Used to parse mathematical expressions in runtime. The default format used is CF_MathExpression. All values are treated as floating point numbers. Expressions are optimized for evaluating, not compiling. Recommended practise is to compile as few times as needed.
auto expr = CF_ExpressionVM.Compile("5 * 5");
float value = expr.Evaluate();
Print(value); // 25For performance reasons every parameter after the first one is evaluated at compile time and as such can't contain user defined variables. The first parameter is treated as if it was in brackets following the BODMAS principle.
auto expr = CF_ExpressionVM.Compile("4 * factor(4, 0, 5)", CF_MathExpression);
float value = expr.Evaluate();
Print(value); // 4PBO config binaries such as SoundShaders use a similar mathematical syntax found in SQF. They make use of square brackets for denoting parameters within a function. For performance reasons, these parameters are evaluated at compile time and as such can't contain user defined variables.
auto expr = CF_ExpressionVM.Compile("4 * (4 factor [0, 5])", CF_SQFExpression);
float value = expr.Evaluate();
Print(value); // 4Functions and operators are treated the same way. Not all functions require brackets and parameters. In CF_MathExpression the first 'parameter' is a continuation of the expression and can have variables. The other parameters are evaluated during compilation so can't have variables. In CF_SQFExpression the first 'parameter' is given from context and is decalred before the function call.
Custom functions can be registered for use if needed. They are globally added so any expression in any mod can use them.
class ExpressionFunctionPow : CF_ExpressionFunction
{
static string CF_NAME = "pow";
[CF_EventSubscriber(ExpressionFunctionPow.Init, CF_LifecycleEvents.OnGameCreate)]
static void Init()
{
int params = 1;
int precedence = 1;
int associative = true;
CF_ExpressionVM.AddFunction(CF_NAME, ExpressionFunctionPow, params, precedence, associative);
}
override void Call()
{
//! minimize variable moving and declarations
CF_ExpressionVM.Stack[CF_ExpressionVM.StackPointer] = Math.Pow(CF_ExpressionVM.Stack[CF_ExpressionVM.StackPointer], param1);
}
override string ToStr()
{
return CF_NAME;
}
};The above function would be used like the following in each respective expression type
| Expression Type | Input |
|---|---|
| CF_MathExpression | pow(someVar, 4) |
| CF_SQFExpression | (someVar pow [4]) |
All expressions can make use of user defined variables that can be re-evaluated during runtime. They are loaded from an array of strings during compile. When evaluating the array of floats for the variables must be the same length as the string array.
array<string> variableNames = { "speed" };
array<float> variableValues = { 50.0 };
auto expr = CF_ExpressionVM.Compile("50 * factor(speed, 0, 100)", variableNames, CF_MathExpression);
float value = expr.Evaluate(variableValues);
Print(value); // 25