Implement string interpolation up to SSA.

dart/frog/leg/scanner/parser.dart

 // Copyright (c) 2011, 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.
 
 /**
  * An event generating parser of Dart programs. This parser expects
  * all tokens in a linked list.
  */
 class Parser {
   final Listener listener;
@@ skipping 1041 matching lines @@
     } else if (optional('[]', token)) {
       listener.handleLiteralList(0, token, constKeyword, token);
       return token.next;
     } else {
       listener.unexpected(token);
     }
   }
 
   Token parseMapLiteralEntry(Token token) {
     listener.beginLiteralMapEntry(token);
-    token = parseString(token);
+    // Assume the listener rejects non-string keys.
+    token = parseExpression(token);
     token = expect(':', token);
     token = parseExpression(token);
     listener.endLiteralMapEntry(token);
     return token;
   }
 
   Token parseSendOrFunctionLiteral(Token token) {
     if (!mayParseFunctionExpressions) return parseSend(token);
     Token peek = peekAfterType(token);
     if (peek.kind === IDENTIFIER_TOKEN && isFunctionDeclaration(peek.next)) {
@@ skipping 57 matching lines @@
   }
 
   Token parseLiteralDouble(Token token) {
     listener.handleLiteralDouble(token);
     return token.next;
   }
 
   Token parseLiteralString(Token token) {
     listener.handleLiteralString(token);
     token = token.next;
+    int interpolationCount = 0;
     while (optional('\${', token)) {
       token = parseExpression(token.next);
       token = expect('}', token);
       token = parseString(token);
-      listener.handleStringInterpolationPart(token);
+      ++interpolationCount;
     }
+    listener.handleStringInterpolationParts(interpolationCount);
     return token;
   }
 
   Token parseLiteralBool(Token token) {
     listener.handleLiteralBool(token);
     return token.next;
   }
 
   Token parseLiteralNull(Token token) {
     listener.handleLiteralNull(token);
@@ skipping 301 matching lines @@
     }
     listener.handleContinueStatement(hasTarget, continueKeyword, token);
     return expectSemicolon(token);
   }
 
   Token parseEmptyStatement(Token token) {
     listener.handleEmptyStatement(token);
     return expectSemicolon(token);
   }
 }