Big merge from experimental to bleeding edge.

sdk/lib/async/string_transform.dart

+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// part of dart.async;
+
+abstract class _StringDecoder extends _StreamTransformer<List<int>, String> {
+
+  handleData(List<int> bytes, StreamSink<String> sink) {
+    var data = _carry;
+    data.addAll(bytes);
+    _carry = [];
+    var buffer = new StringBuffer();
+    int pos = 0;
+    while (pos < data.length) {
+      int currentPos = pos;
+      int getNext() {
+        if (pos < data.length) {
+          return data[pos++];
+        }
+        return -1;
+      }
+      _chars = [];
+      if (_processByte(data[pos++], getNext)) {
+        _chars.forEach(buffer.addCharCode);
+      } else {
+        _carry = data.getRange(currentPos, data.length - currentPos);
+        break;
+      }
+    }
+    sink.add(buffer.toString());
+  }
+
+  void handleDone(StreamSink<String> sink) {
+    if (!_carry.isEmpty) {
+      sink.signalError(new AsyncError(
+            new StateError("Unhandled tailing utf8 chars")));
+    }
+    sink.close();
+  }
+
+  bool _processByte(int byte, int getNext());
+
+  void addChar(int char) {
+    _chars.add(char);
+  }
+
+  List<int> _carry = [];
+  List<int> _chars;
+}
+
+/**
+ * StringTransformer class that decodes a utf8 encoded bytes.
+ */
+class Utf8DecoderTransformer extends _StringDecoder {
+  bool _processByte(int byte, int getNext()) {
+    int value = byte & 0xFF;
+    if ((value & 0x80) == 0x80) {
+      int additionalBytes;
+      if ((value & 0xe0) == 0xc0) {  // 110xxxxx
+        value = value & 0x1F;
+        additionalBytes = 1;
+      } else if ((value & 0xf0) == 0xe0) {  // 1110xxxx
+        value = value & 0x0F;
+        additionalBytes = 2;
+      } else {  // 11110xxx
+        value = value & 0x07;
+        additionalBytes = 3;
+      }
+      for (int i = 0; i < additionalBytes; i++) {
+        int next = getNext();
+        if (next < 0) return false;
+        value = value << 6 | (next & 0x3F);
+      }
+    }
+    addChar(value);
+    return true;
+  }
+}
+
+
+abstract class _StringEncoder extends _StreamTransformer<String, List<int>> {
+  handleData(String string, StreamSink<List<int>> sink) {
+    sink.add(_processString(string));
+  }
+
+  List<int> _processString(String string);
+}
+
+/**
+ * StringTransformer class that utf8 encodes a string.
+ */
+class Utf8EncoderTransformer extends _StringEncoder {
+  List<int> _processString(String string) {
+    var bytes = [];
+    int pos = 0;
+    int length = string.length;
+    for (int i = 0; i < length; i++) {
+      int additionalBytes;
+      int charCode = string.charCodeAt(i);
+      if (charCode <= 0x007F) {
+        additionalBytes = 0;
+        bytes.add(charCode);
+      } else if (charCode <= 0x07FF) {
+        // 110xxxxx (xxxxx is top 5 bits).
+        bytes.add(((charCode >> 6) & 0x1F) | 0xC0);
+        additionalBytes = 1;
+      } else if (charCode <= 0xFFFF) {
+        // 1110xxxx (xxxx is top 4 bits)
+        bytes.add(((charCode >> 12) & 0x0F)| 0xE0);
+        additionalBytes = 2;
+      } else {
+        // 11110xxx (xxx is top 3 bits)
+        bytes.add(((charCode >> 18) & 0x07) | 0xF0);
+        additionalBytes = 3;
+      }
+      for (int i = additionalBytes; i > 0; i--) {
+        // 10xxxxxx (xxxxxx is next 6 bits from the top).
+        bytes.add(((charCode >> (6 * (i - 1))) & 0x3F) | 0x80);
+      }
+      pos += additionalBytes + 1;
+    }
+    return bytes;
+  }
+}
+
+