Mercurial > genshi > genshi-test
view genshi/path.py @ 289:7487632f467c stable-0.3.x
Ported [356] to 0.3.x branch.
author | cmlenz |
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date | Fri, 13 Oct 2006 07:43:41 +0000 |
parents | c685294b1156 |
children | 6e6950ac0e56 059d6e7415d2 |
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# -*- coding: utf-8 -*- # # Copyright (C) 2006 Edgewall Software # All rights reserved. # # This software is licensed as described in the file COPYING, which # you should have received as part of this distribution. The terms # are also available at http://genshi.edgewall.org/wiki/License. # # This software consists of voluntary contributions made by many # individuals. For the exact contribution history, see the revision # history and logs, available at http://genshi.edgewall.org/log/. """Basic support for evaluating XPath expressions against streams. >>> from genshi.input import XML >>> doc = XML('''<doc> ... <items count="2"> ... <item status="new"> ... <summary>Foo</summary> ... </item> ... <item status="closed"> ... <summary>Bar</summary> ... </item> ... </items> ... </doc>''') >>> print doc.select('items/item[@status="closed"]/summary/text()') Bar Because the XPath engine operates on markup streams (as opposed to tree structures), it only implements a subset of the full XPath 1.0 language. """ from math import ceil, floor import re from genshi.core import Stream, Attrs, Namespace, QName from genshi.core import START, END, TEXT, COMMENT, PI __all__ = ['Path', 'PathSyntaxError'] class Axis(object): """Defines constants for the various supported XPath axes.""" ATTRIBUTE = 'attribute' CHILD = 'child' DESCENDANT = 'descendant' DESCENDANT_OR_SELF = 'descendant-or-self' SELF = 'self' def forname(cls, name): """Return the axis constant for the given name, or `None` if no such axis was defined. """ return getattr(cls, name.upper().replace('-', '_'), None) forname = classmethod(forname) ATTRIBUTE = Axis.ATTRIBUTE CHILD = Axis.CHILD DESCENDANT = Axis.DESCENDANT DESCENDANT_OR_SELF = Axis.DESCENDANT_OR_SELF SELF = Axis.SELF class Path(object): """Implements basic XPath support on streams. Instances of this class represent a "compiled" XPath expression, and provide methods for testing the path against a stream, as well as extracting a substream matching that path. """ def __init__(self, text, filename=None, lineno=-1): """Create the path object from a string. @param text: the path expression """ self.source = text self.paths = PathParser(text, filename, lineno).parse() def __repr__(self): paths = [] for path in self.paths: steps = [] for axis, nodetest, predicates in path: steps.append('%s::%s' % (axis, nodetest)) for predicate in predicates: steps[-1] += '[%s]' % predicate paths.append('/'.join(steps)) return '<%s "%s">' % (self.__class__.__name__, '|'.join(paths)) def select(self, stream, namespaces=None, variables=None): """Returns a substream of the given stream that matches the path. If there are no matches, this method returns an empty stream. >>> from genshi.input import XML >>> xml = XML('<root><elem><child>Text</child></elem></root>') >>> print Path('.//child').select(xml) <child>Text</child> >>> print Path('.//child/text()').select(xml) Text @param stream: the stream to select from @param namespaces: (optional) a mapping of namespace prefixes to URIs @param variables: (optional) a mapping of variable names to values @return: the substream matching the path, or an empty stream """ if namespaces is None: namespaces = {} if variables is None: variables = {} stream = iter(stream) def _generate(): test = self.test() for kind, data, pos in stream: result = test(kind, data, pos, namespaces, variables) if result is True: yield kind, data, pos depth = 1 while depth > 0: subkind, subdata, subpos = stream.next() if subkind is START: depth += 1 elif subkind is END: depth -= 1 yield subkind, subdata, subpos test(subkind, subdata, subpos, namespaces, variables) elif result: yield result return Stream(_generate()) def test(self, ignore_context=False): """Returns a function that can be used to track whether the path matches a specific stream event. The function returned expects the positional arguments `kind`, `data`, `pos` (basically an unpacked stream event), as well as `namespaces` and `variables`. The latter two are a mapping of namespace prefixes to URIs, and a mapping of variable names to values, respectively. If the path matches the event, the function returns the match (for example, a `START` or `TEXT` event.) Otherwise, it returns `None`. >>> from genshi.input import XML >>> xml = XML('<root><elem><child id="1"/></elem><child id="2"/></root>') >>> test = Path('child').test() >>> for kind, data, pos in xml: ... if test(kind, data, pos, {}, {}): ... print kind, data START (u'child', [(u'id', u'2')]) """ paths = [(p, len(p), [0], [], [0] * len(p)) for p in self.paths] def _test(kind, data, pos, namespaces, variables): retval = None for steps, size, cursors, cutoff, counter in paths: # Manage the stack that tells us "where we are" in the stream if kind is END: if cursors: cursors.pop() continue elif kind is START: cursors.append(cursors and cursors[-1] or 0) if retval or not cursors: continue cursor = cursors[-1] depth = len(cursors) if cutoff and depth + int(kind is not START) > cutoff[0]: continue ctxtnode = not ignore_context and kind is START \ and depth == 2 matched = None while 1: # Fetch the next location step axis, nodetest, predicates = steps[cursor] # If this is the start event for the context node, and the # axis of the location step doesn't include the current # element, skip the test if ctxtnode and (axis is CHILD or axis is DESCENDANT): break # Is this the last step of the location path? last_step = cursor + 1 == size # Perform the actual node test matched = nodetest(kind, data, pos, namespaces, variables) # The node test matched if matched: # Check all the predicates for this step if predicates: for predicate in predicates: pretval = predicate(kind, data, pos, namespaces, variables) if type(pretval) is float: counter[cursor] += 1 if counter[cursor] != int(pretval): pretval = False if not pretval: matched = None break # Both the node test and the predicates matched if matched: if last_step: if not ctxtnode or kind is not START \ or axis is ATTRIBUTE or axis is SELF: retval = matched elif not ctxtnode or axis is SELF \ or axis is DESCENDANT_OR_SELF: cursor += 1 cursors[-1] = cursor cutoff[:] = [] elif not ignore_context and kind is START: cutoff[:] = [depth] if last_step and not ignore_context and kind is START: if (axis is not DESCENDANT and axis is not DESCENDANT_OR_SELF): cutoff[:] = [depth] if kind is START and not last_step: next_axis = steps[cursor][0] if next_axis is ATTRIBUTE: # If the axis of the next location step is the # attribute axis, we need to move on to processing # that step without waiting for the next markup # event continue # We're done with this step if it's the last step or the # axis isn't "self" if last_step or (axis is not SELF and axis is not DESCENDANT_OR_SELF): break if kind is START and axis is not DESCENDANT \ and axis is not DESCENDANT_OR_SELF: # If this step is not a closure, it cannot be matched until # the current element is closed... so we need to move the # cursor back to the previous closure and retest that # against the current element backsteps = [(k, d, p) for k, d, p in steps[:cursor] if k is DESCENDANT or k is DESCENDANT_OR_SELF] backsteps.reverse() for axis, nodetest, predicates in backsteps: matched = nodetest(kind, data, pos, namespaces, variables) if not matched: cursor -= 1 cutoff[:] = [] break cursors[-1] = cursor return retval return _test class PathSyntaxError(Exception): """Exception raised when an XPath expression is syntactically incorrect.""" def __init__(self, message, filename=None, lineno=-1, offset=-1): if filename: message = '%s (%s, line %d)' % (message, filename, lineno) Exception.__init__(self, message) self.filename = filename self.lineno = lineno self.offset = offset class PathParser(object): """Tokenizes and parses an XPath expression.""" _QUOTES = (("'", "'"), ('"', '"')) _TOKENS = ('::', ':', '..', '.', '//', '/', '[', ']', '()', '(', ')', '@', '=', '!=', '!', '|', ',', '>=', '>', '<=', '<', '$') _tokenize = re.compile('("[^"]*")|(\'[^\']*\')|((?:\d+)?\.\d+)|(%s)|([^%s\s]+)|\s+' % ( '|'.join([re.escape(t) for t in _TOKENS]), ''.join([re.escape(t[0]) for t in _TOKENS]))).findall def __init__(self, text, filename=None, lineno=-1): self.filename = filename self.lineno = lineno self.tokens = filter(None, [dqstr or sqstr or number or token or name for dqstr, sqstr, number, token, name in self._tokenize(text)]) self.pos = 0 # Tokenizer at_end = property(lambda self: self.pos == len(self.tokens) - 1) cur_token = property(lambda self: self.tokens[self.pos]) def next_token(self): self.pos += 1 return self.tokens[self.pos] def peek_token(self): if not self.at_end: return self.tokens[self.pos + 1] return None # Recursive descent parser def parse(self): """Parses the XPath expression and returns a list of location path tests. For union expressions (such as `*|text()`), this function returns one test for each operand in the union. For patch expressions that don't use the union operator, the function always returns a list of size 1. Each path test in turn is a sequence of tests that correspond to the location steps, each tuples of the form `(axis, testfunc, predicates)` """ paths = [self._location_path()] while self.cur_token == '|': self.next_token() paths.append(self._location_path()) if not self.at_end: raise PathSyntaxError('Unexpected token %r after end of expression' % self.cur_token, self.filename, self.lineno) return paths def _location_path(self): steps = [] while True: if self.cur_token.startswith('/'): if self.cur_token == '//': steps.append((DESCENDANT_OR_SELF, NodeTest(), [])) elif not steps: raise PathSyntaxError('Absolute location paths not ' 'supported', self.filename, self.lineno) self.next_token() axis, nodetest, predicates = self._location_step() if not axis: axis = CHILD steps.append((axis, nodetest, predicates)) if self.at_end or not self.cur_token.startswith('/'): break return steps def _location_step(self): if self.cur_token == '@': axis = ATTRIBUTE self.next_token() elif self.cur_token == '.': axis = SELF elif self.cur_token == '..': raise PathSyntaxError('Unsupported axis "parent"', self.filename, self.lineno) elif self.peek_token() == '::': axis = Axis.forname(self.cur_token) if axis is None: raise PathSyntaxError('Unsupport axis "%s"' % axis, self.filename, self.lineno) self.next_token() self.next_token() else: axis = None nodetest = self._node_test(axis or CHILD) predicates = [] while self.cur_token == '[': predicates.append(self._predicate()) return axis, nodetest, predicates def _node_test(self, axis=None): test = prefix = None next_token = self.peek_token() if next_token in ('(', '()'): # Node type test test = self._node_type() elif next_token == ':': # Namespace prefix prefix = self.cur_token self.next_token() localname = self.next_token() if localname == '*': test = QualifiedPrincipalTypeTest(axis, prefix) else: test = QualifiedNameTest(axis, prefix, localname) else: # Name test if self.cur_token == '*': test = PrincipalTypeTest(axis) elif self.cur_token == '.': test = NodeTest() else: test = LocalNameTest(axis, self.cur_token) if not self.at_end: self.next_token() return test def _node_type(self): name = self.cur_token self.next_token() args = [] if self.cur_token != '()': # The processing-instruction() function optionally accepts the # name of the PI as argument, which must be a literal string self.next_token() # ( if self.cur_token != ')': string = self.cur_token if (string[0], string[-1]) in self._QUOTES: string = string[1:-1] args.append(string) cls = _nodetest_map.get(name) if not cls: raise PathSyntaxError('%s() not allowed here' % name, self.filename, self.lineno) return cls(*args) def _predicate(self): assert self.cur_token == '[' self.next_token() expr = self._or_expr() if self.cur_token != ']': raise PathSyntaxError('Expected "]" to close predicate, ' 'but found "%s"' % self.cur_token, self.filename, self.lineno) if not self.at_end: self.next_token() return expr def _or_expr(self): expr = self._and_expr() while self.cur_token == 'or': self.next_token() expr = OrOperator(expr, self._and_expr()) return expr def _and_expr(self): expr = self._equality_expr() while self.cur_token == 'and': self.next_token() expr = AndOperator(expr, self._equality_expr()) return expr def _equality_expr(self): expr = self._relational_expr() while self.cur_token in ('=', '!='): op = _operator_map[self.cur_token] self.next_token() expr = op(expr, self._relational_expr()) return expr def _relational_expr(self): expr = self._primary_expr() while self.cur_token in ('>', '>=', '<', '>='): op = _operator_map[self.cur_token] self.next_token() expr = op(expr, self._primary_expr()) return expr def _primary_expr(self): token = self.cur_token if len(token) > 1 and (token[0], token[-1]) in self._QUOTES: self.next_token() return StringLiteral(token[1:-1]) elif token[0].isdigit() or token[0] == '.': self.next_token() return NumberLiteral(float(token)) elif token == '$': token = self.next_token() self.next_token() return VariableReference(token) elif not self.at_end and self.peek_token().startswith('('): return self._function_call() else: axis = None if token == '@': axis = ATTRIBUTE self.next_token() return self._node_test(axis) def _function_call(self): name = self.cur_token if self.next_token() == '()': args = [] else: assert self.cur_token == '(' self.next_token() args = [self._or_expr()] while self.cur_token == ',': self.next_token() args.append(self._or_expr()) if not self.cur_token == ')': raise PathSyntaxError('Expected ")" to close function argument ' 'list, but found "%s"' % self.cur_token, self.filename, self.lineno) self.next_token() cls = _function_map.get(name) if not cls: raise PathSyntaxError('Unsupported function "%s"' % name, self.filename, self.lineno) return cls(*args) # Node tests class PrincipalTypeTest(object): """Node test that matches any event with the given principal type.""" __slots__ = ['principal_type'] def __init__(self, principal_type): self.principal_type = principal_type def __call__(self, kind, data, pos, namespaces, variables): if kind is START: if self.principal_type is ATTRIBUTE: return data[1] or None else: return True def __repr__(self): return '*' class QualifiedPrincipalTypeTest(object): """Node test that matches any event with the given principal type in a specific namespace.""" __slots__ = ['principal_type', 'prefix'] def __init__(self, principal_type, prefix): self.principal_type = principal_type self.prefix = prefix def __call__(self, kind, data, pos, namespaces, variables): namespace = Namespace(namespaces.get(self.prefix)) if kind is START: if self.principal_type is ATTRIBUTE and data[1]: return Attrs([(name, value) for name, value in data[1] if name in namespace]) or None else: return data[0] in namespace def __repr__(self): return '%s:*' % self.prefix class LocalNameTest(object): """Node test that matches any event with the given prinipal type and local name. """ __slots__ = ['principal_type', 'name'] def __init__(self, principal_type, name): self.principal_type = principal_type self.name = name def __call__(self, kind, data, pos, namespaces, variables): if kind is START: if self.principal_type is ATTRIBUTE and self.name in data[1]: return data[1].get(self.name) else: return data[0].localname == self.name def __repr__(self): return self.name class QualifiedNameTest(object): """Node test that matches any event with the given prinipal type and qualified name. """ __slots__ = ['principal_type', 'prefix', 'name'] def __init__(self, principal_type, prefix, name): self.principal_type = principal_type self.prefix = prefix self.name = name def __call__(self, kind, data, pos, namespaces, variables): qname = QName('%s}%s' % (namespaces.get(self.prefix), self.name)) if kind is START: if self.principal_type is ATTRIBUTE and qname in data[1]: return data[1].get(qname) else: return data[0] == qname def __repr__(self): return '%s:%s' % (self.prefix, self.name) class CommentNodeTest(object): """Node test that matches any comment events.""" __slots__ = [] def __call__(self, kind, data, pos, namespaces, variables): return kind is COMMENT and (kind, data, pos) def __repr__(self): return 'comment()' class NodeTest(object): """Node test that matches any node.""" __slots__ = [] def __call__(self, kind, data, pos, namespaces, variables): if kind is START: return True return kind, data, pos def __repr__(self): return 'node()' class ProcessingInstructionNodeTest(object): """Node test that matches any processing instruction event.""" __slots__ = ['target'] def __init__(self, target=None): self.target = target def __call__(self, kind, data, pos, namespaces, variables): if kind is PI and (not self.target or data[0] == self.target): return (kind, data, pos) def __repr__(self): arg = '' if self.target: arg = '"' + self.target + '"' return 'processing-instruction(%s)' % arg class TextNodeTest(object): """Node test that matches any text event.""" __slots__ = [] def __call__(self, kind, data, pos, namespaces, variables): return kind is TEXT and (kind, data, pos) def __repr__(self): return 'text()' _nodetest_map = {'comment': CommentNodeTest, 'node': NodeTest, 'processing-instruction': ProcessingInstructionNodeTest, 'text': TextNodeTest} # Functions class Function(object): """Base class for function nodes in XPath expressions.""" class BooleanFunction(Function): """The `boolean` function, which converts its argument to a boolean value. """ __slots__ = ['expr'] def __init__(self, expr): self.expr = expr def __call__(self, kind, data, pos, namespaces, variables): val = self.expr(kind, data, pos, namespaces, variables) return bool(val) def __repr__(self): return 'boolean(%r)' % self.expr class CeilingFunction(Function): """The `ceiling` function, which returns the nearest lower integer number for the given number. """ __slots__ = ['number'] def __init__(self, number): self.number = number def __call__(self, kind, data, pos, namespaces, variables): number = self.number(kind, data, pos, namespaces, variables) return ceil(float(number)) def __repr__(self): return 'ceiling(%r)' % self.number class ConcatFunction(Function): """The `concat` function, which concatenates (joins) the variable number of strings it gets as arguments. """ __slots__ = ['exprs'] def __init__(self, *exprs): self.exprs = exprs def __call__(self, kind, data, pos, namespaces, variables): strings = [] for item in [expr(kind, data, pos, namespaces, variables) for expr in self.exprs]: strings.append(item) return u''.join(strings) def __repr__(self): return 'concat(%s)' % ', '.join([repr(expr) for expr in self.exprs]) class ContainsFunction(Function): """The `contains` function, which returns whether a string contains a given substring. """ __slots__ = ['string1', 'string2'] def __init__(self, string1, string2): self.string1 = string1 self.string2 = string2 def __call__(self, kind, data, pos, namespaces, variables): string1 = self.string1(kind, data, pos, namespaces, variables) string2 = self.string2(kind, data, pos, namespaces, variables) return string2 in string1 def __repr__(self): return 'contains(%r, %r)' % (self.string1, self.string2) class FalseFunction(Function): """The `false` function, which always returns the boolean `false` value.""" __slots__ = [] def __call__(self, kind, data, pos, namespaces, variables): return False def __repr__(self): return 'false()' class FloorFunction(Function): """The `ceiling` function, which returns the nearest higher integer number for the given number. """ __slots__ = ['number'] def __init__(self, number): self.number = number def __call__(self, kind, data, pos, namespaces, variables): number = self.number(kind, data, pos, namespaces, variables) return floor(float(number)) def __repr__(self): return 'floor(%r)' % self.number class LocalNameFunction(Function): """The `local-name` function, which returns the local name of the current element. """ __slots__ = [] def __call__(self, kind, data, pos, namespaces, variables): if kind is START: return data[0].localname def __repr__(self): return 'local-name()' class NameFunction(Function): """The `name` function, which returns the qualified name of the current element. """ __slots__ = [] def __call__(self, kind, data, pos, namespaces, variables): if kind is START: return data[0] def __repr__(self): return 'name()' class NamespaceUriFunction(Function): """The `namespace-uri` function, which returns the namespace URI of the current element. """ __slots__ = [] def __call__(self, kind, data, pos, namespaces, variables): if kind is START: return data[0].namespace def __repr__(self): return 'namespace-uri()' class NotFunction(Function): """The `not` function, which returns the negated boolean value of its argument. """ __slots__ = ['expr'] def __init__(self, expr): self.expr = expr def __call__(self, kind, data, pos, namespaces, variables): return not self.expr(kind, data, pos, namespaces, variables) def __repr__(self): return 'not(%s)' % self.expr class NormalizeSpaceFunction(Function): """The `normalize-space` function, which removes leading and trailing whitespace in the given string, and replaces multiple adjacent whitespace characters inside the string with a single space. """ __slots__ = ['expr'] _normalize = re.compile(r'\s{2,}').sub def __init__(self, expr): self.expr = expr def __call__(self, kind, data, pos, namespaces, variables): string = self.expr(kind, data, pos, namespaces, variables) return self._normalize(' ', string.strip()) def __repr__(self): return 'normalize-space(%s)' % repr(self.expr) class NumberFunction(Function): """The `number` function that converts its argument to a number.""" __slots__ = ['expr'] def __init__(self, expr): self.expr = expr def __call__(self, kind, data, pos, namespaces, variables): val = self.expr(kind, data, pos, namespaces, variables) return float(val) def __repr__(self): return 'number(%r)' % self.expr class RoundFunction(Function): """The `round` function, which returns the nearest integer number for the given number. """ __slots__ = ['number'] def __init__(self, number): self.number = number def __call__(self, kind, data, pos, namespaces, variables): number = self.number(kind, data, pos, namespaces, variables) return round(float(number)) def __repr__(self): return 'round(%r)' % self.number class StartsWithFunction(Function): """The `starts-with` function that returns whether one string starts with a given substring. """ __slots__ = ['string1', 'string2'] def __init__(self, string1, string2): self.string1 = string1 self.string2 = string2 def __call__(self, kind, data, pos, namespaces, variables): string1 = self.string1(kind, data, pos, namespaces, variables) string2 = self.string2(kind, data, pos, namespaces, variables) return string1.startswith(string2) def __repr__(self): return 'starts-with(%r, %r)' % (self.string1, self.string2) class StringLengthFunction(Function): """The `string-length` function that returns the length of the given string. """ __slots__ = ['expr'] def __init__(self, expr): self.expr = expr def __call__(self, kind, data, pos, namespaces, variables): string = self.expr(kind, data, pos, namespaces, variables) return len(string) def __repr__(self): return 'string-length(%r)' % self.expr class SubstringFunction(Function): """The `substring` function that returns the part of a string that starts at the given offset, and optionally limited to the given length. """ __slots__ = ['string', 'start', 'length'] def __init__(self, string, start, length=None): self.string = string self.start = start self.length = length def __call__(self, kind, data, pos, namespaces, variables): string = self.string(kind, data, pos, namespaces, variables) start = self.start(kind, data, pos, namespaces, variables) length = 0 if self.length is not None: length = self.length(kind, data, pos, namespaces, variables) return string[int(start):len(string) - int(length)] def __repr__(self): if self.length is not None: return 'substring(%r, %r, %r)' % (self.string, self.start, self.length) else: return 'substring(%r, %r)' % (self.string, self.start) class SubstringAfterFunction(Function): """The `substring-after` function that returns the part of a string that is found after the given substring. """ __slots__ = ['string1', 'string2'] def __init__(self, string1, string2): self.string1 = string1 self.string2 = string2 def __call__(self, kind, data, pos, namespaces, variables): string1 = self.string1(kind, data, pos, namespaces, variables) string2 = self.string2(kind, data, pos, namespaces, variables) index = string1.find(string2) if index >= 0: return string1[index + len(string2):] return u'' def __repr__(self): return 'substring-after(%r, %r)' % (self.string1, self.string2) class SubstringBeforeFunction(Function): """The `substring-before` function that returns the part of a string that is found before the given substring. """ __slots__ = ['string1', 'string2'] def __init__(self, string1, string2): self.string1 = string1 self.string2 = string2 def __call__(self, kind, data, pos, namespaces, variables): string1 = self.string1(kind, data, pos, namespaces, variables) string2 = self.string2(kind, data, pos, namespaces, variables) index = string1.find(string2) if index >= 0: return string1[:index] return u'' def __repr__(self): return 'substring-after(%r, %r)' % (self.string1, self.string2) class TranslateFunction(Function): """The `translate` function that translates a set of characters in a string to target set of characters. """ __slots__ = ['string', 'fromchars', 'tochars'] def __init__(self, string, fromchars, tochars): self.string = string self.fromchars = fromchars self.tochars = tochars def __call__(self, kind, data, pos, namespaces, variables): string = self.string(kind, data, pos, namespaces, variables) fromchars = self.fromchars(kind, data, pos, namespaces, variables) tochars = self.tochars(kind, data, pos, namespaces, variables) table = dict(zip([ord(c) for c in fromchars], [ord(c) for c in tochars])) return string.translate(table) def __repr__(self): return 'translate(%r, %r, %r)' % (self.string, self.fromchars, self.tochars) class TrueFunction(Function): """The `true` function, which always returns the boolean `true` value.""" __slots__ = [] def __call__(self, kind, data, pos, namespaces, variables): return True def __repr__(self): return 'true()' _function_map = {'boolean': BooleanFunction, 'ceiling': CeilingFunction, 'concat': ConcatFunction, 'contains': ContainsFunction, 'false': FalseFunction, 'floor': FloorFunction, 'local-name': LocalNameFunction, 'name': NameFunction, 'namespace-uri': NamespaceUriFunction, 'normalize-space': NormalizeSpaceFunction, 'not': NotFunction, 'number': NumberFunction, 'round': RoundFunction, 'starts-with': StartsWithFunction, 'string-length': StringLengthFunction, 'substring': SubstringFunction, 'substring-after': SubstringAfterFunction, 'substring-before': SubstringBeforeFunction, 'translate': TranslateFunction, 'true': TrueFunction} # Literals & Variables class Literal(object): """Abstract base class for literal nodes.""" class StringLiteral(Literal): """A string literal node.""" __slots__ = ['text'] def __init__(self, text): self.text = text def __call__(self, kind, data, pos, namespaces, variables): return self.text def __repr__(self): return '"%s"' % self.text class NumberLiteral(Literal): """A number literal node.""" __slots__ = ['number'] def __init__(self, number): self.number = number def __call__(self, kind, data, pos, namespaces, variables): return self.number def __repr__(self): return str(self.number) class VariableReference(Literal): """A variable reference node.""" __slots__ = ['name'] def __init__(self, name): self.name = name def __call__(self, kind, data, pos, namespaces, variables): return variables.get(self.name) def __repr__(self): return str(self.name) # Operators class AndOperator(object): """The boolean operator `and`.""" __slots__ = ['lval', 'rval'] def __init__(self, lval, rval): self.lval = lval self.rval = rval def __call__(self, kind, data, pos, namespaces, variables): lval = self.lval(kind, data, pos, namespaces, variables) if not lval: return False rval = self.rval(kind, data, pos, namespaces, variables) return bool(rval) def __repr__(self): return '%s and %s' % (self.lval, self.rval) class EqualsOperator(object): """The equality operator `=`.""" __slots__ = ['lval', 'rval'] def __init__(self, lval, rval): self.lval = lval self.rval = rval def __call__(self, kind, data, pos, namespaces, variables): lval = self.lval(kind, data, pos, namespaces, variables) rval = self.rval(kind, data, pos, namespaces, variables) return lval == rval def __repr__(self): return '%s=%s' % (self.lval, self.rval) class NotEqualsOperator(object): """The equality operator `!=`.""" __slots__ = ['lval', 'rval'] def __init__(self, lval, rval): self.lval = lval self.rval = rval def __call__(self, kind, data, pos, namespaces, variables): lval = self.lval(kind, data, pos, namespaces, variables) rval = self.rval(kind, data, pos, namespaces, variables) return lval != rval def __repr__(self): return '%s!=%s' % (self.lval, self.rval) class OrOperator(object): """The boolean operator `or`.""" __slots__ = ['lval', 'rval'] def __init__(self, lval, rval): self.lval = lval self.rval = rval def __call__(self, kind, data, pos, namespaces, variables): lval = self.lval(kind, data, pos, namespaces, variables) if lval: return True rval = self.rval(kind, data, pos, namespaces, variables) return bool(rval) def __repr__(self): return '%s or %s' % (self.lval, self.rval) class GreaterThanOperator(object): """The relational operator `>` (greater than).""" __slots__ = ['lval', 'rval'] def __init__(self, lval, rval): self.lval = lval self.rval = rval def __call__(self, kind, data, pos, namespaces, variables): lval = self.lval(kind, data, pos, namespaces, variables) rval = self.rval(kind, data, pos, namespaces, variables) return float(lval) > float(rval) def __repr__(self): return '%s>%s' % (self.lval, self.rval) class GreaterThanOrEqualOperator(object): """The relational operator `>=` (greater than or equal).""" __slots__ = ['lval', 'rval'] def __init__(self, lval, rval): self.lval = lval self.rval = rval def __call__(self, kind, data, pos, namespaces, variables): lval = self.lval(kind, data, pos, namespaces, variables) rval = self.rval(kind, data, pos, namespaces, variables) return float(lval) >= float(rval) def __repr__(self): return '%s>=%s' % (self.lval, self.rval) class LessThanOperator(object): """The relational operator `<` (less than).""" __slots__ = ['lval', 'rval'] def __init__(self, lval, rval): self.lval = lval self.rval = rval def __call__(self, kind, data, pos, namespaces, variables): lval = self.lval(kind, data, pos, namespaces, variables) rval = self.rval(kind, data, pos, namespaces, variables) return float(lval) < float(rval) def __repr__(self): return '%s<%s' % (self.lval, self.rval) class LessThanOrEqualOperator(object): """The relational operator `<=` (less than or equal).""" __slots__ = ['lval', 'rval'] def __init__(self, lval, rval): self.lval = lval self.rval = rval def __call__(self, kind, data, pos, namespaces, variables): lval = self.lval(kind, data, pos, namespaces, variables) rval = self.rval(kind, data, pos, namespaces, variables) return float(lval) <= float(rval) def __repr__(self): return '%s<=%s' % (self.lval, self.rval) _operator_map = {'=': EqualsOperator, '!=': NotEqualsOperator, '>': GreaterThanOperator, '>=': GreaterThanOrEqualOperator, '<': LessThanOperator, '>=': LessThanOrEqualOperator}