# -*- coding: utf-8 -*- # # Copyright (C) 2006-2008 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/. """Implementation of the various template directives.""" import compiler try: frozenset except NameError: from sets import ImmutableSet as frozenset from genshi.core import QName, Stream from genshi.path import Path from genshi.template.base import TemplateRuntimeError, TemplateSyntaxError, \ EXPR, _apply_directives, _eval_expr, \ _exec_suite from genshi.template.eval import Expression, ExpressionASTTransformer, _parse __all__ = ['AttrsDirective', 'ChooseDirective', 'ContentDirective', 'DefDirective', 'ForDirective', 'IfDirective', 'MatchDirective', 'OtherwiseDirective', 'ReplaceDirective', 'StripDirective', 'WhenDirective', 'WithDirective'] __docformat__ = 'restructuredtext en' class DirectiveMeta(type): """Meta class for template directives.""" def __new__(cls, name, bases, d): d['tagname'] = name.lower().replace('directive', '') return type.__new__(cls, name, bases, d) class Directive(object): """Abstract base class for template directives. A directive is basically a callable that takes three positional arguments: ``ctxt`` is the template data context, ``stream`` is an iterable over the events that the directive applies to, and ``directives`` is is a list of other directives on the same stream that need to be applied. Directives can be "anonymous" or "registered". Registered directives can be applied by the template author using an XML attribute with the corresponding name in the template. Such directives should be subclasses of this base class that can be instantiated with the value of the directive attribute as parameter. Anonymous directives are simply functions conforming to the protocol described above, and can only be applied programmatically (for example by template filters). """ __metaclass__ = DirectiveMeta __slots__ = ['expr'] def __init__(self, value, template=None, namespaces=None, lineno=-1, offset=-1): self.expr = self._parse_expr(value, template, lineno, offset) def attach(cls, template, stream, value, namespaces, pos): """Called after the template stream has been completely parsed. :param template: the `Template` object :param stream: the event stream associated with the directive :param value: the argument value for the directive; if the directive was specified as an element, this will be an `Attrs` instance with all specified attributes, otherwise it will be a `unicode` object with just the attribute value :param namespaces: a mapping of namespace URIs to prefixes :param pos: a ``(filename, lineno, offset)`` tuple describing the location where the directive was found in the source This class method should return a ``(directive, stream)`` tuple. If ``directive`` is not ``None``, it should be an instance of the `Directive` class, and gets added to the list of directives applied to the substream at runtime. `stream` is an event stream that replaces the original stream associated with the directive. """ return cls(value, template, namespaces, *pos[1:]), stream attach = classmethod(attach) def __call__(self, stream, directives, ctxt, **vars): """Apply the directive to the given stream. :param stream: the event stream :param directives: a list of the remaining directives that should process the stream :param ctxt: the context data :param vars: additional variables that should be made available when Python code is executed """ raise NotImplementedError def __repr__(self): expr = '' if getattr(self, 'expr', None) is not None: expr = ' "%s"' % self.expr.source return '<%s%s>' % (self.__class__.__name__, expr) def _parse_expr(cls, expr, template, lineno=-1, offset=-1): """Parses the given expression, raising a useful error message when a syntax error is encountered. """ try: return expr and Expression(expr, template.filepath, lineno, lookup=template.lookup) or None except SyntaxError, err: err.msg += ' in expression "%s" of "%s" directive' % (expr, cls.tagname) raise TemplateSyntaxError(err, template.filepath, lineno, offset + (err.offset or 0)) _parse_expr = classmethod(_parse_expr) def _assignment(ast): """Takes the AST representation of an assignment, and returns a function that applies the assignment of a given value to a dictionary. """ def _names(node): if isinstance(node, (compiler.ast.AssTuple, compiler.ast.Tuple)): return tuple([_names(child) for child in node.nodes]) elif isinstance(node, (compiler.ast.AssName, compiler.ast.Name)): return node.name def _assign(data, value, names=_names(ast)): if type(names) is tuple: for idx in range(len(names)): _assign(data, value[idx], names[idx]) else: data[names] = value return _assign class AttrsDirective(Directive): """Implementation of the ``py:attrs`` template directive. The value of the ``py:attrs`` attribute should be a dictionary or a sequence of ``(name, value)`` tuples. The items in that dictionary or sequence are added as attributes to the element: >>> from genshi.template import MarkupTemplate >>> tmpl = MarkupTemplate('''''') >>> print tmpl.generate(foo={'class': 'collapse'}) >>> print tmpl.generate(foo=[('class', 'collapse')]) If the value evaluates to ``None`` (or any other non-truth value), no attributes are added: >>> print tmpl.generate(foo=None) """ __slots__ = [] def __call__(self, stream, directives, ctxt, **vars): def _generate(): kind, (tag, attrib), pos = stream.next() attrs = _eval_expr(self.expr, ctxt, **vars) if attrs: if isinstance(attrs, Stream): try: attrs = iter(attrs).next() except StopIteration: attrs = [] elif not isinstance(attrs, list): # assume it's a dict attrs = attrs.items() attrib -= [name for name, val in attrs if val is None] attrib |= [(QName(name), unicode(val).strip()) for name, val in attrs if val is not None] yield kind, (tag, attrib), pos for event in stream: yield event return _apply_directives(_generate(), directives, ctxt, **vars) class ContentDirective(Directive): """Implementation of the ``py:content`` template directive. This directive replaces the content of the element with the result of evaluating the value of the ``py:content`` attribute: >>> from genshi.template import MarkupTemplate >>> tmpl = MarkupTemplate('''''') >>> print tmpl.generate(bar='Bye') """ __slots__ = [] def attach(cls, template, stream, value, namespaces, pos): if type(value) is dict: raise TemplateSyntaxError('The content directive can not be used ' 'as an element', template.filepath, *pos[1:]) expr = cls._parse_expr(value, template, *pos[1:]) return None, [stream[0], (EXPR, expr, pos), stream[-1]] attach = classmethod(attach) class DefDirective(Directive): """Implementation of the ``py:def`` template directive. This directive can be used to create "Named Template Functions", which are template snippets that are not actually output during normal processing, but rather can be expanded from expressions in other places in the template. A named template function can be used just like a normal Python function from template expressions: >>> from genshi.template import MarkupTemplate >>> tmpl = MarkupTemplate('''
...

... ${greeting}, ${name}! ...

... ${echo('Hi', name='you')} ...
''') >>> print tmpl.generate(bar='Bye')

Hi, you!

If a function does not require parameters, the parenthesis can be omitted in the definition: >>> tmpl = MarkupTemplate('''
...

... Hello, world! ...

... ${helloworld()} ...
''') >>> print tmpl.generate(bar='Bye')

Hello, world!

""" __slots__ = ['name', 'args', 'star_args', 'dstar_args', 'defaults'] def __init__(self, args, template, namespaces=None, lineno=-1, offset=-1): Directive.__init__(self, None, template, namespaces, lineno, offset) ast = _parse(args).node self.args = [] self.star_args = None self.dstar_args = None self.defaults = {} if isinstance(ast, compiler.ast.CallFunc): self.name = ast.node.name for arg in ast.args: if isinstance(arg, compiler.ast.Keyword): self.args.append(arg.name) self.defaults[arg.name] = Expression(arg.expr, template.filepath, lineno, lookup=template.lookup) else: self.args.append(arg.name) if ast.star_args: self.star_args = ast.star_args.name if ast.dstar_args: self.dstar_args = ast.dstar_args.name else: self.name = ast.name def attach(cls, template, stream, value, namespaces, pos): if type(value) is dict: value = value.get('function') return super(DefDirective, cls).attach(template, stream, value, namespaces, pos) attach = classmethod(attach) def __call__(self, stream, directives, ctxt, **vars): stream = list(stream) def function(*args, **kwargs): scope = {} args = list(args) # make mutable for name in self.args: if args: scope[name] = args.pop(0) else: if name in kwargs: val = kwargs.pop(name) else: val = _eval_expr(self.defaults.get(name), ctxt, **vars) scope[name] = val if not self.star_args is None: scope[self.star_args] = args if not self.dstar_args is None: scope[self.dstar_args] = kwargs ctxt.push(scope) for event in _apply_directives(stream, directives, ctxt, **vars): yield event ctxt.pop() try: function.__name__ = self.name except TypeError: # Function name can't be set in Python 2.3 pass # Store the function reference in the bottom context frame so that it # doesn't get popped off before processing the template has finished # FIXME: this makes context data mutable as a side-effect ctxt.frames[-1][self.name] = function return [] def __repr__(self): return '<%s "%s">' % (self.__class__.__name__, self.name) class ForDirective(Directive): """Implementation of the ``py:for`` template directive for repeating an element based on an iterable in the context data. >>> from genshi.template import MarkupTemplate >>> tmpl = MarkupTemplate('''''') >>> print tmpl.generate(items=[1, 2, 3]) """ __slots__ = ['assign', 'filename'] def __init__(self, value, template, namespaces=None, lineno=-1, offset=-1): if ' in ' not in value: raise TemplateSyntaxError('"in" keyword missing in "for" directive', template.filepath, lineno, offset) assign, value = value.split(' in ', 1) ast = _parse(assign, 'exec') value = 'iter(%s)' % value.strip() self.assign = _assignment(ast.node.nodes[0].expr) self.filename = template.filepath Directive.__init__(self, value, template, namespaces, lineno, offset) def attach(cls, template, stream, value, namespaces, pos): if type(value) is dict: value = value.get('each') return super(ForDirective, cls).attach(template, stream, value, namespaces, pos) attach = classmethod(attach) def __call__(self, stream, directives, ctxt, **vars): iterable = _eval_expr(self.expr, ctxt, **vars) if iterable is None: return assign = self.assign scope = {} stream = list(stream) for item in iterable: assign(scope, item) ctxt.push(scope) for event in _apply_directives(stream, directives, ctxt, **vars): yield event ctxt.pop() def __repr__(self): return '<%s>' % self.__class__.__name__ class IfDirective(Directive): """Implementation of the ``py:if`` template directive for conditionally excluding elements from being output. >>> from genshi.template import MarkupTemplate >>> tmpl = MarkupTemplate('''
... ${bar} ...
''') >>> print tmpl.generate(foo=True, bar='Hello')
Hello
""" __slots__ = [] def attach(cls, template, stream, value, namespaces, pos): if type(value) is dict: value = value.get('test') return super(IfDirective, cls).attach(template, stream, value, namespaces, pos) attach = classmethod(attach) def __call__(self, stream, directives, ctxt, **vars): value = _eval_expr(self.expr, ctxt, **vars) if value: return _apply_directives(stream, directives, ctxt, **vars) return [] class MatchDirective(Directive): """Implementation of the ``py:match`` template directive. >>> from genshi.template import MarkupTemplate >>> tmpl = MarkupTemplate('''
... ... Hello ${select('@name')} ... ... ...
''') >>> print tmpl.generate()
Hello Dude
""" __slots__ = ['path', 'namespaces', 'hints'] def __init__(self, value, template, hints=None, namespaces=None, lineno=-1, offset=-1): Directive.__init__(self, None, template, namespaces, lineno, offset) self.path = Path(value, template.filepath, lineno) self.namespaces = namespaces or {} self.hints = hints or () def attach(cls, template, stream, value, namespaces, pos): hints = [] if type(value) is dict: if value.get('buffer', '').lower() == 'false': hints.append('not_buffered') if value.get('once', '').lower() == 'true': hints.append('match_once') if value.get('recursive', '').lower() == 'false': hints.append('not_recursive') value = value.get('path') return cls(value, template, frozenset(hints), namespaces, *pos[1:]), \ stream attach = classmethod(attach) def __call__(self, stream, directives, ctxt, **vars): ctxt._match_templates.append((self.path.test(ignore_context=True), self.path, list(stream), self.hints, self.namespaces, directives)) return [] def __repr__(self): return '<%s "%s">' % (self.__class__.__name__, self.path.source) class ReplaceDirective(Directive): """Implementation of the ``py:replace`` template directive. This directive replaces the element with the result of evaluating the value of the ``py:replace`` attribute: >>> from genshi.template import MarkupTemplate >>> tmpl = MarkupTemplate('''
... Hello ...
''') >>> print tmpl.generate(bar='Bye')
Bye
This directive is equivalent to ``py:content`` combined with ``py:strip``, providing a less verbose way to achieve the same effect: >>> tmpl = MarkupTemplate('''
... Hello ...
''') >>> print tmpl.generate(bar='Bye')
Bye
""" __slots__ = [] def attach(cls, template, stream, value, namespaces, pos): if type(value) is dict: value = value.get('value') if not value: raise TemplateSyntaxError('missing value for "replace" directive', template.filepath, *pos[1:]) expr = cls._parse_expr(value, template, *pos[1:]) return None, [(EXPR, expr, pos)] attach = classmethod(attach) class StripDirective(Directive): """Implementation of the ``py:strip`` template directive. When the value of the ``py:strip`` attribute evaluates to ``True``, the element is stripped from the output >>> from genshi.template import MarkupTemplate >>> tmpl = MarkupTemplate('''
...
foo
...
''') >>> print tmpl.generate()
foo
Leaving the attribute value empty is equivalent to a truth value. This directive is particulary interesting for named template functions or match templates that do not generate a top-level element: >>> tmpl = MarkupTemplate('''
...
... ${what} ...
... ${echo('foo')} ...
''') >>> print tmpl.generate()
foo
""" __slots__ = [] def __call__(self, stream, directives, ctxt, **vars): def _generate(): if _eval_expr(self.expr, ctxt, **vars): stream.next() # skip start tag previous = stream.next() for event in stream: yield previous previous = event else: for event in stream: yield event return _apply_directives(_generate(), directives, ctxt, **vars) def attach(cls, template, stream, value, namespaces, pos): if not value: return None, stream[1:-1] return super(StripDirective, cls).attach(template, stream, value, namespaces, pos) attach = classmethod(attach) class ChooseDirective(Directive): """Implementation of the ``py:choose`` directive for conditionally selecting one of several body elements to display. If the ``py:choose`` expression is empty the expressions of nested ``py:when`` directives are tested for truth. The first true ``py:when`` body is output. If no ``py:when`` directive is matched then the fallback directive ``py:otherwise`` will be used. >>> from genshi.template import MarkupTemplate >>> tmpl = MarkupTemplate('''
... 0 ... 1 ... 2 ...
''') >>> print tmpl.generate()
1
If the ``py:choose`` directive contains an expression, the nested ``py:when`` directives are tested for equality to the ``py:choose`` expression: >>> tmpl = MarkupTemplate('''
... 1 ... 2 ...
''') >>> print tmpl.generate()
2
Behavior is undefined if a ``py:choose`` block contains content outside a ``py:when`` or ``py:otherwise`` block. Behavior is also undefined if a ``py:otherwise`` occurs before ``py:when`` blocks. """ __slots__ = ['matched', 'value'] def attach(cls, template, stream, value, namespaces, pos): if type(value) is dict: value = value.get('test') return super(ChooseDirective, cls).attach(template, stream, value, namespaces, pos) attach = classmethod(attach) def __call__(self, stream, directives, ctxt, **vars): info = [False, bool(self.expr), None] if self.expr: info[2] = _eval_expr(self.expr, ctxt, **vars) ctxt._choice_stack.append(info) for event in _apply_directives(stream, directives, ctxt, **vars): yield event ctxt._choice_stack.pop() class WhenDirective(Directive): """Implementation of the ``py:when`` directive for nesting in a parent with the ``py:choose`` directive. See the documentation of the `ChooseDirective` for usage. """ __slots__ = ['filename'] def __init__(self, value, template, namespaces=None, lineno=-1, offset=-1): Directive.__init__(self, value, template, namespaces, lineno, offset) self.filename = template.filepath def attach(cls, template, stream, value, namespaces, pos): if type(value) is dict: value = value.get('test') return super(WhenDirective, cls).attach(template, stream, value, namespaces, pos) attach = classmethod(attach) def __call__(self, stream, directives, ctxt, **vars): info = ctxt._choice_stack and ctxt._choice_stack[-1] if not info: raise TemplateRuntimeError('"when" directives can only be used ' 'inside a "choose" directive', self.filename, *stream.next()[2][1:]) if info[0]: return [] if not self.expr and not info[1]: raise TemplateRuntimeError('either "choose" or "when" directive ' 'must have a test expression', self.filename, *stream.next()[2][1:]) if info[1]: value = info[2] if self.expr: matched = value == _eval_expr(self.expr, ctxt, **vars) else: matched = bool(value) else: matched = bool(_eval_expr(self.expr, ctxt, **vars)) info[0] = matched if not matched: return [] return _apply_directives(stream, directives, ctxt, **vars) class OtherwiseDirective(Directive): """Implementation of the ``py:otherwise`` directive for nesting in a parent with the ``py:choose`` directive. See the documentation of `ChooseDirective` for usage. """ __slots__ = ['filename'] def __init__(self, value, template, namespaces=None, lineno=-1, offset=-1): Directive.__init__(self, None, template, namespaces, lineno, offset) self.filename = template.filepath def __call__(self, stream, directives, ctxt, **vars): info = ctxt._choice_stack and ctxt._choice_stack[-1] if not info: raise TemplateRuntimeError('an "otherwise" directive can only be ' 'used inside a "choose" directive', self.filename, *stream.next()[2][1:]) if info[0]: return [] info[0] = True return _apply_directives(stream, directives, ctxt, **vars) class WithDirective(Directive): """Implementation of the ``py:with`` template directive, which allows shorthand access to variables and expressions. >>> from genshi.template import MarkupTemplate >>> tmpl = MarkupTemplate('''
... $x $y $z ...
''') >>> print tmpl.generate(x=42)
42 7 52
""" __slots__ = ['vars'] def __init__(self, value, template, namespaces=None, lineno=-1, offset=-1): Directive.__init__(self, None, template, namespaces, lineno, offset) self.vars = [] value = value.strip() try: ast = _parse(value, 'exec').node for node in ast.nodes: if isinstance(node, compiler.ast.Discard): continue elif not isinstance(node, compiler.ast.Assign): raise TemplateSyntaxError('only assignment allowed in ' 'value of the "with" directive', template.filepath, lineno, offset) self.vars.append(([_assignment(n) for n in node.nodes], Expression(node.expr, template.filepath, lineno, lookup=template.lookup))) except SyntaxError, err: err.msg += ' in expression "%s" of "%s" directive' % (value, self.tagname) raise TemplateSyntaxError(err, template.filepath, lineno, offset + (err.offset or 0)) def attach(cls, template, stream, value, namespaces, pos): if type(value) is dict: value = value.get('vars') return super(WithDirective, cls).attach(template, stream, value, namespaces, pos) attach = classmethod(attach) def __call__(self, stream, directives, ctxt, **vars): frame = {} ctxt.push(frame) for targets, expr in self.vars: value = _eval_expr(expr, ctxt, **vars) for assign in targets: assign(frame, value) for event in _apply_directives(stream, directives, ctxt, **vars): yield event ctxt.pop() def __repr__(self): return '<%s>' % (self.__class__.__name__)