XTML Expression System

The XTML Expression System allows you to compute values dynamically within <xtml> blocks. It supports numeric, string, boolean, and array types, and provides operators for arithmetic, logical, comparison, and unary operations.

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Data Types

• Number: Represents numeric values (integers and decimals).
• String: Represents text values.
• Boolean: Represented as "1" (true) or "0" (false).
• Array: A list of var elements.

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Operators

Arithmetic

Operator	Description	Example
+	Addition or string concatenation	5 + 3 → 8 "Hello " + "World" → "Hello World"
-	Subtraction	10 - 4 → 6
*	Multiplication	2 * 3 → 6
/	Division	10 / 2 → 5
%	Modulo	10 % 3 → 1

Comparison

Operator	Description	Example
==	Equal to	5 == 5 → "1"
!=	Not equal to	5 != 3 → "1"
<	Less than	3 < 5 → "1"
<=	Less than or equal	5 <= 5 → "1"
>	Greater than	10 > 2 → "1"
>=	Greater than or equal	2 >= 3 → "0"

Logical

Operator	Description	Example
&&	Logical AND	"1" && "0" → "0"
`		`
!	Logical NOT	! "0" → "1"

Unary Operators

Operator	Description	Example
++	Increment (prefix/postfix)	++i or i++
--	Decrement (prefix/postfix)	--i or i--
-	Unary minus	-5 → -5
+	Unary plus	+5 → 5

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Expressions in XTML

Expressions are evaluated inside <xtml> blocks. You can store results in variables or return them from functions.

<xtml>
    var a = 5;
    var b = 10;
    var sum = a + b;
    var isEqual = (a + b) == 15;
</xtml>

Notes

• Logical and comparison operations always return a var of type DT_BOOL ("true" for true, "false" for false).
• Arithmetic on mixed types (e.g., string + number) will perform string concatenation if one operand is a string.
• Unary operations (++, --) can be prefix or postfix and affect the variable directly if applied to a variable reference.