class ExprTools

package haxe.macro

This class provides some utility methods to work with expressions. It is best used through 'using haxe.macro.ExprTools' syntax and then provides additional methods on haxe.macro.Expr instances.

While mainly intended to be used in macros, it works in non-macro code as well.

Static methods

staticgetValue(e:Expr):Dynamic

Returns the value e represents.

Supported expressions are:

  • Int, Float and String literals
  • identifiers true, false and null
  • structure declarations if all their fields are values
  • array declarations if all their elements are values
  • unary operators -, ! and ~ if the operand is a value
  • binary operators except =>, ... and assignments

Parentheses, metadata and the untyped keyword are ignored.

If any non-value is encountered, an exception of type String is thrown.

If e is null, the result is unspecified.

staticiter(e:Expr, f:Expr ‑> Void):Void

Calls function f on each sub-expression of e.

If e has no sub-expressions, this operation has no effect.

Otherwise f is called once per sub-expression of e, with the sub-expression as argument. These calls are done in order of the sub-expression declarations.

This method does not call itself recursively. It should instead be used in a recursive function which handles the expression nodes of interest.

Usage example:

function findStrings(e:Expr) {
	switch(e.expr) {
		case EConst(CString(s)):
			// handle s
		case _:
			ExprTools.iter(e, findStrings);
	}
}

staticmap(e:Expr, f:Expr ‑> Expr):Expr

Transforms the sub-expressions of e by calling f on each of them.

If e has no sub-expressions, this operation returns e unchanged.

Otherwise f is called once per sub-expression of e, with the sub-expression as argument. These calls are done in order of the sub-expression declarations.

This method does not call itself recursively. It should instead be used in a recursive function which handles the expression nodes of interest.

Usage example:

function capitalizeStrings(e:Expr) {
	return switch(e.expr) {
		case EConst(CString(s)):
			{ expr: EConst(CString(s.toUpperCase())), pos: e.pos };
		case _:
			ExprTools.map(e, capitalizeStrings);
	}
}

statictoString(e:Expr):String

Converts expression e to a human-readable String representation.

The result is guaranteed to be valid Haxe code, but there may be differences from the original lexical syntax.