Create a tool for collecting statistics about summary files.

pkg/analyzer/tool/summary/stats.dart

Index: pkg/analyzer/tool/summary/stats.dart
diff --git a/pkg/analyzer/tool/summary/stats.dart b/pkg/analyzer/tool/summary/stats.dart
new file mode 100644
index 0000000000000000000000000000000000000000..6d6f10b147a76dd223adb1f8313e927e6f619a5f
--- /dev/null
+++ b/pkg/analyzer/tool/summary/stats.dart
@@ -0,0 +1,101 @@
+// Copyright (c) 2016, 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 file contains code for collecting statistics about the use of fields in
+ * a summary file.
+ */
+library analyzer.tool.summary.stats;
+
+import 'dart:io';
+
+import 'package:analyzer/src/summary/base.dart';
+import 'package:analyzer/src/summary/idl.dart';
+
+main(List<String> args) {
+  if (args.length != 1) {
+    _printUsage();
+    exitCode = 1;
+    return;
+  }
+
+  String inputFilePath = args[0];
+
+  // Read the input.
+  SdkBundle bundle =
+      new SdkBundle.fromBuffer(new File(inputFilePath).readAsBytesSync());
+
+  // Compute and output stats.
+  Stats stats = new Stats();
+  stats.record(bundle);
+  stats.dump();
+}
+
+/**
+ * The name of the stats tool.
+ */
+const String BINARY_NAME = "stats";
+
+/**
+ * Print information about how to use the stats tool.
+ */
+void _printUsage() {
+  print('Usage: $BINARY_NAME input_file_path');
+}
+
+/**
+ * An instance of [Stats] keeps track of statistics about the use of fields in
+ * summary objects.
+ */
+class Stats {
+  /**
+   * Map from type to field name to a count of how often the field is used.
+   */
+  Map<Type, Map<String, int>> counts = <Type, Map<String, int>>{};
+
+  /**
+   * Print out statistics gathered so far.
+   */
+  void dump() {
+    counts.forEach((Type type, Map<String, int> typeCounts) {
+      print(type);
+      List<String> keys = typeCounts.keys.toList();
+      keys.sort((String a, String b) => typeCounts[b].compareTo(typeCounts[a]));
+      for (String key in keys) {
+        print('  $key: ${typeCounts[key]}');
+      }
+      print('');
+    });
+  }
+
+  /**
+   * Record statistics for [obj] and all objects it refers to.
+   */
+  void record(SummaryClass obj) {
+    Map<String, int> typeCounts =
+        counts.putIfAbsent(obj.runtimeType, () => <String, int>{});
+    obj.toMap().forEach((String key, Object value) {
+      if (value == null ||
+          value == 0 ||
+          value == false ||
+          value == '' ||
+          value is List && value.isEmpty) {
+        return;
+      }
+      if (!typeCounts.containsKey(key)) {
+        typeCounts[key] = 0;
+      }
+      typeCounts[key]++;
+      if (value is SummaryClass) {
+        record(value);
+      } else if (value is List) {
+        value.forEach((Object element) {
+          if (element is SummaryClass) {
+            record(element);
+          }
+        });
+      }
+    });
+  }
+}