Use iterator, moveNext(), current.

sdk/lib/utf/utf32.dart

Index: sdk/lib/utf/utf32.dart
diff --git a/sdk/lib/utf/utf32.dart b/sdk/lib/utf/utf32.dart
index 5180f2d17234efacfa2949669d5a80fdcd5e4c83..fc0ea013f3103028656084e33c6a289576357d89 100644
--- a/sdk/lib/utf/utf32.dart
+++ b/sdk/lib/utf/utf32.dart
@@ -185,7 +185,7 @@ class IterableUtf32Decoder extends Iterable<int> {
 
   IterableUtf32Decoder._(this.codeunitsProvider);
 
-  Utf32BytesDecoder iterator() => codeunitsProvider();
+  Utf32BytesDecoder get iterator => codeunitsProvider();
 }
 
 /**
@@ -194,6 +194,7 @@ class IterableUtf32Decoder extends Iterable<int> {
 class Utf32BytesDecoder implements _ListRangeIterator {
   final _ListRangeIterator utf32EncodedBytesIterator;
   final int replacementCodepoint;
+  int _current = -1;
 
   Utf32BytesDecoder._fromListRangeIterator(
       this.utf32EncodedBytesIterator, this.replacementCodepoint);
@@ -219,19 +220,27 @@ class Utf32BytesDecoder implements _ListRangeIterator {
   List<int> decodeRest() {
     List<int> codeunits = new List<int>(remaining);
     int i = 0;
-    while (hasNext) {
-      codeunits[i++] = next();
+    while (moveNext()) {
+      codeunits[i++] = current;
     }
     return codeunits;
   }
 
-  bool get hasNext => utf32EncodedBytesIterator.hasNext;
+  int get current {
+    if (_current == -1) {
+      // TODO(floitsch): bad error message.
+      throw new StateError("No more elements");
+    }
+    return _current;
+  }
 
-  int next() {
+  bool moveNext() {
+    _current = -1;
     if (utf32EncodedBytesIterator.remaining < 4) {
       utf32EncodedBytesIterator.skip(utf32EncodedBytesIterator.remaining);
       if (replacementCodepoint != null) {
-          return replacementCodepoint;
+          _current = replacementCodepoint;
+          return true;
       } else {
         throw new ArgumentError(
             "Invalid UTF32 at ${utf32EncodedBytesIterator.position}");
@@ -239,9 +248,11 @@ class Utf32BytesDecoder implements _ListRangeIterator {
     } else {
       int codepoint = decode();
       if (_validCodepoint(codepoint)) {
-        return codepoint;
+        _current = codepoint;
+        return true;
       } else if (replacementCodepoint != null) {
-          return replacementCodepoint;
+        _current = replacementCodepoint;
+        return true;
       } else {
         throw new ArgumentError(
             "Invalid UTF32 at ${utf32EncodedBytesIterator.position}");
@@ -272,18 +283,23 @@ class Utf32beBytesDecoder extends Utf32BytesDecoder {
   Utf32beBytesDecoder(List<int> utf32EncodedBytes, [int offset = 0,
       int length, bool stripBom = true,
       int replacementCodepoint = UNICODE_REPLACEMENT_CHARACTER_CODEPOINT]) :
-      super._fromListRangeIterator((new _ListRange(utf32EncodedBytes, offset,
-      length)).iterator(), replacementCodepoint) {
+      super._fromListRangeIterator(
+          (new _ListRange(utf32EncodedBytes, offset, length)).iterator,
+          replacementCodepoint) {
     if (stripBom && hasUtf32beBom(utf32EncodedBytes, offset, length)) {
       skip();
     }
   }
 
   int decode() {
-    int value = utf32EncodedBytesIterator.next();
-    value = (value << 8) + utf32EncodedBytesIterator.next();
-    value = (value << 8) + utf32EncodedBytesIterator.next();
-    value = (value << 8) + utf32EncodedBytesIterator.next();
+    utf32EncodedBytesIterator.moveNext();
+    int value = utf32EncodedBytesIterator.current;
+    utf32EncodedBytesIterator.moveNext();
+    value = (value << 8) + utf32EncodedBytesIterator.current;
+    utf32EncodedBytesIterator.moveNext();
+    value = (value << 8) + utf32EncodedBytesIterator.current;
+    utf32EncodedBytesIterator.moveNext();
+    value = (value << 8) + utf32EncodedBytesIterator.current;
     return value;
   }
 }
@@ -296,18 +312,23 @@ class Utf32leBytesDecoder extends Utf32BytesDecoder {
   Utf32leBytesDecoder(List<int> utf32EncodedBytes, [int offset = 0,
       int length, bool stripBom = true,
       int replacementCodepoint = UNICODE_REPLACEMENT_CHARACTER_CODEPOINT]) :
-      super._fromListRangeIterator((new _ListRange(utf32EncodedBytes, offset,
-      length)).iterator(), replacementCodepoint) {
+      super._fromListRangeIterator(
+          (new _ListRange(utf32EncodedBytes, offset, length)).iterator,
+          replacementCodepoint) {
     if (stripBom && hasUtf32leBom(utf32EncodedBytes, offset, length)) {
       skip();
     }
   }
 
   int decode() {
-    int value = (utf32EncodedBytesIterator.next());
-    value += (utf32EncodedBytesIterator.next() << 8);
-    value += (utf32EncodedBytesIterator.next() << 16);
-    value += (utf32EncodedBytesIterator.next() << 24);
+    utf32EncodedBytesIterator.moveNext();
+    int value = utf32EncodedBytesIterator.current;
+    utf32EncodedBytesIterator.moveNext();
+    value += (utf32EncodedBytesIterator.current << 8);
+    utf32EncodedBytesIterator.moveNext();
+    value += (utf32EncodedBytesIterator.current << 16);
+    utf32EncodedBytesIterator.moveNext();
+    value += (utf32EncodedBytesIterator.current << 24);
     return value;
   }
 }