zope.configuration.xmlconfig — zope.configuration 4.0 documentation

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# Source code for zope.configuration.xmlconfig

    ##############################################################################
    #
    # Copyright (c) 2001, 2002, 2003 Zope Foundation and Contributors.
    # All Rights Reserved.
    #
    # This software is subject to the provisions of the Zope Public License,
    # Version 2.1 (ZPL).  A copy of the ZPL should accompany this distribution.
    # THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
    # WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
    # WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
    # FOR A PARTICULAR PURPOSE.
    #
    ##############################################################################
    """Support for the XML configuration file format

    Note, for a detailed description of the way that conflicting
    configuration actions are resolved, see the detailed example in
    test_includeOverrides in tests/test_xmlconfig.py
    """
    __docformat__ = 'restructuredtext'

    import errno
    from glob import glob
    import logging
    import os
    import sys
    from xml.sax import make_parser
    from xml.sax.xmlreader import InputSource
    from xml.sax.handler import ContentHandler, feature_namespaces
    from xml.sax import SAXParseException

    from zope.interface import Interface
    from zope.schema import NativeStringLine

    from zope.configuration.config import ConfigurationMachine
    from zope.configuration.config import defineGroupingDirective
    from zope.configuration.config import defineSimpleDirective
    from zope.configuration.config import GroupingContextDecorator
    from zope.configuration.config import GroupingStackItem
    from zope.configuration.config import resolveConflicts
    from zope.configuration.exceptions import ConfigurationError
    from zope.configuration.fields import GlobalObject
    from zope.configuration.zopeconfigure import IZopeConfigure
    from zope.configuration.zopeconfigure import ZopeConfigure
    from zope.configuration._compat import StringIO
    from zope.configuration._compat import reraise
    from zope.configuration._compat import u

    logger = logging.getLogger("config")

    ZCML_NAMESPACE = "http://namespaces.zope.org/zcml"
    ZCML_CONDITION = (ZCML_NAMESPACE, u("condition"))

    class ZopeXMLConfigurationError(ConfigurationError):
        """Zope XML Configuration error

        These errors are wrappers for other errors. They include configuration
        info and the wrapped error type and value.
        """
        def __init__(self, info, etype, evalue):
            self.info, self.etype, self.evalue = info, etype, evalue

        def __str__(self):
            # Only use the repr of the info. This is because we expect to
            # get a parse info and we only want the location information.
            return "%s\n    %s: %s" % (
                repr(self.info), self.etype.__name__, self.evalue)

    class ZopeSAXParseException(ConfigurationError):
        """Sax Parser errors, reformatted in an emacs friendly way
        """
        def __init__(self, v):
            self._v = v

        def __str__(self):
            v = self._v
            s = tuple(str(v).split(':'))
            if len(s) == 4:
                return 'File "%s", line %s.%s, %s' % s
            else:
                return str(v)

    class ParserInfo(object):
        """Information about a directive based on parser data

        This includes the directive location, as well as text data
        contained in the directive.
        """
        text = u('')

        def __init__(self, file, line, column):
            self.file, self.line, self.column = file, line, column
            self.eline, self.ecolumn = line, column

        def end(self, line, column):
            self.eline, self.ecolumn = line, column

        def __repr__(self):
            if (self.line, self.column) == (self.eline, self.ecolumn):
                return 'File "%s", line %s.%s' % (
                    self.file, self.line, self.column)

            return 'File "%s", line %s.%s-%s.%s' % (
                self.file, self.line, self.column, self.eline, self.ecolumn)

        def __str__(self):
            if (self.line, self.column) == (self.eline, self.ecolumn):
                return 'File "%s", line %s.%s' % (
                    self.file, self.line, self.column)

            file = self.file
            if file == 'tests//sample.zcml':
                # special case for testing
                file = os.path.join(os.path.dirname(__file__),
                                    'tests', 'sample.zcml')

            try:
                with open(file) as f:
                    lines = f.readlines()[self.line-1:self.eline]
            except IOError:
                src = "  Could not read source."
            else:
                ecolumn = self.ecolumn
                if lines[-1][ecolumn:ecolumn+2] == '</': #pragma NO COVER
                    # We're pointing to the start of an end tag. Try to find
                    # the end
                    l = lines[-1].find('>', ecolumn)
                    if l >= 0:
                        lines[-1] = lines[-1][:l+1]
                else: #pragma NO COVER
                    lines[-1] = lines[-1][:ecolumn+1]

                column = self.column
                if lines[0][:column].strip(): #pragma NO COVER
                    # Remove text before start if it's noy whitespace
                    lines[0] = lines[0][self.column:]

                pad = u('  ')
                blank = u('')
                try:
                    src = blank.join([pad + l for l in lines])
                except UnicodeDecodeError: #pragma NO COVER
                    # XXX:
                    # I hope so most internation zcml will use UTF-8 as encoding
                    # otherwise this code must be made more clever
                    src = blank.join([pad + l.decode('utf-8') for l in lines])
                    # unicode won't be printable, at least on my console
                    src = src.encode('ascii','replace')

            return "%s\n%s" % (repr(self), src)

        def characters(self, characters):
            self.text += characters

    class ConfigurationHandler(ContentHandler):
        """Interface to the xml parser

        Translate parser events into calls into the configuration system.
        """
        locator = None

        def __init__(self, context, testing=False):
            self.context = context
            self.testing = testing
            self.ignore_depth = 0

        def setDocumentLocator(self, locator):
            self.locator = locator

        def characters(self, text):
            self.context.getInfo().characters(text)

        def startElementNS(self, name, qname, attrs):
            if self.ignore_depth:
                self.ignore_depth += 1
                return

            data = {}
            for (ns, aname), value in attrs.items():
                # NB: even though on CPython, 'ns' will be ``None`` always,
                # do not change the below to "if ns is None" because Jython's
                # sax parser generates attrs that have empty strings for
                # the namepace instead of ``None``.
                if not ns:
                    aname = str(aname)
                    data[aname] = value
                if (ns, aname) == ZCML_CONDITION:
                    # need to process the expression to determine if we
                    # use this element and it's descendents
                    use = self.evaluateCondition(value)
                    if not use:
                        self.ignore_depth = 1
                        return

            info = ParserInfo(
                self.locator.getSystemId(),
                self.locator.getLineNumber(),
                self.locator.getColumnNumber(),
                )

            try:
                self.context.begin(name, data, info)
            except (KeyboardInterrupt, SystemExit): #pragma NO COVER
                raise
            except:
                if self.testing:
                    raise
                reraise(ZopeXMLConfigurationError(info,
                                                  sys.exc_info()[0],
                                                  sys.exc_info()[1]),
                        None, sys.exc_info()[2])

            self.context.setInfo(info)

        def evaluateCondition(self, expression):
            """Evaluate a ZCML condition.

            ``expression`` is a string of the form "verb arguments".

            Currently the supported verbs are ``have``, ``not-have``,
            ``installed`` and ``not-installed``.
            """
            arguments = expression.split(None)
            verb = arguments.pop(0)

            if verb in ('have', 'not-have'):
                if not arguments:
                    raise ValueError("Feature name missing: %r" % expression)
                if len(arguments) > 1:
                    raise ValueError("Only one feature allowed: %r" % expression)

                if verb == 'have':
                    return self.context.hasFeature(arguments[0])
                elif verb == 'not-have':
                    return not self.context.hasFeature(arguments[0])

            elif verb in ('installed', 'not-installed'):
                if not arguments:
                    raise ValueError("Package name missing: %r" % expression)
                if len(arguments) > 1:
                    raise ValueError("Only one package allowed: %r" % expression)

                try:
                    __import__(arguments[0])
                    installed = True
                except ImportError:
                    installed = False

                if verb == 'installed':
                    return installed
                elif verb == 'not-installed':
                    return not installed
            else:
                raise ValueError("Invalid ZCML condition: %r" % expression)

        def endElementNS(self, name, qname):
            # If ignore_depth is set, this element will be ignored, even
            # if this this decrements ignore_depth to 0.
            if self.ignore_depth:
                self.ignore_depth -= 1
                return

            info = self.context.getInfo()
            info.end(
                self.locator.getLineNumber(),
                self.locator.getColumnNumber(),
                )

            try:
                self.context.end()
            except (KeyboardInterrupt, SystemExit): #pragma NO COVER
                raise
            except:
                if self.testing:
                    raise
                reraise(ZopeXMLConfigurationError(info,
                                                  sys.exc_info()[0],
                                                  sys.exc_info()[1]),
                        None, sys.exc_info()[2])

    def processxmlfile(file, context, testing=False):
        """Process a configuration file

        See examples in tests/text_xmlconfig.py
        """
        src = InputSource(getattr(file, 'name', '<string>'))
        src.setByteStream(file)
        parser = make_parser()
        parser.setContentHandler(ConfigurationHandler(context, testing=testing))
        parser.setFeature(feature_namespaces, True)
        try:
            parser.parse(src)
        except SAXParseException:
            reraise(ZopeSAXParseException(sys.exc_info()[1]),
                    None, sys.exc_info()[2])

    def openInOrPlain(filename):
        """Open a file, falling back to filename.in.

        If the requested file does not exist and filename.in does, fall
        back to filename.in.  If opening the original filename fails for
        any other reason, allow the failure to propogate.
        """
        try:
            return open(filename)
        except IOError as e:
            code, msg = e.args
            if code == errno.ENOENT:
                fn = filename + ".in"
                if os.path.exists(fn):
                    return open(fn)
            raise

    class IInclude(Interface):
        """The ``include``, ``includeOverrides`` and ``exclude`` directives

        These directives allows you to include or preserve including of another
        ZCML file in the configuration. This enables you to write configuration
        files in each package and then link them together.
        """

        file = NativeStringLine(
            title=u("Configuration file name"),
            description=u("The name of a configuration file to be included/"
                          "excluded, relative to the directive containing the "
                          "including configuration file."),
            required=False,
            )

        files = NativeStringLine(
            title=u("Configuration file name pattern"),
            description=u("""
            The names of multiple configuration files to be included/excluded,
            expressed as a file-name pattern, relative to the directive
            containing the including or excluding configuration file.
            The pattern can include:

            - ``*`` matches 0 or more characters

            - ``?`` matches a single character

            - ``[<seq>]`` matches any character in seq

            - ``[!<seq>]`` matches any character not in seq

            The file names are included in sorted order, where sorting is
            without regard to case.
            """),
            required=False,
            )

        package = GlobalObject(
            title=u("Include or exclude package"),
            description=u("""
            Include or exclude the named file (or configure.zcml) from the
            directory of this package.
            """),
            required=False,
            )

    def include(_context, file=None, package=None, files=None):
        """Include a zcml file

        See examples in tests/text_xmlconfig.py
        """

        if files:
            if file:
                raise ValueError("Must specify only one of file or files")
        elif not file:
            file = 'configure.zcml'

        # This is a tad tricky. We want to behave as a grouping directive.

        context = GroupingContextDecorator(_context)
        if package is not None:
            context.package = package
            context.basepath = None

        if files:
            paths = glob(context.path(files))
            paths = sorted(zip([path.lower() for path in paths], paths))
            paths = [path for (l, path) in paths]
        else:
            paths = [context.path(file)]

        for path in paths:
            if context.processFile(path):
                with openInOrPlain(path) as f:
                    logger.debug("include %s" % f.name)

                    context.basepath = os.path.dirname(path)
                    context.includepath = _context.includepath + (f.name, )
                    _context.stack.append(GroupingStackItem(context))

                    processxmlfile(f, context)
                assert _context.stack[-1].context is context
                _context.stack.pop()

    def exclude(_context, file=None, package=None, files=None):
        """Exclude a zcml file

        This directive should be used before any ZML that includes
        configuration you want to exclude.
        """

        if files:
            if file:
                raise ValueError("Must specify only one of file or files")
        elif not file:
            file = 'configure.zcml'

        context = GroupingContextDecorator(_context)
        if package is not None:
            context.package = package
            context.basepath = None

        if files:
            paths = glob(context.path(files))
            paths = sorted(zip([path.lower() for path in paths], paths))
            paths = [path for (l, path) in paths]
        else:
            paths = [context.path(file)]

        for path in paths:
            # processFile returns a boolean indicating if the file has been
            # processed or not, it *also* marks the file as having been processed,
            # here the side effect is used to keep the given file from being
            # processed in the future
            context.processFile(path)

    def includeOverrides(_context, file=None, package=None, files=None):
        """Include zcml file containing overrides

        The actions in the included file are added to the context as if they
        were in the including file directly.

        See the detailed example in test_includeOverrides in
        tests/text_xmlconfig.py
        """

        # We need to remember how many actions we had before
        nactions = len(_context.actions)

        # We'll give the new actions this include path
        includepath = _context.includepath

        # Now we'll include the file. We'll munge the actions after
        include(_context, file, package, files)

        # Now we'll grab the new actions, resolve conflicts,
        # and munge the includepath:
        newactions = []

        for action in resolveConflicts(_context.actions[nactions:]):
            action['includepath'] = includepath
            newactions.append(action)

        _context.actions[nactions:] = newactions

    def registerCommonDirectives(context):
        # We have to use the direct definition functions to define
        # a directive for all namespaces.

        defineSimpleDirective(
            context, "include", IInclude, include, namespace="*")

        defineSimpleDirective(
            context, "exclude", IInclude, exclude, namespace="*")

        defineSimpleDirective(
            context, "includeOverrides", IInclude, includeOverrides, namespace="*")

        defineGroupingDirective(
            context,
            name="configure",
            namespace="*",
            schema=IZopeConfigure,
            handler=ZopeConfigure,
            )

    def file(name, package=None, context=None, execute=True):
        """Execute a zcml file
        """

        if context is None:
            context = ConfigurationMachine()
            registerCommonDirectives(context)
            context.package = package

        include(context, name, package)
        if execute:
            context.execute_actions()

        return context

    def string(s, context=None, name="<string>", execute=True):
        """Execute a zcml string
        """
        if context is None:
            context = ConfigurationMachine()
            registerCommonDirectives(context)

        f = StringIO(s)
        f.name = name
        processxmlfile(f, context)

        if execute:
            context.execute_actions()

        return context

    ##############################################################################
    # Backward compatability, mainly for tests

    _context = None
    def _clearContext():
        global _context
        _context = ConfigurationMachine()
        registerCommonDirectives(_context)

    def _getContext():
        global _context
        if _context is None:
            _clearContext()
            try:
                from zope.testing.cleanup import addCleanUp
            except ImportError: #pragma NO COVER
                pass
            else: #pragma NO COVER
                addCleanUp(_clearContext)
                del addCleanUp
        return _context

    class XMLConfig(object):
        """Provide high-level handling of configuration files.

        See examples in tests/text_xmlconfig.py
        """

        def __init__(self, file_name, module=None):
            context = _getContext()
            include(context, file_name, module)
            self.context = context

        def __call__(self):
            self.context.execute_actions()

    def xmlconfig(file, testing=False):
        context = _getContext()
        processxmlfile(file, context, testing=testing)
        context.execute_actions(testing=testing)

    def testxmlconfig(file):
        """xmlconfig that doesn't raise configuration errors

        This is useful for testing, as it doesn't mask exception types.
        """
        context = _getContext()
        processxmlfile(file, context, testing=True)
        context.execute_actions(testing=True)

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