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//===- llvm/ADT/SetVector.h - Set with insert order iteration ---*- C++ -*-===//
// The LLVM Compiler Infrastructure
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
// This file implements a set that has insertion order iteration
// characteristics. This is useful for keeping a set of things that need to be
// visited later but in a deterministic order (insertion order). The interface
// is purposefully minimal.
// This file defines SetVector and SmallSetVector, which performs no allocations
// if the SetVector has less than a certain number of elements.
#include "llvm/ADT/SmallSet.h"
#include <algorithm>
#include <cassert>
#include <vector>
namespace llvm {
/// \brief A vector that has set insertion semantics.
/// This adapter class provides a way to keep a set of things that also has the
/// property of a deterministic iteration order. The order of iteration is the
/// order of insertion.
template <typename T, typename Vector = std::vector<T>,
typename Set = SmallSet<T, 16> >
class SetVector {
typedef T value_type;
typedef T key_type;
typedef T& reference;
typedef const T& const_reference;
typedef Set set_type;
typedef Vector vector_type;
typedef typename vector_type::const_iterator iterator;
typedef typename vector_type::const_iterator const_iterator;
typedef typename vector_type::size_type size_type;
/// \brief Construct an empty SetVector
SetVector() {}
/// \brief Initialize a SetVector with a range of elements
template<typename It>
SetVector(It Start, It End) {
insert(Start, End);
/// \brief Determine if the SetVector is empty or not.
bool empty() const {
return vector_.empty();
/// \brief Determine the number of elements in the SetVector.
size_type size() const {
return vector_.size();
/// \brief Get an iterator to the beginning of the SetVector.
iterator begin() {
return vector_.begin();
/// \brief Get a const_iterator to the beginning of the SetVector.
const_iterator begin() const {
return vector_.begin();
/// \brief Get an iterator to the end of the SetVector.
iterator end() {
return vector_.end();
/// \brief Get a const_iterator to the end of the SetVector.
const_iterator end() const {
return vector_.end();
/// \brief Return the last element of the SetVector.
const T &back() const {
assert(!empty() && "Cannot call back() on empty SetVector!");
return vector_.back();
/// \brief Index into the SetVector.
const_reference operator[](size_type n) const {
assert(n < vector_.size() && "SetVector access out of range!");
return vector_[n];
/// \brief Insert a new element into the SetVector.
/// \returns true iff the element was inserted into the SetVector.
bool insert(const value_type &X) {
bool result = set_.insert(X);
if (result)
return result;
/// \brief Insert a range of elements into the SetVector.
template<typename It>
void insert(It Start, It End) {
for (; Start != End; ++Start)
if (set_.insert(*Start))
/// \brief Remove an item from the set vector.
bool remove(const value_type& X) {
if (set_.erase(X)) {
typename vector_type::iterator I =
std::find(vector_.begin(), vector_.end(), X);
assert(I != vector_.end() && "Corrupted SetVector instances!");
return true;
return false;
/// \brief Remove items from the set vector based on a predicate function.
/// This is intended to be equivalent to the following code, if we could
/// write it:
/// \code
/// V.erase(std::remove_if(V.begin(), V.end(), P), V.end());
/// \endcode
/// However, SetVector doesn't expose non-const iterators, making any
/// algorithm like remove_if impossible to use.
/// \returns true if any element is removed.
template <typename UnaryPredicate>
bool remove_if(UnaryPredicate P) {
typename vector_type::iterator I
= std::remove_if(vector_.begin(), vector_.end(),
TestAndEraseFromSet<UnaryPredicate>(P, set_));
if (I == vector_.end())
return false;
vector_.erase(I, vector_.end());
return true;
/// \brief Count the number of elements of a given key in the SetVector.
/// \returns 0 if the element is not in the SetVector, 1 if it is.
size_type count(const key_type &key) const {
return set_.count(key);
/// \brief Completely clear the SetVector
void clear() {
/// \brief Remove the last element of the SetVector.
void pop_back() {
assert(!empty() && "Cannot remove an element from an empty SetVector!");
T Ret = back();
return Ret;
bool operator==(const SetVector &that) const {
return vector_ == that.vector_;
bool operator!=(const SetVector &that) const {
return vector_ != that.vector_;
/// \brief A wrapper predicate designed for use with std::remove_if.
/// This predicate wraps a predicate suitable for use with std::remove_if to
/// call set_.erase(x) on each element which is slated for removal.
template <typename UnaryPredicate>
class TestAndEraseFromSet {
UnaryPredicate P;
set_type &set_;
TestAndEraseFromSet(UnaryPredicate P, set_type &set_) : P(P), set_(set_) {}
template <typename ArgumentT>
bool operator()(const ArgumentT &Arg) {
if (P(Arg)) {
return true;
return false;
set_type set_; ///< The set.
vector_type vector_; ///< The vector.
/// \brief A SetVector that performs no allocations if smaller than
/// a certain size.
template <typename T, unsigned N>
class SmallSetVector : public SetVector<T, SmallVector<T, N>, SmallSet<T, N> > {
SmallSetVector() {}
/// \brief Initialize a SmallSetVector with a range of elements
template<typename It>
SmallSetVector(It Start, It End) {
this->insert(Start, End);
} // End llvm namespace
// vim: sw=2 ai