Operators and Keywords

Standard Operators

ExpressionEvaluator manage a large set of C# operators (See C# Operators)

ExpressionEvaluator respect the C# precedence rules of operators

Here is a list of which operators are supported in ExpressionEvaluator or not

Type	Operator	Support
Primary	x.y	Supported
Primary	x?.y	Supported
Primary	x?[y]	Supported
Primary	f(x)	Supported
Primary	a[x]	Supported
Primary	x++	Supported Warning change the state of the postfixed element
Primary	x--	Supported Warning change the state of the postfixed element
Primary	new	Supported you can also use new() function
Primary	typeof	Supported
Primary	checked	Not Supported
Primary	unchecked	Not Supported
Primary	default(T)	Supported
Primary	delegate	Not Supported
Primary	sizeof	Not Supported
Primary	->	Not Supported
Unary	+x	Supported
Unary	-x	Supported
Unary	!x	Supported
Unary	~x	Not Supported
Unary	++x	Not Supported
Unary	--x	Not Supported
Unary	(T)x	Supported
Unary	await	Not Supported
Unary	&x	Not Supported
Unary	*x	Not Supported
Multiplicative	x * y	Supported
Multiplicative	x / y	Supported
Multiplicative	x % y	Supported
Additive	x + y	Supported
Additive	x - y	Supported
Shift	x << y	Supported
Shift	x >> y	Supported
Relational	x < y	Supported
Relational	x > y	Supported
Relational	x <= y	Supported
Relational	x >= y	Supported
Type-testing	is	Supported
Type-testing	as	Not Supported
Equality	x == y	Supported
Equality	x != y	Supported
Logical AND	x & y	Supported
Logical XOR	x ^ y	Supported
Logical OR	x | y	Supported
Conditional AND	x && y	Supported
Conditional OR	x || y	Supported
Null-coalescing	x ?? y	Supported
Conditional	t ? x : y	Supported
Lambda	=>	Supported

Assignation operators

Warning all of the following operators change the value of their left element.

Assignation operators (and also postfix operators (++ and --)) are usable on :

Elements	What is changing	Options
Custom variables	The variable in the Variables dictionary is changed and if the variable doesn't exists, it automatically created with the = operator	Can be disabled with evaluator.OptionVariableAssignationActive = false;
Properties or fields on objects	If the property/field is not readonly it is changed	Can be disabled with evaluator.OptionPropertyOrFieldSetActive = false;
Indexed object like arrays, list or dictionaries	The value at the specified index is changed	Can be disabled with evaluator.OptionIndexingAssignationActive = false;

Here is the list of available assignation operator

Operator	Support
=	Supported (Can be use to declare a new variable that will be injected in the Variables dictionary)
+=	Supported
-=	Supported
*=	Supported
/=	Supported
%=	Supported
&=	Supported
|=	Supported
^=	Supported
<<=	Supported
>>=	Supported

To declare a variable, types are not yet supported and are for now dynamically deduced.

// Not supported
int x = 2;
string text = "hello";

for(int i = 0; i < 10; i++)
...

// Write this instead :
x = 2;
text = "hello";

for(i = 0; i < 10; i++)
...

Scripts

Scripts keywords

In addition to simple expression evaluation you can also evaluate small scripts with the method :

//object ScriptEvaluate(string script)
evaluator.ScriptEvaluate(script);

Scripts are just a serie of expressions to evaluate separated with a ; character and leaded by severals additionals keywords.

Currently the following scripts keywords are supported

Type	Operator	Support
Selection	if	Supported
Selection	else if	Supported
Selection	else	Supported
Selection	switch case	Not yet supported
Iteration	do ... while	Supported
Iteration	for	Supported
Iteration	foreach, in	Supported
Iteration	while	Supported
Jump	break	Supported in do, for and while blocks
Jump	continue	Supported in do, for and while blocks
Jump	goto	Not supported (But if you looked after it -> Booo !!! Bad code)
Jump	return	Supported
Jump/Exception	throw	Supported
Exception Handling	try-catch	Supported
Exception Handling	try-finally	Supported
Exception Handling	try-catch-finally	Supported

Remark : The way ScriptEvaluate works is to evaluate expressions one by one. There is no syntax check before the evaluation. So be aware that syntax or naming bugs only appears in execution and some code can already be evaluated at this time. Futhermore a syntaxic/naming bug in an if-else block for example can simply be ignored until the corresponding condition is met to evaluate the specific line of code.