Source Code for Module pyrobase.templating

  1  # -*- coding: utf-8 -*- 
  2  # pylint: disable=too-few-public-methods 
  3  """ Templating Helpers. 
  4   
  5      Copyright (c) 2012 The PyroScope Project <pyroscope.project@gmail.com> 
  6  """ 
  7  # This program is free software; you can redistribute it and/or modify 
  8  # it under the terms of the GNU General Public License as published by 
  9  # the Free Software Foundation; either version 2 of the License, or 
 10  # (at your option) any later version. 
 11  # 
 12  # This program is distributed in the hope that it will be useful, 
 13  # but WITHOUT ANY WARRANTY; without even the implied warranty of 
 14  # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
 15  # GNU General Public License for more details. 
 16  # 
 17  # You should have received a copy of the GNU General Public License along 
 18  # with this program; if not, write to the Free Software Foundation, Inc., 
 19  # 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. 
 20  from __future__ import with_statement 
 21   
 22  import os 
 23  from contextlib import closing 
 24   
 25   
 26 -class InterpolationTemplate(object): 
 27      """ Simple string interpolation. 
 28      """ 
 29   
 30 -    def __init__(self, fmt, mapping=None): 
 31          """ Create template ADT wrapper object. 
 32          """ 
 33          self.fmt = unicode(fmt) 
 34          self.mapping = mapping or (lambda _: _) 
 35          self.__engine__ = "interpolation" 
 36          self.__file__ = None 
 37          self.__text__ = '' 
 38   
 39   
 40 -    def __repr__(self): 
 41          """ Returns interpolation string. 
 42          """ 
 43          return self.fmt 
 44   
 45   
 46 -    def __str__(self): 
 47          """ Returns interpolation string. 
 48          """ 
 49          return self.fmt 
 50   
 51   
 52 -    def substitute(self, **variables): 
 53          """ Return expanded template for given variable set. 
 54          """ 
 55          return self.fmt % self.mapping(variables) 
 56   
 57   
 58 -def preparse(template_text, lookup=None): 
 59      """ Do any special processing of a template, including recognizing the templating language 
 60          and resolving file: references, then return an appropriate wrapper object. 
 61   
 62          Currently Tempita and Python string interpolation are supported. 
 63          `lookup` is an optional callable that resolves any ambiguous template path. 
 64      """ 
 65      # First, try to resolve file: references to their contents 
 66      template_path = None 
 67      try: 
 68          is_file = template_text.startswith("file:") 
 69      except (AttributeError, TypeError): 
 70          pass # not a string 
 71      else: 
 72          if is_file: 
 73              template_path = template_text[5:] 
 74              if template_path.startswith('/'): 
 75                  template_path = '/' + template_path.lstrip('/') 
 76              elif template_path.startswith('~'): 
 77                  template_path = os.path.expanduser(template_path) 
 78              elif lookup: 
 79                  template_path = lookup(template_path) 
 80   
 81              with closing(open(template_path, "r")) as handle: 
 82                  template_text = handle.read().rstrip() 
 83   
 84      if hasattr(template_text, "__engine__"): 
 85          # Already preparsed 
 86          template = template_text 
 87      else: 
 88          if template_text.startswith("{{"): 
 89              import tempita  # only on demand 
 90   
 91              template = tempita.Template(template_text, name=template_path) 
 92              template.__engine__ = "tempita" 
 93          else: 
 94              template = InterpolationTemplate(template_text)  # pylint: disable=redefined-variable-type 
 95   
 96          template.__file__ = template_path 
 97   
 98      template.__text__ = template_text 
 99      return template 
100