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|
# -*- 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>''')
>>> 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>')
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>')
>>> 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>')
>>> 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>')
>>> 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>')
>>> 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>')
>>> 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>')
>>> 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>')
>>> 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>')
>>> 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>')
>>> 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>')
>>> 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>')
>>> 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>')
>>> 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>')
>>> 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>')
>>> 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>')
>>> 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>')
>>> 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>')
>>> 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>')
>>> 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>')
>>> 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>')
>>> 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>')
>>> 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>')
>>> 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>')
>>> 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>')
>>> 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)
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