Overload List
| # | Signature | Description |
|---|---|---|
| 1 | TValueRec Evaluate | Evaluates all expressions from the list. |
| 2 | TValueRec Evaluate(Int32 Index) | Evaluates expression at the specified index. |
Overload 1: TValueRec Evaluate
Evaluates all expressions from the list.
Returns: TValueRec - result of the latest expression.
Overload 2: TValueRec Evaluate(Int32 Index)
Evaluates expression at the specified index.
| # | Name | Type | Description |
|---|---|---|---|
| 1 | Index | Int32 | start index |
Returns: TValueRec - result of the expression, evaluated at specific index.
If the Index parameter is specified to be -1, the method will evaluate all expressions in the list starting with the first and return the result of the last expression in the list.
The function returns TValueRec. This object contains information about the type of the result and the result itself. To determine the type read the TValueRec.ValueType property.
The types in the expression are resolved at compile time and may not change after the first call to the Evalute function. The result of a given expression will therefore always have the same type.
This allows for omission of certain checks and further increase of code speed. Instead of calling EvaluateDouble method, it would be faster to call just:
myDouble := myParser.Evaluate.DoubleValue;
,if you know that the result of the expression is a variable of type double.
function TMtxExpression.EvaluateDouble(Index :integer): Double;
TValueRec vr;
vr = Evaluate(Index);
case vr.ValueType of
vtDoubleValue:
result = vr.DoubleValue;
Exit;
vtComplexValue:
if vr.ComplexValue.Im = 0 then begin
result = vr.ComplexValue.Re;
Exit;
raise EMtxParseError.Create (@"TMtxExpression.EvaluateDouble: double value expected");