Let docgen detect a dart-sdk directory that's differently named, and do it correctly on bleeding ed…

pkg/docgen/lib/src/package_helpers.dart

Index: pkg/docgen/lib/src/package_helpers.dart
diff --git a/pkg/docgen/lib/src/package_helpers.dart b/pkg/docgen/lib/src/package_helpers.dart
index ca189fa15c08d64b463e791d02f2a1805d744819..6bb2f61bdca4af33c96e57689375f1e13fd93fec 100644
--- a/pkg/docgen/lib/src/package_helpers.dart
+++ b/pkg/docgen/lib/src/package_helpers.dart
@@ -23,10 +23,17 @@ String get rootDirectory {
   var scriptDir = path.absolute(path.dirname(Platform.script.toFilePath()));
   var root = scriptDir;
   var base = path.basename(root);
-  // When we find dart-sdk or sdk we are one level below the root.
-  while (base != 'dart-sdk' && base != 'sdk' && base != 'pkg') {
+  var found = false;
+  // When we find a version file or sdk we are one level below the root.

[ricow1, 2014/11/20 07:38:30]

comment don't match the case where we hit pkg?

+  while (!found && base != 'sdk' && base != 'pkg') {

[ricow1, 2014/11/20 07:38:30]

looking at the 3 examples in the function comment we would never hit sdk

     root = path.dirname(root);
     base = path.basename(root);
+    // Look for something that looks like the dart-sdk directory, which we
+    // expect to be in the path above us and to have a 'version' file containing
+    // the same version as we are running.

[ricow1, 2014/11/20 07:38:30]

could you elaborate on _why_ it is important for the versions to match?

+    if (hasMatchingVersionFile(root)) {
+      found = true;
+    }
     if (root == base) {
       // We have reached the root of the filesystem without finding anything.
       throw new FileSystemException("Cannot find SDK directory starting from ",
@@ -38,6 +45,27 @@ String get rootDirectory {
 }
 String _rootDirectoryCache;
 
+
+/// Does this directory contain a version file that has the same version as
+/// we do.
+bool hasMatchingVersionFile(String root) {
+  var versionFile = new File(path.join(root, 'version'));
+  if (!versionFile.existsSync()) return false;
+  var version = versionFile.readAsStringSync().trim();
+  var vmVersion = Platform.version;
+  return vmVersion.startsWith(withoutEdge(version));
+}
+
+/// Returns a version string with the bleeding edge revision number removed,
+/// if it was present.
+String withoutEdge(String version) =>
+    version.substring(0, edgePosition(version));

[ricow1, 2014/11/20 07:38:30]

remove edgePosition below and just do:
Sting withoutEdge(String version) => version.split('-edge').first;

[ricow1, 2014/11/20 07:55:00]

s/Sting/String :-)

+
+/// Returns the index in version in which the bleeding edge indicator "edge."
+/// occurs.
+int edgePosition(String version) =>
+    version.indexOf("edge.") == -1 ? version.length : version.indexOf("edge");
+
 /// Given a LibraryMirror that is a library, return the name of the directory
 /// holding the package information for that library. If the library is not
 /// part of a package, return null.