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"""Validate extended attributes."""


import re


class IDLExtendedAttributeFileFormatError(Exception):
    pass


class IDLInvalidExtendedAttributeError(Exception):
    pass


def validate_extended_attributes(definitions, basename, idl_attributes_filename):
    extended_attribute_validator = IDLExtendedAttributeValidator(idl_attributes_filename)
    extended_attribute_validator.validate_extended_attributes(definitions, basename)


def read_extended_attributes_file(extended_attributes_filename):
    valid_extended_attributes = {}
    with open(extended_attributes_filename) as extended_attributes_file:
        for line in extended_attributes_file:
            line = line.strip()
            if not line or line.startswith('#'):
                continue
            name, _, values_string = map(str.strip, line.partition('='))
            if not name:
                raise IDLExtendedAttributeFileFormatError('The format of %s is wrong, in line "%s"' % (extended_attributes_filename, line))
            valid_extended_attributes[name] = set()
            value_list = values_string.split('|')
            if not value_list:
                valid_extended_attributes[name].add(None)
                continue
            for value in value_list:
                value = value.strip()
                if not value:
                    value = None
                valid_extended_attributes[name].add(value)
    return valid_extended_attributes


class IDLExtendedAttributeValidator:
    def __init__(self, extended_attributes_filename):
        self.valid_extended_attributes = read_extended_attributes_file(extended_attributes_filename)

    def validate_extended_attributes(self, definitions, idl_filename):
        # FIXME: this should be done when parsing the file, rather than after.
        try:
            for interface in definitions.interfaces.itervalues():
                self.validate_extended_attributes_node(interface)
                for attribute in interface.attributes:
                    self.validate_extended_attributes_node(attribute)
                for operation in interface.operations:
                    self.validate_extended_attributes_node(operation)
                    for argument in operation.arguments:
                        self.validate_extended_attributes_node(argument)
        except IDLInvalidExtendedAttributeError, error:
            raise IDLInvalidExtendedAttributeError("""IDL ATTRIBUTE ERROR in file %s:
%s
If you want to add a new IDL extended attribute, please add it to bindings/scripts/IDLAttributes.txt and add an explanation to the Blink IDL document at http://chromium.org/blink/webidl
""" % (idl_filename, str(error)))

    def validate_extended_attributes_node(self, node):
        for name, values_string in node.extended_attributes.iteritems():
            self.validate_name_values_string(name, values_string)

    def validate_name_values_string(self, name, values_string):
        if name == 'ImplementedBy':  # attribute added when merging interfaces
            return
        if name not in self.valid_extended_attributes:
            raise IDLInvalidExtendedAttributeError('Unknown extended attribute [%s]' % name)
        valid_values = self.valid_extended_attributes[name]
        if '*' in valid_values:  # wildcard, any value ok
            return
        if values_string is None:
            value_list = [None]
        else:
            value_list = re.split('[|&]', values_string)
        for value in value_list:
            if value not in valid_values:
                raise IDLInvalidExtendedAttributeError('Invalid value "%s" found in extended attribute [%s=%s]' % (value, name, values_string))