jinja/environment.py

   1 # -*- coding: utf-8 -*-
   2 """
   3     jinja.environment
   4     ~~~~~~~~~~~~~~~~~
   5
   6     Provides a class that holds runtime and parsing time options.
   7
   8     :copyright: 2006 by Armin Ronacher.
   9     :license: BSD, see LICENSE for more details.
  10 """
  11 from jinja.lexer import Lexer
  12 from jinja.parser import Parser
  13 from jinja.datastructure import LoopContext, Undefined
  14 from jinja.exceptions import FilterNotFound
  15 from jinja.defaults import DEFAULT_FILTERS
  16
  17
  18 class Environment(object):
  19     """
  20     The jinja environment.
  21     """
  22
  23     def __init__(self,
  24                  block_start_string='{%',
  25                  block_end_string='%}',
  26                  variable_start_string='{{',
  27                  variable_end_string='}}',
  28                  comment_start_string='{#',
  29                  comment_end_string='#}',
  30                  template_charset='utf-8',
  31                  charset='utf-8',
  32                  loader=None,
  33                  filters=None):
  34
  35         # lexer / parser information
  36         self.block_start_string = block_start_string
  37         self.block_end_string = block_end_string
  38         self.variable_start_string = variable_start_string
  39         self.variable_end_string = variable_end_string
  40         self.comment_start_string = comment_start_string
  41         self.comment_end_string = comment_end_string
  42
  43         # other stuff
  44         self.template_charset = template_charset
  45         self.charset = charset
  46         self.loader = loader
  47         self.filters = filters or DEFAULT_FILTERS.copy()
  48
  49         # create lexer
  50         self.lexer = Lexer(self)
  51
  52     def parse(self, source):
  53         """Function that creates a new parser and parses the source."""
  54         parser = Parser(self, source)
  55         return parser.parse_page()
  56
  57     def to_unicode(self, value):
  58         """
  59         Convert a value to unicode with the rules defined on the environment.
  60         """
  61         if isinstance(value, unicode):
  62             return value
  63         else:
  64             try:
  65                 return unicode(value)
  66             except UnicodeError:
  67                 return str(value).decode(self.charset, 'ignore')
  68
  69     def iterate(self, seq):
  70         """
  71         Helper function used by the python translator runtime code to
  72         iterate over a sequence.
  73         """
  74         try:
  75             length = len(seq)
  76         except TypeError:
  77             seq = list(seq)
  78             length = len(seq)
  79         loop_data = LoopContext(0, length)
  80         for item in seq:
  81             loop_data.index += 1
  82             yield loop_data, item
  83
  84     def prepare_filter(self, name, *args):
  85         """
  86         Prepare a filter.
  87         """
  88         try:
  89             return self.filters[name](*args)
  90         except KeyError:
  91             raise FilterNotFound(name)
  92
  93     def apply_filters(self, value, context, filters):
  94         """
  95         Apply a list of filters on the variable.
  96         """
  97         for f in filters:
  98             value = f(self, context, value)
  99         return value
 100
 101     def get_attribute(self, obj, name):
 102         """
 103         Get the attribute name from obj.
 104         """
 105         try:
 106             return getattr(obj, name)
 107         except AttributeError:
 108             return obj[name]
 109         except:
 110             return Undefined