Vector.h
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/*
* Copyright 2008 Free Software Foundation, Inc.
* Copyright 2014 Range Networks, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* This use of this software may be subject to additional restrictions.
* See the LEGAL file in the main directory for details.
*/
/**@file Simplified Vector template with aliases. */
#ifndef VECTOR_H
#define VECTOR_H
#include <string.h>
#include <iostream>
#include <assert.h>
#include <stdio.h>
// We cant use Logger.h in this file...
extern int gVectorDebug;
//#define ENABLE_VECTORDEBUG
#ifdef ENABLE_VECTORDEBUG
#define VECTORDEBUG(...) { printf(__VA_ARGS__); printf(" this=%p [%p,%p,%p]\n",(void*)this,(void*)&mData,mStart,mEnd); }
//#define VECTORDEBUG(msg) { std::cout<<msg<<std::endl; }
#else
#define VECTORDEBUG(...)
#endif
#define BITVECTOR_REFCNTS 0
#if BITVECTOR_REFCNTS
// (pat) Started to add refcnts, decided against it for now.
template <class T> class RCData : public RefCntBase {
public:
T* mPointer;
};
#endif
/**
A simplified Vector template with aliases.
Unlike std::vector, this class does not support dynamic resizing.
Unlike std::vector, this class does support "aliases" and subvectors.
*/
// (pat) Nov 2013: Vector and the derived classes BitVector and SoftVector were originally written with behavior
// that differed for const and non-const cases, making them very difficult to use and resulting in many extremely
// difficult to find bugs in the code base.
// Ultimately these classes should all be converted to reference counted methodologies, but as an interim measure
// I am rationalizing their behavior until we flush out all places in the code base that inadvertently depended
// on the original behavior. This is done with assert statements in BitVector methods.
// ====
// What the behavior was probably supposed to be:
// Vectors can 'own' the data they point to or not. Only one Vector 'owns' the memory at a time,
// so that automatic destruction can be used. So whenever there is an operation that yields one
// vector from another the options were: clone (allocate a new vector from memory), alias (make the
// new vector point into the memory of the original vector) or shift (the new Vector steals the
// memory ownership from the original vector.)
// The const copy-constructor did a clone, the non-const copy constructor did a shiftMem, and the segment and
// related methods (head, tail, etc) returned aliases.
// Since a copy-constructor is inserted transparently in sometimes surprising places, this made the
// class very difficult to use. Moreover, since the C++ standard specifies that a copy-constructor is used
// to copy the return value from functions, it makes it literally impossible for a function to fully control
// the return value. Our code has relied on the "Return Value Optimization" which says that the C++ compiler
// may omit the copy-construction of the return value even if the copy-constructor has side-effects, which ours does.
// This methodology is fundamentally incompatible with C++.
// What the original behavior actually was:
// class Vector:
// The copy-constructor and assignment operators did a clone for the const case and a shift for the non-const case.
// This is really horrible.
// The segment methods were identical for const and non-const cases, always returning an alias.
// This also resulted in zillions of redundant mallocs and copies throughout the code base.
// class BitVector:
// Copy-constructor:
// BitVector did not have any copy-constructors, and I think the intent was that it would have the same behavior
// as Vector, but that is not how C++ works: with no copy-constructor the default copy-constructor
// uses only the const case, so only the const Vector copy-constructor was used. Therefore it always cloned,
// and the code base relied heavily on the "Return Value Optimization" to work at all.
// Assignment operator:
// BitVector did not have one, so C++ makes a default one that calls Vector::operator=() as a side effect,
// which did a clone; not sure if there was a non-const version and no longer care.
// segment methods:
// The non-const segment() returned an alias, and the const segment() returned a clone.
// I think the intent was that the behavior should be the same as Vector, but there was a conversion
// of the result of the const segment() method from Vector to BitVector which caused the Vector copy-constructor
// to be (inadvertently) invoked, resulting in the const version of the segment method returning a clone.
// What the behavior is now:
// VectorBase:
// There is a new VectorBase class that has only the common methods and extremely basic constructors.
// The VectorBase class MUST NOT CONTAIN: copy constructors, non-trivial constructors called from derived classes,
// or any method that returns a VectorBase type object. Why? Because any of the above when used in derived classes
// can cause copy-constructor invocation, often surprisingly, obfuscating the code.
// Each derived class must provide its own: copy-constructors and segment() and related methods, since we do not
// want to inadvertently invoke a copy-constructor to convert the segment() result from VectorBase to the derived type.
// BitVector:
// The BitVector copy-constructor and assignment operator (inherited from VectorBase) paradigm is:
// if the copied Vector owned memory, perform a clone so the new vector owns memory also,
// otherwise just do a simple copy, which is another alias. This isnt perfect but works every place
// in our code base and easier to use than the previous paradigm.
// The segment method always returns an alias.
// If you want a clone of a segment, use cloneSegment(), which replaces the previous: const segment(...) const method.
// Note that the semantics of cloneSegment still rely on the Return Value Optimization. Oh well, we should use refcnts.
// Vector:
// I left Vector alone (except for rearrangement to separate out VectorBase.) Vector should just not be used.
// SoftVector:
// SoftVector and signalVector should be updated similar to BitVector, but I did not want to disturb them.
// What the behavior should be:
// All these should be reference-counted, similar to ByteVector.
template <class T> class VectorBase
{
// TODO -- Replace memcpy calls with for-loops. (pat) in case class T is not POD [Plain Old Data]
protected:
#if BITVECTOR_REFCNTS
typedef RefCntPointer<RCData<T> > VectorDataType;
#else
typedef T* VectorDataType;
#endif
VectorDataType mData; ///< allocated data block.
T* mStart; ///< start of useful data
T* mEnd; ///< end of useful data + 1
// Init vector with specified size. Previous contents are completely discarded. This is only used for initialization.
void vInit(size_t elements)
{
mData = elements ? new T[elements] : NULL;
mStart = mData; // This is where mStart get set to zero
mEnd = mStart + elements;
}
/** Assign from another Vector, shifting ownership. */
// (pat) This should be eliminated, but it is used by Vector and descendents.
void shiftMem(VectorBase<T>&other)
{
VECTORDEBUG("VectorBase::shiftMem(%p)",(void*)&other);
this->clear();
this->mData=other.mData;
this->mStart=other.mStart;
this->mEnd=other.mEnd;
other.mData=NULL;
}
// Assign from another Vector, making this an alias to other.
void makeAlias(const VectorBase<T> &other)
{
if (this->getData()) {
assert(this->getData() != other.getData()); // Not possible by the semantics of Vector.
this->clear();
}
this->mStart=const_cast<T*>(other.mStart);
this->mEnd=const_cast<T*>(other.mEnd);
}
public:
/** Return the size of the Vector in units, ie, the number of T elements. */
size_t size() const
{
assert(mStart>=mData);
assert(mEnd>=mStart);
return mEnd - mStart;
}
/** Return size in bytes. */
size_t bytes() const { return this->size()*sizeof(T); }
/** Change the size of the Vector in items (not bytes), discarding content. */
void resize(size_t newElements) {
//VECTORDEBUG("VectorBase::resize("<<(void*)this<<","<<newElements<<")");
VECTORDEBUG("VectorBase::resize(%p,%d) %s",this,newElements, (mData?"delete":""));
if (mData!=NULL) delete[] mData;
vInit(newElements);
}
/** Release memory and clear pointers. */
void clear() { this->resize(0); }
/** Copy data from another vector. */
void clone(const VectorBase<T>& other) {
this->resize(other.size());
memcpy(mData,other.mStart,other.bytes());
}
void vConcat(const VectorBase<T>&other1, const VectorBase<T>&other2) {
this->resize(other1.size()+other2.size());
memcpy(this->mStart, other1.mStart, other1.bytes());
memcpy(this->mStart+other1.size(), other2.mStart, other2.bytes());
}
protected:
VectorBase() : mData(0), mStart(0), mEnd(0) {}
/** Build a Vector with explicit values. */
VectorBase(VectorDataType wData, T* wStart, T* wEnd) :mData(wData),mStart(wStart),mEnd(wEnd) {
//VECTORDEBUG("VectorBase("<<(void*)wData);
VECTORDEBUG("VectorBase(%p,%p,%p)",this->getData(),wStart,wEnd);
}
public:
/** Destroy a Vector, deleting held memory. */
~VectorBase() {
//VECTORDEBUG("~VectorBase("<<(void*)this<<")");
VECTORDEBUG("~VectorBase(%p)",this);
this->clear();
}
bool isOwner() { return !!this->mData; } // Do we own any memory ourselves?
std::string inspect() const {
char buf[100];
snprintf(buf,100," mData=%p mStart=%p mEnd=%p ",(void*)mData,mStart,mEnd);
return std::string(buf);
}
/**
Copy part of this Vector to a segment of another Vector.
@param other The other vector.
@param start The start point in the other vector.
@param span The number of elements to copy.
*/
void copyToSegment(VectorBase<T>& other, size_t start, size_t span) const
{
T* base = other.mStart + start;
assert(base+span<=other.mEnd);
assert(mStart+span<=mEnd);
memcpy(base,mStart,span*sizeof(T));
}
/** Copy all of this Vector to a segment of another Vector. */
void copyToSegment(VectorBase<T>& other, size_t start=0) const { copyToSegment(other,start,size()); }
void copyTo(VectorBase<T>& other) const { copyToSegment(other,0,size()); }
/**
Copy a segment of this vector into another.
@param other The other vector (to copt into starting at 0.)
@param start The start point in this vector.
@param span The number of elements to copy.
WARNING: This function does NOT resize the result - you must set the result size before entering.
*/
void segmentCopyTo(VectorBase<T>& other, size_t start, size_t span) const
{
const T* base = mStart + start;
assert(base+span<=mEnd);
assert(other.mStart+span<=other.mEnd);
memcpy(other.mStart,base,span*sizeof(T));
}
void fill(const T& val)
{
T* dp=mStart;
while (dp<mEnd) *dp++=val;
}
void fill(const T& val, unsigned start, unsigned length)
{
T* dp=mStart+start;
T* end=dp+length;
assert(end<=mEnd);
while (dp<end) *dp++=val;
}
/** Assign from another Vector. */
// (pat) This is used for both const and non-const cases.
// If the original vector owned memory, clone it, otherwise just copy the segment data.
void operator=(const VectorBase<T>& other) {
//std::cout << "Vector=(this="<<this->inspect()<<",other="<<other.inspect()<<")"<<endl;
if (other.getData()) {
this->clone(other);
} else {
this->makeAlias(other);
}
//std::cout << "Vector= after(this="<<this->inspect()<<")"<<endl;
}
T& operator[](size_t index)
{
assert(mStart+index<mEnd);
return mStart[index];
}
const T& operator[](size_t index) const
{
assert(mStart+index<mEnd);
return mStart[index];
}
const T* begin() const { return this->mStart; }
T* begin() { return this->mStart; }
const T* end() const { return this->mEnd; }
T* end() { return this->mEnd; }
#if BITVECTOR_REFCNTS
const T*getData() const { return this->mData.isNULL() ? 0 : this->mData->mPointer; }
#else
const T*getData() const { return this->mData; }
#endif
};
// (pat) Nov 2013. This class retains the original poor behavior. See comments at VectorBase
template <class T> class Vector : public VectorBase<T>
{
public:
/** Build an empty Vector of a given size. */
Vector(size_t wSize=0) { this->resize(wSize); }
/** Build a Vector by shifting the data block. */
Vector(Vector<T>& other) : VectorBase<T>(other.mData,other.mStart,other.mEnd) { other.mData=NULL; }
/** Build a Vector by copying another. */
Vector(const Vector<T>& other):VectorBase<T>() { this->clone(other); }
/** Build a Vector with explicit values. */
Vector(T* wData, T* wStart, T* wEnd) : VectorBase<T>(wData,wStart,wEnd) { }
/** Build a vector from an existing block, NOT to be deleted upon destruction. */
Vector(T* wStart, size_t span) : VectorBase<T>(NULL,wStart,wStart+span) { }
/** Build a Vector by concatenation. */
Vector(const Vector<T>& other1, const Vector<T>& other2):VectorBase<T>() {
assert(this->mData == 0);
this->vConcat(other1,other2);
}
//@{
/** Assign from another Vector, shifting ownership. */
void operator=(Vector<T>& other) { this->shiftMem(other); }
/** Assign from another Vector, copying. */
void operator=(const Vector<T>& other) { this->clone(other); }
/** Return an alias to a segment of this Vector. */
Vector<T> segment(size_t start, size_t span)
{
T* wStart = this->mStart + start;
T* wEnd = wStart + span;
assert(wEnd<=this->mEnd);
return Vector<T>(NULL,wStart,wEnd);
}
/** Return an alias to a segment of this Vector. */
const Vector<T> segment(size_t start, size_t span) const
{
T* wStart = this->mStart + start;
T* wEnd = wStart + span;
assert(wEnd<=this->mEnd);
return Vector<T>(NULL,wStart,wEnd);
}
Vector<T> head(size_t span) { return segment(0,span); }
const Vector<T> head(size_t span) const { return segment(0,span); }
Vector<T> tail(size_t start) { return segment(start,this->size()-start); }
const Vector<T> tail(size_t start) const { return segment(start,this->size()-start); }
/**@name Iterator types. */
//@{
typedef T* iterator;
typedef const T* const_iterator;
//@}
//@}
};
/** Basic print operator for Vector objects. */
template <class T>
std::ostream& operator<<(std::ostream& os, const Vector<T>& v)
{
for (unsigned i=0; i<v.size(); i++) os << v[i] << " ";
return os;
}
#endif
// vim: ts=4 sw=4
VECTORDEBUG
#define VECTORDEBUG(...)
Definition Vector.h:39
gVectorDebug
int gVectorDebug
operator<<
std::ostream & operator<<(std::ostream &os, const Vector< T > &v)
Definition Vector.h:388
VectorBase
Definition Vector.h:122
VectorBase::operator=
void operator=(const VectorBase< T > &other)
Definition Vector.h:282
VectorBase::begin
T * begin()
Definition Vector.h:306
VectorBase::fill
void fill(const T &val, unsigned start, unsigned length)
Definition Vector.h:271
VectorBase::VectorDataType
T * VectorDataType
Definition Vector.h:129
VectorBase::size
size_t size() const
Definition Vector.h:169
VectorBase::mData
VectorDataType mData
allocated data block.
Definition Vector.h:131
VectorBase::vInit
void vInit(size_t elements)
Definition Vector.h:136
VectorBase::inspect
std::string inspect() const
Definition Vector.h:224
VectorBase::getData
const T * getData() const
Definition Vector.h:312
VectorBase::vConcat
void vConcat(const VectorBase< T > &other1, const VectorBase< T > &other2)
Definition Vector.h:197
VectorBase::VectorBase
VectorBase()
Definition Vector.h:205
VectorBase::segmentCopyTo
void segmentCopyTo(VectorBase< T > &other, size_t start, size_t span) const
Definition Vector.h:257
VectorBase::end
T * end()
Definition Vector.h:308
VectorBase::end
const T * end() const
Definition Vector.h:307
VectorBase::copyToSegment
void copyToSegment(VectorBase< T > &other, size_t start, size_t span) const
Definition Vector.h:237
VectorBase::clear
void clear()
Definition Vector.h:188
VectorBase::mStart
T * mStart
start of useful data
Definition Vector.h:132
VectorBase::copyTo
void copyTo(VectorBase< T > &other) const
Definition Vector.h:248
VectorBase::copyToSegment
void copyToSegment(VectorBase< T > &other, size_t start=0) const
Definition Vector.h:246
VectorBase::operator[]
T & operator[](size_t index)
Definition Vector.h:293
VectorBase::isOwner
bool isOwner()
Definition Vector.h:222
VectorBase::clone
void clone(const VectorBase< T > &other)
Definition Vector.h:192
VectorBase::bytes
size_t bytes() const
Definition Vector.h:177
VectorBase::fill
void fill(const T &val)
Definition Vector.h:265
VectorBase::operator[]
const T & operator[](size_t index) const
Definition Vector.h:299
VectorBase::mEnd
T * mEnd
end of useful data + 1
Definition Vector.h:133
VectorBase::~VectorBase
~VectorBase()
Definition Vector.h:216
VectorBase::resize
void resize(size_t newElements)
Definition Vector.h:180
VectorBase::makeAlias
void makeAlias(const VectorBase< T > &other)
Definition Vector.h:156
VectorBase::begin
const T * begin() const
Definition Vector.h:305
VectorBase::VectorBase
VectorBase(VectorDataType wData, T *wStart, T *wEnd)
Definition Vector.h:208
VectorBase::shiftMem
void shiftMem(VectorBase< T > &other)
Definition Vector.h:145
Vector
Definition Vector.h:318
Vector::segment
const Vector< T > segment(size_t start, size_t span) const
Definition Vector.h:360
Vector::tail
const Vector< T > tail(size_t start) const
Definition Vector.h:371
Vector::operator=
void operator=(Vector< T > &other)
Definition Vector.h:345
Vector::Vector
Vector(T *wData, T *wStart, T *wEnd)
Definition Vector.h:331
Vector::iterator
T * iterator
Definition Vector.h:375
Vector::head
const Vector< T > head(size_t span) const
Definition Vector.h:369
Vector::Vector
Vector(const Vector< T > &other1, const Vector< T > &other2)
Definition Vector.h:337
Vector::head
Vector< T > head(size_t span)
Definition Vector.h:368
Vector::tail
Vector< T > tail(size_t start)
Definition Vector.h:370
Vector::segment
Vector< T > segment(size_t start, size_t span)
Definition Vector.h:351
Vector::const_iterator
const T * const_iterator
Definition Vector.h:376
Vector::Vector
Vector(const Vector< T > &other)
Definition Vector.h:328
Vector::Vector
Vector(T *wStart, size_t span)
Definition Vector.h:334
Vector::operator=
void operator=(const Vector< T > &other)
Definition Vector.h:348
Vector::Vector
Vector(size_t wSize=0)
Definition Vector.h:322
Vector::Vector
Vector(Vector< T > &other)
Definition Vector.h:325