Handle multiline interpolated strings in line-based scanner.

dart/site/try/src/interaction_manager.dart

 // Copyright (c) 2014, 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.
 
 library trydart.interaction_manager;
 
 import 'dart:html';
 
 import 'dart:convert' show
     JSON;
 
 import 'dart:math' show
     max,
     min;
 
 import 'dart:async' show
     Completer,
     Future,
     Timer;
 
 import 'dart:collection' show
     Queue;
 
 import 'package:compiler/implementation/scanner/scannerlib.dart' show
     BeginGroupToken,
     EOF_TOKEN,
     ErrorToken,
+    STRING_INTERPOLATION_IDENTIFIER_TOKEN,
+    STRING_INTERPOLATION_TOKEN,
+    STRING_TOKEN,
     StringScanner,
     Token,
     UnmatchedToken,
     UnterminatedToken;
 
 import 'package:compiler/implementation/source_file.dart' show
     StringSourceFile;
 
+import 'package:compiler/implementation/string_validator.dart' show
+    StringValidator;
+
+import 'package:compiler/implementation/tree/tree.dart' show
+    StringQuoting;
+
 import 'compilation.dart' show
     currentSource,
     startCompilation;
 
 import 'ui.dart' show
     currentTheme,
     hackDiv,
     mainEditorPane,
     observer,
     outputDiv,
@@ skipping 1082 matching lines @@
 
     Token tokenToDecorate = token;
     if (token is UnterminatedToken && isUnterminatedMultiLineToken(token)) {
       newState += '${token.start}';
       continue; // This might not be an error.
     } else {
       Token follow = token.next;
       if (token is BeginGroupToken && token.endGroup != null) {
         follow = token.endGroup.next;
       }
+      if (token.kind == STRING_TOKEN) {
+        follow = followString(follow);
+        if (follow is UnmatchedToken) {
+          if ('${follow.begin.value}' == r'${') {
+            newState += '${extractQuote(token.value)}';
+          }
+        }
+      }
       if (follow is ErrorToken && follow.charOffset == token.charOffset) {
         if (follow is UnmatchedToken) {
           newState += '${follow.begin.value}';
         } else {
           tokenToDecorate = follow;
         }
       }
     }
 
     if (charOffset < offset) {
@@ skipping 127 matching lines @@
     // Safari can also reach this code, but the offset isn't wrong, just
     // inconsistent.  After moving the cursor back and forth, Safari will make
     // the offset relative to a text node.
     selection
         ..modify('move', 'backward', 'character')
         ..modify('move', 'forward', 'character');
     print('Selection adjusted $node@$offset -> '
           '${selection.anchorNode}@${selection.anchorOffset}.');
   }
 }
+
+/// Compute the token following a string. Compare to parseSingleLiteralString
+/// in parser.dart.
+Token followString(Token token) {
+  // TODO(ahe): I should be able to get rid of this if I change the scanner to
+  // create BeginGroupToken for strings.
+  int kind = token.kind;
+  while (kind != EOF_TOKEN) {
+    if (kind == STRING_INTERPOLATION_TOKEN) {
+      // Looking at ${expression}.
+      BeginGroupToken begin = token;
+      token = begin.endGroup.next;
+    } else if (kind == STRING_INTERPOLATION_IDENTIFIER_TOKEN) {
+      // Looking at $identifier.

[kasperl, 2014/07/07 11:16:39]

So token is $ and token.next is the identifier and token.next.next is the
"string" that follows a string interpolation identifier token. Is there a next
too many here? Maybe add a comment if this is correct.

[ahe, 2014/07/09 10:11:13]

Good catch!

+      token = token.next.next.next;
+    } else {
+      return token;
+    }
+    kind = token.kind;
+    if (kind != STRING_TOKEN) return token;
+    token = token.next;
+    kind = token.kind;
+  }
+  return token;
+}
+
+String extractQuote(String string) {

[kasperl, 2014/07/07 11:16:39]

Would this fit better in the StringQuoting implementation?

[ahe, 2014/07/09 10:11:13]

Perhaps, but dart2js wouldn't use it.

+  StringQuoting q = StringValidator.quotingFromString(string);
+  return (q.raw ? 'r' : '') + (q.quoteChar * q.leftQuoteLength);
+}