Initial cut for a development server

lib/src/utils.dart

Index: lib/src/utils.dart
diff --git a/lib/src/utils.dart b/lib/src/utils.dart
index 09bc4300a810728e1606bcdf6d4e5c65349b3409..f813772aff76ec69002b1d04f65fa08ef7f6c8fe 100644
--- a/lib/src/utils.dart
+++ b/lib/src/utils.dart
@@ -14,12 +14,15 @@ import 'package:analyzer/src/generated/ast.dart'
         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;
@@ -232,3 +235,33 @@ class OutWriter {
     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');
+}