Allow surrogates in string literals.

pkg/compiler/lib/src/string_validator.dart

 // Copyright (c) 2012, 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.
 
 // Check the validity of string literals.
 
 library stringvalidator;
 
 import 'dart:collection';
 
@@ skipping 93 matching lines @@
   }
 
   /**
    * Validates the escape sequences and special characters of a string literal.
    * Returns a DartString if valid, and null if not.
    */
   DartString validateString(
       Token token, int startOffset, String string, StringQuoting quoting) {
     // We need to check for invalid x and u escapes, for line
     // terminators in non-multiline strings, and for invalid Unicode
-    // scalar values (either directly or as u-escape values).  We also check
-    // for unpaired UTF-16 surrogates.
+    // code points (either directly or as u-escape values).
     int length = 0;
     int index = startOffset;
     bool containsEscape = false;
-    bool previousWasLeadSurrogate = false;
-    bool invalidUtf16 = false;
     var stringIter = string.codeUnits.iterator;
     for (HasNextIterator<int> iter = new HasNextIterator(stringIter);
         iter.hasNext;
         length++) {
       index++;
       int code = iter.next();
       if (code == $BACKSLASH) {
         if (quoting.raw) continue;
         containsEscape = true;
         if (!iter.hasNext) {
@@ skipping 61 matching lines @@
                 stringParseError(
                     "Invalid character in escape sequence", token, index);
                 return null;
               }
               value = value * 16 + hexDigitValue(code);
             }
           }
           code = value;
         }
       }
-      if (code >= 0x10000) length++;
-      // This handles both unescaped characters and the value of unicode
-      // escapes.
-      if (previousWasLeadSurrogate) {
-        if (!isUtf16TrailSurrogate(code)) {
-          invalidUtf16 = true;
-          break;
+      if (code >= 0x10000) {
+        length++;
+        if (code > 0x10FFFF) {
+          stringParseError("Invalid code point", token, index);
         }
-        previousWasLeadSurrogate = false;
-      } else if (isUtf16LeadSurrogate(code)) {
-        previousWasLeadSurrogate = true;
-      } else if (!isUnicodeScalarValue(code)) {
-        invalidUtf16 = true;
-        break;
       }
     }
-    if (previousWasLeadSurrogate || invalidUtf16) {
-      stringParseError("Invalid Utf16 surrogate", token, index);
-      return null;
-    }
     // String literal successfully validated.
     if (quoting.raw || !containsEscape) {
       // A string without escapes could just as well have been raw.
       return new DartString.rawString(string, length);
     }
     return new DartString.escapedString(string, length);
   }
 }