kc3-lang/libxml2/python/tests/input_callback.py

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• Hash : 48da90bc
  Author :
  Date : 2013-02-25T15:54:25
  

  Python binding for xmlRegisterInputCallback
  
  It is possible to make xmlIO handle any protocol by means of
  xmlRegisterInputCallback(). However, that function is currently only
  available in C API. So, the natural solution seems to be implementing Python
  bindings for the xmlRegisterInputCallback.
  
  * python/generator.py: skip xmlPopInputCallbacks
  * python/libxml.c python/libxml.py python/libxml_wrap.h: implement the
    wrappers
  * python/tests/input_callback.py python/tests/Makefile.am: also add a test case
  

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• python/tests/input_callback.py

• #!/usr/bin/python -u
  #
  # This tests custom input callbacks
  #
  import sys
  import StringIO
  import libxml2
  
  # We implement a new scheme, py://strings/ that will reference this dictionary
  pystrings = {
      'catalogs/catalog.xml' :
  '''<?xml version="1.0" encoding="utf-8"?>
  <!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN" "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd">
  <catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog">
    <rewriteSystem systemIdStartString="http://example.com/dtds/" rewritePrefix="../dtds/"/>
  </catalog>''',
  
      'xml/sample.xml' :
  '''<?xml version="1.0" encoding="utf-8"?>
  <!DOCTYPE root SYSTEM "http://example.com/dtds/sample.dtd">
  <root>&sample.entity;</root>''',
  
      'dtds/sample.dtd' :
  '''
  <!ELEMENT root (#PCDATA)>
  <!ENTITY sample.entity "replacement text">'''
  }
  
  def verify_doc(doc):
      e = doc.getRootElement()
      if e.name != 'root':
          raise ValueError("name")
      if e.content != 'replacement text':
          raise ValueError("content")
  
  prefix = "py://strings/"
  def my_input_cb(URI):
      idx = URI.startswith(prefix)
      if idx == -1:
          return None
      path = URI[len(prefix):]
      if path not in pystrings:
          print "my_input_cb: path does not exist, '%s'" % path
          return None
      print "my_input_cb: loading '%s'" % URI
      return StringIO.StringIO(pystrings[path])
  
  opts = libxml2.XML_PARSE_DTDLOAD | libxml2.XML_PARSE_NONET | libxml2.XML_PARSE_COMPACT
  startURL = prefix + "xml/sample.xml"
  catURL = prefix + "catalogs/catalog.xml"
  
  # Check that we cannot read custom schema without custom callback
  print
  print "Test 1: Expecting failure to load (custom scheme not handled)"
  try:
      doc = libxml2.readFile(startURL, None, opts)
      print "Read custom scheme without registering handler succeeded?"
      sys.exit(1)
  except libxml2.treeError, e:
      pass
  
  # Register handler and try to load the same entity
  print
  print "Test 2: Expecting failure to load (no catalog - cannot load DTD)"
  libxml2.registerInputCallback(my_input_cb)
  doc = libxml2.readFile(startURL, None, opts)
  try:
      verify_doc(doc)
      print "Doc was loaded?"
  except ValueError, e:
      if str(e) != "content":
          print "Doc verify failed"
  doc.freeDoc()
  
  # Register a catalog (also accessible via pystr://) and retry
  print
  print "Test 3: Expecting successful loading"
  parser = libxml2.createURLParserCtxt(startURL, opts)
  parser.addLocalCatalog(catURL)
  parser.parseDocument()
  doc = parser.doc()
  verify_doc(doc)
  doc.freeDoc()
  
  # Unregister custom callback when parser is already created
  print
  print "Test 4: Expect failure to read (custom callback unregistered during read)"
  parser = libxml2.createURLParserCtxt(startURL, opts)
  libxml2.popInputCallbacks()
  parser.addLocalCatalog(catURL)
  parser.parseDocument()
  doc = parser.doc()
  try:
      verify_doc(doc)
      print "Doc was loaded?"
  except ValueError, e:
      if str(e) != "content":
          print "Doc verify failed"
  doc.freeDoc()
  
  # Try to load the document again
  print
  print "Test 5: Expect failure to load (callback unregistered)"
  try:
      doc = libxml2.readFile(startURL, None, opts)
      print "Read custom scheme without registering handler succeeded?"
      sys.exit(1)
  except libxml2.treeError, e:
      pass
  
  # But should be able to read standard I/O yet...
  print
  print "Test 6: Expect successful loading using standard I/O"
  doc = libxml2.readFile("tst.xml", None, opts)
  doc.freeDoc()
  
  # Now pop ALL input callbacks, should fail to load even standard I/O
  print
  print "Test 7: Remove all input callbacks, expect failure to load using standard I/O"
  try:
      while True:
          libxml2.popInputCallbacks()
  except IndexError, e:
      print "Popped all input callbacks: " + str(e)
  try:
      doc = libxml2.readFile("tst.xml", None, opts)
  except libxml2.treeError, e:
      pass
  

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