Initial cut for a development server

lib/src/utils.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.
 
 /// Holds a couple utility functions used at various places in the system.
 library ddc.src.utils;
 
 import 'dart:io';
 
 import 'package:path/path.dart' as path;
 import 'package:analyzer/src/generated/ast.dart'
     show
         ImportDirective,
         ExportDirective,
         PartDirective,
         CompilationUnit,
-        Identifier;
+        Identifier,
+        AnnotatedNode,
+        AstNode;
 import 'package:analyzer/src/generated/engine.dart'
     show ParseDartTask, AnalysisContext;
 import 'package:analyzer/src/generated/source.dart' show Source;
 import 'package:analyzer/src/generated/element.dart';
 import 'package:analyzer/analyzer.dart' show parseDirectives;
+import 'package:source_span/source_span.dart';
 
 bool isDartPrivateLibrary(LibraryElement library) {
   var uri = library.source.uri;
   if (uri.scheme != "dart") return false;
   return Identifier.isPrivateName(uri.path);
 }
 
 /// Choose a canonical name from the library element. This is safe to use as a
 /// namespace in JS and Dart code generation.  This never uses the library's
 /// name (the identifier in the `library` declaration) as it doesn't have any
@@ skipping 192 matching lines @@
   void dec([int n = 2]) {
     _indent = _indent - n;
     assert(_indent >= 0);
     _prefix = "".padRight(_indent);
   }
 
   void close() {
     new File(_path).writeAsStringSync('$_sb');
   }
 }
+
+SourceLocation locationFor(CompilationUnit unit, Uri uri, int offset) {

[Jennifer Messerly, 2015/03/03 02:24:22]

not sure the "For" adds much. "getSourceLocation"?

[Siggi Cherem (dart-lang), 2015/03/04 04:44:24]

What do you think about locationForOffset?

[Jennifer Messerly, 2015/03/04 15:35:10]

yeah that works too.
Just curious, is it intentional to avoid the "get" verb?

[Siggi Cherem (dart-lang), 2015/03/04 17:38:16]

funny - technically no, but every time I start naming something with `get` it
gets me thinking about whether there is a more descriptive way to name it.
Adding `get` in  `getLocationForOffset` seemed unnecessary. What's your
inclination on it?

+  var lineInfo = unit.lineInfo.getLocation(offset);
+  return new SourceLocation(offset,
+      sourceUrl: uri,
+      line: lineInfo.lineNumber - 1,
+      column: lineInfo.columnNumber - 1);
+}
+
+SourceSpan spanFor(CompilationUnit unit, Uri uri, AstNode node) {
+  var currentToken = node is AnnotatedNode
+      ? node.firstTokenAfterCommentAndMetadata
+      : node.beginToken;
+  var begin = currentToken.offset;
+  var endToken = node.endToken;
+  var text = new StringBuffer();

[Jennifer Messerly, 2015/03/03 02:24:22]

I presume there is a method to this madness :-)

guessing here ... can we get back to the Source to actually just copy the input
text on demand?
however we get at the text, it seems really important to do it lazily ... spans
should be O(1) to create not O(NumTokensInSpan)

[Siggi Cherem (dart-lang), 2015/03/04 04:44:24]

yeah, this was more twisted than it needed to be :)

Normally you'd get this data by doing:

  unit.source.contents.data

however, the unit I'm getting here doesn't have a link to its source because I'm
using a digest parsing that only parses directives.

Of course, at the point were I used this I had the source available, so now I'm
just passing that in here.

+  append(tok) {
+    var offset = tok.offset;
+    var diff = offset - begin - text.length;
+    text.write(' ' * diff);
+    text.write(tok.lexeme);
+  }
+  while (currentToken != endToken) {
+    append(currentToken);
+    currentToken = currentToken.next;
+  }
+  append(currentToken);
+  return new SourceSpan(
+      locationFor(unit, uri, begin), locationFor(unit, uri, node.end), '$text');
+}