Mercurial > genshi > mirror
annotate markup/path.py @ 37:37557b8fb925 trunk
Moved some of the tests for the strip directive to a new unittest test case to not clutter up the documentation.
| author | cmlenz |
|---|---|
| date | Sun, 02 Jul 2006 23:10:27 +0000 |
| parents | 1fdb7054fb42 |
| children | ee669cb9cccc |
| rev | line source |
|---|---|
| 1 | 1 # -*- coding: utf-8 -*- |
| 2 # | |
| 27 | 3 # Copyright (C) 2006 Christopher Lenz |
| 1 | 4 # All rights reserved. |
| 5 # | |
| 6 # This software is licensed as described in the file COPYING, which | |
| 7 # you should have received as part of this distribution. The terms | |
| 27 | 8 # are also available at http://markup.cmlenz.net/wiki/License. |
| 1 | 9 # |
| 10 # This software consists of voluntary contributions made by many | |
| 11 # individuals. For the exact contribution history, see the revision | |
| 27 | 12 # history and logs, available at http://markup.cmlenz.net/log/. |
| 1 | 13 |
| 14 """Basic support for evaluating XPath expressions against streams.""" | |
| 15 | |
| 16 import re | |
| 17 | |
| 18 from markup.core import QName, Stream | |
| 19 | |
| 20 __all__ = ['Path'] | |
| 21 | |
| 22 | |
| 23 class Path(object): | |
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24 """Implements basic XPath support on streams. |
| 1 | 25 |
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26 Instances of this class represent a "compiled" XPath expression, and provide |
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27 methods for testing the path against a stream, as well as extracting a |
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28 substream matching that path. |
| 1 | 29 """ |
| 30 _TOKEN_RE = re.compile('(::|\.\.|\(\)|[/.:\[\]\(\)@=!])|' | |
| 31 '([^/:\[\]\(\)@=!\s]+)|' | |
| 32 '\s+') | |
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33 _QUOTES = (("'", "'"), ('"', '"')) |
| 1 | 34 |
| 35 def __init__(self, text): | |
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36 """Create the path object from a string. |
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37 |
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38 @param text: the path expression |
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39 """ |
| 1 | 40 self.source = text |
| 41 | |
| 42 steps = [] | |
| 43 cur_op = '' | |
| 44 cur_tag = '' | |
| 45 in_predicate = False | |
| 46 for op, tag in self._TOKEN_RE.findall(text): | |
| 47 if op: | |
| 48 if op == '[': | |
| 49 in_predicate = True | |
| 50 elif op == ']': | |
| 51 in_predicate = False | |
| 52 elif op.startswith('('): | |
| 53 if cur_tag == 'text': | |
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54 steps[-1] = (False, self._FunctionText(), []) |
| 1 | 55 else: |
| 56 raise NotImplementedError('XPath function "%s" not ' | |
| 57 'supported' % cur_tag) | |
| 58 else: | |
| 59 cur_op += op | |
| 60 cur_tag = '' | |
| 61 else: | |
| 62 closure = cur_op in ('', '//') | |
| 63 if cur_op == '@': | |
| 64 if tag == '*': | |
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65 node_test = self._AnyAttribute() |
| 1 | 66 else: |
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67 node_test = self._AttributeByName(tag) |
| 1 | 68 else: |
| 69 if tag == '*': | |
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70 node_test = self._AnyElement() |
| 1 | 71 elif in_predicate: |
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72 if len(tag) > 1 and (tag[0], tag[-1]) in self._QUOTES: |
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73 node_test = self._LiteralString(tag[1:-1]) |
| 1 | 74 if cur_op == '=': |
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75 node_test = self._OperatorEq(steps[-1][2][-1], |
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76 node_test) |
| 1 | 77 steps[-1][2].pop() |
| 78 elif cur_op == '!=': | |
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79 node_test = self._OperatorNeq(steps[-1][2][-1], |
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80 node_test) |
| 1 | 81 steps[-1][2].pop() |
| 82 else: | |
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83 node_test = self._ElementByName(tag) |
| 1 | 84 if in_predicate: |
| 85 steps[-1][2].append(node_test) | |
| 86 else: | |
| 87 steps.append([closure, node_test, []]) | |
| 88 cur_op = '' | |
| 89 cur_tag = tag | |
| 90 self.steps = steps | |
| 91 | |
| 92 def __repr__(self): | |
| 93 return '<%s "%s">' % (self.__class__.__name__, self.source) | |
| 94 | |
| 95 def select(self, stream): | |
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96 """Returns a substream of the given stream that matches the path. |
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97 |
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98 If there are no matches, this method returns an empty stream. |
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99 |
| 33 | 100 >>> from markup.input import XML |
| 101 >>> xml = XML('<root><elem><child>Text</child></elem></root>') | |
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102 |
| 33 | 103 >>> print Path('child').select(xml) |
| 104 <child>Text</child> | |
| 105 | |
| 106 >>> print Path('child/text()').select(xml) | |
| 107 Text | |
| 108 | |
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109 @param stream: the stream to select from |
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110 @return: the substream matching the path, or an empty stream |
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111 """ |
| 1 | 112 stream = iter(stream) |
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113 def _generate(): |
| 1 | 114 test = self.test() |
| 115 for kind, data, pos in stream: | |
| 116 result = test(kind, data, pos) | |
| 117 if result is True: | |
| 118 yield kind, data, pos | |
| 119 depth = 1 | |
| 120 while depth > 0: | |
| 121 ev = stream.next() | |
| 122 if ev[0] is Stream.START: | |
| 123 depth += 1 | |
| 124 elif ev[0] is Stream.END: | |
| 125 depth -= 1 | |
| 126 yield ev | |
| 127 test(*ev) | |
| 128 elif result: | |
| 129 yield result | |
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130 return Stream(_generate()) |
| 1 | 131 |
| 132 def test(self): | |
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133 """Returns a function that can be used to track whether the path matches |
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134 a specific stream event. |
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135 |
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136 The function returned expects the positional arguments `kind`, `data`, |
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137 and `pos`, i.e. basically an unpacked stream event. If the path matches |
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138 the event, the function returns the match (for example, a `START` or |
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139 `TEXT` event.) Otherwise, it returns `None` or `False`. |
| 33 | 140 |
| 141 >>> from markup.input import XML | |
| 142 >>> xml = XML('<root><elem><child id="1"/></elem><child id="2"/></root>') | |
| 143 >>> test = Path('child').test() | |
| 144 >>> for kind, data, pos in xml: | |
| 145 ... if test(kind, data, pos): | |
| 146 ... print kind, data | |
| 147 START (u'child', [(u'id', u'1')]) | |
| 148 START (u'child', [(u'id', u'2')]) | |
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149 """ |
| 1 | 150 stack = [0] # stack of cursors into the location path |
| 151 | |
| 152 def _test(kind, data, pos): | |
| 153 if not stack: | |
| 154 return False | |
| 155 | |
| 156 if kind is Stream.END: | |
| 157 stack.pop() | |
| 158 return None | |
| 159 | |
| 160 if kind is Stream.START: | |
| 161 stack.append(stack[-1]) | |
| 162 | |
| 163 matched = False | |
| 164 closure, node_test, predicates = self.steps[stack[-1]] | |
| 165 | |
| 166 matched = node_test(kind, data, pos) | |
| 167 if matched and predicates: | |
| 168 for predicate in predicates: | |
| 169 if not predicate(kind, data, pos): | |
| 170 matched = None | |
| 171 break | |
| 172 | |
| 173 if matched: | |
| 174 if stack[-1] == len(self.steps) - 1: | |
| 175 return matched | |
| 176 | |
| 177 stack[-1] += 1 | |
| 178 | |
| 179 elif kind is Stream.START and not closure: | |
| 24 | 180 # If this step is not a closure, it cannot be matched until the |
| 181 # current element is closed... so we need to move the cursor | |
| 182 # back to the last closure and retest that against the current | |
| 183 # element | |
| 1 | 184 closures = [step for step in self.steps[:stack[-1]] if step[0]] |
| 25 | 185 closures.reverse() |
| 1 | 186 for closure, node_test, predicates in closures: |
| 187 stack[-1] -= 1 | |
| 188 if closure: | |
| 189 matched = node_test(kind, data, pos) | |
| 190 if matched: | |
| 191 stack[-1] += 1 | |
| 192 break | |
| 193 | |
| 194 return None | |
| 195 | |
| 196 return _test | |
| 197 | |
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198 class _AnyElement(object): |
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199 """Node test that matches any element.""" |
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200 def __call__(self, kind, *_): |
| 1 | 201 if kind is Stream.START: |
| 202 return True | |
| 203 return None | |
| 204 def __repr__(self): | |
| 205 return '<%s>' % self.__class__.__name__ | |
| 206 | |
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207 class _ElementByName(object): |
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208 """Node test that matches an element with a specific tag name.""" |
| 1 | 209 def __init__(self, name): |
| 210 self.name = QName(name) | |
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211 def __call__(self, kind, data, _): |
| 1 | 212 if kind is Stream.START: |
| 213 return data[0].localname == self.name | |
| 214 return None | |
| 215 def __repr__(self): | |
| 216 return '<%s "%s">' % (self.__class__.__name__, self.name) | |
| 217 | |
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218 class _AnyAttribute(object): |
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219 """Node test that matches any attribute.""" |
| 1 | 220 def __call__(self, kind, data, pos): |
| 221 if kind is Stream.START: | |
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222 text = ''.join([val for _, val in data[1]]) |
| 1 | 223 if text: |
| 224 return Stream.TEXT, text, pos | |
| 225 return None | |
| 226 return None | |
| 227 def __repr__(self): | |
| 228 return '<%s>' % (self.__class__.__name__) | |
| 229 | |
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230 class _AttributeByName(object): |
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231 """Node test that matches an attribute with a specific name.""" |
| 1 | 232 def __init__(self, name): |
| 233 self.name = QName(name) | |
| 234 def __call__(self, kind, data, pos): | |
| 235 if kind is Stream.START: | |
| 236 if self.name in data[1]: | |
| 237 return Stream.TEXT, data[1].get(self.name), pos | |
| 238 return None | |
| 239 return None | |
| 240 def __repr__(self): | |
| 241 return '<%s "%s">' % (self.__class__.__name__, self.name) | |
| 242 | |
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243 class _FunctionText(object): |
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244 """Function that returns text content.""" |
| 1 | 245 def __call__(self, kind, data, pos): |
| 246 if kind is Stream.TEXT: | |
| 247 return kind, data, pos | |
| 248 return None | |
| 249 def __repr__(self): | |
| 250 return '<%s>' % (self.__class__.__name__) | |
| 251 | |
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252 class _LiteralString(object): |
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253 """Always returns a literal string.""" |
| 1 | 254 def __init__(self, value): |
| 255 self.value = value | |
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256 def __call__(self, *_): |
| 1 | 257 return Stream.TEXT, self.value, (-1, -1) |
| 258 def __repr__(self): | |
| 259 return '<%s>' % (self.__class__.__name__) | |
| 260 | |
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261 class _OperatorEq(object): |
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262 """Equality comparison operator.""" |
| 1 | 263 def __init__(self, lval, rval): |
| 264 self.lval = lval | |
| 265 self.rval = rval | |
| 266 def __call__(self, kind, data, pos): | |
| 267 lval = self.lval(kind, data, pos) | |
| 268 rval = self.rval(kind, data, pos) | |
| 269 return (lval and lval[1]) == (rval and rval[1]) | |
| 270 def __repr__(self): | |
| 271 return '<%s %r = %r>' % (self.__class__.__name__, self.lval, | |
| 272 self.rval) | |
| 273 | |
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274 class _OperatorNeq(object): |
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275 """Inequality comparison operator.""" |
| 1 | 276 def __init__(self, lval, rval): |
| 277 self.lval = lval | |
| 278 self.rval = rval | |
| 279 def __call__(self, kind, data, pos): | |
| 280 lval = self.lval(kind, data, pos) | |
| 281 rval = self.rval(kind, data, pos) | |
| 282 return (lval and lval[1]) != (rval and rval[1]) | |
| 283 def __repr__(self): | |
| 284 return '<%s %r != %r>' % (self.__class__.__name__, self.lval, | |
| 285 self.rval) |