Add a snapshot for docgen and use it in the build

pkg/docgen/lib/docgen.dart

Index: pkg/docgen/lib/docgen.dart
diff --git a/pkg/docgen/lib/docgen.dart b/pkg/docgen/lib/docgen.dart
index d75b60f6910434507e801f508b942d694a4d4623..46e280a075b6b0943e6915a67dcae16e0672e513 100644
--- a/pkg/docgen/lib/docgen.dart
+++ b/pkg/docgen/lib/docgen.dart
@@ -42,11 +42,61 @@ var _outputDirectory;
 
 const String USAGE = 'Usage: dart docgen.dart [OPTIONS] fooDir/barFile';
 
-
 List<String> skippedAnnotations = const [
     'metadata.DocsEditable', '_js_helper.JSName', '_js_helper.Creates',
     '_js_helper.Returns'];
 
+/// If we can't find the SDK introduction text, which will happen if running
+/// from a snapshot and using --parse-sdk or --include-sdk, then use this
+/// hard-coded version. This should be updated to be consistent with the text
+/// in docgen/doc/sdk-introduction.md
+const DEFAULT_SDK_INTRODUCTION = """
+Welcome to the Dart API reference documentation,
+covering the official Dart API libraries.
+Some of the most fundamental Dart libraries include:
+
+* [dart:core](#dart:core):
+  Core functionality such as strings, numbers, collections, errors,
+  dates, and URIs.
+* [dart:html](#dart:html):
+  DOM manipulation for web apps.
+* [dart:io](#dart:io):
+  I/O for command-line apps.
+
+Except for dart:core, you must import a library before you can use it.
+Here's an example of importing dart:html, dart:math, and a
+third popular library called
+[polymer.dart](http://www.dartlang.org/polymer-dart/):
+
+    import 'dart:html';
+    import 'dart:math';
+    import 'package:polymer/polymer.dart';
+
+Polymer.dart is an example of a library that isn't
+included in the Dart download,
+but is easy to get and update using the _pub package manager_.
+For information on finding, using, and publishing libraries (and more)
+with pub, see
+[pub.dartlang.org](http://pub.dartlang.org).
+
+The main site for learning and using Dart is
+[www.dartlang.org](http://www.dartlang.org).
+Check out these pages:
+
+  * [Dart homepage](http://www.dartlang.org)
+  * [Tutorials](http://www.dartlang.org/docs/tutorials/)
+  * [Programmer's Guide](http://www.dartlang.org/docs/)
+  * [Samples](http://www.dartlang.org/samples/)
+  * [A Tour of the Dart Libraries](http://www.dartlang.org/docs/dart-up-and-running/contents/ch03.html)
+
+This API reference is automatically generated from the source code in the
+[Dart project](https://code.google.com/p/dart/).
+If you'd like to contribute to this documentation, see
+[Contributing](https://code.google.com/p/dart/wiki/Contributing)
+and
+[Writing API Documentation](https://code.google.com/p/dart/wiki/WritingApiDocumentation).
+""";
+
 /// Set of libraries declared in the SDK, so libraries that can be accessed
 /// when running dart by default.
 Iterable<LibraryMirror> _sdkLibraries;
@@ -92,7 +142,7 @@ Map _mdn;
 /// Returned Future completes with true if document generation is successful.
 Future<bool> docgen(List<String> files, {String packageRoot,
     bool outputToYaml: true, bool includePrivate: false, bool includeSdk: false,
-    bool parseSdk: false, bool append: false, String introduction: '',
+    bool parseSdk: false, bool append: false, String introFileName: '',
     out: DEFAULT_OUTPUT_DIRECTORY, List<String> excludeLibraries,
     bool includeDependentPackages}) {
   _excluded = excludeLibraries;
@@ -145,7 +195,7 @@ Future<bool> docgen(List<String> files, {String packageRoot,
       librariesToDocument.removeWhere((x) => _excluded.contains(x.simpleName));
       _documentLibraries(librariesToDocument, includeSdk: includeSdk,
           outputToYaml: outputToYaml, append: append, parseSdk: parseSdk,
-          introduction: introduction);
+          introFileName: introFileName);

[ricow1, 2014/01/13 13:14:20]

do we ever read this from a file now? if not just remove this argument here,
above and below

[Alan Knight, 2014/01/13 17:36:04]

We don't in the SDK, but if we're using this to generate docs for an individual
package we want them to be able to provide an introductory text.

       return true;
     });
 }
@@ -258,7 +308,7 @@ String _findPackageRoot(String directory) {
   if (packageRoot != '') {
     packageRoot = path.join(path.dirname(packageRoot), 'packages');
   }
-  return packageRoot;
+  return path.normalize(path.absolute(packageRoot));
 }
 
 /// Read a pubspec and return the library name.
@@ -334,7 +384,7 @@ Future<MirrorSystem> _analyzeLibraries(List<Uri> libraries,
 /// Creates documentation for filtered libraries.
 void _documentLibraries(List<LibraryMirror> libs, {bool includeSdk: false,
     bool outputToYaml: true, bool append: false, bool parseSdk: false,
-    String introduction: ''}) {
+    String introFileName: ''}) {
   libs.forEach((lib) {
     // Files belonging to the SDK have a uri that begins with 'dart:'.
     if (includeSdk || !lib.uri.toString().startsWith('dart:')) {
@@ -357,6 +407,19 @@ void _documentLibraries(List<LibraryMirror> libs, {bool includeSdk: false,
   // This will help the viewer know what libraries are available to read in.
   var libraryMap;
   var linkResolver = (name) => fixReference(name, null, null, null);
+
+  String readIntroductionFile(String fileName, includeSdk) {
+    var defaultText = includeSdk ? DEFAULT_SDK_INTRODUCTION : '';
+    var introText = defaultText;
+    if (fileName.isNotEmpty) {
+      var introFile = new File(fileName);
+      introText = introFile.existsSync() ? introFile.readAsStringSync() :
+          defaultText;
+    }
+    return markdown.markdownToHtml(introText,
+        linkResolver: linkResolver, inlineSyntaxes: markdownSyntaxes);
+  }
+
   if (append) {
     var docsDir = listDir(_outputDirectory);
     if (!docsDir.contains('$_outputDirectory/library_list.json')) {
@@ -368,23 +431,16 @@ void _documentLibraries(List<LibraryMirror> libs, {bool includeSdk: false,
     libraryMap['libraries'].addAll(filteredEntities
         .where((e) => e is Library)
         .map((e) => e.previewMap));
-    if (introduction.isNotEmpty) {
-      var intro = libraryMap['introduction'];
-      if (intro.isNotEmpty) intro += '<br/><br/>';
-      intro += markdown.markdownToHtml(
-          new File(introduction).readAsStringSync(),
-              linkResolver: linkResolver, inlineSyntaxes: markdownSyntaxes);
-      libraryMap['introduction'] = intro;
-    }
+    var intro = libraryMap['introduction'];
+    var spacing = intro.isEmpty ? '' : '<br/><br/>';
+    libraryMap['introduction'] =
+        "$intro$spacing${readIntroductionFile(introFileName, includeSdk)}";
     outputToYaml = libraryMap['filetype'] == 'yaml';
   } else {
     libraryMap = {
       'libraries' : filteredEntities.where((e) =>
           e is Library).map((e) => e.previewMap).toList(),
-      'introduction' : introduction == '' ?
-          '' : markdown.markdownToHtml(new File(introduction)
-              .readAsStringSync(), linkResolver: linkResolver,
-                  inlineSyntaxes: markdownSyntaxes),
+      'introduction' : readIntroductionFile(introFileName, includeSdk),
       'filetype' : outputToYaml ? 'yaml' : 'json'
     };
   }