# keyword.py - keyword expansion for mercurial

'''keyword expansion hack against the grain of a DSCM

This extension lets you expand RCS/CVS-like keywords in a Mercurial

repository.

There are many good reasons why this is not needed in a distributed

SCM, still it may be useful in very small projects based on single

files (like LaTeX packages), that are mostly addressed to an audience

not running a version control system.

    Revision: changeset id

    Author:   full username

    Date:     %a %b %d %H:%M:%S %Y %z $

    RCSFile:  basename,v

    Source:   /path/to/basename,v

    Id:       basename,v csetid %Y-%m-%d %H:%M:%S %z shortname

    Header:   /path/to/basename,v csetid %Y-%m-%d %H:%M:%S %z shortname

Simple setup in hgrc:

    # enable extension

    hgext.keyword =

    # filename patterns for expansion are configured in this section

    [keyword]

    **.py = expand

    ...

'''

import os.path, re

re_kw = re.compile(

        r'\$(Id|Header|Author|Date|Revision|RCSFile|Source)[^$]*?\$')

def kwexpand(matchobj, repo, path, changeid=None, fileid=None, filelog=None):

    Sets supported keywords as local variables and evaluates them to

    their expansion if matchobj is equal to string representation.'''

    c = context.filectx(repo, path,

            changeid=changeid, fileid=fileid, filelog=filelog)

    date = c.date()

    Revision = c.changectx()

    Author = c.user()

    RCSFile = os.path.basename(path)+',v'

    Source = repo.wjoin(path)+',v'

    Date = util.datestr(date=date)

    revdateauth = '%s %s %s' % (Revision,

            util.datestr(date=date, format=util.defaultdateformats[0]),

            util.shortuser(Author))

    Header = '%s %s' % (Source, revdateauth)

    Id = '%s %s' % (RCSFile, revdateauth)

    return '$%s: %s $' % (matchobj.group(1), eval(matchobj.group(1)))

def kwfmatches(ui, repo, files):

    '''Selects candidates for keyword substitution

    configured in keyword section in hgrc.'''

    files = [f for f in files if not f.startswith('.hg')]

    if not files:

        return []

    candidates = []

    fmatchers = [util.matcher(repo.root, '', [pat], [], [])[1]

            for pat, opt in ui.configitems('keyword')

            if opt == 'expand']

    for f in files:

        for mf in fmatchers:

            if mf(f):

                candidates.append(f)

                break

    return candidates

def reposetup(ui, repo):

    if not repo.local():

        return

    class kwrepo(repo.__class__):

        def file(self, f):

            if f[0] == '/':

                f = f[1:]

            return filelog.filelog(self.sopener, f, self, self.revlogversion)

    class kwfilelog(filelog.filelog):

        '''

        Superclass over filelog to customize it's read, add, cmp methods.

        Keywords are "stored" unexpanded, and expanded on reading.

        '''

        def __init__(self, opener, path, repo,

                     defversion=revlog.REVLOG_DEFAULT_VERSION):

            super(kwfilelog, self).__init__(opener, path, defversion)

            self._repo = repo

            self._path = path

        def iskwcandidate(self, data):

            '''Decides whether to act on keywords.'''

            return (kwfmatches(ui, self._repo, [self._path])

                    and not util.binary(data))

        def read(self, node):

            '''Substitutes keywords when reading filelog.'''

            data = super(kwfilelog, self).read(node)

            if self.iskwcandidate(data):

                return re_kw.sub(lambda m:

                        kwexpand(m, self._repo, self._path,

                            fileid=node, filelog=self), data)

            return data

        def add(self, text, meta, tr, link, p1=None, p2=None):

            '''Removes keyword substitutions when adding to filelog.'''

            if self.iskwcandidate(text):

                text = re_kw.sub(r'$\1$', text)

            return super(kwfilelog, self).add(text,

                    meta, tr, link, p1=None, p2=None)

        def cmp(self, node, text):

            '''Removes keyword substitutions for comparison.'''

            if self.iskwcandidate(text):

                text = re_kw.sub(r'$\1$', text)

            return super(kwfilelog, self).cmp(node, text)

    filelog.filelog = kwfilelog

    repo.__class__ = kwrepo