MainTest.hx

package;
import haxe.macro.*;
using haxe.macro.ExprTools;

class MainTest {
    static function main() {
        var data1 = {hello:'world'};
        var data2 = {foo:'bar', hello: null};
        var data3:Dynamic = null;
        var m = getVal(data1.hello);
        var n = getVal(data2.hello);
        var l = getVal(data3.hello.foo.bar, "baz");

        trace(m);
        trace(n);
        trace(l);
        //array access
        trace(get(data3.foo[0].length, 10))
    }

    macro static function get(v:Expr, fallback:Expr = null) {
        var arr = ~/(\.|\[)/g.split(v.toString());
		var added = "";
		var list = [
			for (prop in arr) {
                if (added != "" && prop.indexOf(']') == -1) added += '.';
                //array access check
                if (prop.indexOf(']') != -1) {
                    added += '[';
                }
                added += prop;
                added;
			}
        ];

		var ret = '';
		for (prop in list) {
			if (ret != '') ret += ' && ';
			ret += '$prop != null';
		}
		ret += ' ? ${v.toString()} : ${fallback.toString()}';
		return Context.parse(ret, Context.currentPos());
	}
}