private static bool MergeAddition(ExpressionBase left, ExpressionBase right, out ExpressionBase result)
{
// if either side is a string, combine to a larger string
if (left.Type == ExpressionType.StringConstant || right.Type == ExpressionType.StringConstant)
{
var builder = new StringBuilder();
left.AppendStringLiteral(builder);
right.AppendStringLiteral(builder);
result = new StringConstantExpression(builder.ToString());
return(true);
}
// if either side is a float, convert both to float
if (left.Type == ExpressionType.FloatConstant || right.Type == ExpressionType.FloatConstant)
{
if (!ConvertToFloat(ref left, ref right, out result))
{
return(false);
}
result = new FloatConstantExpression(((FloatConstantExpression)left).Value + ((FloatConstantExpression)right).Value);
return(true);
}
if (left.Type == ExpressionType.IntegerConstant && right.Type == ExpressionType.IntegerConstant)
{
result = new IntegerConstantExpression(((IntegerConstantExpression)left).Value + ((IntegerConstantExpression)right).Value);
return(true);
}
result = new ParseErrorExpression("Cannot add expressions");
return(false);
}
/// <summary>
/// Replaces the variables in the expression with values from <paramref name="scope" />.
/// </summary>
/// <param name="scope">The scope object containing variable values.</param>
/// <param name="result">[out] The new expression containing the replaced variables.</param>
/// <returns>
/// <c>true</c> if substitution was successful, <c>false</c> if something went wrong, in which case <paramref name="result" /> will likely be a <see cref="ParseErrorExpression" />.
/// </returns>
public override bool ReplaceVariables(InterpreterScope scope, out ExpressionBase result)
{
ExpressionBase left;
if (!Left.ReplaceVariables(scope, out left))
{
result = left;
return(false);
}
ExpressionBase right;
if (!Right.ReplaceVariables(scope, out right))
{
result = right;
return(false);
}
var integerLeft = left as IntegerConstantExpression;
var integerRight = right as IntegerConstantExpression;
switch (Operation)
{
case MathematicOperation.Add:
var stringLeft = left as StringConstantExpression;
var stringRight = right as StringConstantExpression;
if (stringLeft != null)
{
if (stringRight != null)
{
result = new StringConstantExpression(stringLeft.Value + stringRight.Value);
return(true);
}
if (integerRight != null)
{
result = new StringConstantExpression(stringLeft.Value + integerRight.Value.ToString());
return(true);
}
}
else if (stringRight != null)
{
if (integerLeft != null)
{
result = new StringConstantExpression(integerLeft.Value.ToString() + stringRight.Value);
return(true);
}
}
// prefer constants on right
if (integerLeft != null && integerRight == null)
{
var temp = left;
left = right;
right = temp;
integerRight = integerLeft;
integerLeft = null;
}
if (integerRight != null)
{
if (integerRight.Value == 0) // anything plus 0 is itself
{
result = left;
return(true);
}
if (integerLeft != null)
{
result = new IntegerConstantExpression(integerLeft.Value + integerRight.Value);
return(true);
}
}
break;
case MathematicOperation.Subtract:
if (integerRight != null)
{
if (integerRight.Value == 0) // anything minus 0 is itself
{
result = left;
return(true);
}
if (integerLeft != null)
{
result = new IntegerConstantExpression(integerLeft.Value - integerRight.Value);
return(true);
}
}
break;
case MathematicOperation.Multiply:
// prefer constants on right
if (integerLeft != null && integerRight == null)
{
var temp = left;
left = right;
right = temp;
integerRight = integerLeft;
integerLeft = null;
}
if (integerRight != null)
{
if (integerRight.Value == 0) // anything times 0 is 0
{
result = right;
return(true);
}
if (integerRight.Value == 1) // anything times 1 is itself
{
result = left;
return(true);
}
if (integerLeft != null)
{
result = new IntegerConstantExpression(integerLeft.Value * integerRight.Value);
return(true);
}
}
break;
case MathematicOperation.Divide:
if (integerRight != null)
{
if (integerRight.Value == 0) // division by 0 is impossible
{
result = new ParseErrorExpression("division by zero", this);
return(false);
}
if (integerRight.Value == 1) // anything divided by 1 is itself
{
result = left;
return(true);
}
if (integerLeft != null)
{
result = new IntegerConstantExpression(integerLeft.Value / integerRight.Value);
return(true);
}
}
break;
case MathematicOperation.Modulus:
if (integerRight != null)
{
if (integerRight.Value == 0) // division by 0 is impossible
{
result = new ParseErrorExpression("division by zero", this);
return(false);
}
if (integerRight.Value == 1) // anything modulus 1 is 0
{
result = new IntegerConstantExpression(0);
return(true);
}
if (integerLeft != null)
{
result = new IntegerConstantExpression(integerLeft.Value % integerRight.Value);
return(true);
}
}
break;
}
var mathematic = new MathematicExpression(left, Operation, right);
mathematic.Line = Line;
mathematic.Column = Column;
result = mathematic;
return(true);
}
public override bool ReplaceVariables(InterpreterScope scope, out ExpressionBase result)
{
result = new StringConstantExpression(Value);
CopyLocation(result);
return(true);
}