Use iterator, moveNext(), current.

sdk/lib/utf/utf8.dart

Index: sdk/lib/utf/utf8.dart
diff --git a/sdk/lib/utf/utf8.dart b/sdk/lib/utf/utf8.dart
index f9ef9fbe969f3a01beddc3534faf6dceedc1389b..6b9573f200c89488470fc64df419bf53d6fb6e25 100644
--- a/sdk/lib/utf/utf8.dart
+++ b/sdk/lib/utf/utf8.dart
@@ -136,8 +136,8 @@ class IterableUtf8Decoder extends Iterable<int> {
   IterableUtf8Decoder(this.bytes, [this.offset = 0, this.length = null,
       this.replacementCodepoint = UNICODE_REPLACEMENT_CHARACTER_CODEPOINT]);
 
-  Utf8Decoder iterator() => new Utf8Decoder(bytes, offset, length,
-          replacementCodepoint);
+  Utf8Decoder get iterator =>
+      new Utf8Decoder(bytes, offset, length, replacementCodepoint);
 }
 
 /**
@@ -151,18 +151,19 @@ class IterableUtf8Decoder extends Iterable<int> {
 class Utf8Decoder implements Iterator<int> {
   final _ListRangeIterator utf8EncodedBytesIterator;
   final int replacementCodepoint;
+  int _current = -1;
 
   Utf8Decoder(List<int> utf8EncodedBytes, [int offset = 0, int length,
       this.replacementCodepoint =
       UNICODE_REPLACEMENT_CHARACTER_CODEPOINT]) :
-      utf8EncodedBytesIterator = (new _ListRange(utf8EncodedBytes, offset,
-          length)).iterator();
+      utf8EncodedBytesIterator =
+          (new _ListRange(utf8EncodedBytes, offset, length)).iterator;
 
 
   Utf8Decoder._fromListRangeIterator(_ListRange source, [
       this.replacementCodepoint =
       UNICODE_REPLACEMENT_CHARACTER_CODEPOINT]) :
-      utf8EncodedBytesIterator = source.iterator();
+      utf8EncodedBytesIterator = source.iterator;
 
   /** Decode the remaininder of the characters in this decoder
     * into a [List<int>].
@@ -170,8 +171,8 @@ class Utf8Decoder implements Iterator<int> {
   List<int> decodeRest() {
     List<int> codepoints = new List<int>(utf8EncodedBytesIterator.remaining);
     int i = 0;
-    while (hasNext) {
-      codepoints[i++] = next();
+    while (moveNext()) {
+      codepoints[i++] = current;
     }
     if (i == codepoints.length) {
       return codepoints;
@@ -182,24 +183,37 @@ class Utf8Decoder implements Iterator<int> {
     }
   }
 
-  bool get hasNext => utf8EncodedBytesIterator.hasNext;
+  int get current {
+    if (_current == -1) {
+      // TODO(floitsch): bad error message.
+      throw new StateError("No more elements");
+    }
+    return _current;
+  }
+
+  bool moveNext() {
+    _current = -1;
+
+    if (!utf8EncodedBytesIterator.moveNext()) return false;
 
-  int next() {
-    int value = utf8EncodedBytesIterator.next();
+    int value = utf8EncodedBytesIterator.current;
     int additionalBytes = 0;
 
     if (value < 0) {
       if (replacementCodepoint != null) {
-        return replacementCodepoint;
+        _current = replacementCodepoint;
+        return true;
       } else {
         throw new ArgumentError(
             "Invalid UTF8 at ${utf8EncodedBytesIterator.position}");
       }
     } else if (value <= _UTF8_ONE_BYTE_MAX) {
-      return value;
+      _current = value;
+      return true;
     } else if (value < _UTF8_FIRST_BYTE_OF_TWO_BASE) {
       if (replacementCodepoint != null) {
-        return replacementCodepoint;
+        _current = replacementCodepoint;
+        return true;
       } else {
         throw new ArgumentError(
             "Invalid UTF8 at ${utf8EncodedBytesIterator.position}");
@@ -220,14 +234,15 @@ class Utf8Decoder implements Iterator<int> {
       value -= _UTF8_FIRST_BYTE_OF_SIX_BASE;
       additionalBytes = 5;
     } else if (replacementCodepoint != null) {
-      return replacementCodepoint;
+      _current = replacementCodepoint;
+      return true;
     } else {
       throw new ArgumentError(
           "Invalid UTF8 at ${utf8EncodedBytesIterator.position}");
     }
     int j = 0;
-    while (j < additionalBytes && utf8EncodedBytesIterator.hasNext) {
-      int nextValue = utf8EncodedBytesIterator.next();
+    while (j < additionalBytes && utf8EncodedBytesIterator.moveNext()) {
+      int nextValue = utf8EncodedBytesIterator.current;
       if (nextValue > _UTF8_ONE_BYTE_MAX &&
           nextValue < _UTF8_FIRST_BYTE_OF_TWO_BASE) {
         value = ((value << 6) | (nextValue & _UTF8_LO_SIX_BIT_MASK));
@@ -249,9 +264,11 @@ class Utf8Decoder implements Iterator<int> {
         (additionalBytes == 3 && value > _UTF8_THREE_BYTE_MAX);
     bool inRange = value <= UNICODE_VALID_RANGE_MAX;
     if (validSequence && nonOverlong && inRange) {
-      return value;
+      _current = value;
+      return true;
     } else if (replacementCodepoint != null) {
-      return replacementCodepoint;
+      _current = replacementCodepoint;
+      return true;
     } else {
       throw new ArgumentError(
           "Invalid UTF8 at ${utf8EncodedBytesIterator.position - j}");