Implement ES6 unicode escapes.

src/parser.cc

Index: src/parser.cc
diff --git a/src/parser.cc b/src/parser.cc
index e34854fe7adacd564655429abd05a62caa2d4b20..81b1ca41d8d6bae2ea3a99eba2dae413ded30a9a 100644
--- a/src/parser.cc
+++ b/src/parser.cc
@@ -4479,7 +4479,7 @@ RegExpTree* RegExpParser::ParseDisjunction() {
       case 'u': {
         Advance(2);
         uc32 value;
-        if (ParseHexEscape(4, &value)) {
+        if (ParseUnicodeEscape(&value)) {
           builder->AddCharacter(value);
         } else {
           builder->AddCharacter('u');
@@ -4732,11 +4732,10 @@ uc32 RegExpParser::ParseOctalLiteral() {
 }
 
 
-bool RegExpParser::ParseHexEscape(int length, uc32 *value) {
+bool RegExpParser::ParseHexEscape(int length, uc32* value) {
   int start = position();
   uc32 val = 0;
-  bool done = false;
-  for (int i = 0; !done; i++) {
+  for (int i = 0; i < length; ++i) {
     uc32 c = current();
     int d = HexValue(c);
     if (d < 0) {
@@ -4745,8 +4744,48 @@ bool RegExpParser::ParseHexEscape(int length, uc32 *value) {
     }
     val = val * 16 + d;
     Advance();
-    if (i == length - 1) {
-      done = true;
+  }
+  *value = val;
+  return true;
+}
+
+
+bool RegExpParser::ParseUnicodeEscape(uc32* value) {
+  if (current() == '{') {
+    int start = position();
+    Advance();
+    if (ParseUnlimitedLengthHexEscape(0x10ffff, value)) {
+      if (current() == '}') {
+        Advance();
+        return true;
+      }
+      Reset(start);
+      return false;
+    }
+    // Parsing the hex number failed.
+    Reset(start);
+    return false;
+  }
+  // \u but no {
+  return ParseHexEscape(4, value);
+}
+
+
+bool RegExpParser::ParseUnlimitedLengthHexEscape(int max_value, uc32* value) {
+  int start = position();
+  uc32 val = 0;
+  int d = HexValue(current());
+  if (d < 0) {
+    Reset(start);
+    return false;
+  }
+  while (d >= 0) {
+    val = val * 16 + d;
+    Advance();
+    d = HexValue(current());
+    if (val > max_value) {
+      Reset(start);
+      return false;
     }
   }
   *value = val;
@@ -4815,11 +4854,12 @@ uc32 RegExpParser::ParseClassCharacterEscape() {
     case 'u': {
       Advance();
       uc32 value;
-      if (ParseHexEscape(4, &value)) {
+      if (ParseUnicodeEscape(&value)) {
+        fprintf(stderr, "worked; returning code point %d\n", value);
         return value;
       }
-      // If \u is not followed by a four-digit hexadecimal, treat it
-      // as an identity escape.
+      // If \u is not followed by a legal hex decimal sequence, treat it as an
+      // identity escape.
       return 'u';
     }
     default: {