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bibconvert_xslt_engine.py
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Fri, Nov 1, 05:14

bibconvert_xslt_engine.py
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# -*- coding: utf-8 -*-
##
## This file is part of Invenio.
## Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010 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:
- 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 invenio.config import \
CFG_ETCDIR, \
CFG_SITE_URL
from invenio.bibconvert import FormatField
# The namespace used for BibConvert functions
CFG_BIBCONVERT_FUNCTION_NS = "http://cdsweb.cern.ch/bibconvert/fn"
# Import one XSLT processor
#
# processor_type:
# -1 : No processor found
# 0 : libxslt
# 1 : 4suite
processor_type = -1
try:
# libxml2 & libxslt
import libxml2
import libxslt
processor_type = 0
except ImportError:
pass
if processor_type == -1:
try:
# 4suite
from Ft.Xml.Xslt import Processor, XsltException
from Ft.Xml import InputSource
from xml.dom import Node
processor_type = 1
except ImportError:
pass
CFG_BIBCONVERT_XSL_PATH = "%s%sbibconvert%sconfig" % (CFG_ETCDIR, os.sep, os.sep)
def bibconvert_function_libxslt(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_function_4suite(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 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 == -1:
# 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 == 0:
# libxml2 & libxslt
# Register BibConvert functions for use in XSL
libxslt.registerExtModuleFunction("format",
CFG_BIBCONVERT_FUNCTION_NS,
bibconvert_function_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 == 1:
# 4suite
# Init
processor = Processor.Processor()
# Register BibConvert functions for use in XSL
processor.registerExtensionFunction(CFG_BIBCONVERT_FUNCTION_NS,
"format",
bibconvert_function_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

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