private object EvaluateOperand(StackValue value)
{
switch (value.Type)
{
case ValType.Integer:
return((int)value.Value);
case ValType.Float:
return((float)value.Value);
case ValType.Bool:
return((bool)value.Value);
case ValType.Char:
return((char)value.Value);
case ValType.String:
return((string)value.Value);
case ValType.Identifier:
return(CurrentScope.Get((string)value.Value));
case ValType.Type:
return(value.CastTo <ValType>());
case ValType.Null:
return(null);
default:
return(0);
}
}
private bool Truthify(StackValue value)
{
switch (value.Type)
{
case ValType.Null:
return(false);
case ValType.Bool:
return(value.CastTo <bool>());
case ValType.Identifier:
return(Truthify(ResolveStackValue(value)));
default:
return(true);
}
}
StackValue ResolveStackValue(StackValue stackValue)
{
if (stackValue.Type == ValType.Identifier)
{
var varname = stackValue.CastTo <string>();
if (!CurrentScope.Contain(varname))
{
RuntimeError($"{varname} is not defined");
}
var value = CurrentScope.Get(varname);
if (value is null)
{
return(new StackValue(ValType.Null, null));
}
else if (value.GetType() == typeof(float))
{
return(new StackValue(ValType.Float, value));
}
else if (value.GetType() == typeof(bool))
{
return(new StackValue(ValType.Bool, value));
}
else if (value.GetType() == typeof(char))
{
return(new StackValue(ValType.Char, value));
}
else if (value.GetType() == typeof(string))
{
return(new StackValue(ValType.String, value));
}
else
{
return(new StackValue(ValType.Integer, value));
}
}
else
{
return(stackValue);
}
}
private StackValue Evaluate(ASTNode Expression)
{
#region operation
int IntegerOperation(StackValue operand1, StackValue operand2, TokenType op)
{
int i1 = (int)operand1.Value;
int i2 = (int)operand2.Value;
switch (op)
{
case TokenType.PLUS:
return(i1 + i2);
case TokenType.MINUS:
return(i1 - i2);
case TokenType.MULTIPLY:
return(i1 * i2);
case TokenType.DIVIDE:
return(i1 / i2);
case TokenType.MODULO:
return(i1 % i2);
}
return(0);
}
float FloatOperation(StackValue operand1, StackValue operand2, TokenType op)
{
float f1 = operand1.Value is float?(float)operand1.Value : (int)operand1.Value;
float f2 = operand2.Value is float?(float)operand2.Value : (int)operand2.Value;
switch (op)
{
case TokenType.PLUS:
return(f1 + f2);
case TokenType.MINUS:
return(f1 - f2);
case TokenType.MULTIPLY:
return(f1 * f2);
case TokenType.DIVIDE:
return(f1 / f2);
case TokenType.EXPONENT:
return((float)Math.Pow(f1, f2));
}
return(0);
}
string StringOperation(StackValue operand1, StackValue operand2, TokenType op)
{
string s1 = operand1.Value.ToString();
string s2 = operand2.Value.ToString();
if (op == TokenType.PLUS)
{
return(s1 + s2);
}
return("");
}
bool BoolOperation(StackValue operand1, StackValue operand2, TokenType op)
{
bool b1 = (bool)operand1.Value;
bool b2 = op == TokenType.NOT ? true : (bool)operand2.Value;
switch (op)
{
case TokenType.AND:
return(b1 && b2);
case TokenType.OR:
return(b1 || b2);
case TokenType.XOR:
return(b1 ^ b2);
case TokenType.NOT:
return(!b1);
}
return(false);
}
bool IntComparison(StackValue operand1, StackValue operand2, TokenType op)
{
int i1 = (int)operand1.Value;
int i2 = (int)operand2.Value;
switch (op)
{
case TokenType.EQUAL:
return(i1 == i2);
case TokenType.NOTEQUAL:
return(i1 != i2);
case TokenType.LARGER:
return(i1 > i2);
case TokenType.LARGEREQUAL:
return(i1 >= i2);
case TokenType.LESSER:
return(i1 < i2);
case TokenType.LESSEREQUAL:
return(i1 <= i2);
}
return(false);
}
bool FloatComparison(StackValue operand1, StackValue operand2, TokenType op)
{
float f1 = (float)operand1.Value;
float f2 = (float)operand2.Value;
switch (op)
{
case TokenType.EQUAL:
return(f1 == f2);
case TokenType.NOTEQUAL:
return(f1 != f2);
case TokenType.LARGER:
return(f1 > f2);
case TokenType.LARGEREQUAL:
return(f1 >= f2);
case TokenType.LESSER:
return(f1 < f2);
case TokenType.LESSEREQUAL:
return(f1 <= f2);
}
return(false);
}
bool CharComparison(StackValue operand1, StackValue operand2, TokenType op)
{
char c1 = (char)operand1.Value;
char c2 = (char)operand2.Value;
switch (op)
{
case TokenType.EQUAL:
return(c1 == c2);
case TokenType.NOTEQUAL:
return(c1 != c2);
case TokenType.LARGER:
return(c1 > c2);
case TokenType.LARGEREQUAL:
return(c1 >= c2);
case TokenType.LESSER:
return(c1 < c2);
case TokenType.LESSEREQUAL:
return(c1 <= c2);
}
return(false);
}
bool StringComparison(StackValue operand1, StackValue operand2, TokenType op)
{
string s1 = (string)operand1.Value;
string s2 = (string)operand2.Value;
var comparison = s1.CompareTo(s2);
switch (op)
{
case TokenType.EQUAL:
return(s1.Equals(s2));
case TokenType.NOTEQUAL:
return(!s1.Equals(s2));
case TokenType.LARGER:
return(comparison > 0);
case TokenType.LARGEREQUAL:
return(comparison >= 0);
case TokenType.LESSER:
return(comparison < 0);
case TokenType.LESSEREQUAL:
return(comparison <= 0);
}
return(false);
}
bool BoolComparison(StackValue operand1, StackValue operand2, TokenType op)
{
bool b1 = (bool)operand1.Value;
bool b2 = (bool)operand2.Value;
switch (op)
{
case TokenType.EQUAL:
return(b1 == b2);
case TokenType.NOTEQUAL:
return(b1 != b2);
}
return(false);
}
bool Comparison(StackValue operand1, StackValue operand2, TokenType op)
{
bool result = true;
switch (operand1.Type)
{
case ValType.Integer:
int i1 = (int)operand1.Value;
if (operand2.Type == ValType.Float)
{
//do int comparison
int i2 = (int)(float)operand2.Value;
switch (op)
{
case TokenType.EQUAL:
result = i1 == i2;
break;
case TokenType.NOTEQUAL:
result = i1 != i2;
break;
case TokenType.LARGER:
result = i1 > i2;
break;
case TokenType.LARGEREQUAL:
result = i1 >= i2;
break;
case TokenType.LESSER:
result = i1 < i2;
break;
case TokenType.LESSEREQUAL:
result = i1 <= i2;
break;
}
}
else if (operand2.Type == ValType.Char)
{
//do int comparison
int i2 = (int)(char)operand2.Value;
switch (op)
{
case TokenType.EQUAL:
result = i1 == i2;
break;
case TokenType.NOTEQUAL:
result = i1 != i2;
break;
case TokenType.LARGER:
result = i1 > i2;
break;
case TokenType.LARGEREQUAL:
result = i1 >= i2;
break;
case TokenType.LESSER:
result = i1 < i2;
break;
case TokenType.LESSEREQUAL:
result = i1 <= i2;
break;
}
}
else
{
BinaryRuntimeError(operand1, operand2, op);
}
break;
case ValType.Float:
float f1 = (float)operand1.Value;
if (operand2.Type == ValType.Integer)
{
//do flt math
float f2 = (float)(int)operand2.Value;
switch (op)
{
case TokenType.EQUAL:
result = f1 == f2;
break;
case TokenType.NOTEQUAL:
result = f1 != f2;
break;
case TokenType.LARGER:
result = f1 > f2;
break;
case TokenType.LARGEREQUAL:
result = f1 >= f2;
break;
case TokenType.LESSER:
result = f1 < f2;
break;
case TokenType.LESSEREQUAL:
result = f1 <= f2;
break;
}
}
else
{
BinaryRuntimeError(operand1, operand2, op);
}
break;
case ValType.Char:
int c1 = (int)(char)operand1.Value;
if (operand2.Type == ValType.Integer)
{
//do int comparison
int c2 = (int)(char)operand2.Value;
switch (op)
{
case TokenType.EQUAL:
result = c1 == c2;
break;
case TokenType.NOTEQUAL:
result = c1 != c2;
break;
case TokenType.LARGER:
result = c1 > c2;
break;
case TokenType.LARGEREQUAL:
result = c1 >= c2;
break;
case TokenType.LESSER:
result = c1 < c2;
break;
case TokenType.LESSEREQUAL:
result = c1 <= c2;
break;
}
}
else
{
BinaryRuntimeError(operand1, operand2, op);
}
break;
case ValType.Bool:
//cause there is no boolean comparison operator with mixed type
BinaryRuntimeError(operand1, operand2, op);
break;
case ValType.String:
//cause there is no string comparison operator with mixed type
BinaryRuntimeError(operand1, operand2, op);
break;
case ValType.Null:
BinaryRuntimeError(operand1, operand2, op);
break;
}
return(result);
}
bool TypeTesting(StackValue operand1, StackValue operand2, TokenType op)
{
ValType type = operand2.CastTo <ValType>();
switch (op)
{
case TokenType.EQUAL:
case TokenType.NOTEQUAL:
if (operand1.Type != ValType.Type)
{
return(false);
}
else
{
var type2 = operand1.CastTo <ValType>();
return(op == TokenType.EQUAL ? type == type2 : !(type == type2));
}
case TokenType.IS:
// <value> is <Type>
return(operand1.Type == type);
}
return(false);
}
#endregion
#region evaluate expression
void EvaluateBinaryOperation(StackValue operand1, StackValue operand2, TokenType op)
{
var v1 = ResolveStackValue(operand1);
var v2 = ResolveStackValue(operand2);
if (v1.Type == v2.Type)
{
switch (v1.Type)
{
case ValType.Integer:
switch (op)
{
case TokenType.PLUS:
case TokenType.MINUS:
case TokenType.MULTIPLY:
case TokenType.DIVIDE:
case TokenType.MODULO:
Push(IntegerOperation(v1, v2, op));
break;
case TokenType.EXPONENT:
Push(FloatOperation(v1, v2, TokenType.EXPONENT));
break;
case TokenType.EQUAL:
case TokenType.NOTEQUAL:
case TokenType.LARGER:
case TokenType.LARGEREQUAL:
case TokenType.LESSER:
case TokenType.LESSEREQUAL:
Push(IntComparison(v1, v2, op));
break;
default:
BinaryRuntimeError(v1, v2, op);
break;
}
break;
case ValType.Float:
switch (op)
{
case TokenType.PLUS:
case TokenType.MINUS:
case TokenType.MULTIPLY:
case TokenType.DIVIDE:
case TokenType.EXPONENT:
Push(FloatOperation(v1, v2, op));
break;
case TokenType.EQUAL:
case TokenType.NOTEQUAL:
case TokenType.LARGER:
case TokenType.LARGEREQUAL:
case TokenType.LESSER:
case TokenType.LESSEREQUAL:
Push(FloatComparison(v1, v2, op));
break;
default:
BinaryRuntimeError(v1, v2, op);
break;
}
break;
case ValType.Bool:
switch (op)
{
case TokenType.AND:
case TokenType.OR:
case TokenType.XOR:
Push(BoolOperation(v1, v2, op));
break;
case TokenType.EQUAL:
case TokenType.NOTEQUAL:
Push(BoolComparison(v1, v2, op));
break;
default:
BinaryRuntimeError(v1, v2, op);
break;
}
break;
case ValType.Char:
//concat char
switch (op)
{
case TokenType.PLUS:
Push(StringOperation(v1, v2, TokenType.PLUS));
break;
case TokenType.EQUAL:
case TokenType.NOTEQUAL:
case TokenType.LARGER:
case TokenType.LARGEREQUAL:
case TokenType.LESSER:
case TokenType.LESSEREQUAL:
Push(CharComparison(v1, v2, op));
break;
default:
BinaryRuntimeError(v1, v2, op);
break;
}
break;
case ValType.String:
//concat string
switch (op)
{
case TokenType.PLUS:
Push(StringOperation(v1, v2, TokenType.PLUS));
break;
case TokenType.EQUAL:
case TokenType.NOTEQUAL:
case TokenType.LARGER:
case TokenType.LARGEREQUAL:
case TokenType.LESSER:
case TokenType.LESSEREQUAL:
Push(StringComparison(v1, v2, op));
break;
default:
BinaryRuntimeError(v1, v2, op);
break;
}
break;
case ValType.Null:
BinaryRuntimeError(v1, v2, op);
break;
case ValType.Type:
switch (op)
{
case TokenType.EQUAL:
case TokenType.NOTEQUAL:
Push(TypeTesting(v1, v2, op));
break;
default:
BinaryRuntimeError(v1, v2, op);
break;
}
break;
default:
switch (op)
{
case TokenType.IS:
Push(TypeTesting(v1, v2, op));
break;
default:
BinaryRuntimeError(v1, v2, op);
break;
}
break;
}
}
else
{
switch (v1.Type)
{
case ValType.Integer:
if (v2.Type == ValType.Float)
{
//do flt math
switch (op)
{
case TokenType.PLUS:
case TokenType.MINUS:
case TokenType.MULTIPLY:
case TokenType.DIVIDE:
case TokenType.EXPONENT:
Push(FloatOperation(v1, v2, op));
break;
case TokenType.EQUAL:
case TokenType.NOTEQUAL:
case TokenType.LARGER:
case TokenType.LARGEREQUAL:
case TokenType.LESSER:
case TokenType.LESSEREQUAL:
Push(Comparison(v1, v2, op));
break;
}
}
else if (v2.Type == ValType.Char)
{
//do int math
switch (op)
{
case TokenType.PLUS:
case TokenType.MINUS:
case TokenType.MULTIPLY:
case TokenType.DIVIDE:
Push(IntegerOperation(v1, v2, op));
break;
case TokenType.EXPONENT:
Push(FloatOperation(v1, v2, TokenType.EXPONENT));
break;
case TokenType.EQUAL:
case TokenType.NOTEQUAL:
case TokenType.LARGER:
case TokenType.LARGEREQUAL:
case TokenType.LESSER:
case TokenType.LESSEREQUAL:
Push(Comparison(v1, v2, op));
break;
}
}
else if (op == TokenType.IS)
{
Push(TypeTesting(v1, v2, op));
}
else
{
BinaryRuntimeError(v1, v2, op);
}
break;
case ValType.Float:
if (v2.Type == ValType.Integer)
{
//do flt math
switch (op)
{
case TokenType.PLUS:
case TokenType.MINUS:
case TokenType.MULTIPLY:
case TokenType.DIVIDE:
case TokenType.EXPONENT:
Push(FloatOperation(v1, v2, op));
break;
case TokenType.EQUAL:
case TokenType.NOTEQUAL:
case TokenType.LARGER:
case TokenType.LARGEREQUAL:
case TokenType.LESSER:
case TokenType.LESSEREQUAL:
Push(Comparison(v1, v2, op));
break;
}
}
else if (op == TokenType.IS)
{
Push(TypeTesting(v1, v2, op));
}
else
{
BinaryRuntimeError(v1, v2, op);
}
break;
case ValType.Char:
switch (op)
{
case TokenType.EQUAL:
case TokenType.NOTEQUAL:
case TokenType.LARGER:
case TokenType.LARGEREQUAL:
case TokenType.LESSER:
case TokenType.LESSEREQUAL:
Push(Comparison(v1, v2, op));
break;
case TokenType.IS:
Push(TypeTesting(v1, v2, op));
break;
default:
BinaryRuntimeError(v1, v2, op);
break;
}
break;
case ValType.Bool:
if (op == TokenType.IS)
{
Push(TypeTesting(v1, v2, op));
}
else
{
BinaryRuntimeError(v1, v2, op);
}
break;
case ValType.String:
//concat string
if (op == TokenType.PLUS)
{
Push(StringOperation(v1, v2, TokenType.PLUS));
}
else if (op == TokenType.IS)
{
Push(TypeTesting(v1, v2, op));
}
else if (op == TokenType.IS)
{
Push(TypeTesting(v1, v2, op));
}
else
{
BinaryRuntimeError(v1, v2, op);
}
break;
default:
switch (op)
{
case TokenType.IS:
Push(TypeTesting(v1, v2, op));
break;
default:
BinaryRuntimeError(v1, v2, op);
break;
}
break;
}
}
}
void EvaluateUnaryOperation(StackValue operand, TokenType op)
{
var v = ResolveStackValue(operand);
switch (op)
{
case TokenType.MINUS:
if (v.Type == ValType.Integer)
{
int i = v.CastTo <int>();
Push(-i);
}
else if (v.Type == ValType.Float)
{
float f = v.CastTo <float>();
Push(-f);
}
else
{
UnaryRuntimeError(operand, op);
}
break;
case TokenType.NOT:
if (v.Type == ValType.Bool)
{
bool b = v.CastTo <bool>();
Push(!b);
}
break;
case TokenType.TYPEOF:
Push(v.Type);
break;
}
}
#endregion
#region visit the astnode
Expression.Accept(this);
#endregion
#region process operand
if (EvaluationStack.Count == 0)
{
return(StackValue.Null);
}
ReverseStack();
while (EvaluationStack.Count > 1)
{
StackValue operand1 = EvaluationStack.Pop();
StackValue operand2 = EvaluationStack.Pop();
TokenType op;
if (operand2.Type == ValType.Operator)
{
//unary opearation
op = (TokenType)operand2.Value;
EvaluateUnaryOperation(operand1, op);
}
else
{
var tots = EvaluationStack.Pop();
op = (TokenType)tots.Value;
if (op == TokenType.ASSIGN)
{
//do assignment
//todo check type
var varname = (string)operand2.Value;
if (!CurrentScope.Contain(varname))
{
RuntimeError($"{varname} is not defined");
}
CurrentScope.Assign(varname, ResolveStackValue(operand1).Value);
Push(ResolveStackValue(operand2));
}
else if (op == TokenType.VAR)
{
//declare a variable in the environment
var varname = operand2.CastTo <string>();
if (CurrentScope.Contain(varname))
{
RuntimeError($"{varname} already defined");
}
CurrentScope.Define(varname, ResolveStackValue(operand1).Value);
Push(ResolveStackValue(operand2));
}
else
{
EvaluateBinaryOperation(operand1, operand2, op);
}
}
}
return(ResolveStackValue(EvaluationStack.Pop()));
#endregion
}