bool GLSLPreProcessor::OnSubstitueStdMacro(const Token& identTkn, TokenPtrString& tokenString)
{
    if (identTkn.Spell() == "__FILE__")
    {
        /* Replace '__FILE__' identifier with index of current filename */
        tokenString.PushBack(Make<Token>(Tokens::IntLiteral, "1"));
        return true;
    }
    return PreProcessor::OnSubstitueStdMacro(identTkn, tokenString);
}