llvm-6502/include/llvm/Support/STLExtras.h
Chris Lattner 643afb3b01 * Fixed mapped_iterator to actually work with functors
* Implement mapto function that works like map in a functional programming language


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@439 91177308-0d34-0410-b5e6-96231b3b80d8
2001-09-07 16:30:28 +00:00

223 lines
7.7 KiB
C++

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