bibconvert_xslt_engine.py
No OneTemporary
Actions

Subscribers

None

File Metadata

Created: Sun, May 19, 21:08

bibconvert_xslt_engine.py
View Options

	# -- coding: utf-8 --
	##
	## This file is part of Invenio.
	## Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 CERN.
	##
	## Invenio is free software; you can redistribute it and/or
	## modify it under the terms of the GNU General Public License as
	## published by the Free Software Foundation; either version 2 of the
	## License, or (at your option) any later version.
	##
	## Invenio is distributed in the hope that it will be useful, but
	## WITHOUT ANY WARRANTY; without even the implied warranty of
	## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	## General Public License for more details.
	##
	## You should have received a copy of the GNU General Public License
	## along with Invenio; if not, write to the Free Software Foundation, Inc.,
	## 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.

	"""
	bibconvert_xslt_engine - Wrapper for an XSLT engine.

	Customized to support BibConvert functions through the
	use of XPath 'format' function.

	Dependencies: Need one of the following XSLT processors:
	- lxml
	- libxml2 & libxslt
	- 4suite

	Used by: bibconvert.in

	FIXME: - Find better namespace for functions
	- Find less bogus URI (given as param to processor)
	for source and template
	- Implement command-line options
	- Think about better handling of 'value' parameter
	in bibconvert_function_*
	"""

	__revision__ = "$Id$"

	import sys
	import os

	from warnings import warn

	from invenio.config import \
	CFG_ETCDIR, \
	CFG_SITE_URL
	from invenio.bibconvert import FormatField
	from invenio.textutils import encode_for_xml

	# The namespace used for BibConvert functions
	CFG_BIBCONVERT_FUNCTION_NS = "http://cdsweb.cern.ch/bibconvert/fn"

	# Import one XSLT processor
	#
	# processor_type:
	# 0 : No processor found
	# 1 : lxml
	# 2 : libxslt
	# 3 : 4suite
	processor_type = 0

	try:
	# lxml
	from lxml import etree
	processor_type = 1
	except ImportError:
	pass

	if processor_type == 0:
	try:
	# libxml2 & libxslt
	import libxml2
	import libxslt
	processor_type = 2
	except ImportError:
	pass

	if processor_type == 0:
	try:
	# 4suite
	from Ft.Xml.Xslt import Processor, XsltException
	from Ft.Xml import InputSource
	from xml.dom import Node
	processor_type = 3
	except ImportError:
	pass

	if processor_type == 0:
	# No XSLT processor found
	sys.stderr.write('No XSLT processor could be found.\n' \
	'No output produced.\n')

	CFG_BIBCONVERT_XSL_PATH = "%s%sbibconvert%sconfig" % (CFG_ETCDIR, os.sep, os.sep)

	def bibconvert_function_lxml(dummy_ctx, value, func):
	"""
	lxml extension function:
	Bridge between BibConvert formatting functions and XSL stylesheets.

	Can be used in that way in XSL stylesheet
	(provided xmlns:fn="http://cdsweb.cern.ch/bibconvert/fn" has been declared):
	<xsl:value-of select="fn:format(., 'ADD(mypref,mysuff)')"/>
	(Adds strings 'mypref' and 'mysuff' as prefix/suffix to current node value,
	using BibConvert ADD function)

	if value is int, value is converted to string
	if value is Node (PyCObj), first child node (text node) is taken as value
	"""
	try:
	if isinstance(value, str):
	string_value = value
	elif isinstance(value, (int, long)):
	string_value = str(value)
	elif isinstance(value, list):
	value = value[0]
	if isinstance(value, str):
	string_value = value
	elif isinstance(value, (int, long)):
	string_value = str(value)
	else:
	string_value = value.text
	else:
	string_value = value.text

	return FormatField(string_value, func).rstrip('\n')

	except Exception, err:
	sys.stderr.write("Error during formatting function evaluation: " + \
	str(err) + \
	'\n')

	return ''

	def bibconvert_escape_lxml(dummy_ctx, value):
	"""
	Bridge to lxml to escape the provided value.
	"""
	try:
	if isinstance(value, str):
	string_value = value
	elif isinstance(value, (int, long)):
	string_value = str(value)
	elif isinstance(value, list):
	value = value[0]
	if isinstance(value, str):
	string_value = value
	elif isinstance(value, (int, long)):
	string_value = str(value)
	else:
	string_value = value.text
	else:
	string_value = value.text

	return encode_for_xml(string_value)

	except Exception, err:
	sys.stderr.write("Error during formatting function evaluation: " + \
	str(err) + \
	'\n')

	return ''

	def bibconvert_function_libxslt(dummy_ctx, value, func):
	"""
	libxslt extension function:
	Bridge between BibConvert formatting functions and XSL stylesheets.

	Can be used in that way in XSL stylesheet
	(provided xmlns:fn="http://cdsweb.cern.ch/bibconvert/fn" has been declared):
	<xsl:value-of select="fn:format(., 'ADD(mypref,mysuff)')"/>
	(Adds strings 'mypref' and 'mysuff' as prefix/suffix to current node value,
	using BibConvert ADD function)

	if value is int, value is converted to string
	if value is Node (PyCObj), first child node (text node) is taken as value
	"""
	try:
	if isinstance(value, str):
	string_value = value
	elif isinstance(value, (int, long)):
	string_value = str(value)
	else:
	string_value = libxml2.xmlNode(_obj=value[0]).children.content

	return FormatField(string_value, func).rstrip('\n')

	except Exception, err:
	sys.stderr.write("Error during formatting function evaluation: " + \
	str(err) + \
	'\n')

	return ''

	def bibconvert_escape_libxslt(dummy_ctx, value):
	"""
	Bridge to libxslt to escape the provided value.
	"""
	try:
	if isinstance(value, str):
	string_value = value
	elif isinstance(value, (int, long)):
	string_value = str(value)
	else:
	string_value = libxml2.xmlNode(_obj=value[0]).serialize('utf8')

	return encode_for_xml(string_value)

	except Exception, err:
	sys.stderr.write("Error during formatting function evaluation: " + \
	str(err) + \
	'\n')

	return ''

	def bibconvert_function_4suite(dummy_ctx, value, func):
	"""
	4suite extension function:
	Bridge between BibConvert formatting functions and XSL stylesheets.

	Can be used in that way in XSL stylesheet
	(provided xmlns:fn="http://cdsweb.cern.ch/bibconvert/fn" has been declared):
	<xsl:value-of select="fn:format(., 'ADD(mypref,mysuff)')"/>
	(Adds strings 'mypref' and 'mysuff' as prefix/suffix to current node value,
	using BibConvert ADD function)

	if value is int, value is converted to string
	if value is Node, first child node (text node) is taken as value
	"""
	try:
	if len(value) > 0 and isinstance(value[0], Node):
	string_value = value[0].firstChild.nodeValue
	if string_value is None:
	string_value = ''
	else:
	string_value = str(value)

	return FormatField(string_value, func).rstrip('\n')

	except Exception, err:
	sys.stderr.write("Error during formatting function evaluation: " + \
	str(err) + \
	'\n')

	return ''

	def bibconvert_escape_4suite(dummy_ctx, value):
	"""
	Bridge to 4suite to escape the provided value.
	"""
	##FIXME: this does not work with 4suite. How one does serialize a Node?
	warn("Invenio fn:escape is currently broken, when using 4suite")
	return value

	def convert(xmltext, template_filename=None, template_source=None):
	"""
	Processes an XML text according to a template, and returns the result.

	The template can be given either by name (or by path) or by source.
	If source is given, name is ignored.

	bibconvert_xslt_engine will look for template_filename in standard directories
	for templates. If not found, template_filename will be assumed to be a path to
	a template. If none can be found, return None.

	Raises an exception if cannot find an appropriate XSLT processor.


	@param xmltext: The string representation of the XML to process
	@param template_filename: The name of the template to use for the processing
	@param template_source: The configuration describing the processing.
	@return: the transformed XML text, or None if an error occured
	"""
	if processor_type == 0:
	# No XSLT processor found
	raise "No XSLT processor could be found"

	# Retrieve template and read it
	if template_source:
	template = template_source
	elif template_filename:
	try:
	path_to_templates = (CFG_BIBCONVERT_XSL_PATH + os.sep +
	template_filename)
	if os.path.exists(path_to_templates):
	template = file(path_to_templates).read()
	elif os.path.exists(template_filename):
	template = file(template_filename).read()
	else:
	sys.stderr.write(template_filename +' does not exist.')
	return None
	except IOError:
	sys.stderr.write(template_filename +' could not be read.')
	return None
	else:
	sys.stderr.write(template_filename +' was not given.')
	return None

	result = ""

	if processor_type == 1:
	# lxml

	try:
	xml = etree.XML(xmltext)
	except etree.XMLSyntaxError, e:
	error = 'The XML code given is invalid. [%s]' % (e,)
	sys.stderr.write(error)
	return None
	except:
	error = 'Failed to process the XML code.'
	sys.stderr.write(error)
	return None

	try:
	xsl = etree.XML(template)
	except etree.XMLSyntaxError, e:
	error = 'The XSL code given is invalid. [%s]' % (e,)
	sys.stderr.write(error)
	return None
	except:
	error = 'Failed to process the XSL code.'
	sys.stderr.write(error)
	return None

	try:
	fns = etree.FunctionNamespace(CFG_BIBCONVERT_FUNCTION_NS)
	fns["format"] = bibconvert_function_lxml
	fns["escape"] = bibconvert_escape_lxml
	except etree.NamespaceRegistryError, e:
	error = 'Failed registering the XPath extension function. [%s]' % (e,)
	sys.stderr.write(error)
	return None

	try:
	xslt = etree.XSLT(xsl)
	except etree.XSLTParseError, e:
	error = 'The XSL code given is invalid. [%s]' % (e,)
	sys.stderr.write(error)
	return None
	except:
	error = 'Failed to process the XSL code.'
	sys.stderr.write(error)
	return None

	try:
	temporary_result = xslt(xml)
	except:
	error = 'Failed to perform the XSL transformation.'
	sys.stderr.write(error)
	return None

	result = str(temporary_result)

	# Housekeeping
	del temporary_result
	del xslt
	del xsl
	del xml

	elif processor_type == 2:
	# libxml2 & libxslt

	# Register BibConvert functions for use in XSL
	libxslt.registerExtModuleFunction("format",
	CFG_BIBCONVERT_FUNCTION_NS,
	bibconvert_function_libxslt)
	libxslt.registerExtModuleFunction("escape",
	CFG_BIBCONVERT_FUNCTION_NS,
	bibconvert_escape_libxslt)

	# Load template and source
	try:
	template_xml = libxml2.parseDoc(template)
	except libxml2.parserError, e:
	sys.stderr.write('Parsing XSL template failed:\n ' + \
	str(e) + '\n')
	return None
	processor = libxslt.parseStylesheetDoc(template_xml)
	try:
	source = libxml2.parseDoc(xmltext)
	except libxml2.parserError, e:
	sys.stderr.write('Parsing XML source failed:\n ' + \
	str(e) + '\n')
	return None

	# Transform
	result_object = processor.applyStylesheet(source, None)
	result = processor.saveResultToString(result_object)

	# Deallocate
	processor.freeStylesheet()
	source.freeDoc()
	result_object.freeDoc()

	elif processor_type == 3:
	# 4suite

	# Init
	processor = Processor.Processor()

	# Register BibConvert functions for use in XSL
	processor.registerExtensionFunction(CFG_BIBCONVERT_FUNCTION_NS,
	"format",
	bibconvert_function_4suite)
	processor.registerExtensionFunction(CFG_BIBCONVERT_FUNCTION_NS,
	"escape",
	bibconvert_escape_4suite)

	# Load template and source
	transform = InputSource.DefaultFactory.fromString(template,
	uri=CFG_SITE_URL)
	source = InputSource.DefaultFactory.fromString(xmltext,
	uri=CFG_SITE_URL)
	try:
	processor.appendStylesheet(transform)
	except XsltException, e:
	sys.stderr.write('Parsing XSL template failed:\n' + str(e))
	return None

	# Transform
	try:
	result = processor.run(source)
	except XsltException, e:
	sys.stderr.write('Conversion failed:\n' + str(e))
	return None
	else:
	sys.stderr.write("No XSLT processor could be found")

	return result

	## def bc_profile():
	## """
	## Runs a benchmark
	## """
	## global xmltext

	## convert(xmltext, 'oaidc2marcxml.xsl')
	## return

	## def benchmark():
	## """
	## Benchmark the module, using profile and pstats
	## """
	## import profile
	## import pstats
	## from invenio.bibformat import record_get_xml

	## global xmltext

	## xmltext = record_get_xml(10, 'oai_dc')
	## profile.run('bc_profile()', "bibconvert_xslt_profile")
	## p = pstats.Stats("bibconvert_xslt_profile")
	## p.strip_dirs().sort_stats("cumulative").print_stats()

	if __name__ == "__main__":
	pass

bibconvert_xslt_engine.pyNo OneTemporaryActions

File Metadata

bibconvert_xslt_engine.pyView Options

Event Timeline

bibconvert_xslt_engine.py
No OneTemporary
Actions

bibconvert_xslt_engine.py
View Options