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"""Read an IDL file or complete IDL interface, producing an IdlDefinitions object.

Design doc:
http://www.chromium.org/developers/design-documents/idl-compiler#TOC-Front-end
"""

import os

import blink_idl_parser
from blink_idl_parser import BlinkIDLParser
from idl_definitions import IdlDefinitions
from idl_validator import EXTENDED_ATTRIBUTES_RELATIVE_PATH, IDLInvalidExtendedAttributeError, IDLExtendedAttributeValidator
from interface_dependency_resolver import InterfaceDependencyResolver


class IdlReader(object):
    def __init__(self, interfaces_info=None, outputdir=''):
        self.extended_attribute_validator = IDLExtendedAttributeValidator()

        if interfaces_info:
            self.interface_dependency_resolver = InterfaceDependencyResolver(interfaces_info, self)
        else:
            self.interface_dependency_resolver = None

        self.parser = BlinkIDLParser(outputdir=outputdir)

    def read_idl_definitions(self, idl_filename):
        """Returns an IdlDefinitions object for an IDL file, including all dependencies."""
        definitions = self.read_idl_file(idl_filename)
        if not self.interface_dependency_resolver:
            return definitions
        self.interface_dependency_resolver.resolve_dependencies(definitions)
        return definitions

    def read_idl_file(self, idl_filename):
        """Returns an IdlDefinitions object for an IDL file, without any dependencies.

        The IdlDefinitions object is guaranteed to contain a single
        IdlInterface; it may also contain other definitions, such as
        callback functions and enumerations."""
        ast = blink_idl_parser.parse_file(self.parser, idl_filename)
        if not ast:
            raise Exception('Failed to parse %s' % idl_filename)
        definitions = IdlDefinitions(ast)

        # Validate file contents with filename convention
        # The Blink IDL filenaming convention is that the file
        # <interface_name>.idl MUST contain exactly 1 interface (or exception),
        # and the interface name must agree with the file's basename,
        # unless it is a partial interface.
        # (e.g., 'partial interface Foo' can be in FooBar.idl).
        number_of_interfaces = len(definitions.interfaces)
        if number_of_interfaces != 1:
            raise Exception(
                'Expected exactly 1 interface in file {0}, but found {1}'
                .format(idl_filename, number_of_interfaces))
        interface = next(definitions.interfaces.itervalues())
        idl_file_basename, _ = os.path.splitext(os.path.basename(idl_filename))
        if not interface.is_partial and interface.name != idl_file_basename:
            raise Exception(
                'Interface name "{0}" disagrees with IDL file basename "{1}".'
                .format(interface.name, idl_file_basename))

        # Validate extended attributes
        if not self.extended_attribute_validator:
            return definitions

        try:
            self.extended_attribute_validator.validate_extended_attributes(definitions)
        except IDLInvalidExtendedAttributeError as error:
            raise IDLInvalidExtendedAttributeError("""
IDL ATTRIBUTE ERROR in file:
%s:
    %s
If you want to add a new IDL extended attribute, please add it to:
    %s
and add an explanation to the Blink IDL documentation at:
    http://www.chromium.org/blink/webidl/blink-idl-extended-attributes
    """ % (idl_filename, str(error), EXTENDED_ATTRIBUTES_RELATIVE_PATH))

        return definitions