view mercurial/templater.py @ 25018:93e015a3d1ea

commit: add ui.allowemptycommit config option

This adds a config flag that enables a user to make empty commits.
This is useful in a number of cases.

For instance, automation that creates release branches via
bookmarks may want to make empty commits to that release bookmark so that it
can't be fast-forwarded and so it can record information about the release
bookmark's creation. This is already possible with named branches, so making it
possible for bookmarks makes sense.

Another case we've wanted it is for mirroring repositories into Mercurial. We
have automation that syncs commits into hg by running things from the command
line. The ability to produce empty commits is useful for syncing unusual commits
from other VCS's.

In general, allowing the user to create the DAG as they see fit seems useful,
and when I mentioned this in IRC more than one person piped up and said they
were already hacking around this limitation by using mq, import, and
commit-dummy-change-then-amend-the-content-away style solutions.

# 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 os, re
import util, config, templatefilters, templatekw, parser, error
import revset as revsetmod
import types
import minirst

# template parsing

elements = {
    "(": (20, ("group", 1, ")"), ("func", 1, ")")),
    ",": (2, None, ("list", 2)),
    "|": (5, None, ("|", 5)),
    "%": (6, None, ("%", 6)),
    ")": (0, None, None),
    "integer": (0, ("integer",), None),
    "symbol": (0, ("symbol",), None),
    "string": (0, ("string",), None),
    "rawstring": (0, ("rawstring",), 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 = False
            else:
                decode = True
            pos += 1
            s = pos
            while pos < end: # find closing quote
                d = program[pos]
                if decode and d == '\\': # skip over escaped characters
                    pos += 2
                    continue
                if d == c:
                    if not decode:
                        yield ('rawstring', program[s:pos], s)
                        break
                    yield ('string', program[s:pos], s)
                    break
                pos += 1
            else:
                raise error.ParseError(_("unterminated string"), s)
        elif c.isdigit() or c == '-':
            s = pos
            if c == '-': # simply take negate operator as part of integer
                pos += 1
            if pos >= end or not program[pos].isdigit():
                raise error.ParseError(_("integer literal without digits"), s)
            pos += 1
            while pos < end:
                d = program[pos]
                if not d.isdigit():
                    break
                pos += 1
            yield ('integer', program[s:pos], s)
            pos -= 1
        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, strtoken="string"):
    parsed = []
    pos, stop = 0, len(tmpl)
    p = parser.parser(tokenizer, elements)
    while pos < stop:
        n = tmpl.find('{', pos)
        if n < 0:
            parsed.append((strtoken, tmpl[pos:]))
            break
        bs = (n - pos) - len(tmpl[pos:n].rstrip('\\'))
        if strtoken == 'string' and bs % 2 == 1:
            # escaped (e.g. '\{', '\\\{', but not '\\{' nor r'\{')
            parsed.append((strtoken, (tmpl[pos:n - 1] + "{")))
            pos = n + 1
            continue
        if n > pos:
            parsed.append((strtoken, tmpl[pos:n]))

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

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

def compileexp(exp, context, curmethods):
    t = exp[0]
    if t in curmethods:
        return curmethods[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, got '%s'") % exp[0])

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

def runinteger(context, mapping, data):
    return int(data)

def runstring(context, mapping, data):
    return data.decode("string-escape")

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

def runsymbol(context, mapping, key):
    v = mapping.get(key)
    if v is None:
        v = context._defaults.get(key)
    if v is None:
        try:
            v = context.process(key, mapping)
        except TemplateNotFound:
            v = ''
    if callable(v):
        return v(**mapping)
    if isinstance(v, types.GeneratorType):
        v = list(v)
    return v

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

def runfilter(context, mapping, data):
    func, data, filt = data
    # func() may return string, generator of strings or arbitrary object such
    # as date tuple, but filter does not want generator.
    thing = func(context, mapping, data)
    if isinstance(thing, types.GeneratorType):
        thing = stringify(thing)
    try:
        return filt(thing)
    except (ValueError, AttributeError, TypeError):
        if isinstance(data, tuple):
            dt = data[1]
        else:
            dt = data
        raise util.Abort(_("template filter '%s' is not compatible with "
                           "keyword '%s'") % (filt.func_name, dt))

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

def runtemplate(context, mapping, template):
    for func, data in template:
        yield func(context, mapping, data)

def runmap(context, mapping, data):
    func, data, ctmpl = data
    d = func(context, mapping, data)
    if callable(d):
        d = d()

    lm = mapping.copy()

    for i in d:
        if isinstance(i, dict):
            lm.update(i)
            lm['originalnode'] = mapping.get('node')
            yield runtemplate(context, lm, ctmpl)
        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, exprmethods) 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))
    raise error.ParseError(_("unknown function '%s'") % n)

def date(context, mapping, args):
    """:date(date[, fmt]): Format a date. See :hg:`help dates` for formatting
    strings."""
    if not (1 <= len(args) <= 2):
        # i18n: "date" is a keyword
        raise error.ParseError(_("date expects one or two arguments"))

    date = args[0][0](context, mapping, args[0][1])
    fmt = None
    if len(args) == 2:
        fmt = stringify(args[1][0](context, mapping, args[1][1]))
    try:
        if fmt is None:
            return util.datestr(date)
        else:
            return util.datestr(date, fmt)
    except (TypeError, ValueError):
        # i18n: "date" is a keyword
        raise error.ParseError(_("date expects a date information"))

def diff(context, mapping, args):
    """:diff([includepattern [, excludepattern]]): Show a diff, optionally
    specifying files to include or exclude."""
    if len(args) > 2:
        # i18n: "diff" is a keyword
        raise error.ParseError(_("diff expects one, two or no arguments"))

    def getpatterns(i):
        if i < len(args):
            s = args[i][1].strip()
            if s:
                return [s]
        return []

    ctx = mapping['ctx']
    chunks = ctx.diff(match=ctx.match([], getpatterns(0), getpatterns(1)))

    return ''.join(chunks)

def fill(context, mapping, args):
    """:fill(text[, width[, initialident[, hangindent]]]): Fill many
    paragraphs with optional indentation. See the "fill" filter."""
    if not (1 <= len(args) <= 4):
        # i18n: "fill" is a keyword
        raise error.ParseError(_("fill expects one to four arguments"))

    text = stringify(args[0][0](context, mapping, args[0][1]))
    width = 76
    initindent = ''
    hangindent = ''
    if 2 <= len(args) <= 4:
        try:
            width = int(stringify(args[1][0](context, mapping, args[1][1])))
        except ValueError:
            # i18n: "fill" is a keyword
            raise error.ParseError(_("fill expects an integer width"))
        try:
            initindent = stringify(_evalifliteral(args[2], context, mapping))
            hangindent = stringify(_evalifliteral(args[3], context, mapping))
        except IndexError:
            pass

    return templatefilters.fill(text, width, initindent, hangindent)

def pad(context, mapping, args):
    """:pad(text, width[, fillchar=' '[, right=False]]): Pad text with a
    fill character."""
    if not (2 <= len(args) <= 4):
        # i18n: "pad" is a keyword
        raise error.ParseError(_("pad() expects two to four arguments"))

    width = int(args[1][1])

    text = stringify(args[0][0](context, mapping, args[0][1]))
    if args[0][0] == runstring:
        text = stringify(runtemplate(context, mapping,
            compiletemplate(text, context)))

    right = False
    fillchar = ' '
    if len(args) > 2:
        fillchar = stringify(args[2][0](context, mapping, args[2][1]))
    if len(args) > 3:
        right = util.parsebool(args[3][1])

    if right:
        return text.rjust(width, fillchar)
    else:
        return text.ljust(width, fillchar)

def get(context, mapping, args):
    """:get(dict, key): Get an attribute/key from an object. Some keywords
    are complex types. This function allows you to obtain the value of an
    attribute on these type."""
    if len(args) != 2:
        # i18n: "get" is a keyword
        raise error.ParseError(_("get() expects two arguments"))

    dictarg = args[0][0](context, mapping, args[0][1])
    if not util.safehasattr(dictarg, 'get'):
        # i18n: "get" is a keyword
        raise error.ParseError(_("get() expects a dict as first argument"))

    key = args[1][0](context, mapping, args[1][1])
    yield dictarg.get(key)

def _evalifliteral(arg, context, mapping):
    t = stringify(arg[0](context, mapping, arg[1]))
    if arg[0] == runstring or arg[0] == runrawstring:
        yield runtemplate(context, mapping,
                          compiletemplate(t, context, strtoken='rawstring'))
    else:
        yield t

def if_(context, mapping, args):
    """:if(expr, then[, else]): Conditionally execute based on the result of
    an expression."""
    if not (2 <= len(args) <= 3):
        # i18n: "if" is a keyword
        raise error.ParseError(_("if expects two or three arguments"))

    test = stringify(args[0][0](context, mapping, args[0][1]))
    if test:
        yield _evalifliteral(args[1], context, mapping)
    elif len(args) == 3:
        yield _evalifliteral(args[2], context, mapping)

def ifcontains(context, mapping, args):
    """:ifcontains(search, thing, then[, else]): Conditionally execute based
    on whether the item "search" is in "thing"."""
    if not (3 <= len(args) <= 4):
        # i18n: "ifcontains" is a keyword
        raise error.ParseError(_("ifcontains expects three or four arguments"))

    item = stringify(args[0][0](context, mapping, args[0][1]))
    items = args[1][0](context, mapping, args[1][1])

    if item in items:
        yield _evalifliteral(args[2], context, mapping)
    elif len(args) == 4:
        yield _evalifliteral(args[3], context, mapping)

def ifeq(context, mapping, args):
    """:ifeq(expr1, expr2, then[, else]): Conditionally execute based on
    whether 2 items are equivalent."""
    if not (3 <= len(args) <= 4):
        # i18n: "ifeq" is a keyword
        raise error.ParseError(_("ifeq expects three or four arguments"))

    test = stringify(args[0][0](context, mapping, args[0][1]))
    match = stringify(args[1][0](context, mapping, args[1][1]))
    if test == match:
        yield _evalifliteral(args[2], context, mapping)
    elif len(args) == 4:
        yield _evalifliteral(args[3], context, mapping)

def join(context, mapping, args):
    """:join(list, sep): Join items in a list with a delimiter."""
    if not (1 <= len(args) <= 2):
        # i18n: "join" is a keyword
        raise error.ParseError(_("join expects one or two arguments"))

    joinset = args[0][0](context, mapping, args[0][1])
    if callable(joinset):
        jf = joinset.joinfmt
        joinset = [jf(x) for x in joinset()]

    joiner = " "
    if len(args) > 1:
        joiner = stringify(args[1][0](context, mapping, args[1][1]))

    first = True
    for x in joinset:
        if first:
            first = False
        else:
            yield joiner
        yield x

def label(context, mapping, args):
    """:label(label, expr): Apply a label to generated content. Content with
    a label applied can result in additional post-processing, such as
    automatic colorization."""
    if len(args) != 2:
        # i18n: "label" is a keyword
        raise error.ParseError(_("label expects two arguments"))

    # ignore args[0] (the label string) since this is supposed to be a a no-op
    yield _evalifliteral(args[1], context, mapping)

def revset(context, mapping, args):
    """:revset(query[, formatargs...]): Execute a revision set query. See
    :hg:`help revset`."""
    if not len(args) > 0:
        # i18n: "revset" is a keyword
        raise error.ParseError(_("revset expects one or more arguments"))

    raw = args[0][1]
    ctx = mapping['ctx']
    repo = ctx.repo()

    def query(expr):
        m = revsetmod.match(repo.ui, expr)
        return m(repo)

    if len(args) > 1:
        formatargs = list([a[0](context, mapping, a[1]) for a in args[1:]])
        revs = query(revsetmod.formatspec(raw, *formatargs))
        revs = list([str(r) for r in revs])
    else:
        revsetcache = mapping['cache'].setdefault("revsetcache", {})
        if raw in revsetcache:
            revs = revsetcache[raw]
        else:
            revs = query(raw)
            revs = list([str(r) for r in revs])
            revsetcache[raw] = revs

    return templatekw.showlist("revision", revs, **mapping)

def rstdoc(context, mapping, args):
    """:rstdoc(text, style): Format ReStructuredText."""
    if len(args) != 2:
        # i18n: "rstdoc" is a keyword
        raise error.ParseError(_("rstdoc expects two arguments"))

    text = stringify(args[0][0](context, mapping, args[0][1]))
    style = stringify(args[1][0](context, mapping, args[1][1]))

    return minirst.format(text, style=style, keep=['verbose'])

def shortest(context, mapping, args):
    """:shortest(node, minlength=4): Obtain the shortest representation of
    a node."""
    if not (1 <= len(args) <= 2):
        # i18n: "shortest" is a keyword
        raise error.ParseError(_("shortest() expects one or two arguments"))

    node = stringify(args[0][0](context, mapping, args[0][1]))

    minlength = 4
    if len(args) > 1:
        minlength = int(args[1][1])

    cl = mapping['ctx']._repo.changelog
    def isvalid(test):
        try:
            try:
                cl.index.partialmatch(test)
            except AttributeError:
                # Pure mercurial doesn't support partialmatch on the index.
                # Fallback to the slow way.
                if cl._partialmatch(test) is None:
                    return False

            try:
                i = int(test)
                # if we are a pure int, then starting with zero will not be
                # confused as a rev; or, obviously, if the int is larger than
                # the value of the tip rev
                if test[0] == '0' or i > len(cl):
                    return True
                return False
            except ValueError:
                return True
        except error.RevlogError:
            return False

    shortest = node
    startlength = max(6, minlength)
    length = startlength
    while True:
        test = node[:length]
        if isvalid(test):
            shortest = test
            if length == minlength or length > startlength:
                return shortest
            length -= 1
        else:
            length += 1
            if len(shortest) <= length:
                return shortest

def strip(context, mapping, args):
    """:strip(text[, chars]): Strip characters from a string."""
    if not (1 <= len(args) <= 2):
        # i18n: "strip" is a keyword
        raise error.ParseError(_("strip expects one or two arguments"))

    text = stringify(args[0][0](context, mapping, args[0][1]))
    if len(args) == 2:
        chars = stringify(args[1][0](context, mapping, args[1][1]))
        return text.strip(chars)
    return text.strip()

def sub(context, mapping, args):
    """:sub(pattern, replacement, expression): Perform text substitution
    using regular expressions."""
    if len(args) != 3:
        # i18n: "sub" is a keyword
        raise error.ParseError(_("sub expects three arguments"))

    pat = stringify(args[0][0](context, mapping, args[0][1]))
    rpl = stringify(args[1][0](context, mapping, args[1][1]))
    src = stringify(_evalifliteral(args[2], context, mapping))
    yield re.sub(pat, rpl, src)

def startswith(context, mapping, args):
    """:startswith(pattern, text): Returns the value from the "text" argument
    if it begins with the content from the "pattern" argument."""
    if len(args) != 2:
        # i18n: "startswith" is a keyword
        raise error.ParseError(_("startswith expects two arguments"))

    patn = stringify(args[0][0](context, mapping, args[0][1]))
    text = stringify(args[1][0](context, mapping, args[1][1]))
    if text.startswith(patn):
        return text
    return ''


def word(context, mapping, args):
    """:word(number, text[, separator]): Return the nth word from a string."""
    if not (2 <= len(args) <= 3):
        # i18n: "word" is a keyword
        raise error.ParseError(_("word expects two or three arguments, got %d")
                               % len(args))

    try:
        num = int(stringify(args[0][0](context, mapping, args[0][1])))
    except ValueError:
        # i18n: "word" is a keyword
        raise error.ParseError(_("word expects an integer index"))
    text = stringify(args[1][0](context, mapping, args[1][1]))
    if len(args) == 3:
        splitter = stringify(args[2][0](context, mapping, args[2][1]))
    else:
        splitter = None

    tokens = text.split(splitter)
    if num >= len(tokens):
        return ''
    else:
        return tokens[num]

# methods to interpret function arguments or inner expressions (e.g. {_(x)})
exprmethods = {
    "integer": lambda e, c: (runinteger, e[1]),
    "string": lambda e, c: (runstring, e[1]),
    "rawstring": lambda e, c: (runrawstring, e[1]),
    "symbol": lambda e, c: (runsymbol, e[1]),
    "group": lambda e, c: compileexp(e[1], c, exprmethods),
#    ".": buildmember,
    "|": buildfilter,
    "%": buildmap,
    "func": buildfunc,
    }

# methods to interpret top-level template (e.g. {x}, {x|_}, {x % "y"})
methods = exprmethods.copy()
methods["integer"] = exprmethods["symbol"]  # '{1}' as variable

funcs = {
    "date": date,
    "diff": diff,
    "fill": fill,
    "get": get,
    "if": if_,
    "ifcontains": ifcontains,
    "ifeq": ifeq,
    "join": join,
    "label": label,
    "pad": pad,
    "revset": revset,
    "rstdoc": rstdoc,
    "shortest": shortest,
    "startswith": startswith,
    "strip": strip,
    "sub": sub,
    "word": word,
}

# template engine

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 unquotestring(s):
    '''unwrap quotes'''
    if len(s) < 2 or s[0] != s[-1]:
        raise SyntaxError(_('unmatched quotes'))
    # de-backslash-ify only <\">. it is invalid syntax in non-string part of
    # template, but we are likely to escape <"> in quoted string and it was
    # accepted before, thanks to issue4290. <\\"> is unmodified because it
    # is ambiguous and it was processed as such before 2.8.1.
    #
    #  template  result
    #  --------- ------------------------
    #  {\"\"}    parse error
    #  "{""}"    {""} -> <>
    #  "{\"\"}"  {""} -> <>
    #  {"\""}    {"\""} -> <">
    #  '{"\""}'  {"\""} -> <">
    #  "{"\""}"  parse error (don't care)
    q = s[0]
    return s[1:-1].replace('\\\\' + q, '\\\\\\' + q).replace('\\' + q, q)

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(runtemplate(self, mapping, self._load(t)))

engines = {'default': engine}

def stylelist():
    paths = templatepaths()
    if not paths:
        return _('no templates found, try `hg debuginstall` for more info')
    dirlist =  os.listdir(paths[0])
    stylelist = []
    for file in dirlist:
        split = file.split(".")
        if split[0] == "map-cmdline":
            stylelist.append(split[1])
    return ", ".join(sorted(stylelist))

class TemplateNotFound(util.Abort):
    pass

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 = {}
        if mapfile:
            self.base = os.path.dirname(mapfile)
        else:
            self.base = ''
        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 '%s' not found") % mapfile,
                             hint=_("available styles: %s") % stylelist())

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

        for key, val in conf[''].items():
            if not val:
                raise SyntaxError(_('%s: missing value') % conf.source('', key))
            if val[0] in "'\"":
                try:
                    self.cache[key] = unquotestring(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 TemplateNotFound(_('"%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 templatepaths():
    '''return locations used for template files.'''
    pathsrel = ['templates']
    paths = [os.path.normpath(os.path.join(util.datapath, f))
             for f in pathsrel]
    return [p for p in paths if os.path.isdir(p)]

def templatepath(name):
    '''return location of template file. returns None if not found.'''
    for p in templatepaths():
        f = os.path.join(p, name)
        if os.path.exists(f):
            return f
    return None

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 = templatepaths()
    elif isinstance(paths, str):
        paths = [paths]

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

    for style in styles:
        # only plain name is allowed to honor template paths
        if (not style
            or style in (os.curdir, os.pardir)
            or os.sep in style
            or os.altsep and os.altsep in 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)

# tell hggettext to extract docstrings from these functions:
i18nfunctions = funcs.values()