SPIRV-Tools/source/opt/iterator.h

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// Copyright (c) 2016 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#ifndef LIBSPIRV_OPT_ITERATOR_H_
#define LIBSPIRV_OPT_ITERATOR_H_
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#include <cstddef> // for ptrdiff_t
#include <iterator>
#include <memory>
#include <type_traits>
#include <vector>
namespace spvtools {
namespace opt {
// An ad hoc iterator class for std::vector<std::unique_ptr<|ValueType|>>. The
// purpose of this iterator class is to provide transparent access to those
// std::unique_ptr managed elements in the vector, behaving like we are using
// std::vector<|ValueType|>.
template <typename ValueType, bool IsConst = false>
class UptrVectorIterator
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: public std::iterator<std::random_access_iterator_tag,
typename std::conditional<IsConst, const ValueType,
ValueType>::type> {
public:
using super = std::iterator<
std::random_access_iterator_tag,
typename std::conditional<IsConst, const ValueType, ValueType>::type>;
using pointer = typename super::pointer;
using reference = typename super::reference;
using difference_type = typename super::difference_type;
// Type aliases. We need to apply constness properly if |IsConst| is true.
using Uptr = std::unique_ptr<ValueType>;
using UptrVector = typename std::conditional<IsConst, const std::vector<Uptr>,
std::vector<Uptr>>::type;
using UnderlyingIterator =
typename std::conditional<IsConst, typename UptrVector::const_iterator,
typename UptrVector::iterator>::type;
// Creates a new iterator from the given |container| and its raw iterator
// |it|.
UptrVectorIterator(UptrVector* container, const UnderlyingIterator& it)
: container_(container), iterator_(it) {}
UptrVectorIterator(const UptrVectorIterator&) = default;
UptrVectorIterator& operator=(const UptrVectorIterator&) = default;
inline UptrVectorIterator& operator++();
inline UptrVectorIterator operator++(int);
inline UptrVectorIterator& operator--();
inline UptrVectorIterator operator--(int);
reference operator*() const { return **iterator_; }
pointer operator->() { return (*iterator_).get(); }
reference operator[](ptrdiff_t index) { return **(iterator_ + index); }
inline bool operator==(const UptrVectorIterator& that) const;
inline bool operator!=(const UptrVectorIterator& that) const;
inline ptrdiff_t operator-(const UptrVectorIterator& that) const;
inline bool operator<(const UptrVectorIterator& that) const;
// Inserts the given |value| to the position pointed to by this iterator
// and returns an iterator to the newly iserted |value|.
// If the underlying vector changes capacity, all previous iterators will be
// invalidated. Otherwise, those previous iterators pointing to after the
// insertion point will be invalidated.
template <bool IsConstForMethod = IsConst>
inline typename std::enable_if<!IsConstForMethod, UptrVectorIterator>::type
InsertBefore(Uptr value);
// Inserts the given |valueVector| to the position pointed to by this iterator
// and returns an iterator to the first newly inserted value.
// If the underlying vector changes capacity, all previous iterators will be
// invalidated. Otherwise, those previous iterators pointing to after the
// insertion point will be invalidated.
template <bool IsConstForMethod = IsConst>
inline typename std::enable_if<!IsConstForMethod, UptrVectorIterator>::type
InsertBefore(UptrVector* valueVector);
// Erases the value at the position pointed to by this iterator
// and returns an iterator to the following value.
// If the underlying vector changes capacity, all previous iterators will be
// invalidated. Otherwise, those previous iterators pointing to after the
// erasure point will be invalidated.
template <bool IsConstForMethod = IsConst>
inline typename std::enable_if<!IsConstForMethod, UptrVectorIterator>::type
Erase();
// Returns the underlying iterator.
UnderlyingIterator Get() const { return iterator_; }
// Returns a valid end iterator for the underlying container.
UptrVectorIterator End() const {
return UptrVectorIterator(container_, container_->end());
}
private:
UptrVector* container_; // The container we are manipulating.
UnderlyingIterator iterator_; // The raw iterator from the container.
};
// Handy class for a (begin, end) iterator pair.
template <typename IteratorType>
class IteratorRange {
public:
IteratorRange(const IteratorType& b, const IteratorType& e)
: begin_(b), end_(e) {}
IteratorRange(IteratorType&& b, IteratorType&& e)
: begin_(std::move(b)), end_(std::move(e)) {}
IteratorType begin() const { return begin_; }
IteratorType end() const { return end_; }
bool empty() const { return begin_ == end_; }
size_t size() const { return end_ - begin_; }
private:
IteratorType begin_;
IteratorType end_;
};
// Returns a (begin, end) iterator pair for the given iterators.
// The iterators must belong to the same container.
template <typename IteratorType>
inline IteratorRange<IteratorType> make_range(const IteratorType& begin,
const IteratorType& end) {
return {begin, end};
}
// Returns a (begin, end) iterator pair for the given iterators.
// The iterators must belong to the same container.
template <typename IteratorType>
inline IteratorRange<IteratorType> make_range(IteratorType&& begin,
IteratorType&& end) {
return {std::move(begin), std::move(end)};
}
// Returns a (begin, end) iterator pair for the given container.
template <typename ValueType,
class IteratorType = UptrVectorIterator<ValueType>>
inline IteratorRange<IteratorType> make_range(
std::vector<std::unique_ptr<ValueType>>& container) {
return {IteratorType(&container, container.begin()),
IteratorType(&container, container.end())};
}
// Returns a const (begin, end) iterator pair for the given container.
template <typename ValueType,
class IteratorType = UptrVectorIterator<ValueType, true>>
inline IteratorRange<IteratorType> make_const_range(
const std::vector<std::unique_ptr<ValueType>>& container) {
return {IteratorType(&container, container.cbegin()),
IteratorType(&container, container.cend())};
}
// Wrapping iterator class that only consider elements that satisfy the given
// predicate |Predicate|. When moving to the next element of the iterator, the
// FilterIterator will iterate over the range until it finds an element that
// satisfies |Predicate| or reaches the end of the iterator.
//
// Currently this iterator is always an input iterator.
template <typename SubIterator, typename Predicate>
class FilterIterator
: public std::iterator<
std::input_iterator_tag, typename SubIterator::value_type,
typename SubIterator::difference_type, typename SubIterator::pointer,
typename SubIterator::reference> {
public:
// Iterator interface.
using iterator_category = typename SubIterator::iterator_category;
using value_type = typename SubIterator::value_type;
using pointer = typename SubIterator::pointer;
using reference = typename SubIterator::reference;
using difference_type = typename SubIterator::difference_type;
using Range = IteratorRange<FilterIterator>;
FilterIterator(const IteratorRange<SubIterator>& iteration_range,
Predicate predicate)
: cur_(iteration_range.begin()),
end_(iteration_range.end()),
predicate_(predicate) {
if (!IsPredicateSatisfied()) {
MoveToNextPosition();
}
}
FilterIterator(const SubIterator& end, Predicate predicate)
: FilterIterator({end, end}, predicate) {}
inline FilterIterator& operator++() {
MoveToNextPosition();
return *this;
}
inline FilterIterator operator++(int) {
FilterIterator old = *this;
MoveToNextPosition();
return old;
}
reference operator*() const { return *cur_; }
pointer operator->() { return &*cur_; }
inline bool operator==(const FilterIterator& rhs) const {
return cur_ == rhs.cur_ && end_ == rhs.end_;
}
inline bool operator!=(const FilterIterator& rhs) const {
return !(*this == rhs);
}
// Returns the underlying iterator.
SubIterator Get() const { return cur_; }
// Returns the sentinel iterator.
FilterIterator GetEnd() const { return FilterIterator(end_, predicate_); }
private:
// Returns true if the predicate is satisfied or the current iterator reached
// the end.
bool IsPredicateSatisfied() { return cur_ == end_ || predicate_(*cur_); }
void MoveToNextPosition() {
if (cur_ == end_) return;
do {
++cur_;
} while (!IsPredicateSatisfied());
}
SubIterator cur_;
SubIterator end_;
Predicate predicate_;
};
template <typename SubIterator, typename Predicate>
FilterIterator<SubIterator, Predicate> MakeFilterIterator(
const IteratorRange<SubIterator>& sub_iterator_range, Predicate predicate) {
return FilterIterator<SubIterator, Predicate>(sub_iterator_range, predicate);
}
template <typename SubIterator, typename Predicate>
FilterIterator<SubIterator, Predicate> MakeFilterIterator(
const SubIterator& begin, const SubIterator& end, Predicate predicate) {
return MakeFilterIterator(make_range(begin, end), predicate);
}
template <typename SubIterator, typename Predicate>
typename FilterIterator<SubIterator, Predicate>::Range MakeFilterIteratorRange(
const SubIterator& begin, const SubIterator& end, Predicate predicate) {
return typename FilterIterator<SubIterator, Predicate>::Range(
MakeFilterIterator(begin, end, predicate),
MakeFilterIterator(end, end, predicate));
}
template <typename VT, bool IC>
inline UptrVectorIterator<VT, IC>& UptrVectorIterator<VT, IC>::operator++() {
++iterator_;
return *this;
}
template <typename VT, bool IC>
inline UptrVectorIterator<VT, IC> UptrVectorIterator<VT, IC>::operator++(int) {
auto it = *this;
++(*this);
return it;
}
template <typename VT, bool IC>
inline UptrVectorIterator<VT, IC>& UptrVectorIterator<VT, IC>::operator--() {
--iterator_;
return *this;
}
template <typename VT, bool IC>
inline UptrVectorIterator<VT, IC> UptrVectorIterator<VT, IC>::operator--(int) {
auto it = *this;
--(*this);
return it;
}
template <typename VT, bool IC>
inline bool UptrVectorIterator<VT, IC>::operator==(
const UptrVectorIterator& that) const {
return container_ == that.container_ && iterator_ == that.iterator_;
}
template <typename VT, bool IC>
inline bool UptrVectorIterator<VT, IC>::operator!=(
const UptrVectorIterator& that) const {
return !(*this == that);
}
template <typename VT, bool IC>
inline ptrdiff_t UptrVectorIterator<VT, IC>::operator-(
const UptrVectorIterator& that) const {
assert(container_ == that.container_);
return iterator_ - that.iterator_;
}
template <typename VT, bool IC>
inline bool UptrVectorIterator<VT, IC>::operator<(
const UptrVectorIterator& that) const {
assert(container_ == that.container_);
return iterator_ < that.iterator_;
}
template <typename VT, bool IC>
template <bool IsConstForMethod>
inline
typename std::enable_if<!IsConstForMethod, UptrVectorIterator<VT, IC>>::type
UptrVectorIterator<VT, IC>::InsertBefore(Uptr value) {
auto index = iterator_ - container_->begin();
container_->insert(iterator_, std::move(value));
return UptrVectorIterator(container_, container_->begin() + index);
}
template <typename VT, bool IC>
template <bool IsConstForMethod>
inline
typename std::enable_if<!IsConstForMethod, UptrVectorIterator<VT, IC>>::type
UptrVectorIterator<VT, IC>::InsertBefore(UptrVector* values) {
const auto pos = iterator_ - container_->begin();
const auto origsz = container_->size();
container_->resize(origsz + values->size());
std::move_backward(container_->begin() + pos, container_->begin() + origsz,
container_->end());
std::move(values->begin(), values->end(), container_->begin() + pos);
return UptrVectorIterator(container_, container_->begin() + pos);
}
template <typename VT, bool IC>
template <bool IsConstForMethod>
inline
typename std::enable_if<!IsConstForMethod, UptrVectorIterator<VT, IC>>::type
UptrVectorIterator<VT, IC>::Erase() {
auto index = iterator_ - container_->begin();
(void)container_->erase(iterator_);
return UptrVectorIterator(container_, container_->begin() + index);
}
} // namespace opt
} // namespace spvtools
#endif // LIBSPIRV_OPT_ITERATOR_H_