Implement experimental exponentiation operator

src/scanner.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Features shared by parsing and pre-parsing scanners.
 
 #include <stdint.h>
 
 #include <cmath>
 
@@ skipping 22 matching lines @@
 // Scanner
 
 Scanner::Scanner(UnicodeCache* unicode_cache)
     : unicode_cache_(unicode_cache),
       octal_pos_(Location::invalid()),
       harmony_scoping_(false),
       harmony_modules_(false),
       harmony_numeric_literals_(false),
       harmony_classes_(false),
       harmony_templates_(false),
-      harmony_unicode_(false) {}
+      harmony_unicode_(false),
+      harmony_exponentiation_(false) {}
 
 
 void Scanner::Initialize(Utf16CharacterStream* source) {
   source_ = source;
   // Need to capture identifiers in order to recognize "get" and "set"
   // in object literals.
   Init();
   // Skip initial whitespace allowing HTML comment ends just like
   // after a newline and scan first token.
   has_line_terminator_before_next_ = true;
@@ skipping 472 matching lines @@
             token = Token::DEC;
           }
         } else if (c0_ == '=') {
           token = Select(Token::ASSIGN_SUB);
         } else {
           token = Token::SUB;
         }
         break;
 
       case '*':
-        // * *=
-        token = Select('=', Token::ASSIGN_MUL, Token::MUL);
+        // * *= ** **=
+        Advance();
+        if (c0_ == '*') {
+          if (HarmonyExponentiation()) {
+            token = Select('=', Token::ASSIGN_EXP, Token::EXP);
+          } else {
+            token = Token::ILLEGAL;
+          }
+        } else if (c0_ == '=') {
+          token = Select(Token::ASSIGN_MUL);
+        } else {
+          token = Token::MUL;
+        }
         break;
 
       case '%':
         // % %=
         token = Select('=', Token::ASSIGN_MOD, Token::MOD);
         break;
 
       case '/':
         // /  // /* /=
         Advance();
@@ skipping 939 matching lines @@
     }
     backing_store_.Add(static_cast<uint8_t>((one_byte_length >> 7) | 0x80u));
   }
   backing_store_.Add(static_cast<uint8_t>(one_byte_length & 0x7f));
 
   backing_store_.AddBlock(bytes);
   return backing_store_.EndSequence().start();
 }
 
 } }  // namespace v8::internal