initial frogpad

frog/pad/frogpad.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.
+
+/**
+ * This is the entrypoint for a version of the frog compiler that 
+ * can run in the browser.
+ * Because this is running in the browser, frog cannot access
+ * the file system.  Instead, we assume the all necessary files
+ * have been placed in inert <script> elements somewhere on the page.  
+ * (See frogpad.py for more details on how the html page is constructed.)
+ */
+
+#import("dart:html", prefix:"html");
+#import("../lang.dart");
+#import("../file_system.dart");
+
+// TODO - remove once corelib has an Exception base class

[Siggi Cherem (dart-lang), 2012/02/13 18:43:49]

I don't think you need this becase you don't extend from [Exception_],
[Exception] has a default implementation, so below you can simply do:
  new Exception(s)
instead of 
  new Exception_(s)

[Jennifer Messerly, 2012/02/13 19:12:12]

Agree

[mattsh, 2012/02/13 20:57:36]

Done.

[mattsh, 2012/02/13 20:57:36]

Done.

+class Exception_ implements Exception {
+  final String message;
+  Exception_(String message) : message = message {}
+  String toString() { return message; }

[Bob Nystrom, 2012/02/13 18:10:18]

Why not just:

String toString() => message;

[mattsh, 2012/02/13 20:57:36]

Done.

+}
+
+// id of script element containing name of the main dart file

[Bob Nystrom, 2012/02/13 18:10:18]

Should be a complete sentence and capitalized.

[mattsh, 2012/02/13 20:57:36]

Prefer to keep it lowercase since then it matches how id looks in html
attributes.

[Bob Nystrom, 2012/02/13 21:33:40]

Then do "The id"?

+// to compile.
+final String MAIN_ID = "main_id";

[Bob Nystrom, 2012/02/13 18:10:18]

I think our (undocumented at this point) convention is to prefer single-quoted
strings when possible.

[mattsh, 2012/02/13 20:57:36]

Prefer to keep double quotes here.

[Bob Nystrom, 2012/02/13 21:33:40]

Why?

+
+void main() {
+  String warnings = "";
+  HtmlFileSystem fs = new HtmlFileSystem();

[Bob Nystrom, 2012/02/13 18:10:18]

These type annotations seem pretty redundant...

[mattsh, 2012/02/13 20:57:36]

Prefer to keep type annotations.

+  String mainFile = getText(MAIN_ID); 
+  setText("input", fs.readAll(mainFile));
+
+  // TODO - figure out why parseOptions ignores its first two arguments

[Bob Nystrom, 2012/02/13 18:10:18]

TODO(mattsh)...

[Siggi Cherem (dart-lang), 2012/02/13 18:43:49]

it currently does because in all shell programms arg[0] is the binary, in script
programs, arg[0] is the script runtime, while arg[1] is the script itself (frog
in this particular example). The actual command line arguments start in arg[2]

[mattsh, 2012/02/13 20:57:36]

Done.

[mattsh, 2012/02/13 20:57:36]

Done.

+  List<String> args = ["dummy_arg1", "dummy_arg2", mainFile];
+
+  // TODO - figure out whether this home directory argument is needed

[Emily Fortuna, 2012/02/13 18:27:58]

TODO(mattsh) (again)

[Siggi Cherem (dart-lang), 2012/02/13 18:43:49]

IIRC, this is only needed to determine where to find the libraries in the file
system.

[mattsh, 2012/02/13 20:57:36]

Done.

[mattsh, 2012/02/13 20:57:36]

Done.

+  parseOptions("dummy_home_dir", args, fs);
+
+  options.useColors = false;
+
+  initializeWorld(fs);
+  world.messageHandler = void _(

[Bob Nystrom, 2012/02/13 18:10:18]

Why not just:

world.messageHandler = (prefix, message, span) {

[mattsh, 2012/02/13 20:57:36]

We want static type checking of the return type, so we need to specify the
return type.

+      String prefix, String message, SourceSpan span) {
+    String location = "";
+    if (span !== null) {

[Bob Nystrom, 2012/02/13 18:10:18]

You can make this a one-liner if you like.

[mattsh, 2012/02/13 20:57:36]

Prefer to keep the curlies.

+      location = span.locationText;
+    }
+    warnings += prefix + message + location + "\n";
+  };
+  bool success = world.compile();
+  if (success) {
+    setText("output", world.getGeneratedCode());
+  }
+  setText("warnings", warnings);
+}
+
+void setText(String id, String text) {
+  html.Element element = html.document.query("#" + id);

[Bob Nystrom, 2012/02/13 18:10:18]

Interpolate.

[mattsh, 2012/02/13 20:57:36]

Done.

+  if (element === null) {
+    throw new Exception_("Can't find element " + id);

[Bob Nystrom, 2012/02/13 18:10:18]

Here too.

[mattsh, 2012/02/13 20:57:36]

Done.

+  }
+  element.innerHTML = htmlEscape(text);
+}
+
+String getText(String id) {
+  html.Element element = html.document.query("#$id");
+  if (element === null) {
+    throw new Exception_("Can't find element " + id);

[Emily Fortuna, 2012/02/13 18:27:58]

Interpolate.

[mattsh, 2012/02/13 20:57:36]

Done.

+  }
+  return element.text.trim();
+}
+
+// TODO(rnystrom): should exist in standard lib somewhere

[Bob Nystrom, 2012/02/13 18:10:18]

No, this still doesn't have a home. Maybe file a bug for it?

[mattsh, 2012/02/13 20:57:36]

http://code.google.com/p/dart/issues/detail?id=1657
Done.

+String htmlEscape(String text) {
+  return text.replaceAll('&', '&').replaceAll(
+      '>', '&gt;').replaceAll('<', '&lt;');
+}
+
+class HtmlFileSystem implements FileSystem {
+
+  HtmlFileSystem() {}
+
+  String readAll(String filename) {
+    String text = getText(idOfFilename(filename));
+    print("read $filename (${text.length} bytes)");

[Bob Nystrom, 2012/02/13 18:10:18]

Is this for debugging? If so, I'd remove it.

[mattsh, 2012/02/13 20:57:36]

Done.

+    return text;
+  }
+
+  /**
+   * Returns the id of the <script> element that contains

[Bob Nystrom, 2012/02/13 18:10:18]

The wrapping is strange here. Should be at 80 chars.

[mattsh, 2012/02/13 20:57:36]

Keep as is.

[Bob Nystrom, 2012/02/13 21:33:40]

Why?

+   * the contents of this file.
+   * The id is constructed by taking the last directory
+   * of the path, plus the file name, and using _ as a 
+   * separator.  So, for example, the file name:
+   *  
+   *   "/usr/local/src/dart/frog/lang.dart" 
+   * 
+   * becomes:
+   * 
+   *   "frog_lang_dart"
+   *  
+   * And, so this file's contents will be found in a <script>
+   * element that looks like this:
+   *
+   *   <script type=application/inert id="frog_lang_dart">
+   *      ... contents of file lang.dart placed here ...
+   *   </script>
+   */
+  String idOfFilename(String filename) {
+    List<String> components = filename.split("/");
+    if (components.isEmpty()) {
+      throw new Exception_("bad filename");
+    }
+    // grab the last two components (the directory name and file name):

[Bob Nystrom, 2012/02/13 18:10:18]

"Grab"

[mattsh, 2012/02/13 20:57:36]

Done.

+    int startIndex = Math.max(0, components.length - 2);
+    int endIndex = components.length - startIndex;    
+    components = components.getRange(startIndex, endIndex);
+    
+    // join components with underscore, and also replace dots with underscore

[Bob Nystrom, 2012/02/13 18:10:18]

Should be a sentence.

[mattsh, 2012/02/13 20:57:36]

Done.

+    return Strings.join(components, "_").replaceAll(".", "_");    
+  }
+
+  void writeString(String outfile, String text) {
+    throw new UnsupportedOperationException("");
+  }
+
+  bool fileExists(String filename) {
+    return true;

[Bob Nystrom, 2012/02/13 18:10:18]

Shouldn't you check for the <div> here?

[mattsh, 2012/02/13 20:57:36]

Added a comment.

+  }
+
+  void createDirectory(String path, [bool recursive]) {
+    throw new UnsupportedOperationException("");
+  }
+  void removeDirectory(String path, [bool recursive]) {

[Bob Nystrom, 2012/02/13 18:10:18]

Add a blank line above this.

[mattsh, 2012/02/13 20:57:36]

Done.

+    throw new UnsupportedOperationException("");
+  }
+}