dart2js: add simple script to compute dependency queries. Currently only

pkg/compiler/tool/code_deps.dart

+// Copyright (c) 2015, 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.
+
+/// Command-line tool to query for code dependncies.

[Harry Terkelsen, 2015/08/11 22:57:42]

dependencies

[Siggi Cherem (dart-lang), 2015/08/12 00:06:01]

Done.

+library compiler.tool.code_deps;
+
+import 'dart:convert';
+import 'dart:io';
+
+import 'package:compiler/src/info/info.dart';
+import 'graph.dart';
+import 'util.dart';
+
+main(args) {
+  if (args.length < 2) {
+    print('usage: dart tool/code_deps.dart path-to-info.json <query>');
+    print('   where <query> can be:');
+    print('     - some_path elementA elementB');
+    // TODO(sigmund): add other queries, such as 'all_paths'.
+    exit(1);
+  }
+
+  var json = JSON.decode(new File(args[0]).readAsStringSync());
+  var info = AllInfo.parseFromJson(json);
+  var graph = graphFromInfo(info);
+
+  var queryName = args[1];
+  if (queryName == 'some_path') {
+    if (args.length < 4) {
+      print('missing arguments for `some_path`');
+      exit(1);
+    }
+    var source =
+        info.functions.firstWhere(_longNameMatcher(new RegExp(args[2])));
+    var target =
+        info.functions.firstWhere(_longNameMatcher(new RegExp(args[3])));
+    print('query: some_path');
+    print('source: ${longName(source)}');
+    print('target: ${longName(target)}');
+    var path = new SomePathQuery(source, target).run(graph);
+    if (path.isEmpty) {
+      print('result: no path found');
+    } else {
+      print('result:');
+      for (int i = 0; i < path.length; i++) {
+        print('  $i. ${longName(path[i])}');
+      }
+    }
+  } else {
+    print('unrecognized query: $queryName');
+  }
+}
+
+/// A query supported by this tool.
+abstract class Query {
+  run(Graph<Info> graph);
+}
+
+/// Query that searches for a single path between two elements.
+class SomePathQuery {
+  /// The info associated with the source element.
+  Info source;
+
+  /// The info associated with the target element.
+  Info target;
+
+  SomePathQuery(this.source, this.target);
+
+  run(Graph<Info> graph) {
+    var seen = new Set();
+    var result = [];
+    helper(n) {
+      if (!seen.add(n)) return false;
+      result.add(n);
+      if (identical(n, target)) return true;
+      if (graph.targetsOf(n).any(helper)) return true;

[Harry Terkelsen, 2015/08/11 22:57:42]

maybe more useful to do a BFS instead to find the shortest path

[Siggi Cherem (dart-lang), 2015/08/12 00:06:01]

Great idea! Updated. I tried it on an example in angular2 from main to
DynamicChangeDetection, and saw a change from a path of 159 steps, to a simple
path of 6 steps.

+      assert(result.removeLast() == n);
+      return false;
+    }
+    helper(source);
+    return result;
+  }
+}
+
+_longNameMatcher(RegExp regexp) => (e) => regexp.hasMatch(longName(e));