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364 lines
8.9 KiB
C++
364 lines
8.9 KiB
C++
//===- llvm/ADT/BitVector.h - Bit vectors -----------------------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file was developed by Evan Cheng and is distributed under
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// the University of Illinois Open Source License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the BitVector class.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_ADT_BITVECTOR_H
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#define LLVM_ADT_BITVECTOR_H
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#include "llvm/Support/MathExtras.h"
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#include <algorithm>
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#include <cstdlib>
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#include <cassert>
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namespace llvm {
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class BitVector {
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typedef unsigned long BitWord;
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enum { BITWORD_SIZE = sizeof(BitWord) * 8 };
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BitWord *Bits; // Actual bits.
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unsigned Size; // Size of bitvector in bits.
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unsigned Capacity; // Size of allocated memory in BitWord.
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public:
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// Encapsulation of a single bit.
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class reference {
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friend class BitVector;
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BitWord *WordRef;
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unsigned BitPos;
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reference(); // Undefined
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public:
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reference(BitVector &b, unsigned Idx) {
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WordRef = &b.Bits[Idx / BITWORD_SIZE];
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BitPos = Idx % BITWORD_SIZE;
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}
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~reference() {}
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reference& operator=(bool t) {
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if (t)
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*WordRef |= 1L << BitPos;
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else
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*WordRef &= ~(1L << BitPos);
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return *this;
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}
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operator bool() const {
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return (*WordRef) & (1L << BitPos);
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}
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};
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/// BitVector default ctor - Creates an empty bitvector.
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BitVector() : Size(0), Capacity(0) {
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Bits = NULL;
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}
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/// BitVector ctor - Creates a bitvector of specified number of bits. All
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/// bits are initialized to the specified value.
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explicit BitVector(unsigned s, bool t = false) : Size(s) {
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Capacity = NumBitWords(s);
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Bits = new BitWord[Capacity];
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init_words(Bits, Capacity, t);
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if (t)
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clear_unused_bits();
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}
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/// BitVector copy ctor.
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BitVector(const BitVector &RHS) : Size(RHS.size()) {
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if (Size == 0) {
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Bits = NULL;
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Capacity = 0;
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return;
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}
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Capacity = NumBitWords(RHS.size());
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Bits = new BitWord[Capacity];
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std::copy(RHS.Bits, &RHS.Bits[Capacity], Bits);
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}
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~BitVector() {
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delete[] Bits;
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}
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/// size - Returns the number of bits in this bitvector.
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unsigned size() const { return Size; }
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/// count - Returns the number of bits which are set.
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unsigned count() const {
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unsigned NumBits = 0;
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for (unsigned i = 0; i < NumBitWords(size()); ++i)
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if (sizeof(BitWord) == 4)
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NumBits += CountPopulation_32(Bits[i]);
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else if (sizeof(BitWord) == 8)
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NumBits += CountPopulation_64(Bits[i]);
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else
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assert(0 && "Unsupported!");
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return NumBits;
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}
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/// any - Returns true if any bit is set.
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bool any() const {
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for (unsigned i = 0; i < NumBitWords(size()); ++i)
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if (Bits[i] != 0)
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return true;
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return false;
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}
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/// none - Returns true if none of the bits are set.
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bool none() const {
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return !any();
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}
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/// find_first - Returns the index of the first set bit, -1 if none
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/// of the bits are set.
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int find_first() const {
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for (unsigned i = 0; i < NumBitWords(size()); ++i)
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if (Bits[i] != 0) {
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if (sizeof(BitWord) == 4)
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return i * BITWORD_SIZE + CountTrailingZeros_32(Bits[i]);
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else if (sizeof(BitWord) == 8)
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return i * BITWORD_SIZE + CountTrailingZeros_64(Bits[i]);
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else
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assert(0 && "Unsupported!");
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}
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return -1;
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}
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/// find_next - Returns the index of the next set bit following the
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/// "Prev" bit. Returns -1 if the next set bit is not found.
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int find_next(unsigned Prev) const {
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++Prev;
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if (Prev >= Size)
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return -1;
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unsigned WordPos = Prev / BITWORD_SIZE;
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unsigned BitPos = Prev % BITWORD_SIZE;
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BitWord Copy = Bits[WordPos];
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// Mask off previous bits.
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Copy &= ~0L << BitPos;
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if (Copy != 0) {
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if (sizeof(BitWord) == 4)
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return WordPos * BITWORD_SIZE + CountTrailingZeros_32(Copy);
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else if (sizeof(BitWord) == 8)
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return WordPos * BITWORD_SIZE + CountTrailingZeros_64(Copy);
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else
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assert(0 && "Unsupported!");
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}
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// Check subsequent words.
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for (unsigned i = WordPos+1; i < NumBitWords(size()); ++i)
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if (Bits[i] != 0) {
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if (sizeof(BitWord) == 4)
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return i * BITWORD_SIZE + CountTrailingZeros_32(Bits[i]);
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else if (sizeof(BitWord) == 8)
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return i * BITWORD_SIZE + CountTrailingZeros_64(Bits[i]);
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else
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assert(0 && "Unsupported!");
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}
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return -1;
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}
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/// clear - Clear all bits.
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void clear() {
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Size = 0;
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}
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/// resize - Grow or shrink the bitvector.
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void resize(unsigned N, bool t = false) {
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if (N > Capacity * BITWORD_SIZE) {
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unsigned OldCapacity = Capacity;
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grow(N);
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init_words(&Bits[OldCapacity], (Capacity-OldCapacity), t);
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}
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Size = N;
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clear_unused_bits();
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}
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void reserve(unsigned N) {
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if (N > Capacity * BITWORD_SIZE)
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grow(N);
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}
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// Set, reset, flip
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BitVector &set() {
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init_words(Bits, Capacity, true);
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clear_unused_bits();
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return *this;
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}
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BitVector &set(unsigned Idx) {
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Bits[Idx / BITWORD_SIZE] |= 1L << (Idx % BITWORD_SIZE);
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return *this;
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}
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BitVector &reset() {
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init_words(Bits, Capacity, false);
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return *this;
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}
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BitVector &reset(unsigned Idx) {
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Bits[Idx / BITWORD_SIZE] &= ~(1L << (Idx % BITWORD_SIZE));
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return *this;
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}
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BitVector &flip() {
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for (unsigned i = 0; i < NumBitWords(size()); ++i)
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Bits[i] = ~Bits[i];
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clear_unused_bits();
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return *this;
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}
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BitVector &flip(unsigned Idx) {
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Bits[Idx / BITWORD_SIZE] ^= 1L << (Idx % BITWORD_SIZE);
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return *this;
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}
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// No argument flip.
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BitVector operator~() const {
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return BitVector(*this).flip();
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}
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// Indexing.
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reference operator[](unsigned Idx) {
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return reference(*this, Idx);
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}
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bool operator[](unsigned Idx) const {
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BitWord Mask = 1L << (Idx % BITWORD_SIZE);
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return (Bits[Idx / BITWORD_SIZE] & Mask) != 0;
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}
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bool test(unsigned Idx) const {
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return (*this)[Idx];
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}
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// Comparison operators.
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bool operator==(const BitVector &RHS) const {
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if (Size != RHS.Size)
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return false;
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for (unsigned i = 0; i < NumBitWords(size()); ++i)
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if (Bits[i] != RHS.Bits[i])
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return false;
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return true;
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}
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bool operator!=(const BitVector &RHS) const {
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return !(*this == RHS);
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}
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// Intersection, union, disjoint union.
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BitVector operator&=(const BitVector &RHS) {
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assert(Size == RHS.Size && "Illegal operation!");
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for (unsigned i = 0; i < NumBitWords(size()); ++i)
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Bits[i] &= RHS.Bits[i];
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return *this;
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}
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BitVector operator|=(const BitVector &RHS) {
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assert(Size == RHS.Size && "Illegal operation!");
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for (unsigned i = 0; i < NumBitWords(size()); ++i)
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Bits[i] |= RHS.Bits[i];
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return *this;
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}
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BitVector operator^=(const BitVector &RHS) {
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assert(Size == RHS.Size && "Illegal operation!");
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for (unsigned i = 0; i < NumBitWords(size()); ++i)
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Bits[i] ^= RHS.Bits[i];
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return *this;
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}
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// Assignment operator.
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const BitVector &operator=(const BitVector &RHS) {
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if (this == &RHS) return *this;
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Size = RHS.size();
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unsigned RHSWords = NumBitWords(Size);
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if (Size <= Capacity * BITWORD_SIZE) {
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std::copy(RHS.Bits, &RHS.Bits[RHSWords], Bits);
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clear_unused_bits();
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return *this;
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}
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// Grow the bitvector to have enough elements.
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Capacity = NumBitWords(Size);
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BitWord *NewBits = new BitWord[Capacity];
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std::copy(RHS.Bits, &RHS.Bits[RHSWords], NewBits);
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// Destroy the old bits.
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delete[] Bits;
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Bits = NewBits;
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return *this;
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}
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private:
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unsigned NumBitWords(unsigned S) const {
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return (S + BITWORD_SIZE-1) / BITWORD_SIZE;
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}
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// Clear the unused top bits in the high word.
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void clear_unused_bits() {
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unsigned ExtraBits = Size % BITWORD_SIZE;
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if (ExtraBits) {
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unsigned index = Size / BITWORD_SIZE;
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Bits[index] &= ~(~0L << ExtraBits);
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}
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}
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void grow(unsigned NewSize) {
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unsigned OldCapacity = Capacity;
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Capacity = NumBitWords(NewSize);
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BitWord *NewBits = new BitWord[Capacity];
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// Copy the old bits over.
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if (OldCapacity != 0)
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std::copy(Bits, &Bits[OldCapacity], NewBits);
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// Destroy the old bits.
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delete[] Bits;
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Bits = NewBits;
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}
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void init_words(BitWord *B, unsigned NumWords, bool t) {
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memset(B, 0 - (int)t, NumWords*sizeof(BitWord));
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}
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};
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inline BitVector operator&(const BitVector &LHS, const BitVector &RHS) {
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BitVector Result(LHS);
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Result &= RHS;
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return Result;
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}
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inline BitVector operator|(const BitVector &LHS, const BitVector &RHS) {
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BitVector Result(LHS);
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Result |= RHS;
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return Result;
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}
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inline BitVector operator^(const BitVector &LHS, const BitVector &RHS) {
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BitVector Result(LHS);
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Result ^= RHS;
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return Result;
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}
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} // End llvm namespace
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#endif
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