llvm-6502/include/llvm/ADT/SmallVector.h
Chris Lattner 0750bec272 add a simple reserve method.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@30011 91177308-0d34-0410-b5e6-96231b3b80d8
2006-09-01 06:08:16 +00:00

402 lines
11 KiB
C++

//===- llvm/ADT/SmallVector.h - 'Normally small' vectors --------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by Chris Lattner and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines the SmallVector class.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_ADT_SMALLVECTOR_H
#define LLVM_ADT_SMALLVECTOR_H
#include <algorithm>
#include <iterator>
#include <memory>
namespace llvm {
/// SmallVectorImpl - This class consists of common code factored out of the
/// SmallVector class to reduce code duplication based on the SmallVector 'N'
/// template parameter.
template <typename T>
class SmallVectorImpl {
T *Begin, *End, *Capacity;
// Allocate raw space for N elements of type T. If T has a ctor or dtor, we
// don't want it to be automatically run, so we need to represent the space as
// something else. An array of char would work great, but might not be
// aligned sufficiently. Instead, we either use GCC extensions, or some
// number of union instances for the space, which guarantee maximal alignment.
protected:
union U {
double D;
long double LD;
long long L;
void *P;
} FirstEl;
// Space after 'FirstEl' is clobbered, do not add any instance vars after it.
public:
// Default ctor - Initialize to empty.
SmallVectorImpl(unsigned N)
: Begin((T*)&FirstEl), End((T*)&FirstEl), Capacity((T*)&FirstEl+N) {
}
~SmallVectorImpl() {
// Destroy the constructed elements in the vector.
destroy_range(Begin, End);
// If this wasn't grown from the inline copy, deallocate the old space.
if (!isSmall())
delete[] (char*)Begin;
}
typedef size_t size_type;
typedef T* iterator;
typedef const T* const_iterator;
typedef T& reference;
typedef const T& const_reference;
bool empty() const { return Begin == End; }
size_type size() const { return End-Begin; }
iterator begin() { return Begin; }
const_iterator begin() const { return Begin; }
iterator end() { return End; }
const_iterator end() const { return End; }
reference operator[](unsigned idx) {
return Begin[idx];
}
const_reference operator[](unsigned idx) const {
return Begin[idx];
}
reference front() {
return begin()[0];
}
const_reference front() const {
return begin()[0];
}
reference back() {
return end()[-1];
}
const_reference back() const {
return end()[-1];
}
void push_back(const_reference Elt) {
if (End < Capacity) {
Retry:
new (End) T(Elt);
++End;
return;
}
grow();
goto Retry;
}
void pop_back() {
--End;
End->~T();
}
void clear() {
destroy_range(Begin, End);
End = Begin;
}
void resize(unsigned N) {
if (N < size()) {
destroy_range(Begin+N, End);
End = Begin+N;
} else if (N > size()) {
if (Begin+N > Capacity)
grow(N);
construct_range(End, Begin+N, T());
End = Begin+N;
}
}
void resize(unsigned N, const T &NV) {
if (N < size()) {
destroy_range(Begin+N, End);
End = Begin+N;
} else if (N > size()) {
if (Begin+N > Capacity)
grow(N);
construct_range(End, Begin+N, NV);
End = Begin+N;
}
}
void reserve(unsigned N) {
if (unsigned(Capacity-Begin) < N)
grow(N);
}
void swap(SmallVectorImpl &RHS);
/// append - Add the specified range to the end of the SmallVector.
///
template<typename in_iter>
void append(in_iter in_start, in_iter in_end) {
unsigned NumInputs = std::distance(in_start, in_end);
// Grow allocated space if needed.
if (End+NumInputs > Capacity)
grow(size()+NumInputs);
// Copy the new elements over.
std::uninitialized_copy(in_start, in_end, End);
End += NumInputs;
}
void assign(unsigned NumElts, const T &Elt) {
clear();
if (Begin+NumElts > Capacity)
grow(NumElts);
End = Begin+NumElts;
construct_range(Begin, End, Elt);
}
void erase(iterator I) {
// Shift all elts down one.
std::copy(I+1, End, I);
// Drop the last elt.
pop_back();
}
void erase(iterator S, iterator E) {
// Shift all elts down.
iterator I = std::copy(E, End, S);
// Drop the last elts.
destroy_range(I, End);
End = I;
}
iterator insert(iterator I, const T &Elt) {
if (I == End) { // Important special case for empty vector.
push_back(Elt);
return end()-1;
}
if (End < Capacity) {
Retry:
new (End) T(back());
++End;
// Push everything else over.
std::copy_backward(I, End-1, End);
*I = Elt;
return I;
}
unsigned EltNo = I-Begin;
grow();
I = Begin+EltNo;
goto Retry;
}
const SmallVectorImpl &operator=(const SmallVectorImpl &RHS);
private:
/// isSmall - Return true if this is a smallvector which has not had dynamic
/// memory allocated for it.
bool isSmall() const {
return (void*)Begin == (void*)&FirstEl;
}
/// grow - double the size of the allocated memory, guaranteeing space for at
/// least one more element or MinSize if specified.
void grow(unsigned MinSize = 0);
void construct_range(T *S, T *E, const T &Elt) {
for (; S != E; ++S)
new (S) T(Elt);
}
void destroy_range(T *S, T *E) {
while (S != E) {
E->~T();
--E;
}
}
};
// Define this out-of-line to dissuade the C++ compiler from inlining it.
template <typename T>
void SmallVectorImpl<T>::grow(unsigned MinSize) {
unsigned CurCapacity = Capacity-Begin;
unsigned CurSize = size();
unsigned NewCapacity = 2*CurCapacity;
if (NewCapacity < MinSize)
NewCapacity = MinSize;
T *NewElts = reinterpret_cast<T*>(new char[NewCapacity*sizeof(T)]);
// Copy the elements over.
std::uninitialized_copy(Begin, End, NewElts);
// Destroy the original elements.
destroy_range(Begin, End);
// If this wasn't grown from the inline copy, deallocate the old space.
if (!isSmall())
delete[] (char*)Begin;
Begin = NewElts;
End = NewElts+CurSize;
Capacity = Begin+NewCapacity;
}
template <typename T>
void SmallVectorImpl<T>::swap(SmallVectorImpl<T> &RHS) {
if (this == &RHS) return;
// We can only avoid copying elements if neither vector is small.
if (!isSmall() && !RHS.isSmall()) {
std::swap(Begin, RHS.Begin);
std::swap(End, RHS.End);
std::swap(Capacity, RHS.Capacity);
return;
}
if (Begin+RHS.size() > Capacity)
grow(RHS.size());
if (RHS.begin()+size() > RHS.Capacity)
RHS.grow(size());
// Swap the shared elements.
unsigned NumShared = size();
if (NumShared > RHS.size()) NumShared = RHS.size();
for (unsigned i = 0; i != NumShared; ++i)
std::swap(Begin[i], RHS[i]);
// Copy over the extra elts.
if (size() > RHS.size()) {
unsigned EltDiff = size() - RHS.size();
std::uninitialized_copy(Begin+NumShared, End, RHS.End);
RHS.End += EltDiff;
destroy_range(Begin+NumShared, End);
End = Begin+NumShared;
} else if (RHS.size() > size()) {
unsigned EltDiff = RHS.size() - size();
std::uninitialized_copy(RHS.Begin+NumShared, RHS.End, End);
End += EltDiff;
destroy_range(RHS.Begin+NumShared, RHS.End);
RHS.End = RHS.Begin+NumShared;
}
}
template <typename T>
const SmallVectorImpl<T> &
SmallVectorImpl<T>::operator=(const SmallVectorImpl<T> &RHS) {
// Avoid self-assignment.
if (this == &RHS) return *this;
// If we already have sufficient space, assign the common elements, then
// destroy any excess.
unsigned RHSSize = RHS.size();
unsigned CurSize = size();
if (CurSize >= RHSSize) {
// Assign common elements.
iterator NewEnd = std::copy(RHS.Begin, RHS.Begin+RHSSize, Begin);
// Destroy excess elements.
destroy_range(NewEnd, End);
// Trim.
End = NewEnd;
return *this;
}
// If we have to grow to have enough elements, destroy the current elements.
// This allows us to avoid copying them during the grow.
if (unsigned(Capacity-Begin) < RHSSize) {
// Destroy current elements.
destroy_range(Begin, End);
End = Begin;
CurSize = 0;
grow(RHSSize);
} else if (CurSize) {
// Otherwise, use assignment for the already-constructed elements.
std::copy(RHS.Begin, RHS.Begin+CurSize, Begin);
}
// Copy construct the new elements in place.
std::uninitialized_copy(RHS.Begin+CurSize, RHS.End, Begin+CurSize);
// Set end.
End = Begin+RHSSize;
return *this;
}
/// SmallVector - This is a 'vector' (really, a variable-sized array), optimized
/// for the case when the array is small. It contains some number of elements
/// in-place, which allows it to avoid heap allocation when the actual number of
/// elements is below that threshold. This allows normal "small" cases to be
/// fast without losing generality for large inputs.
///
/// Note that this does not attempt to be exception safe.
///
template <typename T, unsigned N>
class SmallVector : public SmallVectorImpl<T> {
/// InlineElts - These are 'N-1' elements that are stored inline in the body
/// of the vector. The extra '1' element is stored in SmallVectorImpl.
typedef typename SmallVectorImpl<T>::U U;
enum {
// MinUs - The number of U's require to cover N T's.
MinUs = (sizeof(T)*N+sizeof(U)-1)/sizeof(U),
// NumInlineEltsElts - The number of elements actually in this array. There
// is already one in the parent class, and we have to round up to avoid
// having a zero-element array.
NumInlineEltsElts = (MinUs - 1) > 0 ? (MinUs - 1) : 1,
// NumTsAvailable - The number of T's we actually have space for, which may
// be more than N due to rounding.
NumTsAvailable = (NumInlineEltsElts+1)*sizeof(U) / sizeof(T)
};
U InlineElts[NumInlineEltsElts];
public:
SmallVector() : SmallVectorImpl<T>(NumTsAvailable) {
}
template<typename ItTy>
SmallVector(ItTy S, ItTy E) : SmallVectorImpl<T>(NumTsAvailable) {
append(S, E);
}
SmallVector(const SmallVector &RHS) : SmallVectorImpl<T>(NumTsAvailable) {
operator=(RHS);
}
const SmallVector &operator=(const SmallVector &RHS) {
SmallVectorImpl<T>::operator=(RHS);
return *this;
}
};
} // End llvm namespace
namespace std {
/// Implement std::swap in terms of SmallVector swap.
template<typename T>
inline void
swap(llvm::SmallVectorImpl<T> &LHS, llvm::SmallVectorImpl<T> &RHS) {
LHS.swap(RHS);
}
/// Implement std::swap in terms of SmallVector swap.
template<typename T, unsigned N>
inline void
swap(llvm::SmallVector<T, N> &LHS, llvm::SmallVector<T, N> &RHS) {
LHS.swap(RHS);
}
}
#endif