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"""Lexer for Blink IDL.

The lexer uses the PLY (Python Lex-Yacc) library to build a tokenizer which
understands the Blink dialect of Web IDL and produces a token stream suitable
for the Blink IDL parser.

Blink IDL is identical to Web IDL at the token level, but the base lexer
does not discard comments. We need to override (and not include comments in
the token stream), as otherwise comments must be explicitly included in the
phrase grammar of the parser.

FIXME: Change base lexer to discard comments, and simply used the base
lexer, eliminating this separate lexer.

Web IDL:
    http://www.w3.org/TR/WebIDL/
Web IDL Grammar:
    http://www.w3.org/TR/WebIDL/#idl-grammar
PLY:
    http://www.dabeaz.com/ply/
"""

# Disable attribute validation, as lint can't import parent class to check
# pylint: disable=E1101

import os.path
import sys

# Base lexer is in Chromium src/tools/idl_parser
module_path, module_name = os.path.split(__file__)
tools_dir = os.path.join(module_path, os.pardir, os.pardir, os.pardir, os.pardir, os.pardir, 'tools')
sys.path.append(tools_dir)

from idl_parser.idl_lexer import IDLLexer

REMOVE_TOKENS = ['COMMENT']


class BlinkIDLLexer(IDLLexer):
    # ignore comments
    def t_COMMENT(self, t):
        r'(/\*(.|\n)*?\*/)|(//.*(\n[ \t]*//.*)*)'
        self.AddLines(t.value.count('\n'))

    # Analogs to _AddToken/_AddTokens in base lexer
    # Needed to remove COMMENT token, since comments ignored
    def _RemoveToken(self, token):
        try:
            self.tokens.remove(token)
        except ValueError:
            raise RuntimeError('Token "%s" not present, so cannot be removed ' % token)

    def _RemoveTokens(self, tokens):
        for token in tokens:
            self._RemoveToken(token)

    def __init__(self):
        IDLLexer.__init__(self)
        self._RemoveTokens(REMOVE_TOKENS)


# If run by itself, attempt to build the lexer
if __name__ == '__main__':
    lexer = BlinkIDLLexer()