Add Stdio.readByteSync and Stdio.readLineSync.

sdk/lib/io/stdio.dart

Index: sdk/lib/io/stdio.dart
diff --git a/sdk/lib/io/stdio.dart b/sdk/lib/io/stdio.dart
index afa7ea013bb0fe8a9a123bb1393c75f39034a545..e42b7cbf3b2686ad97f27f7f370a26d92726c6aa 100644
--- a/sdk/lib/io/stdio.dart
+++ b/sdk/lib/io/stdio.dart
@@ -10,6 +10,7 @@ const int _STDIO_HANDLE_TYPE_FILE = 2;
 const int _STDIO_HANDLE_TYPE_SOCKET = 3;
 const int _STDIO_HANDLE_TYPE_OTHER = 4;
 
+
 class _StdStream extends Stream<List<int>> {
   final Stream<List<int>> _stream;
 
@@ -27,6 +28,77 @@ class _StdStream extends Stream<List<int>> {
   }
 }
 
+
+class _StdinEventSink {
+  Function add;
+  Function addError;
+  Function close;
+  _StdinEventSink(this.add, this.addError, this.close);
+}
+
+/**
+ * [Stdin] class that enable both synchronous and asynchronous reads from the
+ * stdin pipe.
+ *
+ * Mixing synchronous and asynchronous reads is undefined.
+ */
+class Stdin extends _StdStream {
+  Stdin._(Stream<List<int>> stream) : super(stream);
+
+  /**
+   * Read a line from stdin. This call will block until a full line is
+   * available. The line will contain the newline character(s).
+   *
+   * If at end of file, `null` is returned.
+   *
+   * If at end of file, while some data is already read, that data is returned.
+   */
+  String readLineSync({Encoding encoding: Encoding.SYSTEM,
+                       bool retainNewlines: false}) {
+    var decoder = new StringDecoder(encoding)._decoder;
+    var line = new StringBuffer();
+    bool end = false;
+    var sink = new _StdinEventSink(
+        (chunk) {

[Bill Hesse, 2013/07/02 11:31:54]

Why is chunk not char, or rune?  It seems misleading, like it could be more than
a single char.

[Anders Johnsen, 2013/07/02 12:21:27]

Done.

+          if (chunk == '\n') end = true;
+          line.write(chunk);
+        },
+        (error) {
+          throw error;
+        }, () {});
+
+    while (!end) {
+      int b = readByteSync();
+      if (b >= 0) {
+        decoder.handleData([b], sink);
+      } else {
+        decoder.handleDone(sink);
+        break;
+      }
+    }
+
+    if (line.isEmpty) return null;
+    line = line.toString();
+    int trim = 0;
+    if (!retainNewlines) {

[Bill Hesse, 2013/07/02 11:31:54]

I would have put this into the sink object, with more logic and a
"lastCharWasCR" bool.  I think it is not too complex to put it there, and reads
better.

[Anders Johnsen, 2013/07/02 12:21:27]

Done.

+      if (line.endsWith('\r\n')) {
+        trim = 2;
+      } else if (line.endsWith('\n')) {
+        trim = 1;
+      }
+    }
+    return line.substring(0, line.length - trim);
+  }
+
+  /**
+   * Read a byte from stdin. This call will block until a byte is available.
+   *
+   * If at end of file, -1 is returned.
+   */
+  int readByteSync();
+}
+
+
 class _StdSink implements IOSink {
   final IOSink _sink;