Add a parseDartString method to pkg/analyzer.

pkg/analyzer_experimental/lib/analyzer.dart

Index: pkg/analyzer_experimental/lib/analyzer.dart
diff --git a/pkg/analyzer_experimental/lib/analyzer.dart b/pkg/analyzer_experimental/lib/analyzer.dart
index a88c94c2060b037c77b9500cb1837b6f55fa18ad..ebb253e56d15b2fe75f74ce1c24e24088ad188c0 100644
--- a/pkg/analyzer_experimental/lib/analyzer.dart
+++ b/pkg/analyzer_experimental/lib/analyzer.dart
@@ -14,6 +14,7 @@ import 'src/generated/error.dart';
 import 'src/generated/parser.dart';
 import 'src/generated/scanner.dart';
 import 'src/generated/source_io.dart';
+import 'src/string_source.dart';
 
 export 'src/error.dart';
 export 'src/generated/ast.dart';
@@ -46,6 +47,24 @@ CompilationUnit parseDartFile(String path) {
   return unit;
 }
 
+/// Parses a string of Dart code into an AST.
+///
+/// If [name] is passed, it's used in error messages as the name of the code
+/// being parsed.
+CompilationUnit parseDartString(String contents, {String name}) {

[Brian Wilkerson, 2013/08/23 14:19:29]

It might be better to name this something like parseCompilationUnit so that we
can later add methods like parseStatement and parseExpression.

[nweiz, 2013/08/26 17:03:39]

Done.

+  var source = name == null ? null : new StringSource(contents, name);

[Brian Wilkerson, 2013/08/23 14:19:29]

It would be good to have some tests for this. In particular, it would be good to
know whether it's really OK to pass in a null source when there are errors being
generated. It might be better to give 'name' a default value of something like
"--unnamed--".

[nweiz, 2013/08/26 17:03:39]

The error message does default to "<unknown source>" if the source is null, but
AnalyzerError is unable to format the exception properly. I've changed it to
create a StringSource with name "<unknown source>".

I've also added a few tests.

+  var errorCollector = new _ErrorCollector();
+  var scanner = new StringScanner(source, contents, errorCollector);
+  var token = scanner.tokenize();
+  var parser = new Parser(source, errorCollector);
+  var unit = parser.parseCompilationUnit(token);
+  unit.lineInfo = new LineInfo(scanner.lineStarts);
+
+  if (errorCollector.hasErrors) throw errorCollector.group;
+
+  return unit;
+}
+
 /// Converts an AST node representing a string literal into a [String].
 String stringLiteralToString(StringLiteral literal) {
   return literal.stringValue;