Mercurial > genshi > mirror
view genshi/filters/transform.py @ 1029:7d4414a4a5d0 trunk
Support slash escaped of CRLF newlines (fixes #569; patch from tetsuya.morimoto@gmail.com).
author | hodgestar |
---|---|
date | Wed, 19 Mar 2014 13:40:47 +0000 |
parents | 1e8c33345e52 |
children | 6fc92535c888 |
line wrap: on
line source
# -*- coding: utf-8 -*- # # Copyright (C) 2007-2009 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/. """A filter for functional-style transformations of markup streams. The `Transformer` filter provides a variety of transformations that can be applied to parts of streams that match given XPath expressions. These transformations can be chained to achieve results that would be comparitively tedious to achieve by writing stream filters by hand. The approach of chaining node selection and transformation has been inspired by the `jQuery`_ Javascript library. .. _`jQuery`: http://jquery.com/ For example, the following transformation removes the ``<title>`` element from the ``<head>`` of the input document: >>> from genshi.builder import tag >>> html = HTML('''<html> ... <head><title>Some Title</title></head> ... <body> ... Some <em>body</em> text. ... </body> ... </html>''', ... encoding='utf-8') >>> print(html | Transformer('body/em').map(unicode.upper, TEXT) ... .unwrap().wrap(tag.u)) <html> <head><title>Some Title</title></head> <body> Some <u>BODY</u> text. </body> </html> The ``Transformer`` support a large number of useful transformations out of the box, but custom transformations can be added easily. :since: version 0.5 """ import re import sys from genshi.builder import Element from genshi.core import Stream, Attrs, QName, TEXT, START, END, _ensure, Markup from genshi.path import Path __all__ = ['Transformer', 'StreamBuffer', 'InjectorTransformation', 'ENTER', 'EXIT', 'INSIDE', 'OUTSIDE', 'BREAK'] class TransformMark(str): """A mark on a transformation stream.""" __slots__ = [] _instances = {} def __new__(cls, val): return cls._instances.setdefault(val, str.__new__(cls, val)) ENTER = TransformMark('ENTER') """Stream augmentation mark indicating that a selected element is being entered.""" INSIDE = TransformMark('INSIDE') """Stream augmentation mark indicating that processing is currently inside a selected element.""" OUTSIDE = TransformMark('OUTSIDE') """Stream augmentation mark indicating that a match occurred outside a selected element.""" ATTR = TransformMark('ATTR') """Stream augmentation mark indicating a selected element attribute.""" EXIT = TransformMark('EXIT') """Stream augmentation mark indicating that a selected element is being exited.""" BREAK = TransformMark('BREAK') """Stream augmentation mark indicating a break between two otherwise contiguous blocks of marked events. This is used primarily by the cut() transform to provide later transforms with an opportunity to operate on the cut buffer. """ class PushBackStream(object): """Allows a single event to be pushed back onto the stream and re-consumed. """ def __init__(self, stream): self.stream = iter(stream) self.peek = None def push(self, event): assert self.peek is None self.peek = event def __iter__(self): while True: if self.peek is not None: peek = self.peek self.peek = None yield peek else: try: event = self.stream.next() yield event except StopIteration: if self.peek is None: raise class Transformer(object): """Stream filter that can apply a variety of different transformations to a stream. This is achieved by selecting the events to be transformed using XPath, then applying the transformations to the events matched by the path expression. Each marked event is in the form (mark, (kind, data, pos)), where mark can be any of `ENTER`, `INSIDE`, `EXIT`, `OUTSIDE`, or `None`. The first three marks match `START` and `END` events, and any events contained `INSIDE` any selected XML/HTML element. A non-element match outside a `START`/`END` container (e.g. ``text()``) will yield an `OUTSIDE` mark. >>> html = HTML('<html><head><title>Some Title</title></head>' ... '<body>Some <em>body</em> text.</body></html>', ... encoding='utf-8') Transformations act on selected stream events matching an XPath expression. Here's an example of removing some markup (the title, in this case) selected by an expression: >>> print(html | Transformer('head/title').remove()) <html><head/><body>Some <em>body</em> text.</body></html> Inserted content can be passed in the form of a string, or a markup event stream, which includes streams generated programmatically via the `builder` module: >>> from genshi.builder import tag >>> print(html | Transformer('body').prepend(tag.h1('Document Title'))) <html><head><title>Some Title</title></head><body><h1>Document Title</h1>Some <em>body</em> text.</body></html> Each XPath expression determines the set of tags that will be acted upon by subsequent transformations. In this example we select the ``<title>`` text, copy it into a buffer, then select the ``<body>`` element and paste the copied text into the body as ``<h1>`` enclosed text: >>> buffer = StreamBuffer() >>> print(html | Transformer('head/title/text()').copy(buffer) ... .end().select('body').prepend(tag.h1(buffer))) <html><head><title>Some Title</title></head><body><h1>Some Title</h1>Some <em>body</em> text.</body></html> Transformations can also be assigned and reused, although care must be taken when using buffers, to ensure that buffers are cleared between transforms: >>> emphasis = Transformer('body//em').attr('class', 'emphasis') >>> print(html | emphasis) <html><head><title>Some Title</title></head><body>Some <em class="emphasis">body</em> text.</body></html> """ __slots__ = ['transforms'] def __init__(self, path='.'): """Construct a new transformation filter. :param path: an XPath expression (as string) or a `Path` instance """ self.transforms = [SelectTransformation(path)] def __call__(self, stream, keep_marks=False): """Apply the transform filter to the marked stream. :param stream: the marked event stream to filter :param keep_marks: Do not strip transformer selection marks from the stream. Useful for testing. :return: the transformed stream :rtype: `Stream` """ transforms = self._mark(stream) for link in self.transforms: transforms = link(transforms) if not keep_marks: transforms = self._unmark(transforms) return Stream(transforms, serializer=getattr(stream, 'serializer', None)) def apply(self, function): """Apply a transformation to the stream. Transformations can be chained, similar to stream filters. Any callable accepting a marked stream can be used as a transform. As an example, here is a simple `TEXT` event upper-casing transform: >>> def upper(stream): ... for mark, (kind, data, pos) in stream: ... if mark and kind is TEXT: ... yield mark, (kind, data.upper(), pos) ... else: ... yield mark, (kind, data, pos) >>> short_stream = HTML('<body>Some <em>test</em> text</body>', ... encoding='utf-8') >>> print(short_stream | Transformer('.//em/text()').apply(upper)) <body>Some <em>TEST</em> text</body> """ transformer = Transformer() transformer.transforms = self.transforms[:] if isinstance(function, Transformer): transformer.transforms.extend(function.transforms) else: transformer.transforms.append(function) return transformer #{ Selection operations def select(self, path): """Mark events matching the given XPath expression, within the current selection. >>> html = HTML('<body>Some <em>test</em> text</body>', encoding='utf-8') >>> print(html | Transformer().select('.//em').trace()) (None, ('START', (QName('body'), Attrs()), (None, 1, 0))) (None, ('TEXT', u'Some ', (None, 1, 6))) ('ENTER', ('START', (QName('em'), Attrs()), (None, 1, 11))) ('INSIDE', ('TEXT', u'test', (None, 1, 15))) ('EXIT', ('END', QName('em'), (None, 1, 19))) (None, ('TEXT', u' text', (None, 1, 24))) (None, ('END', QName('body'), (None, 1, 29))) <body>Some <em>test</em> text</body> :param path: an XPath expression (as string) or a `Path` instance :return: the stream augmented by transformation marks :rtype: `Transformer` """ return self.apply(SelectTransformation(path)) def invert(self): """Invert selection so that marked events become unmarked, and vice versa. Specificaly, all marks are converted to null marks, and all null marks are converted to OUTSIDE marks. >>> html = HTML('<body>Some <em>test</em> text</body>', encoding='utf-8') >>> print(html | Transformer('//em').invert().trace()) ('OUTSIDE', ('START', (QName('body'), Attrs()), (None, 1, 0))) ('OUTSIDE', ('TEXT', u'Some ', (None, 1, 6))) (None, ('START', (QName('em'), Attrs()), (None, 1, 11))) (None, ('TEXT', u'test', (None, 1, 15))) (None, ('END', QName('em'), (None, 1, 19))) ('OUTSIDE', ('TEXT', u' text', (None, 1, 24))) ('OUTSIDE', ('END', QName('body'), (None, 1, 29))) <body>Some <em>test</em> text</body> :rtype: `Transformer` """ return self.apply(InvertTransformation()) def end(self): """End current selection, allowing all events to be selected. Example: >>> html = HTML('<body>Some <em>test</em> text</body>', encoding='utf-8') >>> print(html | Transformer('//em').end().trace()) ('OUTSIDE', ('START', (QName('body'), Attrs()), (None, 1, 0))) ('OUTSIDE', ('TEXT', u'Some ', (None, 1, 6))) ('OUTSIDE', ('START', (QName('em'), Attrs()), (None, 1, 11))) ('OUTSIDE', ('TEXT', u'test', (None, 1, 15))) ('OUTSIDE', ('END', QName('em'), (None, 1, 19))) ('OUTSIDE', ('TEXT', u' text', (None, 1, 24))) ('OUTSIDE', ('END', QName('body'), (None, 1, 29))) <body>Some <em>test</em> text</body> :return: the stream augmented by transformation marks :rtype: `Transformer` """ return self.apply(EndTransformation()) #{ Deletion operations def empty(self): """Empty selected elements of all content. Example: >>> html = HTML('<html><head><title>Some Title</title></head>' ... '<body>Some <em>body</em> text.</body></html>', ... encoding='utf-8') >>> print(html | Transformer('.//em').empty()) <html><head><title>Some Title</title></head><body>Some <em/> text.</body></html> :rtype: `Transformer` """ return self.apply(EmptyTransformation()) def remove(self): """Remove selection from the stream. Example: >>> html = HTML('<html><head><title>Some Title</title></head>' ... '<body>Some <em>body</em> text.</body></html>', ... encoding='utf-8') >>> print(html | Transformer('.//em').remove()) <html><head><title>Some Title</title></head><body>Some text.</body></html> :rtype: `Transformer` """ return self.apply(RemoveTransformation()) #{ Direct element operations def unwrap(self): """Remove outermost enclosing elements from selection. Example: >>> html = HTML('<html><head><title>Some Title</title></head>' ... '<body>Some <em>body</em> text.</body></html>', ... encoding='utf-8') >>> print(html | Transformer('.//em').unwrap()) <html><head><title>Some Title</title></head><body>Some body text.</body></html> :rtype: `Transformer` """ return self.apply(UnwrapTransformation()) def wrap(self, element): """Wrap selection in an element. >>> html = HTML('<html><head><title>Some Title</title></head>' ... '<body>Some <em>body</em> text.</body></html>', ... encoding='utf-8') >>> print(html | Transformer('.//em').wrap('strong')) <html><head><title>Some Title</title></head><body>Some <strong><em>body</em></strong> text.</body></html> :param element: either a tag name (as string) or an `Element` object :rtype: `Transformer` """ return self.apply(WrapTransformation(element)) #{ Content insertion operations def replace(self, content): """Replace selection with content. >>> html = HTML('<html><head><title>Some Title</title></head>' ... '<body>Some <em>body</em> text.</body></html>', ... encoding='utf-8') >>> print(html | Transformer('.//title/text()').replace('New Title')) <html><head><title>New Title</title></head><body>Some <em>body</em> text.</body></html> :param content: Either a callable, an iterable of events, or a string to insert. :rtype: `Transformer` """ return self.apply(ReplaceTransformation(content)) def before(self, content): """Insert content before selection. In this example we insert the word 'emphasised' before the <em> opening tag: >>> html = HTML('<html><head><title>Some Title</title></head>' ... '<body>Some <em>body</em> text.</body></html>', ... encoding='utf-8') >>> print(html | Transformer('.//em').before('emphasised ')) <html><head><title>Some Title</title></head><body>Some emphasised <em>body</em> text.</body></html> :param content: Either a callable, an iterable of events, or a string to insert. :rtype: `Transformer` """ return self.apply(BeforeTransformation(content)) def after(self, content): """Insert content after selection. Here, we insert some text after the </em> closing tag: >>> html = HTML('<html><head><title>Some Title</title></head>' ... '<body>Some <em>body</em> text.</body></html>', ... encoding='utf-8') >>> print(html | Transformer('.//em').after(' rock')) <html><head><title>Some Title</title></head><body>Some <em>body</em> rock text.</body></html> :param content: Either a callable, an iterable of events, or a string to insert. :rtype: `Transformer` """ return self.apply(AfterTransformation(content)) def prepend(self, content): """Insert content after the ENTER event of the selection. Inserting some new text at the start of the <body>: >>> html = HTML('<html><head><title>Some Title</title></head>' ... '<body>Some <em>body</em> text.</body></html>', ... encoding='utf-8') >>> print(html | Transformer('.//body').prepend('Some new body text. ')) <html><head><title>Some Title</title></head><body>Some new body text. Some <em>body</em> text.</body></html> :param content: Either a callable, an iterable of events, or a string to insert. :rtype: `Transformer` """ return self.apply(PrependTransformation(content)) def append(self, content): """Insert content before the END event of the selection. >>> html = HTML('<html><head><title>Some Title</title></head>' ... '<body>Some <em>body</em> text.</body></html>', ... encoding='utf-8') >>> print(html | Transformer('.//body').append(' Some new body text.')) <html><head><title>Some Title</title></head><body>Some <em>body</em> text. Some new body text.</body></html> :param content: Either a callable, an iterable of events, or a string to insert. :rtype: `Transformer` """ return self.apply(AppendTransformation(content)) #{ Attribute manipulation def attr(self, name, value): """Add, replace or delete an attribute on selected elements. If `value` evaulates to `None` the attribute will be deleted from the element: >>> html = HTML('<html><head><title>Some Title</title></head>' ... '<body>Some <em class="before">body</em> <em>text</em>.</body>' ... '</html>', encoding='utf-8') >>> print(html | Transformer('body/em').attr('class', None)) <html><head><title>Some Title</title></head><body>Some <em>body</em> <em>text</em>.</body></html> Otherwise the attribute will be set to `value`: >>> print(html | Transformer('body/em').attr('class', 'emphasis')) <html><head><title>Some Title</title></head><body>Some <em class="emphasis">body</em> <em class="emphasis">text</em>.</body></html> If `value` is a callable it will be called with the attribute name and the `START` event for the matching element. Its return value will then be used to set the attribute: >>> def print_attr(name, event): ... attrs = event[1][1] ... print(attrs) ... return attrs.get(name) >>> print(html | Transformer('body/em').attr('class', print_attr)) Attrs([(QName('class'), u'before')]) Attrs() <html><head><title>Some Title</title></head><body>Some <em class="before">body</em> <em>text</em>.</body></html> :param name: the name of the attribute :param value: the value that should be set for the attribute. :rtype: `Transformer` """ return self.apply(AttrTransformation(name, value)) #{ Buffer operations def copy(self, buffer, accumulate=False): """Copy selection into buffer. The buffer is replaced by each *contiguous* selection before being passed to the next transformation. If accumulate=True, further selections will be appended to the buffer rather than replacing it. >>> from genshi.builder import tag >>> buffer = StreamBuffer() >>> html = HTML('<html><head><title>Some Title</title></head>' ... '<body>Some <em>body</em> text.</body></html>', ... encoding='utf-8') >>> print(html | Transformer('head/title/text()').copy(buffer) ... .end().select('body').prepend(tag.h1(buffer))) <html><head><title>Some Title</title></head><body><h1>Some Title</h1>Some <em>body</em> text.</body></html> This example illustrates that only a single contiguous selection will be buffered: >>> print(html | Transformer('head/title/text()').copy(buffer) ... .end().select('body/em').copy(buffer).end().select('body') ... .prepend(tag.h1(buffer))) <html><head><title>Some Title</title></head><body><h1>Some Title</h1>Some <em>body</em> text.</body></html> >>> print(buffer) <em>body</em> Element attributes can also be copied for later use: >>> html = HTML('<html><head><title>Some Title</title></head>' ... '<body><em>Some</em> <em class="before">body</em>' ... '<em>text</em>.</body></html>', ... encoding='utf-8') >>> buffer = StreamBuffer() >>> def apply_attr(name, entry): ... return list(buffer)[0][1][1].get('class') >>> print(html | Transformer('body/em[@class]/@class').copy(buffer) ... .end().buffer().select('body/em[not(@class)]') ... .attr('class', apply_attr)) <html><head><title>Some Title</title></head><body><em class="before">Some</em> <em class="before">body</em><em class="before">text</em>.</body></html> :param buffer: the `StreamBuffer` in which the selection should be stored :rtype: `Transformer` :note: Copy (and cut) copy each individual selected object into the buffer before passing to the next transform. For example, the XPath ``*|text()`` will select all elements and text, each instance of which will be copied to the buffer individually before passing to the next transform. This has implications for how ``StreamBuffer`` objects can be used, so some experimentation may be required. """ return self.apply(CopyTransformation(buffer, accumulate)) def cut(self, buffer, accumulate=False): """Copy selection into buffer and remove the selection from the stream. >>> from genshi.builder import tag >>> buffer = StreamBuffer() >>> html = HTML('<html><head><title>Some Title</title></head>' ... '<body>Some <em>body</em> text.</body></html>', ... encoding='utf-8') >>> print(html | Transformer('.//em/text()').cut(buffer) ... .end().select('.//em').after(tag.h1(buffer))) <html><head><title>Some Title</title></head><body>Some <em/><h1>body</h1> text.</body></html> Specifying accumulate=True, appends all selected intervals onto the buffer. Combining this with the .buffer() operation allows us operate on all copied events rather than per-segment. See the documentation on buffer() for more information. :param buffer: the `StreamBuffer` in which the selection should be stored :rtype: `Transformer` :note: this transformation will buffer the entire input stream """ return self.apply(CutTransformation(buffer, accumulate)) def buffer(self): """Buffer the entire stream (can consume a considerable amount of memory). Useful in conjunction with copy(accumulate=True) and cut(accumulate=True) to ensure that all marked events in the entire stream are copied to the buffer before further transformations are applied. For example, to move all <note> elements inside a <notes> tag at the top of the document: >>> doc = HTML('<doc><notes></notes><body>Some <note>one</note> ' ... 'text <note>two</note>.</body></doc>', ... encoding='utf-8') >>> buffer = StreamBuffer() >>> print(doc | Transformer('body/note').cut(buffer, accumulate=True) ... .end().buffer().select('notes').prepend(buffer)) <doc><notes><note>one</note><note>two</note></notes><body>Some text .</body></doc> """ return self.apply(list) #{ Miscellaneous operations def filter(self, filter): """Apply a normal stream filter to the selection. The filter is called once for each contiguous block of marked events. >>> from genshi.filters.html import HTMLSanitizer >>> html = HTML('<html><body>Some text<script>alert(document.cookie)' ... '</script> and some more text</body></html>', ... encoding='utf-8') >>> print(html | Transformer('body/*').filter(HTMLSanitizer())) <html><body>Some text and some more text</body></html> :param filter: The stream filter to apply. :rtype: `Transformer` """ return self.apply(FilterTransformation(filter)) def map(self, function, kind): """Applies a function to the ``data`` element of events of ``kind`` in the selection. >>> html = HTML('<html><head><title>Some Title</title></head>' ... '<body>Some <em>body</em> text.</body></html>', ... encoding='utf-8') >>> print(html | Transformer('head/title').map(unicode.upper, TEXT)) <html><head><title>SOME TITLE</title></head><body>Some <em>body</em> text.</body></html> :param function: the function to apply :param kind: the kind of event the function should be applied to :rtype: `Transformer` """ return self.apply(MapTransformation(function, kind)) def substitute(self, pattern, replace, count=1): """Replace text matching a regular expression. Refer to the documentation for ``re.sub()`` for details. >>> html = HTML('<html><body>Some text, some more text and ' ... '<b>some bold text</b>\\n' ... '<i>some italicised text</i></body></html>', ... encoding='utf-8') >>> print(html | Transformer('body/b').substitute('(?i)some', 'SOME')) <html><body>Some text, some more text and <b>SOME bold text</b> <i>some italicised text</i></body></html> >>> tags = tag.html(tag.body('Some text, some more text and\\n', ... Markup('<b>some bold text</b>'))) >>> print(tags.generate() | Transformer('body').substitute( ... '(?i)some', 'SOME')) <html><body>SOME text, some more text and <b>SOME bold text</b></body></html> :param pattern: A regular expression object or string. :param replace: Replacement pattern. :param count: Number of replacements to make in each text fragment. :rtype: `Transformer` """ return self.apply(SubstituteTransformation(pattern, replace, count)) def rename(self, name): """Rename matching elements. >>> html = HTML('<html><body>Some text, some more text and ' ... '<b>some bold text</b></body></html>', ... encoding='utf-8') >>> print(html | Transformer('body/b').rename('strong')) <html><body>Some text, some more text and <strong>some bold text</strong></body></html> """ return self.apply(RenameTransformation(name)) def trace(self, prefix='', fileobj=None): """Print events as they pass through the transform. >>> html = HTML('<body>Some <em>test</em> text</body>', encoding='utf-8') >>> print(html | Transformer('em').trace()) (None, ('START', (QName('body'), Attrs()), (None, 1, 0))) (None, ('TEXT', u'Some ', (None, 1, 6))) ('ENTER', ('START', (QName('em'), Attrs()), (None, 1, 11))) ('INSIDE', ('TEXT', u'test', (None, 1, 15))) ('EXIT', ('END', QName('em'), (None, 1, 19))) (None, ('TEXT', u' text', (None, 1, 24))) (None, ('END', QName('body'), (None, 1, 29))) <body>Some <em>test</em> text</body> :param prefix: a string to prefix each event with in the output :param fileobj: the writable file-like object to write to; defaults to the standard output stream :rtype: `Transformer` """ return self.apply(TraceTransformation(prefix, fileobj=fileobj)) # Internal methods def _mark(self, stream): for event in stream: yield OUTSIDE, event def _unmark(self, stream): for mark, event in stream: kind = event[0] if not (kind is None or kind is ATTR or kind is BREAK): yield event class SelectTransformation(object): """Select and mark events that match an XPath expression.""" def __init__(self, path): """Create selection. :param path: an XPath expression (as string) or a `Path` object """ if not isinstance(path, Path): path = Path(path) self.path = path def __call__(self, stream): """Apply the transform filter to the marked stream. :param stream: the marked event stream to filter """ namespaces = {} variables = {} test = self.path.test() stream = iter(stream) next = stream.next for mark, event in stream: if mark is None: yield mark, event continue result = test(event, namespaces, variables) # XXX This is effectively genshi.core._ensure() for transform # streams. if result is True: if event[0] is START: yield ENTER, event depth = 1 while depth > 0: mark, subevent = next() if subevent[0] is START: depth += 1 elif subevent[0] is END: depth -= 1 if depth == 0: yield EXIT, subevent else: yield INSIDE, subevent test(subevent, namespaces, variables, updateonly=True) else: yield OUTSIDE, event elif isinstance(result, Attrs): # XXX Selected *attributes* are given a "kind" of None to # indicate they are not really part of the stream. yield ATTR, (ATTR, (QName(event[1][0] + '@*'), result), event[2]) yield None, event elif isinstance(result, tuple): yield OUTSIDE, result elif result: # XXX Assume everything else is "text"? yield None, (TEXT, unicode(result), (None, -1, -1)) else: yield None, event class InvertTransformation(object): """Invert selection so that marked events become unmarked, and vice versa. Specificaly, all input marks are converted to null marks, and all input null marks are converted to OUTSIDE marks. """ def __call__(self, stream): """Apply the transform filter to the marked stream. :param stream: the marked event stream to filter """ for mark, event in stream: if mark: yield None, event else: yield OUTSIDE, event class EndTransformation(object): """End the current selection.""" def __call__(self, stream): """Apply the transform filter to the marked stream. :param stream: the marked event stream to filter """ for mark, event in stream: yield OUTSIDE, event class EmptyTransformation(object): """Empty selected elements of all content.""" def __call__(self, stream): """Apply the transform filter to the marked stream. :param stream: the marked event stream to filter """ for mark, event in stream: yield mark, event if mark is ENTER: for mark, event in stream: if mark is EXIT: yield mark, event break class RemoveTransformation(object): """Remove selection from the stream.""" def __call__(self, stream): """Apply the transform filter to the marked stream. :param stream: the marked event stream to filter """ for mark, event in stream: if mark is None: yield mark, event class UnwrapTransformation(object): """Remove outtermost enclosing elements from selection.""" def __call__(self, stream): """Apply the transform filter to the marked stream. :param stream: the marked event stream to filter """ for mark, event in stream: if mark not in (ENTER, EXIT): yield mark, event class WrapTransformation(object): """Wrap selection in an element.""" def __init__(self, element): if isinstance(element, Element): self.element = element else: self.element = Element(element) def __call__(self, stream): for mark, event in stream: if mark: element = list(self.element.generate()) for prefix in element[:-1]: yield None, prefix yield mark, event start = mark stopped = False for mark, event in stream: if start is ENTER and mark is EXIT: yield mark, event stopped = True break if not mark: break yield mark, event else: stopped = True yield None, element[-1] if not stopped: yield mark, event else: yield mark, event class TraceTransformation(object): """Print events as they pass through the transform.""" def __init__(self, prefix='', fileobj=None): """Trace constructor. :param prefix: text to prefix each traced line with. :param fileobj: the writable file-like object to write to """ self.prefix = prefix self.fileobj = fileobj or sys.stdout def __call__(self, stream): """Apply the transform filter to the marked stream. :param stream: the marked event stream to filter """ for event in stream: self.fileobj.write('%s%s\n' % (self.prefix, event)) yield event class FilterTransformation(object): """Apply a normal stream filter to the selection. The filter is called once for each selection.""" def __init__(self, filter): """Create the transform. :param filter: The stream filter to apply. """ self.filter = filter def __call__(self, stream): """Apply the transform filter to the marked stream. :param stream: The marked event stream to filter """ def flush(queue): if queue: for event in self.filter(queue): yield OUTSIDE, event del queue[:] queue = [] for mark, event in stream: if mark is ENTER: queue.append(event) for mark, event in stream: queue.append(event) if mark is EXIT: break for queue_event in flush(queue): yield queue_event elif mark is OUTSIDE: stopped = False queue.append(event) for mark, event in stream: if mark is not OUTSIDE: break queue.append(event) else: stopped = True for queue_event in flush(queue): yield queue_event if not stopped: yield mark, event else: yield mark, event for queue_event in flush(queue): yield queue_event class MapTransformation(object): """Apply a function to the `data` element of events of ``kind`` in the selection. """ def __init__(self, function, kind): """Create the transform. :param function: the function to apply; the function must take one argument, the `data` element of each selected event :param kind: the stream event ``kind`` to apply the `function` to """ self.function = function self.kind = kind def __call__(self, stream): """Apply the transform filter to the marked stream. :param stream: The marked event stream to filter """ for mark, (kind, data, pos) in stream: if mark and self.kind in (None, kind): yield mark, (kind, self.function(data), pos) else: yield mark, (kind, data, pos) class SubstituteTransformation(object): """Replace text matching a regular expression. Refer to the documentation for ``re.sub()`` for details. """ def __init__(self, pattern, replace, count=0): """Create the transform. :param pattern: A regular expression object, or string. :param replace: Replacement pattern. :param count: Number of replacements to make in each text fragment. """ if isinstance(pattern, basestring): self.pattern = re.compile(pattern) else: self.pattern = pattern self.count = count self.replace = replace def __call__(self, stream): """Apply the transform filter to the marked stream. :param stream: The marked event stream to filter """ for mark, (kind, data, pos) in stream: if mark is not None and kind is TEXT: new_data = self.pattern.sub(self.replace, data, self.count) if isinstance(data, Markup): data = Markup(new_data) else: data = new_data yield mark, (kind, data, pos) class RenameTransformation(object): """Rename matching elements.""" def __init__(self, name): """Create the transform. :param name: New element name. """ self.name = QName(name) def __call__(self, stream): """Apply the transform filter to the marked stream. :param stream: The marked event stream to filter """ for mark, (kind, data, pos) in stream: if mark is ENTER: data = self.name, data[1] elif mark is EXIT: data = self.name yield mark, (kind, data, pos) class InjectorTransformation(object): """Abstract base class for transformations that inject content into a stream. >>> class Top(InjectorTransformation): ... def __call__(self, stream): ... for event in self._inject(): ... yield event ... for event in stream: ... yield event >>> html = HTML('<body>Some <em>test</em> text</body>', encoding='utf-8') >>> print(html | Transformer('.//em').apply(Top('Prefix '))) Prefix <body>Some <em>test</em> text</body> """ def __init__(self, content): """Create a new injector. :param content: An iterable of Genshi stream events, or a string to be injected. """ self.content = content def _inject(self): content = self.content if hasattr(content, '__call__'): content = content() for event in _ensure(content): yield None, event class ReplaceTransformation(InjectorTransformation): """Replace selection with content.""" def __call__(self, stream): """Apply the transform filter to the marked stream. :param stream: The marked event stream to filter """ stream = PushBackStream(stream) for mark, event in stream: if mark is not None: start = mark for subevent in self._inject(): yield subevent for mark, event in stream: if start is ENTER: if mark is EXIT: break elif mark != start: stream.push((mark, event)) break else: yield mark, event class BeforeTransformation(InjectorTransformation): """Insert content before selection.""" def __call__(self, stream): """Apply the transform filter to the marked stream. :param stream: The marked event stream to filter """ stream = PushBackStream(stream) for mark, event in stream: if mark is not None: start = mark for subevent in self._inject(): yield subevent yield mark, event for mark, event in stream: if mark != start and start is not ENTER: stream.push((mark, event)) break yield mark, event if start is ENTER and mark is EXIT: break else: yield mark, event class AfterTransformation(InjectorTransformation): """Insert content after selection.""" def __call__(self, stream): """Apply the transform filter to the marked stream. :param stream: The marked event stream to filter """ stream = PushBackStream(stream) for mark, event in stream: yield mark, event if mark: start = mark for mark, event in stream: if start is not ENTER and mark != start: stream.push((mark, event)) break yield mark, event if start is ENTER and mark is EXIT: break for subevent in self._inject(): yield subevent class PrependTransformation(InjectorTransformation): """Prepend content to the inside of selected elements.""" def __call__(self, stream): """Apply the transform filter to the marked stream. :param stream: The marked event stream to filter """ for mark, event in stream: yield mark, event if mark is ENTER: for subevent in self._inject(): yield subevent class AppendTransformation(InjectorTransformation): """Append content after the content of selected elements.""" def __call__(self, stream): """Apply the transform filter to the marked stream. :param stream: The marked event stream to filter """ for mark, event in stream: yield mark, event if mark is ENTER: for mark, event in stream: if mark is EXIT: break yield mark, event for subevent in self._inject(): yield subevent yield mark, event class AttrTransformation(object): """Set an attribute on selected elements.""" def __init__(self, name, value): """Construct transform. :param name: name of the attribute that should be set :param value: the value to set """ self.name = name self.value = value def __call__(self, stream): """Apply the transform filter to the marked stream. :param stream: The marked event stream to filter """ callable_value = hasattr(self.value, '__call__') for mark, (kind, data, pos) in stream: if mark is ENTER: if callable_value: value = self.value(self.name, (kind, data, pos)) else: value = self.value if value is None: attrs = data[1] - [QName(self.name)] else: attrs = data[1] | [(QName(self.name), value)] data = (data[0], attrs) yield mark, (kind, data, pos) class StreamBuffer(Stream): """Stream event buffer used for cut and copy transformations.""" def __init__(self): """Create the buffer.""" Stream.__init__(self, []) def append(self, event): """Add an event to the buffer. :param event: the markup event to add """ self.events.append(event) def reset(self): """Empty the buffer of events.""" del self.events[:] class CopyTransformation(object): """Copy selected events into a buffer for later insertion.""" def __init__(self, buffer, accumulate=False): """Create the copy transformation. :param buffer: the `StreamBuffer` in which the selection should be stored """ if not accumulate: buffer.reset() self.buffer = buffer self.accumulate = accumulate def __call__(self, stream): """Apply the transformation to the marked stream. :param stream: the marked event stream to filter """ stream = PushBackStream(stream) for mark, event in stream: if mark: if not self.accumulate: self.buffer.reset() events = [(mark, event)] self.buffer.append(event) start = mark for mark, event in stream: if start is not ENTER and mark != start: stream.push((mark, event)) break events.append((mark, event)) self.buffer.append(event) if start is ENTER and mark is EXIT: break for i in events: yield i else: yield mark, event class CutTransformation(object): """Cut selected events into a buffer for later insertion and remove the selection. """ def __init__(self, buffer, accumulate=False): """Create the cut transformation. :param buffer: the `StreamBuffer` in which the selection should be stored """ self.buffer = buffer self.accumulate = accumulate def __call__(self, stream): """Apply the transform filter to the marked stream. :param stream: the marked event stream to filter """ attributes = [] stream = PushBackStream(stream) broken = False if not self.accumulate: self.buffer.reset() for mark, event in stream: if mark: # Send a BREAK event if there was no other event sent between if not self.accumulate: if not broken and self.buffer: yield BREAK, (BREAK, None, None) self.buffer.reset() self.buffer.append(event) start = mark if mark is ATTR: attributes.extend([name for name, _ in event[1][1]]) for mark, event in stream: if start is mark is ATTR: attributes.extend([name for name, _ in event[1][1]]) # Handle non-element contiguous selection if start is not ENTER and mark != start: # Operating on the attributes of a START event if start is ATTR: kind, data, pos = event assert kind is START data = (data[0], data[1] - attributes) attributes = None stream.push((mark, (kind, data, pos))) else: stream.push((mark, event)) break self.buffer.append(event) if start is ENTER and mark is EXIT: break broken = False else: broken = True yield mark, event if not broken and self.buffer: yield BREAK, (BREAK, None, None)