[dart:io] Move Platform.ansiSupported to {Stdin,Stdout}.supportsAnsiEscapes

sdk/lib/io/stdio.dart

 // Copyright (c) 2013, 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.io;
 
 const int _STDIO_HANDLE_TYPE_TERMINAL = 0;
 const int _STDIO_HANDLE_TYPE_PIPE = 1;
 const int _STDIO_HANDLE_TYPE_FILE = 2;
 const int _STDIO_HANDLE_TYPE_SOCKET = 3;
@@ skipping 119 matching lines @@
    * If enabled, characters are delayed until a new-line character is entered.
    * If disabled, characters will be available as typed.
    *
    * Default depends on the parent process, but usually enabled.
    *
    * On Windows this mode can only be disabled if [echoMode] is disabled as well.
    */
   external void set lineMode(bool enabled);
 
   /**
+    * Whether connected to a terminal that supports ANSI escape sequences.
+    *
+    * Not all terminals are recognized, and not all recognized terminals can
+    * report whether they support ANSI escape sequences, so this value is a
+    * best-effort attempt at detecting the support.
+    *
+    * The actual escape sequence support may differ between terminals,
+    * with some terminals supporting more escape sequences than others,
+    * and some terminals even differing in behavior for the same escape
+    * sequence.
+    *
+    * The ANSI color selection is generally supported.
+    *
+    * Currently, a `TERM` environment variable containing the string `xterm`
+    * will be taken as evidence that ANSI escape sequences are supported.
+    * On Windows, only versions of Windows 10 after v.1511
+    * ("TH2", OS build 10586) will be detected as supporting the output of
+    * ANSI escape sequences, and only versions after v.1607 ("Anniversery
+    * Update", OS build 14393) will be detected as supporting the input of
+    * ANSI escape sequences.
+    */
+  external bool get supportsAnsiEscapes;
+
+  /**
    * Synchronously read a byte from stdin. This call will block until a byte is
    * available.
    *
    * If at end of file, -1 is returned.
    */
   external int readByteSync();
 }
 
 /**
  * [Stdout] represents the [IOSink] for either `stdout` or `stderr`.
@@ skipping 21 matching lines @@
   bool get hasTerminal => _hasTerminal(_fd);
 
   /**
    * Get the number of columns of the terminal.
    *
    * If no terminal is attached to stdout, a [StdoutException] is thrown. See
    * [hasTerminal] for more info.
    */
   int get terminalColumns => _terminalColumns(_fd);
 
-  /**
+  /*
    * Get the number of lines of the terminal.
    *
    * If no terminal is attached to stdout, a [StdoutException] is thrown. See
    * [hasTerminal] for more info.
    */
   int get terminalLines => _terminalLines(_fd);
 
+  /**
+    * Whether connected to a terminal that supports ANSI escape sequences.
+    *
+    * Not all terminals are recognized, and not all recognized terminals can
+    * report whether they support ANSI escape sequences, so this value is a
+    * best-effort attempt at detecting the support.
+    *
+    * The actual escape sequence support may differ between terminals,
+    * with some terminals supporting more escape sequences than others,
+    * and some terminals even differing in behavior for the same escape
+    * sequence.
+    *
+    * The ANSI color selection is generally supported.
+    *
+    * Currently, a `TERM` environment variable containing the string `xterm`
+    * will be taken as evidence that ANSI escape sequences are supported.
+    * On Windows, only versions of Windows 10 after v.1511
+    * ("TH2", OS build 10586) will be detected as supporting the output of
+    * ANSI escape sequences, and only versions after v.1607 ("Anniversery
+    * Update", OS build 14393) will be detected as supporting the input of
+    * ANSI escape sequences.
+    */
+  bool get supportsAnsiEscapes => _supportsAnsiEscapes(_fd);
+
   external bool _hasTerminal(int fd);
   external int _terminalColumns(int fd);
   external int _terminalLines(int fd);
+  external static bool _supportsAnsiEscapes(int fd);
 
   /**
    * Get a non-blocking `IOSink`.
    */
   IOSink get nonBlocking {
     if (_nonBlocking == null) {
       _nonBlocking = new IOSink(new _FileStreamConsumer.fromStdio(_fd));
     }
     return _nonBlocking;
   }
@@ skipping 198 matching lines @@
 }
 
 class _StdIOUtils {
   external static _getStdioOutputStream(int fd);
   external static Stdin _getStdioInputStream();
 
   /// Returns the socket type or `null` if [socket] is not a builtin socket.
   external static int _socketType(Socket socket);
   external static _getStdioHandleType(int fd);
 }