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//===--- CharUnits.h - Character units for sizes and offsets ----*- C++ -*-===//

//

// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.

// See https://llvm.org/LICENSE.txt for license information.

// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

//

//===----------------------------------------------------------------------===//

//

//  This file defines the CharUnits class

//

//===----------------------------------------------------------------------===//

#ifndef LLVM_CLANG_AST_CHARUNITS_H

#define LLVM_CLANG_AST_CHARUNITS_H

#include "llvm/ADT/DenseMapInfo.h"

#include "llvm/Support/Alignment.h"

#include "llvm/Support/DataTypes.h"

#include "llvm/Support/MathExtras.h"

namespace clang {

  /// CharUnits - This is an opaque type for sizes expressed in character units.

  /// Instances of this type represent a quantity as a multiple of the size

  /// of the standard C type, char, on the target architecture. As an opaque

  /// type, CharUnits protects you from accidentally combining operations on

  /// quantities in bit units and character units.

  ///

  /// In both C and C++, an object of type 'char', 'signed char', or 'unsigned

  /// char' occupies exactly one byte, so 'character unit' and 'byte' refer to

  /// the same quantity of storage. However, we use the term 'character unit'

  /// rather than 'byte' to avoid an implication that a character unit is

  /// exactly 8 bits.

  ///

  /// For portability, never assume that a target character is 8 bits wide. Use

  /// CharUnit values wherever you calculate sizes, offsets, or alignments

  /// in character units.

  class CharUnits {

    public:

      typedef int64_t QuantityType;

    private:

      QuantityType Quantity = 0;

      explicit CharUnits(QuantityType C) : Quantity(C) {}

    public:

      /// CharUnits - A default constructor.

      CharUnits() = default;

      /// Zero - Construct a CharUnits quantity of zero.

      static CharUnits Zero() {

        return CharUnits(0);

      }

      /// One - Construct a CharUnits quantity of one.

      static CharUnits One() {

        return CharUnits(1);

      }

      /// fromQuantity - Construct a CharUnits quantity from a raw integer type.

      static CharUnits fromQuantity(QuantityType Quantity) {

        return CharUnits(Quantity);

      }

      /// fromQuantity - Construct a CharUnits quantity from an llvm::Align

      /// quantity.

      static CharUnits fromQuantity(llvm::Align Quantity) {

        return CharUnits(Quantity.value());

      }

      // Compound assignment.

      CharUnits& operator+= (const CharUnits &Other) {

        Quantity += Other.Quantity;

        return *this;

      }

      CharUnits& operator++ () {

        ++Quantity;

        return *this;

      }

      CharUnits operator++ (int) {

        return CharUnits(Quantity++);

      }

      CharUnits& operator-= (const CharUnits &Other) {

        Quantity -= Other.Quantity;

        return *this;

      }

      CharUnits& operator-- () {

        --Quantity;

        return *this;

      }

      CharUnits operator-- (int) {

        return CharUnits(Quantity--);

      }

      // Comparison operators.

      bool operator== (const CharUnits &Other) const {

        return Quantity == Other.Quantity;

      }

      bool operator!= (const CharUnits &Other) const {

        return Quantity != Other.Quantity;

      }

      // Relational operators.

      bool operator<  (const CharUnits &Other) const {

        return Quantity <  Other.Quantity;

      }

      bool operator<= (const CharUnits &Other) const {

        return Quantity <= Other.Quantity;

      }

      bool operator>  (const CharUnits &Other) const {

        return Quantity >  Other.Quantity;

      }

      bool operator>= (const CharUnits &Other) const {

        return Quantity >= Other.Quantity;

      }

      // Other predicates.

      /// isZero - Test whether the quantity equals zero.

      bool isZero() const     { return Quantity == 0; }

      /// isOne - Test whether the quantity equals one.

      bool isOne() const      { return Quantity == 1; }

      /// isPositive - Test whether the quantity is greater than zero.

      bool isPositive() const { return Quantity  > 0; }

      /// isNegative - Test whether the quantity is less than zero.

      bool isNegative() const { return Quantity  < 0; }

      /// isPowerOfTwo - Test whether the quantity is a power of two.

      /// Zero is not a power of two.

      bool isPowerOfTwo() const {

        return (Quantity & -Quantity) == Quantity;

      }

      /// Test whether this is a multiple of the other value.

      ///

      /// Among other things, this promises that

      /// self.alignTo(N) will just return self.

      bool isMultipleOf(CharUnits N) const {

        return (*this % N) == 0;

      }

      // Arithmetic operators.

      CharUnits operator* (QuantityType N) const {

        return CharUnits(Quantity * N);

      }

      CharUnits &operator*= (QuantityType N) {

        Quantity *= N;

        return *this;

      }

      CharUnits operator/ (QuantityType N) const {

        return CharUnits(Quantity / N);

      }

      CharUnits &operator/= (QuantityType N) {

        Quantity /= N;

        return *this;

      }

      QuantityType operator/ (const CharUnits &Other) const {

        return Quantity / Other.Quantity;

      }

      CharUnits operator% (QuantityType N) const {

        return CharUnits(Quantity % N);

      }

      QuantityType operator% (const CharUnits &Other) const {

        return Quantity % Other.Quantity;

      }

      CharUnits operator+ (const CharUnits &Other) const {

        return CharUnits(Quantity + Other.Quantity);

      }

      CharUnits operator- (const CharUnits &Other) const {

        return CharUnits(Quantity - Other.Quantity);

      }

      CharUnits operator- () const {

        return CharUnits(-Quantity);

      }

      // Conversions.

      /// getQuantity - Get the raw integer representation of this quantity.

      QuantityType getQuantity() const { return Quantity; }

      /// getAsAlign - Returns Quantity as a valid llvm::Align,

      /// Beware llvm::Align assumes power of two 8-bit bytes.

      llvm::Align getAsAlign() const { return llvm::Align(Quantity); }

      /// getAsMaybeAlign - Returns Quantity as a valid llvm::Align or

      /// std::nullopt, Beware llvm::MaybeAlign assumes power of two 8-bit

      /// bytes.

      llvm::MaybeAlign getAsMaybeAlign() const {

        return llvm::MaybeAlign(Quantity);

      }

      /// alignTo - Returns the next integer (mod 2**64) that is

      /// greater than or equal to this quantity and is a multiple of \p Align.

      /// Align must be non-zero.

      CharUnits alignTo(const CharUnits &Align) const {

        return CharUnits(llvm::alignTo(Quantity, Align.Quantity));

      }

      /// Given that this is a non-zero alignment value, what is the

      /// alignment at the given offset?

      CharUnits alignmentAtOffset(CharUnits offset) const {

        assert(Quantity != 0 && "offsetting from unknown alignment?");

        return CharUnits(llvm::MinAlign(Quantity, offset.Quantity));

      }

      /// Given that this is the alignment of the first element of an

      /// array, return the minimum alignment of any element in the array.

      CharUnits alignmentOfArrayElement(CharUnits elementSize) const {

        // Since we don't track offsetted alignments, the alignment of

        // the second element (or any odd element) will be minimally

        // aligned.

        return alignmentAtOffset(elementSize);

      }

  }; // class CharUnit

} // namespace clang

inline clang::CharUnits operator* (clang::CharUnits::QuantityType Scale,

                                   const clang::CharUnits &CU) {

  return CU * Scale;

}

namespace llvm {

template<> struct DenseMapInfo<clang::CharUnits> {

  static clang::CharUnits getEmptyKey() {

    clang::CharUnits::QuantityType Quantity =

      DenseMapInfo<clang::CharUnits::QuantityType>::getEmptyKey();

    return clang::CharUnits::fromQuantity(Quantity);

  }

  static clang::CharUnits getTombstoneKey() {

    clang::CharUnits::QuantityType Quantity =

      DenseMapInfo<clang::CharUnits::QuantityType>::getTombstoneKey();

    return clang::CharUnits::fromQuantity(Quantity);

  }

  static unsigned getHashValue(const clang::CharUnits &CU) {

    clang::CharUnits::QuantityType Quantity = CU.getQuantity();

    return DenseMapInfo<clang::CharUnits::QuantityType>::getHashValue(Quantity);

  }

  static bool isEqual(const clang::CharUnits &LHS,

                      const clang::CharUnits &RHS) {

    return LHS == RHS;

  }

};

} // end namespace llvm

#endif // LLVM_CLANG_AST_CHARUNITS_H