mercurial/templater.py

convert: keep branch switching merges with ancestors (issue3340)

When running convert with a filemap, merge parents which are ancestors
of other parents are ignored. This is hardly a problem when parents
belong to the same branch, but the result could be confusing when named
branches are involved. With:

  -o-a1-a2-a3...     <- A
    \           \
     b1-b2-b3...-m-  <- B

If all b* revisions are discarded, it is useful to preserve 'm' even if
it is empty after filtering to record the branch switch.

This patch makes filemap preserve "ancestor parents" if there is no
"non-ancestor parent" on the same branch than the merge revision.

Remarks:
- I am not completely convinced by the reasons given above and those
  detailed by Matt in this thread:

http://selenic.com/pipermail/mercurial-devel/2012-May/040627.html

  The properties we try to preserve are not clearly defined. That said,
  I know this patch already helped someone on IRC and the tests output
  look reasonable.

- This is a new version of the original "convert: filemap must preserve
  fast-forward merges" patch. It has exactly the same output for 2
  parents merges, the additional complexity is here to handle more than
  two parents.

# templater.py - template expansion for output
#
# Copyright 2005, 2006 Matt Mackall <[e-mail]>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

from i18n import _
import sys, os
import util, config, templatefilters, parser, error

# template parsing

elements = {
    "(": (20, ("group", 1, ")"), ("func", 1, ")")),
    ",": (2, None, ("list", 2)),
    "|": (5, None, ("|", 5)),
    "%": (6, None, ("%", 6)),
    ")": (0, None, None),
    "symbol": (0, ("symbol",), None),
    "string": (0, ("string",), None),
    "end": (0, None, None),
}

def tokenizer(data):
    program, start, end = data
    pos = start
    while pos < end:
        c = program[pos]
        if c.isspace(): # skip inter-token whitespace
            pass
        elif c in "(,)%|": # handle simple operators
            yield (c, None, pos)
        elif (c in '"\'' or c == 'r' and
              program[pos:pos + 2] in ("r'", 'r"')): # handle quoted strings
            if c == 'r':
                pos += 1
                c = program[pos]
                decode = lambda x: x
            else:
                decode = lambda x: x.decode('string-escape')
            pos += 1
            s = pos
            while pos < end: # find closing quote
                d = program[pos]
                if d == '\\': # skip over escaped characters
                    pos += 2
                    continue
                if d == c:
                    yield ('string', decode(program[s:pos]), s)
                    break
                pos += 1
            else:
                raise error.ParseError(_("unterminated string"), s)
        elif c.isalnum() or c in '_':
            s = pos
            pos += 1
            while pos < end: # find end of symbol
                d = program[pos]
                if not (d.isalnum() or d == "_"):
                    break
                pos += 1
            sym = program[s:pos]
            yield ('symbol', sym, s)
            pos -= 1
        elif c == '}':
            pos += 1
            break
        else:
            raise error.ParseError(_("syntax error"), pos)
        pos += 1
    yield ('end', None, pos)

def compiletemplate(tmpl, context):
    parsed = []
    pos, stop = 0, len(tmpl)
    p = parser.parser(tokenizer, elements)

    while pos < stop:
        n = tmpl.find('{', pos)
        if n < 0:
            parsed.append(("string", tmpl[pos:]))
            break
        if n > 0 and tmpl[n - 1] == '\\':
            # escaped
            parsed.append(("string", tmpl[pos:n - 1] + "{"))
            pos = n + 1
            continue
        if n > pos:
            parsed.append(("string", tmpl[pos:n]))

        pd = [tmpl, n + 1, stop]
        parseres, pos = p.parse(pd)
        parsed.append(parseres)

    return [compileexp(e, context) for e in parsed]

def compileexp(exp, context):
    t = exp[0]
    if t in methods:
        return methods[t](exp, context)
    raise error.ParseError(_("unknown method '%s'") % t)

# template evaluation

def getsymbol(exp):
    if exp[0] == 'symbol':
        return exp[1]
    raise error.ParseError(_("expected a symbol"))

def getlist(x):
    if not x:
        return []
    if x[0] == 'list':
        return getlist(x[1]) + [x[2]]
    return [x]

def getfilter(exp, context):
    f = getsymbol(exp)
    if f not in context._filters:
        raise error.ParseError(_("unknown function '%s'") % f)
    return context._filters[f]

def gettemplate(exp, context):
    if exp[0] == 'string':
        return compiletemplate(exp[1], context)
    if exp[0] == 'symbol':
        return context._load(exp[1])
    raise error.ParseError(_("expected template specifier"))

def runstring(context, mapping, data):
    return data

def runsymbol(context, mapping, key):
    v = mapping.get(key)
    if v is None:
        v = context._defaults.get(key, '')
    if util.safehasattr(v, '__call__'):
        return v(**mapping)
    return v

def buildfilter(exp, context):
    func, data = compileexp(exp[1], context)
    filt = getfilter(exp[2], context)
    return (runfilter, (func, data, filt))

def runfilter(context, mapping, data):
    func, data, filt = data
    return filt(func(context, mapping, data))

def buildmap(exp, context):
    func, data = compileexp(exp[1], context)
    ctmpl = gettemplate(exp[2], context)
    return (runmap, (func, data, ctmpl))

def runmap(context, mapping, data):
    func, data, ctmpl = data
    d = func(context, mapping, data)
    lm = mapping.copy()

    for i in d:
        if isinstance(i, dict):
            lm.update(i)
            for f, d in ctmpl:
                yield f(context, lm, d)
        else:
            # v is not an iterable of dicts, this happen when 'key'
            # has been fully expanded already and format is useless.
            # If so, return the expanded value.
            yield i

def buildfunc(exp, context):
    n = getsymbol(exp[1])
    args = [compileexp(x, context) for x in getlist(exp[2])]
    if n in funcs:
        f = funcs[n]
        return (f, args)
    if n in context._filters:
        if len(args) != 1:
            raise error.ParseError(_("filter %s expects one argument") % n)
        f = context._filters[n]
        return (runfilter, (args[0][0], args[0][1], f))

methods = {
    "string": lambda e, c: (runstring, e[1]),
    "symbol": lambda e, c: (runsymbol, e[1]),
    "group": lambda e, c: compileexp(e[1], c),
#    ".": buildmember,
    "|": buildfilter,
    "%": buildmap,
    "func": buildfunc,
    }

funcs = {
}

# template engine

path = ['templates', '../templates']
stringify = templatefilters.stringify

def _flatten(thing):
    '''yield a single stream from a possibly nested set of iterators'''
    if isinstance(thing, str):
        yield thing
    elif not util.safehasattr(thing, '__iter__'):
        if thing is not None:
            yield str(thing)
    else:
        for i in thing:
            if isinstance(i, str):
                yield i
            elif not util.safehasattr(i, '__iter__'):
                if i is not None:
                    yield str(i)
            elif i is not None:
                for j in _flatten(i):
                    yield j

def parsestring(s, quoted=True):
    '''parse a string using simple c-like syntax.
    string must be in quotes if quoted is True.'''
    if quoted:
        if len(s) < 2 or s[0] != s[-1]:
            raise SyntaxError(_('unmatched quotes'))
        return s[1:-1].decode('string_escape')

    return s.decode('string_escape')

class engine(object):
    '''template expansion engine.

    template expansion works like this. a map file contains key=value
    pairs. if value is quoted, it is treated as string. otherwise, it
    is treated as name of template file.

    templater is asked to expand a key in map. it looks up key, and
    looks for strings like this: {foo}. it expands {foo} by looking up
    foo in map, and substituting it. expansion is recursive: it stops
    when there is no more {foo} to replace.

    expansion also allows formatting and filtering.

    format uses key to expand each item in list. syntax is
    {key%format}.

    filter uses function to transform value. syntax is
    {key|filter1|filter2|...}.'''

    def __init__(self, loader, filters={}, defaults={}):
        self._loader = loader
        self._filters = filters
        self._defaults = defaults
        self._cache = {}

    def _load(self, t):
        '''load, parse, and cache a template'''
        if t not in self._cache:
            self._cache[t] = compiletemplate(self._loader(t), self)
        return self._cache[t]

    def process(self, t, mapping):
        '''Perform expansion. t is name of map element to expand.
        mapping contains added elements for use during expansion. Is a
        generator.'''
        return _flatten(func(self, mapping, data) for func, data in
                         self._load(t))

engines = {'default': engine}

class templater(object):

    def __init__(self, mapfile, filters={}, defaults={}, cache={},
                 minchunk=1024, maxchunk=65536):
        '''set up template engine.
        mapfile is name of file to read map definitions from.
        filters is dict of functions. each transforms a value into another.
        defaults is dict of default map definitions.'''
        self.mapfile = mapfile or 'template'
        self.cache = cache.copy()
        self.map = {}
        self.base = (mapfile and os.path.dirname(mapfile)) or ''
        self.filters = templatefilters.filters.copy()
        self.filters.update(filters)
        self.defaults = defaults
        self.minchunk, self.maxchunk = minchunk, maxchunk
        self.ecache = {}

        if not mapfile:
            return
        if not os.path.exists(mapfile):
            raise util.Abort(_('style not found: %s') % mapfile)

        conf = config.config()
        conf.read(mapfile)

        for key, val in conf[''].items():
            if val[0] in "'\"":
                try:
                    self.cache[key] = parsestring(val)
                except SyntaxError, inst:
                    raise SyntaxError('%s: %s' %
                                      (conf.source('', key), inst.args[0]))
            else:
                val = 'default', val
                if ':' in val[1]:
                    val = val[1].split(':', 1)
                self.map[key] = val[0], os.path.join(self.base, val[1])

    def __contains__(self, key):
        return key in self.cache or key in self.map

    def load(self, t):
        '''Get the template for the given template name. Use a local cache.'''
        if t not in self.cache:
            try:
                self.cache[t] = util.readfile(self.map[t][1])
            except KeyError, inst:
                raise util.Abort(_('"%s" not in template map') % inst.args[0])
            except IOError, inst:
                raise IOError(inst.args[0], _('template file %s: %s') %
                              (self.map[t][1], inst.args[1]))
        return self.cache[t]

    def __call__(self, t, **mapping):
        ttype = t in self.map and self.map[t][0] or 'default'
        if ttype not in self.ecache:
            self.ecache[ttype] = engines[ttype](self.load,
                                                 self.filters, self.defaults)
        proc = self.ecache[ttype]

        stream = proc.process(t, mapping)
        if self.minchunk:
            stream = util.increasingchunks(stream, min=self.minchunk,
                                           max=self.maxchunk)
        return stream

def templatepath(name=None):
    '''return location of template file or directory (if no name).
    returns None if not found.'''
    normpaths = []

    # executable version (py2exe) doesn't support __file__
    if util.mainfrozen():
        module = sys.executable
    else:
        module = __file__
    for f in path:
        if f.startswith('/'):
            p = f
        else:
            fl = f.split('/')
            p = os.path.join(os.path.dirname(module), *fl)
        if name:
            p = os.path.join(p, name)
        if name and os.path.exists(p):
            return os.path.normpath(p)
        elif os.path.isdir(p):
            normpaths.append(os.path.normpath(p))

    return normpaths

def stylemap(styles, paths=None):
    """Return path to mapfile for a given style.

    Searches mapfile in the following locations:
    1. templatepath/style/map
    2. templatepath/map-style
    3. templatepath/map
    """

    if paths is None:
        paths = templatepath()
    elif isinstance(paths, str):
        paths = [paths]

    if isinstance(styles, str):
        styles = [styles]

    for style in styles:
        if not style:
            continue
        locations = [os.path.join(style, 'map'), 'map-' + style]
        locations.append('map')

        for path in paths:
            for location in locations:
                mapfile = os.path.join(path, location)
                if os.path.isfile(mapfile):
                    return style, mapfile

    raise RuntimeError("No hgweb templates found in %r" % paths)