week06

env/lib/python3.12/site-packages/lxml/isoschematron/__init__.py

@@ -0,0 +1,348 @@
+"""The ``lxml.isoschematron`` package implements ISO Schematron support on top
+of the pure-xslt 'skeleton' implementation.
+"""
+
+import sys
+import os.path
+from lxml import etree as _etree # due to validator __init__ signature
+
+
+# some compat stuff, borrowed from lxml.html
+try:
+    unicode
+except NameError:
+    # Python 3
+    unicode = str
+try:
+    basestring
+except NameError:
+    # Python 3
+    basestring = str
+
+
+__all__ = ['extract_xsd', 'extract_rng', 'iso_dsdl_include',
+           'iso_abstract_expand', 'iso_svrl_for_xslt1',
+           'svrl_validation_errors', 'schematron_schema_valid',
+           'stylesheet_params', 'Schematron']
+
+
+# some namespaces
+#FIXME: Maybe lxml should provide a dedicated place for common namespace
+#FIXME: definitions?
+XML_SCHEMA_NS = "http://www.w3.org/2001/XMLSchema"
+RELAXNG_NS = "http://relaxng.org/ns/structure/1.0"
+SCHEMATRON_NS = "http://purl.oclc.org/dsdl/schematron"
+SVRL_NS = "http://purl.oclc.org/dsdl/svrl"
+
+
+# some helpers
+_schematron_root = '{%s}schema' % SCHEMATRON_NS
+_xml_schema_root = '{%s}schema' % XML_SCHEMA_NS
+_resources_dir = os.path.join(os.path.dirname(__file__), 'resources')
+
+
+# the iso-schematron skeleton implementation steps aka xsl transformations
+extract_xsd = _etree.XSLT(_etree.parse(
+    os.path.join(_resources_dir, 'xsl', 'XSD2Schtrn.xsl')))
+extract_rng = _etree.XSLT(_etree.parse(
+    os.path.join(_resources_dir, 'xsl', 'RNG2Schtrn.xsl')))
+iso_dsdl_include = _etree.XSLT(_etree.parse(
+    os.path.join(_resources_dir, 'xsl', 'iso-schematron-xslt1',
+                 'iso_dsdl_include.xsl')))
+iso_abstract_expand = _etree.XSLT(_etree.parse(
+    os.path.join(_resources_dir, 'xsl', 'iso-schematron-xslt1',
+                 'iso_abstract_expand.xsl')))
+iso_svrl_for_xslt1 = _etree.XSLT(_etree.parse(
+    os.path.join(_resources_dir,
+                 'xsl', 'iso-schematron-xslt1', 'iso_svrl_for_xslt1.xsl')))
+
+
+# svrl result accessors
+svrl_validation_errors = _etree.XPath(
+    '//svrl:failed-assert', namespaces={'svrl': SVRL_NS})
+
+# RelaxNG validator for schematron schemas
+schematron_schema_valid_supported = False
+try:
+    schematron_schema_valid = _etree.RelaxNG(
+        file=os.path.join(_resources_dir, 'rng', 'iso-schematron.rng'))
+    schematron_schema_valid_supported = True
+except _etree.RelaxNGParseError:
+    # Some distributions delete the file due to licensing issues.
+    def schematron_schema_valid(arg):
+        raise NotImplementedError("Validating the ISO schematron requires iso-schematron.rng")
+
+
+def stylesheet_params(**kwargs):
+    """Convert keyword args to a dictionary of stylesheet parameters.
+    XSL stylesheet parameters must be XPath expressions, i.e.:
+
+    * string expressions, like "'5'"
+    * simple (number) expressions, like "5"
+    * valid XPath expressions, like "/a/b/text()"
+
+    This function converts native Python keyword arguments to stylesheet
+    parameters following these rules:
+    If an arg is a string wrap it with XSLT.strparam().
+    If an arg is an XPath object use its path string.
+    If arg is None raise TypeError.
+    Else convert arg to string.
+    """
+    result = {}
+    for key, val in kwargs.items():
+        if isinstance(val, basestring):
+            val = _etree.XSLT.strparam(val)
+        elif val is None:
+            raise TypeError('None not allowed as a stylesheet parameter')
+        elif not isinstance(val, _etree.XPath):
+            val = unicode(val)
+        result[key] = val
+    return result
+
+
+# helper function for use in Schematron __init__
+def _stylesheet_param_dict(paramsDict, kwargsDict):
+    """Return a copy of paramsDict, updated with kwargsDict entries, wrapped as
+    stylesheet arguments.
+    kwargsDict entries with a value of None are ignored.
+    """
+    # beware of changing mutable default arg
+    paramsDict = dict(paramsDict)
+    for k, v in kwargsDict.items():
+        if v is not None: # None values do not override
+            paramsDict[k] = v
+    paramsDict = stylesheet_params(**paramsDict)
+    return paramsDict
+
+
+class Schematron(_etree._Validator):
+    """An ISO Schematron validator.
+
+    Pass a root Element or an ElementTree to turn it into a validator.
+    Alternatively, pass a filename as keyword argument 'file' to parse from
+    the file system.
+
+    Schematron is a less well known, but very powerful schema language.
+    The main idea is to use the capabilities of XPath to put restrictions on
+    the structure and the content of XML documents.
+
+    The standard behaviour is to fail on ``failed-assert`` findings only
+    (``ASSERTS_ONLY``).  To change this, you can either pass a report filter
+    function to the ``error_finder`` parameter (e.g. ``ASSERTS_AND_REPORTS``
+    or a custom ``XPath`` object), or subclass isoschematron.Schematron for
+    complete control of the validation process.
+
+    Built on the Schematron language 'reference' skeleton pure-xslt
+    implementation, the validator is created as an XSLT 1.0 stylesheet using
+    these steps:
+
+     0) (Extract from XML Schema or RelaxNG schema)
+     1) Process inclusions
+     2) Process abstract patterns
+     3) Compile the schematron schema to XSLT
+
+    The ``include`` and ``expand`` keyword arguments can be used to switch off
+    steps 1) and 2).
+    To set parameters for steps 1), 2) and 3) hand parameter dictionaries to the
+    keyword arguments ``include_params``, ``expand_params`` or
+    ``compile_params``.
+    For convenience, the compile-step parameter ``phase`` is also exposed as a
+    keyword argument ``phase``. This takes precedence if the parameter is also
+    given in the parameter dictionary.
+
+    If ``store_schematron`` is set to True, the (included-and-expanded)
+    schematron document tree is stored and available through the ``schematron``
+    property.
+    If ``store_xslt`` is set to True, the validation XSLT document tree will be
+    stored and can be retrieved through the ``validator_xslt`` property.
+    With ``store_report`` set to True (default: False), the resulting validation
+    report document gets stored and can be accessed as the ``validation_report``
+    property.
+
+    If ``validate_schema`` is set to False, the validation of the schema file
+    itself is disabled.  Validation happens by default after building the full
+    schema, unless the schema validation file cannot be found at import time,
+    in which case the validation gets disabled.  Some lxml distributions exclude
+    this file due to licensing issues.  ISO-Schematron validation can then still
+    be used normally, but the schemas themselves cannot be validated.
+
+    Here is a usage example::
+
+      >>> from lxml import etree
+      >>> from lxml.isoschematron import Schematron
+
+      >>> schematron = Schematron(etree.XML('''
+      ... <schema xmlns="http://purl.oclc.org/dsdl/schematron" >
+      ...   <pattern id="id_only_attribute">
+      ...     <title>id is the only permitted attribute name</title>
+      ...     <rule context="*">
+      ...       <report test="@*[not(name()='id')]">Attribute
+      ...         <name path="@*[not(name()='id')]"/> is forbidden<name/>
+      ...       </report>
+      ...     </rule>
+      ...   </pattern>
+      ... </schema>'''),
+      ... error_finder=Schematron.ASSERTS_AND_REPORTS)
+
+      >>> xml = etree.XML('''
+      ... <AAA name="aaa">
+      ...   <BBB id="bbb"/>
+      ...   <CCC color="ccc"/>
+      ... </AAA>
+      ... ''')
+
+      >>> schematron.validate(xml)
+      False
+
+      >>> xml = etree.XML('''
+      ... <AAA id="aaa">
+      ...   <BBB id="bbb"/>
+      ...   <CCC/>
+      ... </AAA>
+      ... ''')
+
+      >>> schematron.validate(xml)
+      True
+    """
+
+    # libxml2 error categorization for validation errors
+    _domain = _etree.ErrorDomains.SCHEMATRONV
+    _level = _etree.ErrorLevels.ERROR
+    _error_type = _etree.ErrorTypes.SCHEMATRONV_ASSERT
+
+    # convenience definitions for common behaviours
+    ASSERTS_ONLY = svrl_validation_errors  # Default
+    ASSERTS_AND_REPORTS = _etree.XPath(
+        '//svrl:failed-assert | //svrl:successful-report',
+        namespaces={'svrl': SVRL_NS})
+
+    def _extract(self, element):
+        """Extract embedded schematron schema from non-schematron host schema.
+        This method will only be called by __init__ if the given schema document
+        is not a schematron schema by itself.
+        Must return a schematron schema document tree or None.
+        """
+        schematron = None
+        if element.tag == _xml_schema_root:
+            schematron = self._extract_xsd(element)
+        elif element.nsmap.get(element.prefix) == RELAXNG_NS:
+            # RelaxNG does not have a single unique root element
+            schematron = self._extract_rng(element)
+        return schematron
+
+    # customization points
+    # etree.XSLT objects that provide the extract, include, expand, compile
+    # steps
+    _extract_xsd = extract_xsd
+    _extract_rng = extract_rng
+    _include = iso_dsdl_include
+    _expand = iso_abstract_expand
+    _compile = iso_svrl_for_xslt1
+
+    # etree.xpath object that determines input document validity when applied to
+    # the svrl result report; must return a list of result elements (empty if
+    # valid)
+    _validation_errors = ASSERTS_ONLY
+
+    def __init__(self, etree=None, file=None, include=True, expand=True,
+                 include_params={}, expand_params={}, compile_params={},
+                 store_schematron=False, store_xslt=False, store_report=False,
+                 phase=None, error_finder=ASSERTS_ONLY,
+                 validate_schema=schematron_schema_valid_supported):
+        super().__init__()
+
+        self._store_report = store_report
+        self._schematron = None
+        self._validator_xslt = None
+        self._validation_report = None
+        if error_finder is not self.ASSERTS_ONLY:
+            self._validation_errors = error_finder
+
+        # parse schema document, may be a schematron schema or an XML Schema or
+        # a RelaxNG schema with embedded schematron rules
+        root = None
+        try:
+            if etree is not None:
+                if _etree.iselement(etree):
+                    root = etree
+                else:
+                    root = etree.getroot()
+            elif file is not None:
+                root = _etree.parse(file).getroot()
+        except Exception:
+            raise _etree.SchematronParseError(
+                "No tree or file given: %s" % sys.exc_info()[1])
+        if root is None:
+            raise ValueError("Empty tree")
+        if root.tag == _schematron_root:
+            schematron = root
+        else:
+            schematron = self._extract(root)
+        if schematron is None:
+            raise _etree.SchematronParseError(
+                "Document is not a schematron schema or schematron-extractable")
+        # perform the iso-schematron skeleton implementation steps to get a
+        # validating xslt
+        if include:
+            schematron = self._include(schematron, **include_params)
+        if expand:
+            schematron = self._expand(schematron, **expand_params)
+        if validate_schema and not schematron_schema_valid(schematron):
+            raise _etree.SchematronParseError(
+                "invalid schematron schema: %s" %
+                schematron_schema_valid.error_log)
+        if store_schematron:
+            self._schematron = schematron
+        # add new compile keyword args here if exposing them
+        compile_kwargs = {'phase': phase}
+        compile_params = _stylesheet_param_dict(compile_params, compile_kwargs)
+        validator_xslt = self._compile(schematron, **compile_params)
+        if store_xslt:
+            self._validator_xslt = validator_xslt
+        self._validator = _etree.XSLT(validator_xslt)
+
+    def __call__(self, etree):
+        """Validate doc using Schematron.
+
+        Returns true if document is valid, false if not.
+        """
+        self._clear_error_log()
+        result = self._validator(etree)
+        if self._store_report:
+            self._validation_report = result
+        errors = self._validation_errors(result)
+        if errors:
+            if _etree.iselement(etree):
+                fname = etree.getroottree().docinfo.URL or '<file>'
+            else:
+                fname = etree.docinfo.URL or '<file>'
+            for error in errors:
+                # Does svrl report the line number, anywhere? Don't think so.
+                self._append_log_message(
+                    domain=self._domain, type=self._error_type,
+                    level=self._level, line=0,
+                    message=_etree.tostring(error, encoding='unicode'),
+                    filename=fname)
+            return False
+        return True
+
+    @property
+    def schematron(self):
+        """ISO-schematron schema document (None if object has been initialized
+        with store_schematron=False).
+        """
+        return self._schematron
+
+    @property
+    def validator_xslt(self):
+        """ISO-schematron skeleton implementation XSLT validator document (None
+        if object has been initialized with store_xslt=False).
+        """
+        return self._validator_xslt
+
+    @property
+    def validation_report(self):
+        """ISO-schematron validation result report (None if result-storing has
+        been turned off).
+        """
+        return self._validation_report