expr.cxx

ecos实时嵌入式操作系统

    CYG_PRECONDITION_CLASSC(expr);

    CdlReference ref(reference);
    expr->references.push_back(ref);
    int result = (int) expr->references.size() - 1;

    CYG_REPORT_RETVAL(result);
    return result;
}

// A utility to add a subexpression, returning its index.
static void
push_subexpression(CdlExpression expr, const CdlSubexpression& subexpr)
{
    CYG_REPORT_FUNCNAME("push_subexpression");
    CYG_PRECONDITION_CLASSC(expr);

    expr->sub_expressions.push_back(subexpr);
    expr->first_subexpression = ((int) expr->sub_expressions.size()) - 1;

    CYG_REPORT_RETURN();
}

// Another utility to hold of the most recent subexpression
static CdlSubexpression&
current_subexpression(CdlExpression expr)
{
    CYG_REPORT_FUNCNAME("current_subexpression");

    CdlSubexpression& result = expr->sub_expressions[expr->first_subexpression];

    CYG_REPORT_RETURN();
    return result;
}

static void
parse_function(CdlExpression expr)
{
    CYG_REPORT_FUNCNAME("parse_function");
    CYG_REPORT_FUNCARG1XV(expr);
    CYG_PRECONDITION_CLASSC(expr);

    CdlSubexpression subexpr;
    subexpr.op          = CdlExprOp_Function;
    subexpr.func        = current_function_id;

    int number_of_args  = CdlFunction::get_args_count(current_function_id);
    CYG_ASSERTC((0 < number_of_args) && (number_of_args <= CdlFunction_MaxArgs));
    std::string name    = current_special;

    // check for the opening bracket: xyzzy(arg1, arg2)
    next_token();
    if (T_OpenBracket != current_token) {
        throw CdlParseException(std::string("Expected opening bracket after function ") + name + "\n" + get_error_location());
    }
    next_token();

    int i;
    for (i = 0; i < number_of_args; i++) {
        parse_expression(expr);
        subexpr.args[i] = expr->first_subexpression;
        if (i < (number_of_args - 1)) {
            if (T_Comma != current_token) {
                throw CdlParseException(std::string("Expected comma between arguments in function ") +
                                        name + "\n" + get_error_location());
            }
            next_token();
        }
    }
    if (T_Comma == current_token) {
        throw CdlParseException(std::string("Too many arguments passed to function ") + name + "\n" + get_error_location());
    }
    if (T_CloseBracket != current_token) {
        throw CdlParseException(std::string("Expected closing bracket after function ") + name + "\n" + get_error_location());
    }
    next_token();
    
    // Allow the function implementation to check its arguments if it is so inclined.
    CdlFunction::check(expr, subexpr);
    
    push_subexpression(expr, subexpr);
    CYG_REPORT_RETURN();
}

static void
parse_unary(CdlExpression expr)
{
    CYG_REPORT_FUNCNAME("parse_operand");
    CYG_REPORT_FUNCARG1XV(expr);
    CYG_PRECONDITION_CLASSC(expr);

    CdlSubexpression subexpr;

    switch(current_token) {
      case T_EOD :
      {
        // This warrants a special case
        throw CdlParseException("End of expression reached when expecting an operand.\n" + get_error_location());
      }

      case T_Function :
      {
          parse_function(expr);
          break;
      }
      
      case T_Reference :
      {
        subexpr.op              = CdlExprOp_Reference;
        subexpr.reference_index = push_reference(expr, current_reference);
        push_subexpression(expr, subexpr);
        next_token();
        break;
      }
      
      case T_String :
      {
        subexpr.op              = CdlExprOp_StringConstant;
        subexpr.constants       = current_string;
        push_subexpression(expr, subexpr);
        next_token();
        break;
      }
      
      case T_Integer :
      {
        subexpr.op               = CdlExprOp_IntegerConstant;
        subexpr.constants.set_integer_value(current_int, current_format);
        push_subexpression(expr, subexpr);
        next_token();
        break;
      }
      
      case T_Double :
      {
        subexpr.op              = CdlExprOp_DoubleConstant;
        subexpr.constants.set_double_value(current_double, current_format);
        push_subexpression(expr, subexpr);
        next_token();
        break;
      }
      
      case T_OpenBracket :
      {
        next_token();
        parse_expression(expr);
        if (T_CloseBracket != current_token) {
            throw CdlParseException("Missing close bracket after subexpression.\n" + get_error_location());
        }
        next_token();
        break;
      }
      
      case T_Minus :
      {
        next_token();
        parse_unary(expr);
        CdlSubexpression& last_sub      = current_subexpression(expr);
        if (CdlExprOp_IntegerConstant == last_sub.op) {
            // Do the negating inline, no need for another subexpression.
            last_sub.constants = last_sub.constants.get_integer_value() * -1;
        } else if (CdlExprOp_DoubleConstant == last_sub.op) {
            last_sub.constants = last_sub.constants.get_double_value() * -1;
        } else {
            // We could detect certain cases such as string constants etc.
            // For now don't bother.
            subexpr.op          = CdlExprOp_Negate;
            subexpr.lhs_index   = expr->first_subexpression;
            push_subexpression(expr, subexpr);
        }
        break;
      }
      
      case T_Plus :
      {
        next_token();
        parse_unary(expr);
        CdlSubexpression& last_sub      = current_subexpression(expr);
        if ((CdlExprOp_IntegerConstant == last_sub.op) || (CdlExprOp_DoubleConstant == last_sub.op)) {
            // No need to do anything here.
        } else {
            subexpr.op          = CdlExprOp_Plus;
            subexpr.lhs_index   = expr->first_subexpression;
            push_subexpression(expr, subexpr);
        }
        break;
      }

      case T_Times :
      {
          next_token();
          parse_unary(expr);
          subexpr.op            = CdlExprOp_Indirect;
          subexpr.lhs_index     = expr->first_subexpression;
          push_subexpression(expr, subexpr);
          break;
      }
      
      case T_Exclamation :
      {
          next_token();
          parse_unary(expr);
          subexpr.op            = CdlExprOp_LogicalNot;
          subexpr.lhs_index     = expr->first_subexpression;
          push_subexpression(expr, subexpr);
          break;
      }

      case T_Tilde :
      {
          next_token();
          parse_unary(expr);
          subexpr.op            = CdlExprOp_BitNot;
          subexpr.lhs_index     = expr->first_subexpression;
          push_subexpression(expr, subexpr);
          break;
      }

      case T_Questionmark:
      {
          // This is the `active' operator, it can only be applied directly to a reference.
          next_token();
          parse_unary(expr);
          CdlSubexpression& last_sub = current_subexpression(expr);
          if (CdlExprOp_Reference != last_sub.op) {
              throw CdlParseException("The active operator ? can only be applied directly to a reference.\n" +
                                      get_error_location());
          }
          // There is no point in creating a new subexpression object, just modify
          // the existing one. This has the useful side effect of avoiding
          // reference substitution in the eval code.
          last_sub.op           = CdlExprOp_Active;
          break;
      }
      default:
      {
        throw CdlParseException("Unexpected token `" + token_to_string() + "', expecting an operand.\n" +
                                get_error_location());
      }
    }

    CYG_REPORT_RETURN();
}

static void
parse_multiply(CdlExpression expr)
{
    CYG_REPORT_FUNCNAME("parse_multiply");
    
    parse_unary(expr);
    while ((T_Times == current_token) || (T_Divide == current_token) || (T_Remainder == current_token)) {

        CdlSubexpression subexpr;
        subexpr.op      =
            (T_Times  == current_token) ? CdlExprOp_Multiply :
            (T_Divide == current_token) ? CdlExprOp_Divide : CdlExprOp_Remainder;
        subexpr.lhs_index = expr->first_subexpression;
        
        next_token();
        parse_unary(expr);

        subexpr.rhs_index = expr->first_subexpression;
        push_subexpression(expr, subexpr);
    }
    
    CYG_REPORT_RETURN();
}

static void
parse_add(CdlExpression expr)
{
    CYG_REPORT_FUNCNAME("parse_add");
    
    parse_multiply(expr);
    while ((T_Plus == current_token)  ||
           (T_Minus == current_token) ||
           (T_StringConcat == current_token)) {

        CdlSubexpression subexpr;
        subexpr.op = (T_Plus == current_token) ? CdlExprOp_Add :
                     (T_Minus == current_token) ? CdlExprOp_Subtract :
                     CdlExprOp_StringConcat;
        subexpr.lhs_index = expr->first_subexpression;
        
        next_token();
        parse_multiply(expr);

        subexpr.rhs_index = expr->first_subexpression;
        push_subexpression(expr, subexpr);
    }
    
    CYG_REPORT_RETURN();
}

static void
parse_shift(CdlExpression expr)
{
    CYG_REPORT_FUNCNAME("parse_shift");
    
    parse_add(expr);
    while ((T_LeftShift == current_token) || (T_RightShift == current_token)) {

        CdlSubexpression subexpr;
        subexpr.op = (T_LeftShift == current_token) ? CdlExprOp_LeftShift : CdlExprOp_RightShift;
        subexpr.lhs_index = expr->first_subexpression;
        
        next_token();
        parse_add(expr);

        subexpr.rhs_index = expr->first_subexpression;
        push_subexpression(expr, subexpr);
    }
    
    CYG_REPORT_RETURN();
}

static void
parse_comparison(CdlExpression expr)
{
    CYG_REPORT_FUNCNAME("parse_comparison");
    
    parse_shift(expr);
    while ((T_LessThan == current_token)    || (T_LessEqual    == current_token) ||
           (T_GreaterThan == current_token) || (T_GreaterEqual == current_token))  {

        CdlSubexpression subexpr;
        subexpr.op =
            (T_LessThan    == current_token) ? CdlExprOp_LessThan : 
            (T_LessEqual   == current_token) ? CdlExprOp_LessEqual :
            (T_GreaterThan == current_token) ? CdlExprOp_GreaterThan : CdlExprOp_GreaterEqual;
        subexpr.lhs_index = expr->first_subexpression;
        
        next_token();
        parse_shift(expr);

        subexpr.rhs_index = expr->first_subexpression;
        push_subexpression(expr, subexpr);
    }
    
    CYG_REPORT_RETURN();
}

static void
parse_equals(CdlExpression expr)
{
    CYG_REPORT_FUNCNAME("parse_equals");
    
    parse_comparison(expr);
    while ((T_Equal == current_token) ||
           (T_NotEqual == current_token)) {

        CdlSubexpression subexpr;
        subexpr.op = (T_Equal == current_token) ? CdlExprOp_Equal : CdlExprOp_NotEqual;
        subexpr.lhs_index = expr->first_subexpression;
        
        next_token();
        parse_comparison(expr);

        subexpr.rhs_index = expr->first_subexpression;
        push_subexpression(expr, subexpr);
    }
    
    CYG_REPORT_RETURN();
}

static void
parse_bitand(CdlExpression expr)
{
    CYG_REPORT_FUNCNAME("parse_bitand");
    
    parse_equals(expr);
    while (T_BitAnd == current_token) {

        CdlSubexpression subexpr;
        subexpr.op = CdlExprOp_BitAnd;
        subexpr.lhs_index = expr->first_subexpression;
        
        next_token();
        parse_equals(expr);

        subexpr.rhs_index = expr->first_subexpression;
        push_subexpression(expr, subexpr);
    }
    
    CYG_REPORT_RETURN();
}

static void
parse_bitxor(CdlExpression expr)
{