mercurial/templater.py

hgweb: be sure to drain request data even in early error conditions

Thanks to Mads Kiilerich with noticing this. The hg client can only read data
after all the sent data has been read, so we have to read all the request data
even if we're not going to do anything with it (in error conditions). This
is not easy to fix in the client, because we're using Python's httplib, which
is strictly stateful. Abstracted the draining into a separate method.

# 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, incorporated herein by reference.

from i18n import _
import re, sys, os
from mercurial import util

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

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

        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 _template(self, t):
        '''Get the template for the given template name. Use a local cache.'''
        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]))
        return self.cache[t]

    def _process(self, tmpl, map):
        '''Render a template. Returns a generator.'''
        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)
                    t = self._template(format)
                    yield self._process(t, lm)
            else:
                if fl:
                    for f in fl.split("|")[1:]:
                        v = self.filters[f](v)
                yield v

    def __call__(self, t, **map):
        '''Perform expansion. t is name of map element to expand. map contains
        added elements for use during expansion. Is a generator.'''
        tmpl = self._template(t)
        iters = [self._process(tmpl, map)]
        while iters:
            try:
                item = iters[0].next()
            except StopIteration:
                iters.pop(0)
                continue
            if isinstance(item, str):
                yield item
            elif item is None:
                yield ''
            elif hasattr(item, '__iter__'):
                iters.insert(0, iter(item))
            else:
                yield str(item)

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 hasattr(sys, 'frozen'):
        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 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)