Add fields to platform library, implement them on runtime dart.

sdk/lib/platform/platform.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.
 
 /**
  * Runtime information about the current platform.
  */
 library dart.platform;
+
+class _Platform {

[ahe, 2013/10/24 15:38:16]

This API does not make sense for dart2js.

[Bill Hesse, 2013/10/25 11:06:34]

I think we would add fields that report important info about the dart2js
platform, that should be exposed.

Fields that are not applicable to dart2js will return null, as documented.

If we wanted to divide the specific info for each platform up more, we could
report a "Dart2jsPlatform" property, that would have specific details as fields,
rather than putting them at the top level.

There is top-level consensus that platform should not be in dart:io, because
some things are more general, and should be available on all platforms where
they make sense.

+  int get numberOfProcessors;
+  String get pathSeparator;
+  String get operatingSystem;
+  String get localHostname;
+  String get version;
+  Map get environment;
+  String get script;
+  String get executable;
+  List<String>  get executableArguments;
+  String get packageRoot;
+}
+
+// The _Platform object from the patch file, or set by the embedder,
+// that fetches the platform information.
+_Platform get _platform => _PatchWorkaround._platform;
+
+// Issue 6997: Patching top-level statics has a problem.

[floitsch, 2013/10/24 15:50:58]

TODO(6997): ...

[Bill Hesse, 2013/10/25 11:06:34]

Done.

+class _PatchWorkaround {
+  external static _Platform get _platform;
+}
+
+/**
+ * Get the number of processors of the machine.

[floitsch, 2013/10/24 15:50:58]

"Gets" or simply "The number of ...".

Ditto for all other comments.

[Bill Hesse, 2013/10/25 11:06:34]

Done.

+ * Returns null if no information is available.

[floitsch, 2013/10/24 15:50:58]

New line before the "Returns".

+ */
+final int numberOfProcessors = _platform.numberOfProcessors;

[ahe, 2013/10/24 15:38:16]

This generates rather horrible code in dart2js.

Why is this not:

external int get numberOfProcessors;

[Bill Hesse, 2013/10/25 11:06:34]

All of them changed to 
external String get foo, as you suggest.

+
+/**
+ * Get the path separator used by the operating system to separate
+ * components in file paths.
+ */
+final String pathSeparator = _platform.pathSeparator;
+
+
+/**
+ * Get a string (`linux`, `macos`, `windows` or `android`

[floitsch, 2013/10/24 15:50:58]

missing closing parenthesis.

[Bill Hesse, 2013/10/25 11:06:34]

Done.

+ * representing the operating system. Returns null if not supported.

[Anders Johnsen, 2013/10/24 17:21:01]

Maybe change to

  Returns `null` if the operating system could not be determined.

The current text sounds like we don't support the OS if it's `null`.

Same goes for all the other ones.

[Bill Hesse, 2013/10/25 11:06:34]

Done.

+ */
+final String operatingSystem = _platform.operatingSystem;
+
+/**
+ * Get the local hostname for the system. Returns null if not supported.
+ */
+final String localHostname = _platform.localHostname;
+
+/**
+ * Returns the version of the current Dart runtime.
+ * Returns null if not supported.
+ */
+final String version = _platform.version;
+
+/**
+ * Returns true if the operating system is Linux.
+ */
+bool get isLinux => operatingSystem == "linux";
+
+/**
+ * Returns true if the operating system is Mac OS.
+ */
+bool get isMacOS => operatingSystem == "macos";
+
+/**
+ * Returns true if the operating system is Windows.
+ */
+bool get isWindows => operatingSystem == "windows";
+
+/**
+ * Returns true if the operating system is Android.
+ */
+bool get isAndroid => operatingSystem == "android";
+
+/**
+ * Get the environment for this process.
+ *
+ * Environment variables on Windows are case-insensitive. The map
+ * returned on Windows is therefore case-insensitive and will convert

[floitsch, 2013/10/24 15:50:58]

converts (no need for future)

[Bill Hesse, 2013/10/25 11:06:34]

Done.

+ * all keys to upper case. On other platforms the returned map is
+ * a standard case-sensitive map.
+ * Returns null if not supported.
+ */
+final Map<String, String>  environment = _platform.environment;
+
+/**
+ * Returns the path of the executable used to run the script in this
+ * isolate.
+ *
+ * Returns null if the execution environment does not support [executable].
+ */
+final String executable = _platform.executable;
+
+/**
+   * Returns the URI (in String form of the script being run in this

[floitsch, 2013/10/24 15:50:58]

missing closing parenthesis.

[Bill Hesse, 2013/10/25 11:06:34]

Done.

+   * isolate. If the URI is relative it is relative to the file URI of
+   * the working directory of the VM when it was started.
+   *
+   * Returns null if the executable environment does not support [script].
+   */
+final String  script = _platform.script;
+
+/**
+ * Returns the flags passed to the executable used to run the script in this
+ * isolate. These are the command-line flags between the executable name
+ * and the script name. Each fetch of [executableArguments] returns a new

[floitsch, 2013/10/24 15:50:58]

Don't overspecify. No need to specify that the result is a copy.

[Bill Hesse, 2013/10/25 11:06:34]

Done.

+ * List, containing the flags passed to the executable.
+ *
+ * Returns the empty list if [executableArguments] is not supported.
+ */
+final List<String> executableArguments = _platform.executableArguments;
+
+/**
+ * Returns the value of the --package-root flag passed to the executable
+ * used to run the script in this isolate.  This is the directory in which
+ * Dart packages are looked up.
+ *
+ * If there is no --package-root flag, then the empty string is returned.
+ *
+ * Returns null if not supported.
+ */
+final String packageRoot = _platform.packageRoot;