Add command line options to rank_stacks

pkg/compiler/tool/status_files/rank_stacks.dart

 // Copyright (c) 2017, 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.
 
 /*
 Usage:
 
   $ tools/test.py -m release                         \
       -c dart2js -r d8 --dart2js-batch --report      \
       --host-checked                                 \
       --dart2js_options="--library-root=out/ReleaseX64/dart-sdk/ --use-kernel" \
       language corelib library_2 corelib_2           \
       dart2js_native dart2js_extra                   \
       2>&1 > LOG
 
   $ sdk/bin/dart pkg/compiler/tool/status_files/rank_stacks.dart LOG > STACKS.txt
 */
 
 import 'dart:io';
 
 import 'log_parser.dart';
 import 'record.dart';
 
-// TODO(sra): Allow command-line setting of these parameters.
-const STACK_PRINT_LENGTH = 12;
-const HOW_MANY_STACKS = 30;
+const DEFAULT_STACK_PRINT_LENGTH = 12;
+const DEFAULT_HOW_MANY_STACKS = 20;
+const USAGE = """
+dart rank_stacks.dart [options] test-log
+
+--stacks=N, -sN: Print highest ranking N stacks (0 means all stacks).
+    Defaults to top ${DEFAULT_HOW_MANY_STACKS} stacks.
+
+--length=N, -lN: Print N frames of each stack.
+    Defaults to ${DEFAULT_STACK_PRINT_LENGTH} frames.
+""";
+
+int stackPrintLength = DEFAULT_STACK_PRINT_LENGTH;
+int howManyStacks = DEFAULT_HOW_MANY_STACKS;
+
+void die(String why) {
+  print(why);
+  print('Usage:\n${USAGE}');
+  exit(1);
+}
 
 main(args) {
   String text;
 
+  // Parse options.
   for (String arg in args) {
-    // Parse options.
+    Match m;
+    if ((m = new RegExp(r'(--stacks=|-s)(\d+)$').matchAsPrefix(arg)) != null) {

[Siggi Cherem (dart-lang), 2017/08/26 02:09:00]

consider using the `args` package?

[sra1, 2017/08/29 19:53:03]

Done.

+      howManyStacks = int.parse(m.group(2));
+      continue;
+    }
+
+    if ((m = new RegExp(r'(--length=|-l)(\d+)$').matchAsPrefix(arg)) != null) {
+      stackPrintLength = int.parse(m.group(2));
+      continue;
+    }
+
+    if (arg.startsWith('-')) die("Unknown option '$arg'");
 
     if (text == null) {
       var uri = Uri.base.resolve(arg);
       var file = new File.fromUri(uri);
       if (!file.existsSync()) {
-        print('File not found: $file.');
-        exit(1);
+        die('File not found: $file.');
       }
       text = file.readAsStringSync();
     } else {
-      print("Extra file argument '$arg'.");
-      exit(1);
+      die("Extra file argument '$arg'.");
     }
   }
 
   if (text == null) {
-    print('No input file.');
-    exit(1);
+    die('No input file.');
   }
 
   var records = parse(text);
   var trie = new TrieNode(null);
   for (var record in records) {
     enter(record, 0, trie);
   }
 
   var leaves = trieLeaves(trie).toList();
   leaves.sort((a, b) => b.length.compareTo(a.length));
-  for (var leaf in leaves.take(HOW_MANY_STACKS)) {
+  for (var leaf in howManyStacks == 0 ? leaves : leaves.take(howManyStacks)) {
     print('');
     var examples = leaf.members.map((r) => r.fullReason).toSet().toList();
     examples.sort();
     print('${leaf.length} of:');
     for (var example in examples) {
       var count = leaf.members.where((r) => r.fullReason == example).length;
       var countAligned = '$count'.padLeft(6);
       if (examples.length == 1) countAligned = '     .';
       var indentedExample = '\t' + example.replaceAll('\n', '\n\t');
       print('${countAligned}${indentedExample}');
     }
 
-    for (var line in leaf.members.first.stack.take(STACK_PRINT_LENGTH)) {
+    for (var line in leaf.members.first.stack.take(stackPrintLength)) {
       print('  $line');
     }
   }
 }
 
 class TrieNode {
   final int depth;
   final String key;
   final Map<String, TrieNode> map = <String, TrieNode>{};
   final List<Record> members = <Record>[];
@@ skipping 23 matching lines @@
 
 trieLeaves(node) sync* {
   if (node.map.isEmpty) {
     yield node;
   } else {
     for (var v in node.map.values) {
       yield* trieLeaves(v);
     }
   }
 }