add class UtfIter

test/Main.hx

@@ -10,6 +10,7 @@ class Main {
 		r.add(new TestUtf32());
 		r.add(new TestInternalEncoding());
 		r.add(new TestInternalEncodingIter());
+		r.add(new TestUtfIter());
 		r.add(new TestCodePoint());
 		r.run();
 	}

test/TestUtfIter.hx

@@ -0,0 +1,34 @@
+package test;
+
+import unifill.UtfIter;
+import unifill.Utf;
+import unifill.Utf8;
+import unifill.Utf16;
+import unifill.Utf32;
+
+class TestUtfIter extends haxe.unit.TestCase {
+
+	function utfIter<S : Utf>(s : S, index : Array<Int>) {
+		var itr = new UtfIter<S>(s, 0, s.length);
+		var i = 0;
+		while (i < index.length - 1) {
+			assertTrue(itr.hasNext());
+			assertEquals(index[i++], itr.next());
+		}
+		assertFalse(itr.hasNext());
+		assertEquals(index[i], itr.index);
+	}
+
+	public function test_UtfIter_Utf8() {
+		utfIter(Utf8.fromString("𩸽あëa"), [0, 4, 7, 9, 10]);
+	}
+
+	public function test_UtfIter_Utf16() {
+		utfIter(Utf16.fromString("𩸽あëa"), [0, 2, 3, 4, 5]);
+	}
+
+	public function test_UtfIter_Utf32() {
+		utfIter(Utf32.fromString("𩸽あëa"), [0, 1, 2, 3, 4]);
+	}
+
+}

unifill/UtfIter.hx

@@ -0,0 +1,25 @@
+package unifill;
+
+class UtfIter<S : Utf> {
+
+	public var string : S;
+	public var index : Int;
+	public var endIndex : Int;
+
+	public inline function new(s : S, beginIndex : Int, endIndex : Int) {
+		string = s;
+		this.index = beginIndex;
+		this.endIndex = endIndex;
+	}
+
+	public inline function hasNext() : Bool {
+		return index < endIndex;
+	}
+
+	public inline function next() : Int {
+		var i = index;
+		index += string.codePointWidthAt(index);
+		return i;
+	}
+
+}