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1 """ |
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2 This is the Django template system. |
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3 |
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4 How it works: |
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5 |
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6 The Lexer.tokenize() function converts a template string (i.e., a string containing |
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7 markup with custom template tags) to tokens, which can be either plain text |
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8 (TOKEN_TEXT), variables (TOKEN_VAR) or block statements (TOKEN_BLOCK). |
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9 |
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10 The Parser() class takes a list of tokens in its constructor, and its parse() |
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11 method returns a compiled template -- which is, under the hood, a list of |
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12 Node objects. |
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13 |
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14 Each Node is responsible for creating some sort of output -- e.g. simple text |
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15 (TextNode), variable values in a given context (VariableNode), results of basic |
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16 logic (IfNode), results of looping (ForNode), or anything else. The core Node |
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17 types are TextNode, VariableNode, IfNode and ForNode, but plugin modules can |
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18 define their own custom node types. |
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19 |
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20 Each Node has a render() method, which takes a Context and returns a string of |
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21 the rendered node. For example, the render() method of a Variable Node returns |
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22 the variable's value as a string. The render() method of an IfNode returns the |
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23 rendered output of whatever was inside the loop, recursively. |
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24 |
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25 The Template class is a convenient wrapper that takes care of template |
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26 compilation and rendering. |
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27 |
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28 Usage: |
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29 |
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30 The only thing you should ever use directly in this file is the Template class. |
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31 Create a compiled template object with a template_string, then call render() |
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32 with a context. In the compilation stage, the TemplateSyntaxError exception |
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33 will be raised if the template doesn't have proper syntax. |
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34 |
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35 Sample code: |
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36 |
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37 >>> from django import template |
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38 >>> s = u'<html>{% if test %}<h1>{{ varvalue }}</h1>{% endif %}</html>' |
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39 >>> t = template.Template(s) |
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40 |
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41 (t is now a compiled template, and its render() method can be called multiple |
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42 times with multiple contexts) |
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43 |
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44 >>> c = template.Context({'test':True, 'varvalue': 'Hello'}) |
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45 >>> t.render(c) |
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46 u'<html><h1>Hello</h1></html>' |
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47 >>> c = template.Context({'test':False, 'varvalue': 'Hello'}) |
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48 >>> t.render(c) |
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49 u'<html></html>' |
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50 """ |
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51 import re |
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52 from inspect import getargspec |
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53 |
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54 from django.conf import settings |
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55 from django.template.context import Context, RequestContext, ContextPopException |
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56 from django.utils.importlib import import_module |
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57 from django.utils.itercompat import is_iterable |
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58 from django.utils.functional import curry, Promise |
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59 from django.utils.text import smart_split, unescape_string_literal |
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60 from django.utils.encoding import smart_unicode, force_unicode, smart_str |
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61 from django.utils.translation import ugettext as _ |
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62 from django.utils.safestring import SafeData, EscapeData, mark_safe, mark_for_escaping |
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63 from django.utils.html import escape |
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64 |
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65 __all__ = ('Template', 'Context', 'RequestContext', 'compile_string') |
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66 |
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67 TOKEN_TEXT = 0 |
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68 TOKEN_VAR = 1 |
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69 TOKEN_BLOCK = 2 |
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70 TOKEN_COMMENT = 3 |
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71 |
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72 # template syntax constants |
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73 FILTER_SEPARATOR = '|' |
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74 FILTER_ARGUMENT_SEPARATOR = ':' |
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75 VARIABLE_ATTRIBUTE_SEPARATOR = '.' |
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76 BLOCK_TAG_START = '{%' |
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77 BLOCK_TAG_END = '%}' |
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78 VARIABLE_TAG_START = '{{' |
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79 VARIABLE_TAG_END = '}}' |
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80 COMMENT_TAG_START = '{#' |
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81 COMMENT_TAG_END = '#}' |
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82 SINGLE_BRACE_START = '{' |
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83 SINGLE_BRACE_END = '}' |
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84 |
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85 ALLOWED_VARIABLE_CHARS = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_.' |
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86 |
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87 # what to report as the origin for templates that come from non-loader sources |
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88 # (e.g. strings) |
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89 UNKNOWN_SOURCE="<unknown source>" |
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90 |
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91 # match a variable or block tag and capture the entire tag, including start/end delimiters |
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92 tag_re = re.compile('(%s.*?%s|%s.*?%s|%s.*?%s)' % (re.escape(BLOCK_TAG_START), re.escape(BLOCK_TAG_END), |
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93 re.escape(VARIABLE_TAG_START), re.escape(VARIABLE_TAG_END), |
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94 re.escape(COMMENT_TAG_START), re.escape(COMMENT_TAG_END))) |
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95 |
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96 # global dictionary of libraries that have been loaded using get_library |
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97 libraries = {} |
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98 # global list of libraries to load by default for a new parser |
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99 builtins = [] |
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100 |
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101 # True if TEMPLATE_STRING_IF_INVALID contains a format string (%s). None means |
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102 # uninitialised. |
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103 invalid_var_format_string = None |
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104 |
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105 class TemplateSyntaxError(Exception): |
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106 def __str__(self): |
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107 try: |
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108 import cStringIO as StringIO |
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109 except ImportError: |
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110 import StringIO |
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111 output = StringIO.StringIO() |
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112 output.write(Exception.__str__(self)) |
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113 # Check if we wrapped an exception and print that too. |
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114 if hasattr(self, 'exc_info'): |
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115 import traceback |
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116 output.write('\n\nOriginal ') |
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117 e = self.exc_info |
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118 traceback.print_exception(e[0], e[1], e[2], 500, output) |
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119 return output.getvalue() |
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120 |
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121 class TemplateDoesNotExist(Exception): |
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122 pass |
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123 |
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124 class TemplateEncodingError(Exception): |
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125 pass |
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126 |
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127 class VariableDoesNotExist(Exception): |
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128 |
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129 def __init__(self, msg, params=()): |
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130 self.msg = msg |
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131 self.params = params |
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132 |
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133 def __str__(self): |
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134 return unicode(self).encode('utf-8') |
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135 |
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136 def __unicode__(self): |
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137 return self.msg % tuple([force_unicode(p, errors='replace') for p in self.params]) |
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138 |
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139 class InvalidTemplateLibrary(Exception): |
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140 pass |
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141 |
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142 class Origin(object): |
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143 def __init__(self, name): |
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144 self.name = name |
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145 |
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146 def reload(self): |
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147 raise NotImplementedError |
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148 |
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149 def __str__(self): |
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150 return self.name |
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151 |
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152 class StringOrigin(Origin): |
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153 def __init__(self, source): |
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154 super(StringOrigin, self).__init__(UNKNOWN_SOURCE) |
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155 self.source = source |
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156 |
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157 def reload(self): |
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158 return self.source |
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159 |
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160 class Template(object): |
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161 def __init__(self, template_string, origin=None, name='<Unknown Template>'): |
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162 try: |
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163 template_string = smart_unicode(template_string) |
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164 except UnicodeDecodeError: |
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165 raise TemplateEncodingError("Templates can only be constructed from unicode or UTF-8 strings.") |
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166 if settings.TEMPLATE_DEBUG and origin is None: |
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167 origin = StringOrigin(template_string) |
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168 self.nodelist = compile_string(template_string, origin) |
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169 self.name = name |
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170 |
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171 def __iter__(self): |
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172 for node in self.nodelist: |
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173 for subnode in node: |
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174 yield subnode |
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175 |
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176 def render(self, context): |
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177 "Display stage -- can be called many times" |
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178 return self.nodelist.render(context) |
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179 |
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180 def compile_string(template_string, origin): |
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181 "Compiles template_string into NodeList ready for rendering" |
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182 if settings.TEMPLATE_DEBUG: |
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183 from debug import DebugLexer, DebugParser |
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184 lexer_class, parser_class = DebugLexer, DebugParser |
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185 else: |
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186 lexer_class, parser_class = Lexer, Parser |
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187 lexer = lexer_class(template_string, origin) |
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188 parser = parser_class(lexer.tokenize()) |
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189 return parser.parse() |
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190 |
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191 class Token(object): |
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192 def __init__(self, token_type, contents): |
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193 # token_type must be TOKEN_TEXT, TOKEN_VAR, TOKEN_BLOCK or TOKEN_COMMENT. |
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194 self.token_type, self.contents = token_type, contents |
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195 |
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196 def __str__(self): |
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197 return '<%s token: "%s...">' % \ |
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198 ({TOKEN_TEXT: 'Text', TOKEN_VAR: 'Var', TOKEN_BLOCK: 'Block', TOKEN_COMMENT: 'Comment'}[self.token_type], |
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199 self.contents[:20].replace('\n', '')) |
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200 |
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201 def split_contents(self): |
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202 split = [] |
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203 bits = iter(smart_split(self.contents)) |
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204 for bit in bits: |
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205 # Handle translation-marked template pieces |
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206 if bit.startswith('_("') or bit.startswith("_('"): |
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207 sentinal = bit[2] + ')' |
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208 trans_bit = [bit] |
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209 while not bit.endswith(sentinal): |
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210 bit = bits.next() |
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211 trans_bit.append(bit) |
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212 bit = ' '.join(trans_bit) |
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213 split.append(bit) |
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214 return split |
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215 |
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216 class Lexer(object): |
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217 def __init__(self, template_string, origin): |
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218 self.template_string = template_string |
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219 self.origin = origin |
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220 |
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221 def tokenize(self): |
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222 "Return a list of tokens from a given template_string." |
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223 in_tag = False |
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224 result = [] |
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225 for bit in tag_re.split(self.template_string): |
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226 if bit: |
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227 result.append(self.create_token(bit, in_tag)) |
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228 in_tag = not in_tag |
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229 return result |
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230 |
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231 def create_token(self, token_string, in_tag): |
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232 """ |
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233 Convert the given token string into a new Token object and return it. |
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234 If in_tag is True, we are processing something that matched a tag, |
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235 otherwise it should be treated as a literal string. |
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236 """ |
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237 if in_tag: |
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238 if token_string.startswith(VARIABLE_TAG_START): |
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239 token = Token(TOKEN_VAR, token_string[len(VARIABLE_TAG_START):-len(VARIABLE_TAG_END)].strip()) |
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240 elif token_string.startswith(BLOCK_TAG_START): |
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241 token = Token(TOKEN_BLOCK, token_string[len(BLOCK_TAG_START):-len(BLOCK_TAG_END)].strip()) |
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242 elif token_string.startswith(COMMENT_TAG_START): |
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243 token = Token(TOKEN_COMMENT, '') |
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244 else: |
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245 token = Token(TOKEN_TEXT, token_string) |
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246 return token |
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247 |
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248 class Parser(object): |
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249 def __init__(self, tokens): |
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250 self.tokens = tokens |
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251 self.tags = {} |
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252 self.filters = {} |
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253 for lib in builtins: |
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254 self.add_library(lib) |
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255 |
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256 def parse(self, parse_until=None): |
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257 if parse_until is None: parse_until = [] |
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258 nodelist = self.create_nodelist() |
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259 while self.tokens: |
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260 token = self.next_token() |
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261 if token.token_type == TOKEN_TEXT: |
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262 self.extend_nodelist(nodelist, TextNode(token.contents), token) |
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263 elif token.token_type == TOKEN_VAR: |
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264 if not token.contents: |
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265 self.empty_variable(token) |
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266 filter_expression = self.compile_filter(token.contents) |
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267 var_node = self.create_variable_node(filter_expression) |
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268 self.extend_nodelist(nodelist, var_node,token) |
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269 elif token.token_type == TOKEN_BLOCK: |
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270 if token.contents in parse_until: |
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271 # put token back on token list so calling code knows why it terminated |
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272 self.prepend_token(token) |
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273 return nodelist |
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274 try: |
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275 command = token.contents.split()[0] |
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276 except IndexError: |
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277 self.empty_block_tag(token) |
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278 # execute callback function for this tag and append resulting node |
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279 self.enter_command(command, token) |
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280 try: |
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281 compile_func = self.tags[command] |
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282 except KeyError: |
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283 self.invalid_block_tag(token, command) |
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284 try: |
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285 compiled_result = compile_func(self, token) |
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286 except TemplateSyntaxError, e: |
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287 if not self.compile_function_error(token, e): |
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288 raise |
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289 self.extend_nodelist(nodelist, compiled_result, token) |
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290 self.exit_command() |
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291 if parse_until: |
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292 self.unclosed_block_tag(parse_until) |
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293 return nodelist |
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294 |
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295 def skip_past(self, endtag): |
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296 while self.tokens: |
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297 token = self.next_token() |
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298 if token.token_type == TOKEN_BLOCK and token.contents == endtag: |
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299 return |
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300 self.unclosed_block_tag([endtag]) |
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301 |
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302 def create_variable_node(self, filter_expression): |
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303 return VariableNode(filter_expression) |
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304 |
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305 def create_nodelist(self): |
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306 return NodeList() |
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307 |
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308 def extend_nodelist(self, nodelist, node, token): |
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309 if node.must_be_first and nodelist: |
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310 try: |
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311 if nodelist.contains_nontext: |
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312 raise AttributeError |
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313 except AttributeError: |
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314 raise TemplateSyntaxError("%r must be the first tag in the template." % node) |
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315 if isinstance(nodelist, NodeList) and not isinstance(node, TextNode): |
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316 nodelist.contains_nontext = True |
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317 nodelist.append(node) |
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318 |
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319 def enter_command(self, command, token): |
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320 pass |
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321 |
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322 def exit_command(self): |
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323 pass |
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324 |
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325 def error(self, token, msg): |
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326 return TemplateSyntaxError(msg) |
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327 |
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328 def empty_variable(self, token): |
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329 raise self.error(token, "Empty variable tag") |
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330 |
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331 def empty_block_tag(self, token): |
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332 raise self.error(token, "Empty block tag") |
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333 |
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334 def invalid_block_tag(self, token, command): |
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335 raise self.error(token, "Invalid block tag: '%s'" % command) |
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336 |
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337 def unclosed_block_tag(self, parse_until): |
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338 raise self.error(None, "Unclosed tags: %s " % ', '.join(parse_until)) |
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339 |
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340 def compile_function_error(self, token, e): |
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341 pass |
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342 |
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343 def next_token(self): |
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344 return self.tokens.pop(0) |
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345 |
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346 def prepend_token(self, token): |
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347 self.tokens.insert(0, token) |
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348 |
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349 def delete_first_token(self): |
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350 del self.tokens[0] |
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351 |
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352 def add_library(self, lib): |
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353 self.tags.update(lib.tags) |
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354 self.filters.update(lib.filters) |
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355 |
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356 def compile_filter(self, token): |
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357 "Convenient wrapper for FilterExpression" |
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358 return FilterExpression(token, self) |
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359 |
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360 def find_filter(self, filter_name): |
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361 if filter_name in self.filters: |
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362 return self.filters[filter_name] |
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363 else: |
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364 raise TemplateSyntaxError("Invalid filter: '%s'" % filter_name) |
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365 |
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366 class TokenParser(object): |
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367 """ |
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368 Subclass this and implement the top() method to parse a template line. When |
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369 instantiating the parser, pass in the line from the Django template parser. |
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370 |
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371 The parser's "tagname" instance-variable stores the name of the tag that |
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372 the filter was called with. |
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373 """ |
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374 def __init__(self, subject): |
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375 self.subject = subject |
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376 self.pointer = 0 |
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377 self.backout = [] |
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378 self.tagname = self.tag() |
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379 |
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380 def top(self): |
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381 "Overload this method to do the actual parsing and return the result." |
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382 raise NotImplementedError() |
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383 |
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384 def more(self): |
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385 "Returns True if there is more stuff in the tag." |
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386 return self.pointer < len(self.subject) |
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387 |
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388 def back(self): |
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389 "Undoes the last microparser. Use this for lookahead and backtracking." |
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390 if not len(self.backout): |
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391 raise TemplateSyntaxError("back called without some previous parsing") |
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392 self.pointer = self.backout.pop() |
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393 |
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394 def tag(self): |
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395 "A microparser that just returns the next tag from the line." |
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396 subject = self.subject |
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397 i = self.pointer |
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398 if i >= len(subject): |
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399 raise TemplateSyntaxError("expected another tag, found end of string: %s" % subject) |
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400 p = i |
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401 while i < len(subject) and subject[i] not in (' ', '\t'): |
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402 i += 1 |
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403 s = subject[p:i] |
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404 while i < len(subject) and subject[i] in (' ', '\t'): |
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405 i += 1 |
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406 self.backout.append(self.pointer) |
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407 self.pointer = i |
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408 return s |
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409 |
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410 def value(self): |
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411 "A microparser that parses for a value: some string constant or variable name." |
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412 subject = self.subject |
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413 i = self.pointer |
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414 if i >= len(subject): |
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415 raise TemplateSyntaxError("Searching for value. Expected another value but found end of string: %s" % subject) |
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416 if subject[i] in ('"', "'"): |
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417 p = i |
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418 i += 1 |
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419 while i < len(subject) and subject[i] != subject[p]: |
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420 i += 1 |
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421 if i >= len(subject): |
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422 raise TemplateSyntaxError("Searching for value. Unexpected end of string in column %d: %s" % (i, subject)) |
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423 i += 1 |
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424 res = subject[p:i] |
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425 while i < len(subject) and subject[i] in (' ', '\t'): |
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426 i += 1 |
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427 self.backout.append(self.pointer) |
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428 self.pointer = i |
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429 return res |
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430 else: |
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431 p = i |
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432 while i < len(subject) and subject[i] not in (' ', '\t'): |
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433 if subject[i] in ('"', "'"): |
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434 c = subject[i] |
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435 i += 1 |
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436 while i < len(subject) and subject[i] != c: |
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437 i += 1 |
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438 if i >= len(subject): |
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439 raise TemplateSyntaxError("Searching for value. Unexpected end of string in column %d: %s" % (i, subject)) |
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440 i += 1 |
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441 s = subject[p:i] |
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442 while i < len(subject) and subject[i] in (' ', '\t'): |
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443 i += 1 |
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444 self.backout.append(self.pointer) |
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445 self.pointer = i |
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446 return s |
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447 |
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448 # This only matches constant *strings* (things in quotes or marked for |
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449 # translation). Numbers are treated as variables for implementation reasons |
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450 # (so that they retain their type when passed to filters). |
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451 constant_string = r""" |
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452 (?:%(i18n_open)s%(strdq)s%(i18n_close)s| |
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453 %(i18n_open)s%(strsq)s%(i18n_close)s| |
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454 %(strdq)s| |
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455 %(strsq)s) |
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456 """ % { |
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457 'strdq': r'"[^"\\]*(?:\\.[^"\\]*)*"', # double-quoted string |
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458 'strsq': r"'[^'\\]*(?:\\.[^'\\]*)*'", # single-quoted string |
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459 'i18n_open' : re.escape("_("), |
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460 'i18n_close' : re.escape(")"), |
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461 } |
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462 constant_string = constant_string.replace("\n", "") |
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463 |
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464 filter_raw_string = r""" |
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465 ^(?P<constant>%(constant)s)| |
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466 ^(?P<var>[%(var_chars)s]+|%(num)s)| |
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467 (?:%(filter_sep)s |
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468 (?P<filter_name>\w+) |
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469 (?:%(arg_sep)s |
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470 (?: |
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471 (?P<constant_arg>%(constant)s)| |
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472 (?P<var_arg>[%(var_chars)s]+|%(num)s) |
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473 ) |
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474 )? |
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475 )""" % { |
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476 'constant': constant_string, |
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477 'num': r'[-+\.]?\d[\d\.e]*', |
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478 'var_chars': "\w\." , |
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479 'filter_sep': re.escape(FILTER_SEPARATOR), |
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480 'arg_sep': re.escape(FILTER_ARGUMENT_SEPARATOR), |
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481 } |
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482 |
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483 filter_re = re.compile(filter_raw_string, re.UNICODE|re.VERBOSE) |
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484 |
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485 class FilterExpression(object): |
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486 r""" |
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487 Parses a variable token and its optional filters (all as a single string), |
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488 and return a list of tuples of the filter name and arguments. |
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489 Sample: |
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490 >>> token = 'variable|default:"Default value"|date:"Y-m-d"' |
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491 >>> p = Parser('') |
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492 >>> fe = FilterExpression(token, p) |
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493 >>> len(fe.filters) |
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494 2 |
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495 >>> fe.var |
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496 <Variable: 'variable'> |
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497 |
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498 This class should never be instantiated outside of the |
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499 get_filters_from_token helper function. |
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500 """ |
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501 def __init__(self, token, parser): |
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502 self.token = token |
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503 matches = filter_re.finditer(token) |
|
504 var_obj = None |
|
505 filters = [] |
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506 upto = 0 |
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507 for match in matches: |
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508 start = match.start() |
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509 if upto != start: |
|
510 raise TemplateSyntaxError("Could not parse some characters: %s|%s|%s" % \ |
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511 (token[:upto], token[upto:start], token[start:])) |
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512 if var_obj is None: |
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513 var, constant = match.group("var", "constant") |
|
514 if constant: |
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515 try: |
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516 var_obj = Variable(constant).resolve({}) |
|
517 except VariableDoesNotExist: |
|
518 var_obj = None |
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519 elif var is None: |
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520 raise TemplateSyntaxError("Could not find variable at start of %s." % token) |
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521 elif var.find(VARIABLE_ATTRIBUTE_SEPARATOR + '_') > -1 or var[0] == '_': |
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522 raise TemplateSyntaxError("Variables and attributes may not begin with underscores: '%s'" % var) |
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523 else: |
|
524 var_obj = Variable(var) |
|
525 else: |
|
526 filter_name = match.group("filter_name") |
|
527 args = [] |
|
528 constant_arg, var_arg = match.group("constant_arg", "var_arg") |
|
529 if constant_arg: |
|
530 args.append((False, Variable(constant_arg).resolve({}))) |
|
531 elif var_arg: |
|
532 args.append((True, Variable(var_arg))) |
|
533 filter_func = parser.find_filter(filter_name) |
|
534 self.args_check(filter_name,filter_func, args) |
|
535 filters.append( (filter_func,args)) |
|
536 upto = match.end() |
|
537 if upto != len(token): |
|
538 raise TemplateSyntaxError("Could not parse the remainder: '%s' from '%s'" % (token[upto:], token)) |
|
539 |
|
540 self.filters = filters |
|
541 self.var = var_obj |
|
542 |
|
543 def resolve(self, context, ignore_failures=False): |
|
544 if isinstance(self.var, Variable): |
|
545 try: |
|
546 obj = self.var.resolve(context) |
|
547 except VariableDoesNotExist: |
|
548 if ignore_failures: |
|
549 obj = None |
|
550 else: |
|
551 if settings.TEMPLATE_STRING_IF_INVALID: |
|
552 global invalid_var_format_string |
|
553 if invalid_var_format_string is None: |
|
554 invalid_var_format_string = '%s' in settings.TEMPLATE_STRING_IF_INVALID |
|
555 if invalid_var_format_string: |
|
556 return settings.TEMPLATE_STRING_IF_INVALID % self.var |
|
557 return settings.TEMPLATE_STRING_IF_INVALID |
|
558 else: |
|
559 obj = settings.TEMPLATE_STRING_IF_INVALID |
|
560 else: |
|
561 obj = self.var |
|
562 for func, args in self.filters: |
|
563 arg_vals = [] |
|
564 for lookup, arg in args: |
|
565 if not lookup: |
|
566 arg_vals.append(mark_safe(arg)) |
|
567 else: |
|
568 arg_vals.append(arg.resolve(context)) |
|
569 if getattr(func, 'needs_autoescape', False): |
|
570 new_obj = func(obj, autoescape=context.autoescape, *arg_vals) |
|
571 else: |
|
572 new_obj = func(obj, *arg_vals) |
|
573 if getattr(func, 'is_safe', False) and isinstance(obj, SafeData): |
|
574 obj = mark_safe(new_obj) |
|
575 elif isinstance(obj, EscapeData): |
|
576 obj = mark_for_escaping(new_obj) |
|
577 else: |
|
578 obj = new_obj |
|
579 return obj |
|
580 |
|
581 def args_check(name, func, provided): |
|
582 provided = list(provided) |
|
583 plen = len(provided) |
|
584 # Check to see if a decorator is providing the real function. |
|
585 func = getattr(func, '_decorated_function', func) |
|
586 args, varargs, varkw, defaults = getargspec(func) |
|
587 # First argument is filter input. |
|
588 args.pop(0) |
|
589 if defaults: |
|
590 nondefs = args[:-len(defaults)] |
|
591 else: |
|
592 nondefs = args |
|
593 # Args without defaults must be provided. |
|
594 try: |
|
595 for arg in nondefs: |
|
596 provided.pop(0) |
|
597 except IndexError: |
|
598 # Not enough |
|
599 raise TemplateSyntaxError("%s requires %d arguments, %d provided" % (name, len(nondefs), plen)) |
|
600 |
|
601 # Defaults can be overridden. |
|
602 defaults = defaults and list(defaults) or [] |
|
603 try: |
|
604 for parg in provided: |
|
605 defaults.pop(0) |
|
606 except IndexError: |
|
607 # Too many. |
|
608 raise TemplateSyntaxError("%s requires %d arguments, %d provided" % (name, len(nondefs), plen)) |
|
609 |
|
610 return True |
|
611 args_check = staticmethod(args_check) |
|
612 |
|
613 def __str__(self): |
|
614 return self.token |
|
615 |
|
616 def resolve_variable(path, context): |
|
617 """ |
|
618 Returns the resolved variable, which may contain attribute syntax, within |
|
619 the given context. |
|
620 |
|
621 Deprecated; use the Variable class instead. |
|
622 """ |
|
623 return Variable(path).resolve(context) |
|
624 |
|
625 class Variable(object): |
|
626 r""" |
|
627 A template variable, resolvable against a given context. The variable may be |
|
628 a hard-coded string (if it begins and ends with single or double quote |
|
629 marks):: |
|
630 |
|
631 >>> c = {'article': {'section':u'News'}} |
|
632 >>> Variable('article.section').resolve(c) |
|
633 u'News' |
|
634 >>> Variable('article').resolve(c) |
|
635 {'section': u'News'} |
|
636 >>> class AClass: pass |
|
637 >>> c = AClass() |
|
638 >>> c.article = AClass() |
|
639 >>> c.article.section = u'News' |
|
640 |
|
641 (The example assumes VARIABLE_ATTRIBUTE_SEPARATOR is '.') |
|
642 """ |
|
643 |
|
644 def __init__(self, var): |
|
645 self.var = var |
|
646 self.literal = None |
|
647 self.lookups = None |
|
648 self.translate = False |
|
649 |
|
650 try: |
|
651 # First try to treat this variable as a number. |
|
652 # |
|
653 # Note that this could cause an OverflowError here that we're not |
|
654 # catching. Since this should only happen at compile time, that's |
|
655 # probably OK. |
|
656 self.literal = float(var) |
|
657 |
|
658 # So it's a float... is it an int? If the original value contained a |
|
659 # dot or an "e" then it was a float, not an int. |
|
660 if '.' not in var and 'e' not in var.lower(): |
|
661 self.literal = int(self.literal) |
|
662 |
|
663 # "2." is invalid |
|
664 if var.endswith('.'): |
|
665 raise ValueError |
|
666 |
|
667 except ValueError: |
|
668 # A ValueError means that the variable isn't a number. |
|
669 if var.startswith('_(') and var.endswith(')'): |
|
670 # The result of the lookup should be translated at rendering |
|
671 # time. |
|
672 self.translate = True |
|
673 var = var[2:-1] |
|
674 # If it's wrapped with quotes (single or double), then |
|
675 # we're also dealing with a literal. |
|
676 try: |
|
677 self.literal = mark_safe(unescape_string_literal(var)) |
|
678 except ValueError: |
|
679 # Otherwise we'll set self.lookups so that resolve() knows we're |
|
680 # dealing with a bonafide variable |
|
681 self.lookups = tuple(var.split(VARIABLE_ATTRIBUTE_SEPARATOR)) |
|
682 |
|
683 def resolve(self, context): |
|
684 """Resolve this variable against a given context.""" |
|
685 if self.lookups is not None: |
|
686 # We're dealing with a variable that needs to be resolved |
|
687 value = self._resolve_lookup(context) |
|
688 else: |
|
689 # We're dealing with a literal, so it's already been "resolved" |
|
690 value = self.literal |
|
691 if self.translate: |
|
692 return _(value) |
|
693 return value |
|
694 |
|
695 def __repr__(self): |
|
696 return "<%s: %r>" % (self.__class__.__name__, self.var) |
|
697 |
|
698 def __str__(self): |
|
699 return self.var |
|
700 |
|
701 def _resolve_lookup(self, context): |
|
702 """ |
|
703 Performs resolution of a real variable (i.e. not a literal) against the |
|
704 given context. |
|
705 |
|
706 As indicated by the method's name, this method is an implementation |
|
707 detail and shouldn't be called by external code. Use Variable.resolve() |
|
708 instead. |
|
709 """ |
|
710 current = context |
|
711 for bit in self.lookups: |
|
712 try: # dictionary lookup |
|
713 current = current[bit] |
|
714 except (TypeError, AttributeError, KeyError): |
|
715 try: # attribute lookup |
|
716 current = getattr(current, bit) |
|
717 if callable(current): |
|
718 if getattr(current, 'alters_data', False): |
|
719 current = settings.TEMPLATE_STRING_IF_INVALID |
|
720 else: |
|
721 try: # method call (assuming no args required) |
|
722 current = current() |
|
723 except TypeError: # arguments *were* required |
|
724 # GOTCHA: This will also catch any TypeError |
|
725 # raised in the function itself. |
|
726 current = settings.TEMPLATE_STRING_IF_INVALID # invalid method call |
|
727 except Exception, e: |
|
728 if getattr(e, 'silent_variable_failure', False): |
|
729 current = settings.TEMPLATE_STRING_IF_INVALID |
|
730 else: |
|
731 raise |
|
732 except (TypeError, AttributeError): |
|
733 try: # list-index lookup |
|
734 current = current[int(bit)] |
|
735 except (IndexError, # list index out of range |
|
736 ValueError, # invalid literal for int() |
|
737 KeyError, # current is a dict without `int(bit)` key |
|
738 TypeError, # unsubscriptable object |
|
739 ): |
|
740 raise VariableDoesNotExist("Failed lookup for key [%s] in %r", (bit, current)) # missing attribute |
|
741 except Exception, e: |
|
742 if getattr(e, 'silent_variable_failure', False): |
|
743 current = settings.TEMPLATE_STRING_IF_INVALID |
|
744 else: |
|
745 raise |
|
746 |
|
747 return current |
|
748 |
|
749 class Node(object): |
|
750 # Set this to True for nodes that must be first in the template (although |
|
751 # they can be preceded by text nodes. |
|
752 must_be_first = False |
|
753 |
|
754 def render(self, context): |
|
755 "Return the node rendered as a string" |
|
756 pass |
|
757 |
|
758 def __iter__(self): |
|
759 yield self |
|
760 |
|
761 def get_nodes_by_type(self, nodetype): |
|
762 "Return a list of all nodes (within this node and its nodelist) of the given type" |
|
763 nodes = [] |
|
764 if isinstance(self, nodetype): |
|
765 nodes.append(self) |
|
766 if hasattr(self, 'nodelist'): |
|
767 nodes.extend(self.nodelist.get_nodes_by_type(nodetype)) |
|
768 return nodes |
|
769 |
|
770 class NodeList(list): |
|
771 # Set to True the first time a non-TextNode is inserted by |
|
772 # extend_nodelist(). |
|
773 contains_nontext = False |
|
774 |
|
775 def render(self, context): |
|
776 bits = [] |
|
777 for node in self: |
|
778 if isinstance(node, Node): |
|
779 bits.append(self.render_node(node, context)) |
|
780 else: |
|
781 bits.append(node) |
|
782 return mark_safe(''.join([force_unicode(b) for b in bits])) |
|
783 |
|
784 def get_nodes_by_type(self, nodetype): |
|
785 "Return a list of all nodes of the given type" |
|
786 nodes = [] |
|
787 for node in self: |
|
788 nodes.extend(node.get_nodes_by_type(nodetype)) |
|
789 return nodes |
|
790 |
|
791 def render_node(self, node, context): |
|
792 return node.render(context) |
|
793 |
|
794 class TextNode(Node): |
|
795 def __init__(self, s): |
|
796 self.s = s |
|
797 |
|
798 def __repr__(self): |
|
799 return "<Text Node: '%s'>" % smart_str(self.s[:25], 'ascii', |
|
800 errors='replace') |
|
801 |
|
802 def render(self, context): |
|
803 return self.s |
|
804 |
|
805 def _render_value_in_context(value, context): |
|
806 """ |
|
807 Converts any value to a string to become part of a rendered template. This |
|
808 means escaping, if required, and conversion to a unicode object. If value |
|
809 is a string, it is expected to have already been translated. |
|
810 """ |
|
811 value = force_unicode(value) |
|
812 if (context.autoescape and not isinstance(value, SafeData)) or isinstance(value, EscapeData): |
|
813 return escape(value) |
|
814 else: |
|
815 return value |
|
816 |
|
817 class VariableNode(Node): |
|
818 def __init__(self, filter_expression): |
|
819 self.filter_expression = filter_expression |
|
820 |
|
821 def __repr__(self): |
|
822 return "<Variable Node: %s>" % self.filter_expression |
|
823 |
|
824 def render(self, context): |
|
825 try: |
|
826 output = self.filter_expression.resolve(context) |
|
827 except UnicodeDecodeError: |
|
828 # Unicode conversion can fail sometimes for reasons out of our |
|
829 # control (e.g. exception rendering). In that case, we fail quietly. |
|
830 return '' |
|
831 return _render_value_in_context(output, context) |
|
832 |
|
833 def generic_tag_compiler(params, defaults, name, node_class, parser, token): |
|
834 "Returns a template.Node subclass." |
|
835 bits = token.split_contents()[1:] |
|
836 bmax = len(params) |
|
837 def_len = defaults and len(defaults) or 0 |
|
838 bmin = bmax - def_len |
|
839 if(len(bits) < bmin or len(bits) > bmax): |
|
840 if bmin == bmax: |
|
841 message = "%s takes %s arguments" % (name, bmin) |
|
842 else: |
|
843 message = "%s takes between %s and %s arguments" % (name, bmin, bmax) |
|
844 raise TemplateSyntaxError(message) |
|
845 return node_class(bits) |
|
846 |
|
847 class Library(object): |
|
848 def __init__(self): |
|
849 self.filters = {} |
|
850 self.tags = {} |
|
851 |
|
852 def tag(self, name=None, compile_function=None): |
|
853 if name == None and compile_function == None: |
|
854 # @register.tag() |
|
855 return self.tag_function |
|
856 elif name != None and compile_function == None: |
|
857 if(callable(name)): |
|
858 # @register.tag |
|
859 return self.tag_function(name) |
|
860 else: |
|
861 # @register.tag('somename') or @register.tag(name='somename') |
|
862 def dec(func): |
|
863 return self.tag(name, func) |
|
864 return dec |
|
865 elif name != None and compile_function != None: |
|
866 # register.tag('somename', somefunc) |
|
867 self.tags[name] = compile_function |
|
868 return compile_function |
|
869 else: |
|
870 raise InvalidTemplateLibrary("Unsupported arguments to Library.tag: (%r, %r)", (name, compile_function)) |
|
871 |
|
872 def tag_function(self,func): |
|
873 self.tags[getattr(func, "_decorated_function", func).__name__] = func |
|
874 return func |
|
875 |
|
876 def filter(self, name=None, filter_func=None): |
|
877 if name == None and filter_func == None: |
|
878 # @register.filter() |
|
879 return self.filter_function |
|
880 elif filter_func == None: |
|
881 if(callable(name)): |
|
882 # @register.filter |
|
883 return self.filter_function(name) |
|
884 else: |
|
885 # @register.filter('somename') or @register.filter(name='somename') |
|
886 def dec(func): |
|
887 return self.filter(name, func) |
|
888 return dec |
|
889 elif name != None and filter_func != None: |
|
890 # register.filter('somename', somefunc) |
|
891 self.filters[name] = filter_func |
|
892 return filter_func |
|
893 else: |
|
894 raise InvalidTemplateLibrary("Unsupported arguments to Library.filter: (%r, %r)", (name, filter_func)) |
|
895 |
|
896 def filter_function(self, func): |
|
897 self.filters[getattr(func, "_decorated_function", func).__name__] = func |
|
898 return func |
|
899 |
|
900 def simple_tag(self,func): |
|
901 params, xx, xxx, defaults = getargspec(func) |
|
902 |
|
903 class SimpleNode(Node): |
|
904 def __init__(self, vars_to_resolve): |
|
905 self.vars_to_resolve = map(Variable, vars_to_resolve) |
|
906 |
|
907 def render(self, context): |
|
908 resolved_vars = [var.resolve(context) for var in self.vars_to_resolve] |
|
909 return func(*resolved_vars) |
|
910 |
|
911 compile_func = curry(generic_tag_compiler, params, defaults, getattr(func, "_decorated_function", func).__name__, SimpleNode) |
|
912 compile_func.__doc__ = func.__doc__ |
|
913 self.tag(getattr(func, "_decorated_function", func).__name__, compile_func) |
|
914 return func |
|
915 |
|
916 def inclusion_tag(self, file_name, context_class=Context, takes_context=False): |
|
917 def dec(func): |
|
918 params, xx, xxx, defaults = getargspec(func) |
|
919 if takes_context: |
|
920 if params[0] == 'context': |
|
921 params = params[1:] |
|
922 else: |
|
923 raise TemplateSyntaxError("Any tag function decorated with takes_context=True must have a first argument of 'context'") |
|
924 |
|
925 class InclusionNode(Node): |
|
926 def __init__(self, vars_to_resolve): |
|
927 self.vars_to_resolve = map(Variable, vars_to_resolve) |
|
928 |
|
929 def render(self, context): |
|
930 resolved_vars = [var.resolve(context) for var in self.vars_to_resolve] |
|
931 if takes_context: |
|
932 args = [context] + resolved_vars |
|
933 else: |
|
934 args = resolved_vars |
|
935 |
|
936 dict = func(*args) |
|
937 |
|
938 if not getattr(self, 'nodelist', False): |
|
939 from django.template.loader import get_template, select_template |
|
940 if not isinstance(file_name, basestring) and is_iterable(file_name): |
|
941 t = select_template(file_name) |
|
942 else: |
|
943 t = get_template(file_name) |
|
944 self.nodelist = t.nodelist |
|
945 return self.nodelist.render(context_class(dict, |
|
946 autoescape=context.autoescape)) |
|
947 |
|
948 compile_func = curry(generic_tag_compiler, params, defaults, getattr(func, "_decorated_function", func).__name__, InclusionNode) |
|
949 compile_func.__doc__ = func.__doc__ |
|
950 self.tag(getattr(func, "_decorated_function", func).__name__, compile_func) |
|
951 return func |
|
952 return dec |
|
953 |
|
954 def get_library(module_name): |
|
955 lib = libraries.get(module_name, None) |
|
956 if not lib: |
|
957 try: |
|
958 mod = import_module(module_name) |
|
959 except ImportError, e: |
|
960 raise InvalidTemplateLibrary("Could not load template library from %s, %s" % (module_name, e)) |
|
961 try: |
|
962 lib = mod.register |
|
963 libraries[module_name] = lib |
|
964 except AttributeError: |
|
965 raise InvalidTemplateLibrary("Template library %s does not have a variable named 'register'" % module_name) |
|
966 return lib |
|
967 |
|
968 def add_to_builtins(module_name): |
|
969 builtins.append(get_library(module_name)) |
|
970 |
|
971 add_to_builtins('django.template.defaulttags') |
|
972 add_to_builtins('django.template.defaultfilters') |