dartfmt line length command line option support.

pkg/analyzer/bin/formatter.dart

 #!/usr/bin/env dart
 
 // Copyright (c) 2013, 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.
 
 import 'dart:convert';
 import 'dart:io';
 
 import 'package:args/args.dart';
 import 'package:path/path.dart' as path;
 
 import 'package:analyzer/src/services/formatter_impl.dart';
 
 
 const BINARY_NAME = 'dartfmt';
 final dartFileRegExp = new RegExp(r'^[^.].*\.dart$', caseSensitive: false);
 final argParser = _initArgParser();
 final defaultSelection = new Selection(-1, -1);
 
 var formatterSettings;
 
 CodeKind kind;
 bool machineFormat;
 bool overwriteFileContents;
 Selection selection;
 final List<String> paths = [];
 
+
+const HELP_FLAG = 'help';
+const KIND_FLAG = 'kind';
+const MACHINE_FLAG = 'machine';
+const WRITE_FLAG = 'write';
+const SELECTION_FLAG = 'selection';
+const TRANSFORM_FLAG = 'transform';
+const MAX_LINE_FLAG = 'max_line_length';
+
+
 const FOLLOW_LINKS = false;
 
 
 main(args) {
   var options = argParser.parse(args);
   if (options['help']) {
     _printUsage();
     return;
   }
 
   _readOptions(options);
 
   if (options.rest.isEmpty) {
     _formatStdin(kind);
   } else {
     paths.addAll(options.rest);
     _formatPaths(paths);
   }
 }
 
 _readOptions(options) {
-  kind = _parseKind(options['kind']);
-  machineFormat = options['machine'];
-  overwriteFileContents = options['write'];
-  selection = _parseSelection(options['selection']);
+  kind = _parseKind(options[KIND_FLAG]);
+  machineFormat = options[MACHINE_FLAG];
+  overwriteFileContents = options[WRITE_FLAG];
+  selection = _parseSelection(options[SELECTION_FLAG]);
   formatterSettings =
-      new FormatterOptions(codeTransforms: options['transform']);
+      new FormatterOptions(codeTransforms: options[TRANSFORM_FLAG],
+          pageWidth: _toInt(options[MAX_LINE_FLAG]));
 }
 
 CodeKind _parseKind(kindOption) {
   switch(kindOption) {
     case 'stmt' :
       return CodeKind.STATEMENT;
     default:
       return CodeKind.COMPILATION_UNIT;
   }
 }
@@ skipping 69 matching lines @@
   stdin.transform(new Utf8Decoder())
       .listen((data) => input.write(data),
         onError: (error) => _log('Error reading from stdin'),
         onDone: () => print(_format(input.toString(), kind)));
 }
 
 /// Initialize the arg parser instance.
 ArgParser _initArgParser() {
   // NOTE: these flags are placeholders only!
   var parser = new ArgParser();
-  parser.addFlag('write', abbr: 'w', negatable: false,
+  parser.addFlag(WRITE_FLAG, abbr: 'w', negatable: false,
       help: 'Write reformatted sources to files (overwriting contents).  '
             'Do not print reformatted sources to standard output.');
-  parser.addOption('kind', abbr: 'k', defaultsTo: 'cu',
+  parser.addFlag(TRANSFORM_FLAG, abbr: 't', negatable: false,
+      help: 'Perform code transformations.');
+  parser.addOption(MAX_LINE_FLAG, abbr: 'l', defaultsTo: '80',

[Brian Wilkerson, 2014/01/27 18:38:42]

Do we want to support an easy way to not wrap lines (as opposed to setting some
ridiculously long line length and hoping it's long enough)?

[pquitslund, 2014/01/27 19:06:03]

Maybe.  I'd rather not add another flag.  Do you think a value like -1 is too
opaque?

[Brian Wilkerson, 2014/01/27 19:12:27]

I agree. Especially since it would then be possible to specify conflicting
options.
Not if you mention it in the help description. (Although "0" would work just as
well and might be easier to parse.)

+      help: 'Wrap lines longer than this length.');
+  parser.addOption(KIND_FLAG, abbr: 'k', defaultsTo: 'cu',
       help: 'Specify source snippet kind ("stmt" or "cu")'
             ' --- [PROVISIONAL API].', hide: true);
-  parser.addFlag('machine', abbr: 'm', negatable: false,
-      help: 'Produce output in a format suitable for parsing.');
-  parser.addOption('selection', abbr: 's',
+  parser.addOption(SELECTION_FLAG, abbr: 's',
       help: 'Specify selection information as an offset,length pair '
             '(e.g., -s "0,4").', hide: true);
-  parser.addFlag('transform', abbr: 't', negatable: true,
-      help: 'Perform code transformations.');
-  parser.addFlag('help', abbr: 'h', negatable: false,
+  parser.addFlag(MACHINE_FLAG, abbr: 'm', negatable: false,
+      help: 'Produce output in a format suitable for parsing.');
+  parser.addFlag(HELP_FLAG, abbr: 'h', negatable: false,
       help: 'Print this usage information.');
   return parser;
 }
 
 
 /// Displays usage information.
 _printUsage() {
   var buffer = new StringBuffer();
   buffer..write('$BINARY_NAME formats Dart programs.')
         ..write('\n\n')
@@ skipping 30 matching lines @@
                      'offset': formatResult.selection.offset,
                      'length': formatResult.selection.length
                   }
     });
 
 /// Log the given [msg].
 _log(String msg) {
   //TODO(pquitslund): add proper log support
   print(msg);
 }