output.txt

$ haxe --run XmlLiteral
XmlLiteral.hx:28: XmlUtil.createElement('x', ['y' => Std.string('uh, ${1+4}')], [XmlUtil.createElement('child1'), Xml.createPCData(Std.string('hi 2×4=${2*4}')), XmlUtil.createElement('child2', ['c2a1' => Std.string('2')])])
XmlLiteral.hx:29: ECall({ expr => EField({ expr => EConst(CIdent(XmlUtil)), pos => #pos(XmlLiteral.hx:15: characters 12-19) },createElement), pos => #pos(XmlLiteral.hx:15: characters 12-33) },[{ expr => EConst(CString(x)), pos => #pos(XmlLiteral.hx:16: characters 16-19) },{ expr => EArrayDecl([{ expr => EBinop(OpArrow,{ expr => EConst(CString(y)), pos => #pos(XmlLiteral.hx:17: characters 18-21) },{ expr => ECall({ expr => EField({ expr => EConst(CIdent(Std)), pos => #pos(XmlLiteral.hx:17: characters 25-28) },string), pos => #pos(XmlLiteral.hx:17: characters 25-35) },[{ expr => EConst(CString(uh, ${1+4})), pos => #pos(XmlLiteral.hx:17: characters 36-48) }]), pos => #pos(XmlLiteral.hx:17: characters 25-49) }), pos => #pos(XmlLiteral.hx:17: characters 18-49) }]), pos => #pos(XmlLiteral.hx:17: characters 16-52) },{ expr => EArrayDecl([{ expr => ECall({ expr => EField({ expr => EConst(CIdent(XmlUtil)), pos => #pos(XmlLiteral.hx:19: characters 20-27) },createElement), pos => #pos(XmlLiteral.hx:19: characters 20-41) },[{ expr => EConst(CString(child1)), pos => #pos(XmlLiteral.hx:19: characters 42-50) }]), pos => #pos(XmlLiteral.hx:19: characters 20-51) },{ expr => ECall({ expr => EField({ expr => EConst(CIdent(Xml)), pos => #pos(XmlLiteral.hx:20: characters 20-23) },createPCData), pos => #pos(XmlLiteral.hx:20: characters 20-36) },[{ expr => ECall({ expr => EField({ expr => EConst(CIdent(Std)), pos => #pos(XmlLiteral.hx:20: characters 37-40) },string), pos => #pos(XmlLiteral.hx:20: characters 37-47) },[{ expr => EConst(CString(hi 2×4=${2*4})), pos => #pos(XmlLiteral.hx:20: characters 48-63) }]), pos => #pos(XmlLiteral.hx:20: characters 37-64) }]), pos => #pos(XmlLiteral.hx:20: characters 20-65) },{ expr => ECall({ expr => EField({ expr => EConst(CIdent(XmlUtil)), pos => #pos(XmlLiteral.hx:21: characters 20-27) },createElement), pos => #pos(XmlLiteral.hx:21: characters 20-41) },[{ expr => EConst(CString(child2)), pos => #pos(XmlLiteral.hx:22: characters 24-32) },{ expr => EArrayDecl([{ expr => EBinop(OpArrow,{ expr => EConst(CString(c2a1)), pos => #pos(XmlLiteral.hx:23: characters 26-32) },{ expr => ECall({ expr => EField({ expr => EConst(CIdent(Std)), pos => #pos(XmlLiteral.hx:23: characters 36-39) },string), pos => #pos(XmlLiteral.hx:23: characters 36-46) },[{ expr => EConst(CString(2)), pos => #pos(XmlLiteral.hx:23: characters 47-50) }]), pos => #pos(XmlLiteral.hx:23: characters 36-51) }), pos => #pos(XmlLiteral.hx:23: characters 26-51) }]), pos => #pos(XmlLiteral.hx:23: characters 24-54) }]), pos => #pos(XmlLiteral.hx:21: lines 21-23) }]), pos => #pos(XmlLiteral.hx:18: lines 18-24) }])
<x y="uh, 5"><child1/>hi 2×4=8<child2 c2a1="2"/></x>

XmlLiteral.hx

import haxe.ds.StringMap;
import haxe.macro.Expr;
import haxe.macro.Printer;

class XmlLiteral {
    public static function main() {
        // See https://gist.github.com/binki/9d09ea0ae8ea43788505af08844dae79

        // It would be cool if the following:

        // showExpression(<x y='uh, ${1+4}'><child1/>hi. 2×4=${2*4}<child2 c2a1="non-interpolated $tring{}"/></x>);

        // Could become this:
        showExpression(
            XmlUtil.createElement(
                'x',
                [ 'y' => Std.string('uh, ${1+4}'), ],
                [
                    XmlUtil.createElement('child1'),
                    Xml.createPCData(Std.string('hi 2×4=${2*4}')),
                    XmlUtil.createElement(
                        'child2',
                        [ 'c2a1' => Std.string('2'), ]),
                ]));
    }

    macro static function showExpression(e:Expr) {
        trace(new Printer().printExpr(e));
        trace(e.expr);
        return macro {
            Sys.stdout().writeString(Std.string($e));
            Sys.stdout().writeString('\n');
        };
    }
}

class XmlUtil {
    public static function createElement(name, ?attributes:StringMap<String>, ?children:Array<Xml>) {
        var element = Xml.createElement(name);
        if (attributes != null) {
            for (attributeName in attributes.keys()) {
                element.set(attributeName, attributes.get(attributeName));
            }
        }
        if (children != null) {
            for (child in children) {
                element.addChild(child);
            }
        }
        return element;
    }
}