# templater.py - template expansion for output

#

# Copyright 2005, 2006 Matt Mackall <mpm@selenic.com>

#

# This software may be used and distributed according to the terms

# of the GNU General Public License, incorporated herein by reference.

from i18n import _

import re, sys, os

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 templater(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|...}.'''

    template_re = re.compile(r"(?:(?:#(?=[\w\|%]+#))|(?:{(?=[\w\|%]+})))"

                             r"(\w+)(?:(?:%(\w+))|((?:\|\w+)*))[#}]")

    def __init__(self, mapfile, filters={}, defaults={}, cache={}):

        '''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 = filters

        self.defaults = defaults

        if not mapfile:

            return

        i = 0

        for l in file(mapfile):

            l = l.strip()

            i += 1

            if not l or l[0] in '#;': continue

            m = re.match(r'([a-zA-Z_][a-zA-Z0-9_]*)\s*=\s*(.+)$', l)

            if m:

                key, val = m.groups()

                if val[0] in "'\"":

                    try:

                        self.cache[key] = parsestring(val)

                    except SyntaxError, inst:

                        raise SyntaxError('%s:%s: %s' %

                                          (mapfile, i, inst.args[0]))

                else:

                    self.map[key] = os.path.join(self.base, val)

            else:

                raise SyntaxError(_("%s:%s: parse error") % (mapfile, i))

    def __contains__(self, key):

        return key in self.cache or key in self.map

    def __call__(self, t, **map):

        '''perform expansion.

        t is name of map element to expand.

        map is added elements to use during expansion.'''

        if not t in self.cache:

            try:

                self.cache[t] = file(self.map[t]).read()

            except IOError, inst:

                raise IOError(inst.args[0], _('template file %s: %s') %

                              (self.map[t], inst.args[1]))

        tmpl = self.cache[t]

        while tmpl:

            m = self.template_re.search(tmpl)

            if not m:

                yield tmpl

                break

            start, end = m.span(0)

            key, format, fl = m.groups()

            if start:

                yield tmpl[:start]

            tmpl = tmpl[end:]

            if key in map:

                v = map[key]

            else:

                v = self.defaults.get(key, "")

            if callable(v):

                v = v(**map)

            if format:

                if not hasattr(v, '__iter__'):

                    raise SyntaxError(_("Error expanding '%s%s'")

                                      % (key, format))

                lm = map.copy()

                for i in v:

                    lm.update(i)

                    yield self(format, **lm)

            else:

                if fl:

                    for f in fl.split("|")[1:]:

                        v = self.filters[f](v)

                yield v

def templatepath(name=None):

    '''return location of template file or directory (if no name).

    returns None if not found.'''

    # executable version (py2exe) doesn't support __file__

    if hasattr(sys, 'frozen'):

        module = sys.executable

    else:

        module = __file__

    for f in 'templates', '../templates':

        fl = f.split('/')

        if name: fl.append(name)

        p = os.path.join(os.path.dirname(module), *fl)

        if (name and os.path.exists(p)) or os.path.isdir(p):

            return os.path.normpath(p)

def stringify(thing):

    '''turn nested template iterator into string.'''

    if hasattr(thing, '__iter__'):

        return "".join([stringify(t) for t in thing if t is not None])

    return str(thing)