pkg/docgen: the big refactor

pkg/docgen/lib/src/package_helpers.dart

+// Copyright (c) 2014, 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.
+
+library docgen.package_helpers;
+
+import '../../../../sdk/lib/_internal/compiler/implementation/mirrors/source_mirrors.dart';
+
+import 'dart:io';
+import 'package:path/path.dart' as path;
+import 'package:yaml/yaml.dart';
+
+/// Helper accessor to determine the full pathname of the root of the dart
+/// checkout. We can be in one of three situations:
+/// 1) Running from pkg/docgen/bin/docgen.dart
+/// 2) Running from a snapshot in a build,
+///   e.g. xcodebuild/ReleaseIA32/dart-sdk/bin
+/// 3) Running from a built distribution,
+///   e.g. ...somename/dart-sdk/bin/snapshots
+String get rootDirectory {
+  if (_rootDirectoryCache != null) return _rootDirectoryCache;
+  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') {
+    root = path.dirname(root);
+    base = path.basename(root);
+    if (root == base) {
+      // We have reached the root of the filesystem without finding anything.
+      throw new FileSystemException("Cannot find SDK directory starting from ",
+          scriptDir);
+    }
+  }
+  _rootDirectoryCache = path.dirname(root);
+  return _rootDirectoryCache;
+}
+String _rootDirectoryCache;
+
+/// 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.
+String getPackageDirectory(LibraryMirror mirror) {
+  var file = mirror.uri.toFilePath();
+  // Any file that's in a package will be in a directory of the form
+  // packagename/lib/.../filename.dart, so we know that a possible
+  // package directory is at least in the directory above the one containing
+  // [file]
+  var directoryAbove = path.dirname(path.dirname(file));
+  var possiblePackage = _packageDirectoryFor(directoryAbove);
+  // We only want components that are somewhere underneath the lib directory.
+  var subPath = path.relative(file, from: possiblePackage);
+  var subPathComponents = path.split(subPath);
+  if (subPathComponents.isNotEmpty && subPathComponents.first == 'lib') {
+    return possiblePackage;
+  } else {
+    return null;
+  }
+}
+
+/// Read a pubspec and return the library name, given a directory
+String packageNameFor(String directoryName) {
+  var pubspecName = path.join(directoryName, 'pubspec.yaml');
+  File pubspec = new File(pubspecName);
+  if (!pubspec.existsSync()) return '';
+  var contents = pubspec.readAsStringSync();
+  var spec = loadYaml(contents);
+  return spec["name"];
+}
+
+/// Recursively walk up from directory name looking for a pubspec. Return
+/// the directory that contains it, or null if none is found.
+String _packageDirectoryFor(String directoryName) {
+  var dir = directoryName;
+  while (!_pubspecFor(dir).existsSync()) {
+    var newDir = path.dirname(dir);
+    if (newDir == dir) return null;
+    dir = newDir;
+  }
+  return dir;
+}
+
+File _pubspecFor(String directoryName) =>
+    new File(path.join(directoryName, 'pubspec.yaml'));