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227 lines
7.8 KiB
C++
227 lines
7.8 KiB
C++
//===-- STLExtras.h - Useful functions when working with the STL -*- C++ -*--=//
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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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// STL at all.
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//
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// No library is required when using these functinons.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_SUPPORT_STL_EXTRAS_H
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#define LLVM_SUPPORT_STL_EXTRAS_H
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#include <functional>
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#include "Support/iterator"
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//===----------------------------------------------------------------------===//
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// Extra additions to <functional>
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//===----------------------------------------------------------------------===//
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// bind_obj - Often times you want to apply the member function of an object
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// as a unary functor. This macro is shorthand that makes it happen less
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// verbosely.
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//
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// Example:
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// struct Summer { void accumulate(int x); }
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// vector<int> Numbers;
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// Summer MyS;
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// for_each(Numbers.begin(), Numbers.end(),
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// bind_obj(&MyS, &Summer::accumulate));
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//
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// TODO: When I get lots of extra time, convert this from an evil macro
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//
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#define bind_obj(OBJ, METHOD) std::bind1st(std::mem_fun(METHOD), OBJ)
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// bitwise_or - This is a simple functor that applys operator| on its two
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// arguments to get a boolean result.
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//
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template<class Ty>
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struct bitwise_or : 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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}
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};
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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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//
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// for_each(V.begin(), B.end(), deleter<Interval>);
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//
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template <class T>
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static inline void deleter(T *Ptr) {
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delete Ptr;
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}
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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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//
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// It turns out that this is disturbingly similar to boost::transform_iterator
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//
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#if 1
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template <class RootIt, class UnaryFunc>
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class mapped_iterator {
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RootIt current;
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UnaryFunc Fn;
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public:
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typedef typename std::iterator_traits<RootIt>::iterator_category
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iterator_category;
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typedef typename std::iterator_traits<RootIt>::difference_type
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difference_type;
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typedef typename UnaryFunc::result_type value_type;
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typedef void pointer;
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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 RootIt &getCurrent() const { return current; }
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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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}
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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 { return _Self(current + n); }
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_Self& operator+= (difference_type n) { current += n; return *this; }
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_Self operator- (difference_type n) const { return _Self(current - n); }
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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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}
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};
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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);
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}
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#else
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// This fails to work, because some iterators are not classes, for example
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// vector iterators are commonly value_type **'s
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template <class RootIt, class UnaryFunc>
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class mapped_iterator : public RootIt {
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UnaryFunc Fn;
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public:
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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 mapped_iterator<RootIt, UnaryFunc> _Self;
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typedef RootIt super;
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inline explicit mapped_iterator(const RootIt &I) : super(I) {}
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inline mapped_iterator(const super &It) : super(It) {}
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inline value_type operator*() const { // All this work to do
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return Fn(super::operator*()); // this little thing
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}
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};
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#endif
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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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//
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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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}
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//===----------------------------------------------------------------------===//
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// Extra additions to <algorithm>
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//===----------------------------------------------------------------------===//
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// apply_until - Apply a functor to a sequence continually, unless the
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// functor returns true. Return true if the functor returned true, return false
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// if the functor never returned true.
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//
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template <class InputIt, class Function>
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bool apply_until(InputIt First, InputIt Last, Function Func) {
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for ( ; First != Last; ++First)
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if (Func(*First)) return true;
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return false;
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}
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// reduce - Reduce a sequence values into a single value, given an initial
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// value and an operator.
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//
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template <class InputIt, class Function, class ValueType>
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ValueType reduce(InputIt First, InputIt Last, Function Func, ValueType Value) {
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for ( ; First != Last; ++First)
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Value = Func(*First, Value);
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return Value;
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}
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#if 1 // This is likely to be more efficient
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// reduce_apply - Reduce the result of applying a function to each value in a
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// sequence, given an initial value, an operator, a function, and a sequence.
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//
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template <class InputIt, class Function, class ValueType, class TransFunc>
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inline ValueType reduce_apply(InputIt First, InputIt Last, Function Func,
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ValueType Value, TransFunc XForm) {
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for ( ; First != Last; ++First)
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Value = Func(XForm(*First), Value);
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return Value;
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}
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#else // This is arguably more elegant
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// reduce_apply - Reduce the result of applying a function to each value in a
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// sequence, given an initial value, an operator, a function, and a sequence.
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//
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template <class InputIt, class Function, class ValueType, class TransFunc>
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inline ValueType reduce_apply2(InputIt First, InputIt Last, Function Func,
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ValueType Value, TransFunc XForm) {
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return reduce(map_iterator(First, XForm), map_iterator(Last, XForm),
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Func, Value);
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}
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#endif
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// reduce_apply_bool - Reduce the result of applying a (bool returning) function
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// to each value in a sequence. All of the bools returned by the mapped
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// function are bitwise or'd together, and the result is returned.
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//
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template <class InputIt, class Function>
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inline bool reduce_apply_bool(InputIt First, InputIt Last, Function Func) {
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return reduce_apply(First, Last, bitwise_or<bool>(), false, Func);
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}
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// map - This function maps the specified input sequence into the specified
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// output iterator, applying a unary function in between.
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//
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template <class InIt, class OutIt, class Functor>
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inline OutIt mapto(InIt Begin, InIt End, OutIt Dest, Functor F) {
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return copy(map_iterator(Begin, F), map_iterator(End, F), Dest);
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}
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#endif
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