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//===- llvm/ADT/STLExtras.h - Useful STL related functions ------*- C++ -*-===//
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// The LLVM Compiler Infrastructure
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//===----------------------------------------------------------------------===//
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// This file contains some templates that are useful if you are working with the
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// No library is required when using these functions.
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_ADT_STLEXTRAS_H
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#define LLVM_ADT_STLEXTRAS_H
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#include <cstddef> // for std::size_t
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#include <cstdlib> // for qsort
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#include <utility> // for std::pair
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//===----------------------------------------------------------------------===//
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// Extra additions to <functional>
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//===----------------------------------------------------------------------===//
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struct less_ptr : public std::binary_function<Ty, Ty, bool> {
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bool operator()(const Ty* left, const Ty* right) const {
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return *left < *right;
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struct greater_ptr : public std::binary_function<Ty, Ty, bool> {
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bool operator()(const Ty* left, const Ty* right) const {
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return *right < *left;
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// deleter - Very very very simple method that is used to invoke operator
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// delete on something. It is used like this:
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// for_each(V.begin(), B.end(), deleter<Interval>);
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static inline void deleter(T *Ptr) {
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//===----------------------------------------------------------------------===//
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// Extra additions to <iterator>
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//===----------------------------------------------------------------------===//
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// mapped_iterator - This is a simple iterator adapter that causes a function to
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// be dereferenced whenever operator* is invoked on the iterator.
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template <class RootIt, class UnaryFunc>
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class mapped_iterator {
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typedef typename std::iterator_traits<RootIt>::iterator_category
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typedef typename std::iterator_traits<RootIt>::difference_type
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typedef typename UnaryFunc::result_type value_type;
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//typedef typename UnaryFunc::result_type *pointer;
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typedef void reference; // Can't modify value returned by fn
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typedef RootIt iterator_type;
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typedef mapped_iterator<RootIt, UnaryFunc> _Self;
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inline const RootIt &getCurrent() const { return current; }
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inline const UnaryFunc &getFunc() const { return Fn; }
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inline explicit mapped_iterator(const RootIt &I, UnaryFunc F)
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: current(I), Fn(F) {}
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inline mapped_iterator(const mapped_iterator &It)
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: current(It.current), Fn(It.Fn) {}
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inline value_type operator*() const { // All this work to do this
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return Fn(*current); // little change
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_Self& operator++() { ++current; return *this; }
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_Self& operator--() { --current; return *this; }
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_Self operator++(int) { _Self __tmp = *this; ++current; return __tmp; }
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_Self operator--(int) { _Self __tmp = *this; --current; return __tmp; }
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_Self operator+ (difference_type n) const {
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return _Self(current + n, Fn);
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_Self& operator+= (difference_type n) { current += n; return *this; }
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_Self operator- (difference_type n) const {
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return _Self(current - n, Fn);
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_Self& operator-= (difference_type n) { current -= n; return *this; }
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reference operator[](difference_type n) const { return *(*this + n); }
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inline bool operator!=(const _Self &X) const { return !operator==(X); }
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inline bool operator==(const _Self &X) const { return current == X.current; }
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inline bool operator< (const _Self &X) const { return current < X.current; }
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inline difference_type operator-(const _Self &X) const {
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return current - X.current;
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template <class _Iterator, class Func>
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inline mapped_iterator<_Iterator, Func>
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operator+(typename mapped_iterator<_Iterator, Func>::difference_type N,
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const mapped_iterator<_Iterator, Func>& X) {
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return mapped_iterator<_Iterator, Func>(X.getCurrent() - N, X.getFunc());
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// map_iterator - Provide a convenient way to create mapped_iterators, just like
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// make_pair is useful for creating pairs...
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template <class ItTy, class FuncTy>
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inline mapped_iterator<ItTy, FuncTy> map_iterator(const ItTy &I, FuncTy F) {
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return mapped_iterator<ItTy, FuncTy>(I, F);
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// next/prior - These functions unlike std::advance do not modify the
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// passed iterator but return a copy.
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// next(myIt) returns copy of myIt incremented once
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// next(myIt, n) returns copy of myIt incremented n times
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// prior(myIt) returns copy of myIt decremented once
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// prior(myIt, n) returns copy of myIt decremented n times
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template <typename ItTy, typename Dist>
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inline ItTy next(ItTy it, Dist n)
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template <typename ItTy>
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inline ItTy next(ItTy it)
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template <typename ItTy, typename Dist>
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inline ItTy prior(ItTy it, Dist n)
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std::advance(it, -n);
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template <typename ItTy>
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inline ItTy prior(ItTy it)
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//===----------------------------------------------------------------------===//
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// Extra additions to <utility>
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//===----------------------------------------------------------------------===//
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// tie - this function ties two objects and returns a temporary object
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// that is assignable from a std::pair. This can be used to make code
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// more readable when using values returned from functions bundled in
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// a std::pair. Since an example is worth 1000 words:
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// typedef std::map<int, int> Int2IntMap;
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// Int2IntMap::iterator where;
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// tie(where, inserted) = myMap.insert(std::make_pair(123,456));
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template <typename T1, typename T2>
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typedef T1 &first_type;
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typedef T2 &second_type;
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tier(first_type f, second_type s) : first(f), second(s) { }
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tier& operator=(const std::pair<T1, T2>& p) {
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template <typename T1, typename T2>
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inline tier<T1, T2> tie(T1& f, T2& s) {
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return tier<T1, T2>(f, s);
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//===----------------------------------------------------------------------===//
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// Extra additions for arrays
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//===----------------------------------------------------------------------===//
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/// Find where an array ends (for ending iterators)
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/// This returns a pointer to the byte immediately
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/// after the end of an array.
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template<class T, std::size_t N>
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inline T *array_endof(T (&x)[N]) {
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/// Find the length of an array.
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template<class T, std::size_t N>
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inline size_t array_lengthof(T (&x)[N]) {
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/// array_pod_sort_comparator - This is helper function for array_pod_sort,
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/// which just uses operator< on T.
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static inline int array_pod_sort_comparator(const void *P1, const void *P2) {
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if (*reinterpret_cast<const T*>(P1) < *reinterpret_cast<const T*>(P2))
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if (*reinterpret_cast<const T*>(P2) < *reinterpret_cast<const T*>(P1))
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/// get_array_pad_sort_comparator - This is an internal helper function used to
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/// get type deduction of T right.
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static int (*get_array_pad_sort_comparator(const T &X))
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(const void*, const void*) {
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return array_pod_sort_comparator<T>;
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/// array_pod_sort - This sorts an array with the specified start and end
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/// extent. This is just like std::sort, except that it calls qsort instead of
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/// using an inlined template. qsort is slightly slower than std::sort, but
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/// most sorts are not performance critical in LLVM and std::sort has to be
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/// template instantiated for each type, leading to significant measured code
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/// bloat. This function should generally be used instead of std::sort where
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/// This function assumes that you have simple POD-like types that can be
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/// compared with operator< and can be moved with memcpy. If this isn't true,
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/// you should use std::sort.
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/// NOTE: If qsort_r were portable, we could allow a custom comparator and
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/// default to std::less.
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template<class IteratorTy>
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static inline void array_pod_sort(IteratorTy Start, IteratorTy End) {
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// Don't dereference start iterator of empty sequence.
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if (Start == End) return;
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qsort(&*Start, End-Start, sizeof(*Start),
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get_array_pad_sort_comparator(*Start));
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template<class IteratorTy>
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static inline void array_pod_sort(IteratorTy Start, IteratorTy End,
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int (*Compare)(const void*, const void*)) {
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// Don't dereference start iterator of empty sequence.
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if (Start == End) return;
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qsort(&*Start, End-Start, sizeof(*Start), Compare);
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} // End llvm namespace