,
    hex_to_bin,
    bin_to_hex,
    is_git_dir
)
from string import digits
import os
import re

__all__ = ["PureReferencesMixin"]

#{ Utilities


def short_to_long(odb, hexsha):
    """:return: long hexadecimal sha1 from the given less-than-40 byte hexsha
        or None if no candidate could be found.
    :param hexsha: hexsha with less than 40 byte"""
    try:
        return bin_to_hex(odb.partial_to_complete_sha_hex(hexsha))
    except BadObject:
        return None
    # END exception handling


def name_to_object(repo, name, return_ref=False):
    """
    :return: object specified by the given name, hexshas ( short and long )
        as well as references are supported
    :param return_ref: if name specifies a reference, we will return the reference
        instead of the object. Otherwise it will raise BadObject
    """
    hexsha = None

    # is it a hexsha ? Try the most common ones, which is 7 to 40
    if repo.re_hexsha_shortened.match(name):
        if len(name) != 40:
            # find long sha for short sha
            hexsha = short_to_long(repo.odb, name)
        else:
            hexsha = name
        # END handle short shas
    # END find sha if it matches

    # if we couldn't find an object for what seemed to be a short hexsha
    # try to find it as reference anyway, it could be named 'aaa' for instance
    if hexsha is None:
        for base in ('%s', 'refs/%s', 'refs/tags/%s', 'refs/heads/%s', 'refs/remotes/%s', 'refs/remotes/%s/HEAD'):
            try:
                hexsha = SymbolicReference.dereference_recursive(repo, base % name)
                if return_ref:
                    return SymbolicReference(repo, base % name)
                # END handle symbolic ref
                break
            except ValueError:
                pass
        # END for each base
    # END handle hexsha

    # didn't find any ref, this is an error
    if return_ref:
        raise BadObject("Couldn't find reference named %r" % name)
    # END handle return ref

    # tried everything ? fail
    if hexsha is None:
        raise BadObject(name)
    # END assert hexsha was found

    return Object.new_from_sha(repo, hex_to_bin(hexsha))


def deref_tag(tag):
    """Recursively dereference a tag and return the resulting object"""
    while True:
        try:
            tag = tag.object
        except AttributeError:
            break
    # END dereference tag
    return tag


def to_commit(obj):
    """Convert the given object to a commit if possible and return it"""
    if obj.type == 'tag':
        obj = deref_tag(obj)

    if obj.type != "commit":
        raise ValueError("Cannot convert object %r to type commit" % obj)
    # END verify type
    return obj


def rev_parse(repo, rev):
    """
    :return: Object at the given revision, either Commit, Tag, Tree or Blob
    :param rev: git-rev-parse compatible revision specification, please see
        http://www.kernel.org/pub/software/scm/git/docs/git-rev-parse.html
        for details
    :note: Currently there is no access to the rev-log, rev-specs may only contain
        topological tokens such ~ and ^.
    :raise BadObject: if the given revision could not be found
    :raise ValueError: If rev couldn't be parsed
    :raise IndexError: If invalid reflog index is specified"""

    # colon search mode ?
    if rev.startswith(':/'):
        # colon search mode
        raise NotImplementedError("commit by message search ( regex )")
    # END handle search

    obj = None
    ref = None
    output_type = "commit"
    start = 0
    parsed_to = 0
    lr = len(rev)
    while start < lr:
        if rev[start] not in "^~:@":
            start += 1
            continue
        # END handle start

        token = rev[start]

        if obj is None:
            # token is a rev name
            if start == 0:
                ref = repo.head.ref
            else:
                if token == '@':
                    ref = name_to_object(repo, rev[:start], return_ref=True)
                else:
                    obj = name_to_object(repo, rev[:start])
                # END handle token
            # END handle refname

            if ref is not None:
                obj = ref.commit
            # END handle ref
        # END initialize obj on first token

        start += 1

        # try to parse {type}
        if start < lr and rev[start] == '{':
            end = rev.find('}', start)
            if end == -1:
                raise ValueError("Missing closing brace to define type in %s" % rev)
            output_type = rev[start + 1:end]  # exclude brace

            # handle type
            if output_type == 'commit':
                pass  # default
            elif output_type == 'tree':
                try:
                    obj = to_commit(obj).tree
                except (AttributeError, ValueError):
                    pass    # error raised later
                # END exception handling
            elif output_type in ('', 'blob'):
                if obj.type == 'tag':
                    obj = deref_tag(obj)
                else:
                    # cannot do anything for non-tags
                    pass
                # END handle tag
            elif token == '@':
                # try single int
                assert ref is not None, "Require Reference to access reflog"
                revlog_index = None
                try:
                    # transform reversed index into the format of our revlog
                    revlog_index = -(int(output_type) + 1)
                except ValueError:
                    # TODO: Try to parse the other date options, using parse_date
                    # maybe
                    raise NotImplementedError("Support for additional @{...} modes not implemented")
                # END handle revlog index

                try:
                    entry = ref.log_entry(revlog_index)
                except IndexError:
                    raise IndexError("Invalid revlog index: %i" % revlog_index)
                # END handle index out of bound

                obj = Object.new_from_sha(repo, hex_to_bin(entry.newhexsha))

                # make it pass the following checks
                output_type = None
            else:
                raise ValueError("Invalid output type: %s ( in %s )" % (output_type, rev))
            # END handle output type

            # empty output types don't require any specific type, its just about dereferencing tags
            if output_type and obj.type != output_type:
                raise ValueError("Could not accomodate requested object type %r, got %s" % (output_type, obj.type))
            # END verify ouput type

            start = end + 1                   # skip brace
            parsed_to = start
            continue
        # END parse type

        # try to parse a number
        num = 0
        if token != ":":
            found_digit = False
            while start < lr:
                if rev[start] in digits:
                    num = num * 10 + int(rev[start])
                    start += 1
                    found_digit = True
                else:
                    break
                # END handle number
            # END number parse loop

            # no explicit number given, 1 is the default
            # It could be 0 though
            if not found_digit:
                num = 1
            # END set default num
        # END number parsing only if non-blob mode

        parsed_to = start
        # handle hiererarchy walk
        try:
            if token == "~":
                obj = to_commit(obj)
                for item in xrange(num):
                    obj = obj.parents[0]
                # END for each history item to walk
            elif token == "^":
                obj = to_commit(obj)
                # must be n'th parent
                if num:
                    obj = obj.parents[num - 1]
            elif token == ":":
                if obj.type != "tree":
                    obj = obj.tree
                # END get tree type
                obj = obj[rev[start:]]
                parsed_to = lr
            else:
                raise ValueError("Invalid token: %r" % token)
            # END end handle tag
        except (IndexError, AttributeError):
            raise BadObject("Invalid Revision in %s" % rev)
        # END exception handling
    # END parse loop

    # still no obj ? Its probably a simple name
    if obj is None:
        obj = name_to_object(repo, rev)
        parsed_to = lr
    # END handle simple name

    if obj is None:
        raise ValueError("Revision specifier could not be parsed: %s" % rev)

    if parsed_to != lr:
        raise ValueError("Didn't consume complete rev spec %s, consumed part: %s" % (rev, rev[:parsed_to]))

    return obj

#} END utilities


class PureReferencesMixin(ReferencesMixin):

    """Pure-Python refparse implementation"""

    re_hexsha_only = re.compile('^[0-9A-Fa-f]{40}$')
    re_hexsha_shortened = re.compile('^[0-9A-Fa-f]{4,40}$')

    #{ Configuration
    # Types to use when instatiating references
    TagReferenceCls = TagReference
    HeadCls = Head
    ReferenceCls = Reference
    HEADCls = HEAD
    CommitCls = Commit
    #} END configuration

    def resolve(self, name):
        return self.resolve_object(name).binsha

    def resolve_object(self, name):
        return rev_parse(self, name)

    @property
    def references(self):
        return self.ReferenceCls.list_items(self)

    @property
    def heads(self):
        return self.HeadCls.list_items(self)

    @property
    def tags(self):
        return self.TagReferenceCls.list_items(self)

    def tag(self, name):
        return self.TagReferenceCls(self, self.TagReferenceCls.to_full_path(name))

    def commit(self, rev=None):
        if rev is None:
            return self.head.commit
        else:
            return self.resolve_object(str(rev) + "^0")
        # END handle revision

    def iter_trees(self, *args, **kwargs):
        return (c.tree for c in self.iter_commits(*args, **kwargs))

    def tree(self, rev=None):
        if rev is None:
            return self.head.commit.tree
        else:
            return self.resolve_object(str(rev) + "^{tree}")

    def iter_commits(self, rev=None, paths='', **kwargs):
        if rev is None:
            rev = self.head.commit

        return self.CommitCls.iter_items(self, rev, paths, **kwargs)

    @property
    def head(self):
        return self.HEADCls(self, 'HEAD')

    def create_head(self, path, commit='HEAD', force=False, logmsg=None):
        return self.HeadCls.create(self, path, commit, force, logmsg)

    def delete_head(self, *heads, **kwargs):
        return self.HeadCls.delete(self, *heads, **kwargs)

    def create_tag(self, path, ref='HEAD', message=None, force=False, **kwargs):
        return self.TagReferenceCls.create(self, path, ref, message, force, **kwargs)

    def delete_tag(self, *tags):
        return self.TagReferenceCls.delete(self, *tags)