view mercurial/templater.py @ 6302:8e3dc3de7e73

Use the pager given by the environment to display long output

Unix systems usually have a PAGER environment variable set.
If it is set, mercurial will use the pager application to display
output.

Two configuration variables are available to influence the behaviour of the
pager. ui.pager sets the pager application. The pager is
only used if ui.usepager is true. By default ui.usepager is disabled.

# 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

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)