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The Tor Browser
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TypeofEqOperand.h (1422B)


      1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
      2 * vim: set ts=8 sts=2 et sw=2 tw=80:
      3 * This Source Code Form is subject to the terms of the Mozilla Public
      4 * License, v. 2.0. If a copy of the MPL was not distributed with this
      5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
      6 
      7 #ifndef vm_TypeofEqOperand_h
      8 #define vm_TypeofEqOperand_h
      9 
     10 #include "mozilla/Assertions.h"  // MOZ_ASSERT
     11 
     12 #include <stdint.h>  // uint8_t
     13 
     14 #include "jspubtd.h"     // JSType
     15 #include "vm/Opcodes.h"  // JSOp
     16 
     17 namespace js {
     18 
     19 struct TypeofEqOperand {
     20  static constexpr uint8_t TYPE_MASK = 0x0f;
     21  static constexpr uint8_t NEQ_BIT = 0x80;
     22 
     23 private:
     24  uint8_t value;
     25 
     26  static uint8_t toNeqBit(JSOp compareOp) {
     27    MOZ_ASSERT(compareOp == JSOp::Eq || compareOp == JSOp::Ne);
     28    return compareOp == JSOp::Ne ? NEQ_BIT : 0;
     29  }
     30 
     31  explicit TypeofEqOperand(uint8_t value) : value(value) {}
     32 
     33 public:
     34  TypeofEqOperand(JSType type, JSOp compareOp)
     35      : value(type | toNeqBit(compareOp)) {}
     36 
     37  static TypeofEqOperand fromRawValue(uint8_t value) {
     38    return TypeofEqOperand(value);
     39  }
     40 
     41  JSType type() const { return JSType(value & TYPE_MASK); }
     42  JSOp compareOp() const { return (value & NEQ_BIT) ? JSOp::Ne : JSOp::Eq; }
     43  uint8_t rawValue() const { return value; }
     44 };
     45 
     46 static_assert((JSTYPE_LIMIT & TypeofEqOperand::TYPE_MASK) == JSTYPE_LIMIT);
     47 
     48 }  // namespace js
     49 
     50 #endif  // vm_TypeofEqOperand_h