override public void Visit(AST_binary_operator binary_operator)
{
binary_operator.LeftOperand.Accept(this);
Variable left = this.Value.Copy();
binary_operator.RightOperand.Accept(this);
Variable right = this.Value.Copy();
switch (left.Type)
{
case AST_type.AST_type_kind.bool_type:
EvaluateBooleanBinaryOperator(binary_operator, left, right);
break;
case AST_type.AST_type_kind.int_type:
EvaluateIntegerBinaryOperator(binary_operator, left, right);
break;
case AST_type.AST_type_kind.string_type:
EvaluateStringBinaryOperator(binary_operator, left, right);
break;
default:
break;
}
}
private void EvaluateIntegerBinaryOperator(AST_binary_operator binary_operator, Variable left, Variable right)
{
switch (binary_operator.Kind)
{
case AST_binary_operator.OperatorKind.Equal:
this.value.Set(left.IntValue == right.IntValue);
break;
case AST_binary_operator.OperatorKind.Less:
this.value.Set(left.IntValue < right.IntValue);
break;
case AST_binary_operator.OperatorKind.Plus:
this.value.Set(left.IntValue + right.IntValue);
break;
case AST_binary_operator.OperatorKind.Minus:
this.value.Set(left.IntValue - right.IntValue);
break;
case AST_binary_operator.OperatorKind.Asterisk:
this.value.Set(left.IntValue * right.IntValue);
break;
case AST_binary_operator.OperatorKind.Slash:
this.value.Set(left.IntValue / right.IntValue);
break;
default:
break;
}
}
public virtual void Visit(AST_binary_operator binary_operator)
{
IncrementDepth();
binary_operator.LeftOperand.Accept(this);
binary_operator.RightOperand.Accept(this);
DecrementDepth();
}
private AST_binary_operator Parse_binary_operator(TokenKind followSet)
{
IncrementDepth();
AST_binary_operator binary_operator;
Token t = GetNextToken();
DebugPrint("op " + t.Lexeme);
AST_binary_operator.OperatorKind kind;
switch (t.Kind)
{
case Plus:
kind = AST_binary_operator.OperatorKind.Plus;
break;
case Minus:
kind = AST_binary_operator.OperatorKind.Minus;
break;
case Asterisk:
kind = AST_binary_operator.OperatorKind.Asterisk;
break;
case Slash:
kind = AST_binary_operator.OperatorKind.Slash;
break;
case Less:
kind = AST_binary_operator.OperatorKind.Less;
break;
case Equal:
kind = AST_binary_operator.OperatorKind.Equal;
break;
case Ampersand:
kind = AST_binary_operator.OperatorKind.Ampersand;
break;
default:
Error("Binary operator expected.", t);
kind = AST_binary_operator.OperatorKind.Plus;
SkipUntilFollow(followSet);
break;
}
binary_operator = new AST_binary_operator(kind);
binary_operator.Row = t.Row;
binary_operator.Column = t.Column;
DecrementDepth();
return(binary_operator);
}
private void EvaluateBooleanBinaryOperator(AST_binary_operator binary_operator, Variable left, Variable right)
{
switch (binary_operator.Kind)
{
case AST_binary_operator.OperatorKind.Ampersand:
this.value.Set(left.BoolValue & right.BoolValue);
break;
case AST_binary_operator.OperatorKind.Equal:
this.value.Set(left.BoolValue == right.BoolValue);
break;
default:
break;
}
}
private AST_expression Parse_expression(TokenKind followSet)
{
IncrementDepth();
DebugPrint("expr");
AST_expression expression;
Token t = LookAheadToken();
switch (t.Kind)
{
case Exclamation:
expression = Parse_unary_operator_operand(followSet);
break;
default:
if (isMemberOf(t.Kind, FirstSet_operand))
{
AST_operand left_operand = Parse_operand(followSet | BinaryOperators);
if (IsBinaryOperator(LookAheadToken().Kind))
{
AST_binary_operator binary_operator = Parse_binary_operator(followSet);
AST_operand right_operand = Parse_operand(followSet);
binary_operator.SetLeft(left_operand);
binary_operator.SetRight(right_operand);
expression = binary_operator;
}
else
{
expression = left_operand;
}
}
else
{
Error("Expression expected. '" + t.ToString() + "' does not start an expression.", t);
expression = new ASTDummy_operand();
SkipUntilFollow(followSet);
}
break;
}
DecrementDepth();
return(expression);
}
private void EvaluateStringBinaryOperator(AST_binary_operator binary_operator, Variable left, Variable right)
{
switch (binary_operator.Kind)
{
case AST_binary_operator.OperatorKind.Equal:
this.value.Set(left.StringValue.Equals(right.StringValue));
break;
case AST_binary_operator.OperatorKind.Less:
this.value.Set(left.StringValue.CompareTo(right.StringValue) < 0);
break;
case AST_binary_operator.OperatorKind.Plus:
this.value.Set(string.Concat(left.StringValue, right.StringValue));
break;
default:
break;
}
}
override public void Visit(AST_binary_operator binary_operator)
{
base.Visit(binary_operator);
if (binary_operator.LeftOperand.DataType != binary_operator.RightOperand.DataType)
{
Error("Left and right operands of binary operator must be of same type.", binary_operator);
}
else
{
AST_type.AST_type_kind t = binary_operator.LeftOperand.DataType;
switch (binary_operator.Kind)
{
case Ampersand:
if (t != bool_type)
{
Error("Binary operator '&' requires bool operands.", binary_operator);
}
break;
case Asterisk:
if (t != int_type)
{
Error("Binary operator '*' requires int operands.", binary_operator);
}
break;
case Equal:
// All types accepted
break;
case Less:
// All types accepted
break;
case Minus:
if (t != int_type)
{
Error("Binary operator '-' requires int operands.", binary_operator);
}
break;
case Plus:
if (t == bool_type)
{
Error("Binary operator '+' requires int or string operands.", binary_operator);
}
break;
case Slash:
if (t != int_type)
{
Error("Binary operator '/' requires int operands.", binary_operator);
}
break;
default:
break;
}
}
switch (binary_operator.Kind)
{
case Equal:
case Less:
case Ampersand:
binary_operator.DataType = bool_type;
break;
default:
binary_operator.DataType = binary_operator.LeftOperand.DataType;
break;
}
}