bibformat_xslt_engine.py
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bibformat_xslt_engine.py
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	# -- coding: utf-8 --
	##
	## This file is part of Invenio.
	## Copyright (C) 2007, 2008, 2009, 2010, 2011 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.

	"""
	bibformat_xslt_engine - Wrapper for an XSLT engine.

	Some functions are registered in order to be used in XSL code:
	- creation_date(recID)
	- modification_date(recID)

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

	Used by: bibformat_engine.py
	"""

	__revision__ = "$Id$"

	import sys
	import os

	from invenio.config import \
	CFG_SITE_URL
	from invenio.bibformat_config import \
	CFG_BIBFORMAT_TEMPLATES_PATH
	from invenio.bibformat_dblayer import \
	get_creation_date, \
	get_modification_date

	# The namespace used for BibFormat function
	CFG_BIBFORMAT_FUNCTION_NS = "http://cdsweb.cern.ch/bibformat/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
	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')
	#sys.exit(1)

	##################################################################
	# Support for 'creation_date' and 'modification_date' functions #

	def get_creation_date_lxml(ctx, recID, fmt="%Y-%m-%dT%H:%M:%SZ"):
	"""
	libxslt extension function:
	Bridge between BibFormat and XSL stylesheets.
	Returns record creation date.

	Can be used in that way in XSL stylesheet
	(provided xmlns:fn="http://cdsweb.cern.ch/bibformat/fn" has been declared):
	<xsl:value-of select="fn:creation_date(445)"/> where 445 is a recID

	if recID is string, value is converted to int
	if recID is Node, first child node (text node) is taken as value

	@param ctx: context as passed by lxml
	@param recID: record ID
	@param fmt: format of the returned date
	@return: creation date of X{recID}
	@rtype: string
	"""
	try:
	if isinstance(recID, str):
	recID_int = int(recID)
	elif isinstance(recID, (int, long)):
	recID_int = recID
	elif isinstance(recID, list):
	recID = recID[0]
	if isinstance(recID, str):
	recID_int = int(recID)
	else:
	recID_int = int(recID.text)
	else:
	recID_int = int(recID.text)

	if isinstance(fmt, str):
	fmt_str = fmt
	elif isinstance(fmt, list):
	fmt = fmt[0]
	if isinstance(fmt, str):
	fmt_str = fmt
	else:
	fmt_str = fmt.text
	else:
	fmt_str = fmt.text

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

	return ''

	def get_creation_date_libxslt(ctx, recID, fmt="%Y-%m-%dT%H:%M:%SZ"):
	"""
	libxslt extension function:
	Bridge between BibFormat and XSL stylesheets.
	Returns record creation date.

	Can be used in that way in XSL stylesheet
	(provided xmlns:fn="http://cdsweb.cern.ch/bibformat/fn" has been declared):
	<xsl:value-of select="fn:creation_date(445)"/> where 445 is a recID

	if recID is string, value is converted to int
	if recID is Node, first child node (text node) is taken as value

	@param ctx: context as passed by libxslt
	@param recID: record ID
	@param fmt: format of the returned date
	@return: creation date of X{recID}
	@rtype: string
	"""
	try:
	if isinstance(recID, str):
	recID_int = int(recID)
	elif isinstance(recID, (int, long)):
	recID_int = recID
	else:
	recID_int = libxml2.xmlNode(_obj=recID[0]).children.content

	if isinstance(fmt, str):
	fmt_str = fmt
	else:
	fmt_str = libxml2.xmlNode(_obj=recID[0]).children.content

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

	return ''

	def get_creation_date_4suite(ctx, recID, fmt="%Y-%m-%dT%H:%M:%SZ"):
	"""
	4suite extension function:
	Bridge between BibFormat and XSL stylesheets.
	Returns record creation date.

	Can be used in that way in XSL stylesheet
	(provided xmlns:fn="http://cdsweb.cern.ch/bibformat/fn" has been declared):
	<xsl:value-of select="fn:creation_date(445)"/>

	if value is int, value is converted to string
	if value is Node, first child node (text node) is taken as value

	@param ctx: context as passed by 4suite
	@param recID: record ID
	@param fmt: format of the returned date
	@return: creation date of X{recID}
	@rtype: string
	"""
	try:
	if len(recID) > 0 and isinstance(recID[0], Node):
	recID_int = recID[0].firstChild.nodeValue
	if recID_int is None:
	return ''
	else:
	recID_int = int(recID)

	if len(fmt) > 0 and isinstance(fmt[0], Node):
	fmt_str = fmt[0].firstChild.nodeValue
	if fmt_str is None:
	fmt_str = "%Y-%m-%dT%H:%M:%SZ"
	else:
	fmt_str = str(fmt)

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

	return ''

	def get_modification_date_lxml(ctx, recID, fmt="%Y-%m-%dT%H:%M:%SZ"):
	"""
	libxslt extension function:
	Bridge between BibFormat and XSL stylesheets.
	Returns record modification date.

	Can be used in that way in XSL stylesheet
	(provided xmlns:fn="http://cdsweb.cern.ch/bibformat/fn" has been declared):
	<xsl:value-of select="fn:creation_date(445)"/> where 445 is a recID

	if recID is string, value is converted to int
	if recID is Node, first child node (text node) is taken as value

	@param ctx: context as passed by lxml
	@param recID: record ID
	@param fmt: format of the returned date
	@return: modification date of X{recID}
	@rtype: string
	"""
	try:
	if isinstance(recID, str):
	recID_int = int(recID)
	elif isinstance(recID, (int, long)):
	recID_int = recID
	elif isinstance(recID, list):
	recID = recID[0]
	if isinstance(recID, str):
	recID_int = int(recID)
	else:
	recID_int = int(recID.text)
	else:
	recID_int = int(recID.text)

	if isinstance(fmt, str):
	fmt_str = fmt
	elif isinstance(fmt, list):
	fmt = fmt[0]
	if isinstance(fmt, str):
	fmt_str = fmt
	else:
	fmt_str = fmt.text
	else:
	fmt_str = fmt.text

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

	return ''

	def get_modification_date_libxslt(ctx, recID, fmt="%Y-%m-%dT%H:%M:%SZ"):
	"""
	libxslt extension function:
	Bridge between BibFormat and XSL stylesheets.
	Returns record modification date.

	Can be used in that way in XSL stylesheet
	(provided xmlns:fn="http://cdsweb.cern.ch/bibformat/fn" has been declared):
	<xsl:value-of select="fn:creation_date(445)"/> where 445 is a recID

	if recID is string, value is converted to int
	if recID is Node, first child node (text node) is taken as value

	@param ctx: context as passed by libxslt
	@param recID: record ID
	@param fmt: format of the returned date
	@return: modification date of X{recID}
	@rtype: string
	"""
	try:
	if isinstance(recID, str):
	recID_int = int(recID)
	elif isinstance(recID, (int, long)):
	recID_int = recID
	else:
	recID_int = libxml2.xmlNode(_obj=recID[0]).children.content

	if isinstance(fmt, str):
	fmt_str = fmt
	else:
	fmt_str = libxml2.xmlNode(_obj=recID[0]).children.content

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

	return ''

	def get_modification_date_4suite(ctx, recID, fmt="%Y-%m-%dT%H:%M:%SZ"):
	"""
	4suite extension function:
	Bridge between BibFormat and XSL stylesheets.
	Returns record modification date.

	Can be used in that way in XSL stylesheet
	(provided xmlns:fn="http://cdsweb.cern.ch/bibformat/fn" has been declared):
	<xsl:value-of select="fn:modification_date(445)"/>

	if value is int, value is converted to string
	if value is Node, first child node (text node) is taken as value

	@param ctx: context as passed by 4suite
	@param recID: record ID
	@param fmt: format of the returned date
	@return: modification date of X{recID}
	@rtype: string
	"""
	try:
	if len(recID) > 0 and isinstance(recID[0], Node):
	recID_int = recID[0].firstChild.nodeValue
	if recID_int is None:
	return ''
	else:
	recID_int = int(recID_int)

	if len(fmt) > 0 and isinstance(fmt[0], Node):
	fmt_str = fmt[0].firstChild.nodeValue
	if fmt_str is None:
	fmt_str = "%Y-%m-%dT%H:%M:%SZ"
	else:
	fmt_str = str(fmt)

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

	return ''

	def eval_bibformat_lxml(ctx, recID, template_code):
	"""
	libxslt extension function:
	Bridge between BibFormat and XSL stylesheets.
	Returns the evaluation of the given piece of format template

	Can be used in that way in XSL stylesheet
	(provided xmlns:fn="http://cdsweb.cern.ch/bibformat/fn" has been declared):
	<xsl:value-of select="fn:eval_bibformat(marc:controlfield[@tag='001'],'<BFE_SERVER_INFO var="recurl">')" />

	if recID is string, value is converted to int
	if recID is Node, first child node (text node) is taken as value
	template_code is evaluated as a format template piece of code. '<'
	and '"' need to be escaped with '<' and '"'

	@param ctx: context as passed by lxml
	@param recID: record ID
	@param template_code: the code calling a BFE_ as it would be use in format template
	@return: the evalued call to a format template (usually a call to a format element)
	@rtype: string
	""" #'
	from invenio.bibformat_engine import \
	format_with_format_template, \
	BibFormatObject
	try:
	if isinstance(recID, str):
	recID_int = int(recID)
	elif isinstance(recID, (int, long)):
	recID_int = recID
	elif isinstance(recID, list):
	recID = recID[0]
	if isinstance(recID, str):
	recID_int = int(recID)
	else:
	recID_int = int(recID.text)
	else:
	recID_int = int(recID.text)

	bfo = BibFormatObject(recID_int)
	return format_with_format_template(None, bfo,
	verbose=0,
	format_template_code=template_code)
	except Exception, err:
	sys.stderr.write("Error during formatting function evaluation: " + \
	str(err) + \
	'\n')

	return ''

	def eval_bibformat_libxslt(ctx, recID, template_code):
	"""
	libxslt extension function:
	Bridge between BibFormat and XSL stylesheets.
	Returns the evaluation of the given piece of format template

	Can be used in that way in XSL stylesheet
	(provided xmlns:fn="http://cdsweb.cern.ch/bibformat/fn" has been declared):
	<xsl:value-of select="fn:eval_bibformat(marc:controlfield[@tag='001'],'<BFE_SERVER_INFO var="recurl">')" />

	if recID is string, value is converted to int
	if recID is Node, first child node (text node) is taken as value
	template_code is evaluated as a format template piece of code. '<'
	and '"' need to be escaped with '<' and '"'

	@param ctx: context as passed by libxslt
	@param recID: record ID
	@param template_code: the code calling a BFE_ as it would be use in format template
	@return: the evalued call to a format template (usually a call to a format element)
	@rtype: string
	""" #'
	from invenio.bibformat_engine import \
	format_with_format_template, \
	BibFormatObject
	try:
	if isinstance(recID, str):
	recID_int = int(recID)
	elif isinstance(recID, (int, long)):
	recID_int = recID
	else:
	recID_int = libxml2.xmlNode(_obj=recID[0]).children.content

	bfo = BibFormatObject(recID_int)
	return format_with_format_template(None, bfo,
	verbose=0,
	format_template_code=template_code)
	except Exception, err:
	sys.stderr.write("Error during formatting function evaluation: " + \
	str(err) + \
	'\n')

	return ''

	def eval_bibformat_4suite(ctx, recID, template_code):
	"""
	4suite extension function:
	Bridge between BibFormat and XSL stylesheets.
	Returns the evaluation of the given piece of format template

	Can be used in that way in XSL stylesheet
	(provided xmlns:fn="http://cdsweb.cern.ch/bibformat/fn" has been declared):
	<xsl:value-of select="fn:eval_bibformat(marc:controlfield[@tag='001'],'<BFE_SERVER_INFO var="recurl">')" />

	if recID is string, value is converted to int
	if recID is Node, first child node (text node) is taken as value
	template_code is evaluated as a format template piece of code. '<'
	and '"' need to be escaped with '<' and '"'

	@param ctx: context as passed by 4suite
	@param recID: record ID
	@param template_code: the code calling a BFE_ as it would be use in format template
	@return: the evalued call to a format template (usually a call to a format element)
	@rtype: string
	""" #'
	from invenio.bibformat_engine import \
	format_with_format_template, \
	BibFormatObject
	try:
	if len(recID) > 0 and isinstance(recID[0], Node):
	recID_int = recID[0].firstChild.nodeValue
	if recID_int is None:
	return ''
	else:
	recID_int = int(recID_int)

	bfo = BibFormatObject(recID_int)
	return format_with_format_template(None, bfo,
	verbose=0,
	format_template_code=template_code)
	except Exception, err:
	sys.stderr.write("Error during formatting function evaluation: " + \
	str(err) + \
	'\n')

	return ''

	# End of date-related functions #
	##################################################################

	def format(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.

	bibformat_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.

	@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.
	"""
	if processor_type == 0:
	# No XSLT processor found
	sys.stderr.write('No XSLT processor could be found.')
	#sys.exit(1)

	# Retrieve template and read it
	if template_source:
	template = template_source
	elif template_filename:
	try:
	path_to_templates = (CFG_BIBFORMAT_TEMPLATES_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

	# Some massaging of the input to avoid the default namespace issue
	# in XPath. More elegant solution might be found though.
	xmltext = xmltext.replace('xmlns="http://www.loc.gov/MARC21/slim"', '')

	# For older MARCXML records stored in bibfmt with empty indicators
	xmltext = xmltext.replace('ind1=""', 'ind1=" "')
	xmltext = xmltext.replace('ind2=""', 'ind2=" "')

	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 result
	except:
	error = 'Failed to process the XML code.'
	sys.stderr.write(error)
	return result

	try:
	xsl = etree.XML(template)
	except etree.XMLSyntaxError, e:
	error = 'The XSL code given is invalid. [%s]' % (e,)
	sys.stderr.write(error)
	return result
	except:
	error = 'Failed to process the XSL code.'
	sys.stderr.write(error)
	return result

	try:
	fns = etree.FunctionNamespace(CFG_BIBFORMAT_FUNCTION_NS)
	fns["creation_date"] = get_creation_date_lxml
	fns["modification_date"] = get_modification_date_lxml
	fns["eval_bibformat"] = eval_bibformat_lxml
	except etree.NamespaceRegistryError, e:
	error = 'Failed registering the XPath extension function. [%s]' % (e,)
	sys.stderr.write(error)
	return result

	try:
	xslt = etree.XSLT(xsl)
	except etree.XSLTParseError, e:
	error = 'The XSL code given is invalid. [%s]' % (e,)
	sys.stderr.write(error)
	return result
	except:
	error = 'Failed to process the XSL code.'
	sys.stderr.write(error)
	return result

	try:
	temporary_result = xslt(xml)
	except:
	error = 'Failed to perform the XSL transformation.'
	sys.stderr.write(error)
	return result

	result = str(temporary_result)

	# Housekeeping
	del temporary_result
	del xslt
	del xsl
	del xml

	elif processor_type == 2:
	# libxml2 & libxslt

	# Register BibFormat functions for use in XSL
	libxslt.registerExtModuleFunction("creation_date",
	CFG_BIBFORMAT_FUNCTION_NS,
	get_creation_date_libxslt)
	libxslt.registerExtModuleFunction("modification_date",
	CFG_BIBFORMAT_FUNCTION_NS,
	get_modification_date_libxslt)
	libxslt.registerExtModuleFunction("eval_bibformat",
	CFG_BIBFORMAT_FUNCTION_NS,
	eval_bibformat_libxslt)
	# Load template and source
	template_xml = libxml2.parseDoc(template)
	processor = libxslt.parseStylesheetDoc(template_xml)
	source = libxml2.parseDoc(xmltext)

	# Transform
	result_object = processor.applyStylesheet(source, None)
	try:
	result = processor.saveResultToString(result_object)
	except SystemError :
	# Catch an exception thrown when result is empty,
	# due to a bug in libxslt
	result = ''

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

	elif processor_type == 3:
	# 4suite

	# Init
	processor = Processor.Processor()

	# Register BibFormat functions for use in XSL
	processor.registerExtensionFunction(CFG_BIBFORMAT_FUNCTION_NS,
	"creation_date",
	get_creation_date_4suite)
	processor.registerExtensionFunction(CFG_BIBFORMAT_FUNCTION_NS,
	"modification_date",
	get_modification_date_4suite)
	processor.registerExtensionFunction(CFG_BIBFORMAT_FUNCTION_NS,
	"eval_bibformat",
	eval_bibformat_4suite)
	# Load template and source
	transform = InputSource.DefaultFactory.fromString(template,
	uri=CFG_SITE_URL)
	source = InputSource.DefaultFactory.fromString(xmltext,
	uri=CFG_SITE_URL)
	processor.appendStylesheet(transform)

	# Transform
	result = processor.run(source)
	else:
	sys.stderr.write("No XSLT processor could be found")

	return result

	if __name__ == "__main__":
	pass

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