srcnativelibs.Include.Tesseract.tesseract.genericvector.h Maven / Gradle / Ivy
///////////////////////////////////////////////////////////////////////
// File: genericvector.h
// Description: Generic vector class
// Author: Daria Antonova
// Created: Mon Jun 23 11:26:43 PDT 2008
//
// (C) Copyright 2007, Google Inc.
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
///////////////////////////////////////////////////////////////////////
//
#ifndef TESSERACT_CCUTIL_GENERICVECTOR_H_
#define TESSERACT_CCUTIL_GENERICVECTOR_H_
#include
#include
#include
#include "tesscallback.h"
#include "errcode.h"
#include "helpers.h"
#include "ndminx.h"
#include "strngs.h"
// Use PointerVector below in preference to GenericVector, as that
// provides automatic deletion of pointers, [De]Serialize that works, and
// sort that works.
template
class GenericVector {
public:
GenericVector() {
init(kDefaultVectorSize);
}
GenericVector(int size, T init_val) {
init(size);
init_to_size(size, init_val);
}
// Copy
GenericVector(const GenericVector& other) {
this->init(other.size());
this->operator+=(other);
}
GenericVector &operator+=(const GenericVector& other);
GenericVector &operator=(const GenericVector& other);
~GenericVector();
// Reserve some memory.
void reserve(int size);
// Double the size of the internal array.
void double_the_size();
// Resizes to size and sets all values to t.
void init_to_size(int size, T t);
// Return the size used.
int size() const {
return size_used_;
}
int size_reserved() const {
return size_reserved_;
}
int length() const {
return size_used_;
}
// Return true if empty.
bool empty() const {
return size_used_ == 0;
}
// Return the object from an index.
T &get(int index) const;
T &back() const;
T &operator[](int index) const;
// Returns the last object and removes it.
T pop_back();
// Return the index of the T object.
// This method NEEDS a compare_callback to be passed to
// set_compare_callback.
int get_index(T object) const;
// Return true if T is in the array
bool contains(T object) const;
// Return true if the index is valid
T contains_index(int index) const;
// Push an element in the end of the array
int push_back(T object);
void operator+=(T t);
// Push an element in the end of the array if the same
// element is not already contained in the array.
int push_back_new(T object);
// Push an element in the front of the array
// Note: This function is O(n)
int push_front(T object);
// Set the value at the given index
void set(T t, int index);
// Insert t at the given index, push other elements to the right.
void insert(T t, int index);
// Removes an element at the given index and
// shifts the remaining elements to the left.
void remove(int index);
// Truncates the array to the given size by removing the end.
// If the current size is less, the array is not expanded.
void truncate(int size) {
if (size < size_used_)
size_used_ = size;
}
// Add a callback to be called to delete the elements when the array took
// their ownership.
void set_clear_callback(TessCallback1* cb);
// Add a callback to be called to compare the elements when needed (contains,
// get_id, ...)
void set_compare_callback(TessResultCallback2* cb);
// Clear the array, calling the clear callback function if any.
// All the owned callbacks are also deleted.
// If you don't want the callbacks to be deleted, before calling clear, set
// the callback to NULL.
void clear();
// Delete objects pointed to by data_[i]
void delete_data_pointers();
// This method clears the current object, then, does a shallow copy of
// its argument, and finally invalidates its argument.
// Callbacks are moved to the current object;
void move(GenericVector* from);
// Read/Write the array to a file. This does _NOT_ read/write the callbacks.
// The callback given must be permanent since they will be called more than
// once. The given callback will be deleted at the end.
// If the callbacks are NULL, then the data is simply read/written using
// fread (and swapping)/fwrite.
// Returns false on error or if the callback returns false.
// DEPRECATED. Use [De]Serialize[Classes] instead.
bool write(FILE* f, TessResultCallback2* cb) const;
bool read(FILE* f, TessResultCallback3* cb, bool swap);
// Writes a vector of simple types to the given file. Assumes that bitwise
// read/write of T will work. Returns false in case of error.
bool Serialize(FILE* fp) const;
// Reads a vector of simple types from the given file. Assumes that bitwise
// read/write will work with ReverseN according to sizeof(T).
// Returns false in case of error.
// If swap is true, assumes a big/little-endian swap is needed.
bool DeSerialize(bool swap, FILE* fp);
// Writes a vector of classes to the given file. Assumes the existence of
// bool T::Serialize(FILE* fp) const that returns false in case of error.
// Returns false in case of error.
bool SerializeClasses(FILE* fp) const;
// Reads a vector of classes from the given file. Assumes the existence of
// bool T::Deserialize(bool swap, FILE* fp) that returns false in case of
// error. Also needs T::T() and T::T(constT&), as init_to_size is used in
// this function. Returns false in case of error.
// If swap is true, assumes a big/little-endian swap is needed.
bool DeSerializeClasses(bool swap, FILE* fp);
// Allocates a new array of double the current_size, copies over the
// information from data to the new location, deletes data and returns
// the pointed to the new larger array.
// This function uses memcpy to copy the data, instead of invoking
// operator=() for each element like double_the_size() does.
static T *double_the_size_memcpy(int current_size, T *data) {
T *data_new = new T[current_size * 2];
memcpy(data_new, data, sizeof(T) * current_size);
delete[] data;
return data_new;
}
// Sorts the members of this vector using the less than comparator (cmp_lt),
// which compares the values. Useful for GenericVectors to primitive types.
// Will not work so great for pointers (unless you just want to sort some
// pointers). You need to provide a specialization to sort_cmp to use
// your type.
void sort();
// Sort the array into the order defined by the qsort function comparator.
// The comparator function is as defined by qsort, ie. it receives pointers
// to two Ts and returns negative if the first element is to appear earlier
// in the result and positive if it is to appear later, with 0 for equal.
void sort(int (*comparator)(const void*, const void*)) {
qsort(data_, size_used_, sizeof(*data_), comparator);
}
// Searches the array (assuming sorted in ascending order, using sort()) for
// an element equal to target and returns true if it is present.
// Use binary_search to get the index of target, or its nearest candidate.
bool bool_binary_search(const T& target) const {
int index = binary_search(target);
if (index >= size_used_)
return false;
return data_[index] == target;
}
// Searches the array (assuming sorted in ascending order, using sort()) for
// an element equal to target and returns the index of the best candidate.
// The return value is conceptually the largest index i such that
// data_[i] <= target or 0 if target < the whole vector.
// NOTE that this function uses operator> so really the return value is
// the largest index i such that data_[i] > target is false.
int binary_search(const T& target) const {
int bottom = 0;
int top = size_used_;
do {
int middle = (bottom + top) / 2;
if (data_[middle] > target)
top = middle;
else
bottom = middle;
}
while (top - bottom > 1);
return bottom;
}
// Compact the vector by deleting elements using operator!= on basic types.
// The vector must be sorted.
void compact_sorted() {
if (size_used_ == 0)
return;
// First element is in no matter what, hence the i = 1.
int last_write = 0;
for (int i = 1; i < size_used_; ++i) {
// Finds next unique item and writes it.
if (data_[last_write] != data_[i])
data_[++last_write] = data_[i];
}
// last_write is the index of a valid data cell, so add 1.
size_used_ = last_write + 1;
}
// Compact the vector by deleting elements for which delete_cb returns
// true. delete_cb is a permanent callback and will be deleted.
void compact(TessResultCallback1* delete_cb) {
int new_size = 0;
int old_index = 0;
// Until the callback returns true, the elements stay the same.
while (old_index < size_used_ && !delete_cb->Run(old_index++))
++new_size;
// Now just copy anything else that gets false from delete_cb.
for (; old_index < size_used_; ++old_index) {
if (!delete_cb->Run(old_index)) {
data_[new_size++] = data_[old_index];
}
}
size_used_ = new_size;
delete delete_cb;
}
T dot_product(const GenericVector& other) const {
T result = static_cast(0);
for (int i = MIN(size_used_, other.size_used_) - 1; i >= 0; --i)
result += data_[i] * other.data_[i];
return result;
}
// Returns the index of what would be the target_index_th item in the array
// if the members were sorted, without actually sorting. Members are
// shuffled around, but it takes O(n) time.
// NOTE: uses operator< and operator== on the members.
int choose_nth_item(int target_index) {
// Make sure target_index is legal.
if (target_index < 0)
target_index = 0; // ensure legal
else if (target_index >= size_used_)
target_index = size_used_ - 1;
unsigned int seed = 1;
return choose_nth_item(target_index, 0, size_used_, &seed);
}
// Swaps the elements with the given indices.
void swap(int index1, int index2) {
if (index1 != index2) {
T tmp = data_[index1];
data_[index1] = data_[index2];
data_[index2] = tmp;
}
}
protected:
// Internal recursive version of choose_nth_item.
int choose_nth_item(int target_index, int start, int end, unsigned int* seed);
// Init the object, allocating size memory.
void init(int size);
// We are assuming that the object generally placed in thie
// vector are small enough that for efficiency it makes sence
// to start with a larger initial size.
static const int kDefaultVectorSize = 4;
inT32 size_used_;
inT32 size_reserved_;
T* data_;
TessCallback1* clear_cb_;
// Mutable because Run method is not const
mutable TessResultCallback2* compare_cb_;
};
namespace tesseract {
// Function to read a GenericVector from a whole file.
// Returns false on failure.
typedef bool (*FileReader)(const STRING& filename, GenericVector* data);
// Function to write a GenericVector to a whole file.
// Returns false on failure.
typedef bool (*FileWriter)(const GenericVector& data,
const STRING& filename);
// The default FileReader loads the whole file into the vector of char,
// returning false on error.
inline bool LoadDataFromFile(const STRING& filename,
GenericVector* data) {
FILE* fp = fopen(filename.string(), "rb");
if (fp == NULL) return false;
fseek(fp, 0, SEEK_END);
size_t size = ftell(fp);
fseek(fp, 0, SEEK_SET);
// Pad with a 0, just in case we treat the result as a string.
data->init_to_size(size + 1, 0);
bool result = fread(&(*data)[0], 1, size, fp) == size;
fclose(fp);
return result;
}
// The default FileWriter writes the vector of char to the filename file,
// returning false on error.
inline bool SaveDataToFile(const GenericVector& data,
const STRING& filename) {
FILE* fp = fopen(filename.string(), "wb");
if (fp == NULL) return false;
bool result =
static_cast(fwrite(&data[0], 1, data.size(), fp)) == data.size();
fclose(fp);
return result;
}
template
bool cmp_eq(T const & t1, T const & t2) {
return t1 == t2;
}
// Used by sort()
// return < 0 if t1 < t2
// return 0 if t1 == t2
// return > 0 if t1 > t2
template
int sort_cmp(const void* t1, const void* t2) {
const T* a = static_cast (t1);
const T* b = static_cast (t2);
if (*a < *b) {
return -1;
} else if (*b < *a) {
return 1;
} else {
return 0;
}
}
// Used by PointerVector::sort()
// return < 0 if t1 < t2
// return 0 if t1 == t2
// return > 0 if t1 > t2
template
int sort_ptr_cmp(const void* t1, const void* t2) {
const T* a = *reinterpret_cast(t1);
const T* b = *reinterpret_cast(t2);
if (*a < *b) {
return -1;
} else if (*b < *a) {
return 1;
} else {
return 0;
}
}
// Subclass for a vector of pointers. Use in preference to GenericVector
// as it provides automatic deletion and correct serialization, with the
// corollary that all copy operations are deep copies of the pointed-to objects.
template
class PointerVector : public GenericVector {
public:
PointerVector() : GenericVector() { }
explicit PointerVector(int size) : GenericVector(size) { }
~PointerVector() {
// Clear must be called here, even though it is called again by the base,
// as the base will call the wrong clear.
clear();
}
// Copy must be deep, as the pointers will be automatically deleted on
// destruction.
PointerVector(const PointerVector& other) {
this->init(other.size());
this->operator+=(other);
}
PointerVector& operator+=(const PointerVector& other) {
this->reserve(this->size_used_ + other.size_used_);
for (int i = 0; i < other.size(); ++i) {
this->push_back(new T(*other.data_[i]));
}
return *this;
}
PointerVector& operator=(const PointerVector& other) {
this->truncate(0);
this->operator+=(other);
return *this;
}
// Removes an element at the given index and
// shifts the remaining elements to the left.
void remove(int index) {
delete GenericVector::data_[index];
GenericVector::remove(index);
}
// Truncates the array to the given size by removing the end.
// If the current size is less, the array is not expanded.
void truncate(int size) {
for (int i = size; i < GenericVector::size_used_; ++i)
delete GenericVector::data_[i];
GenericVector::truncate(size);
}
// Compact the vector by deleting elements for which delete_cb returns
// true. delete_cb is a permanent callback and will be deleted.
void compact(TessResultCallback1* delete_cb) {
int new_size = 0;
int old_index = 0;
// Until the callback returns true, the elements stay the same.
while (old_index < GenericVector::size_used_ &&
!delete_cb->Run(GenericVector::data_[old_index++]))
++new_size;
// Now just copy anything else that gets false from delete_cb.
for (; old_index < GenericVector::size_used_; ++old_index) {
if (!delete_cb->Run(GenericVector::data_[old_index])) {
GenericVector::data_[new_size++] =
GenericVector::data_[old_index];
} else {
delete GenericVector::data_[old_index];
}
}
GenericVector::size_used_ = new_size;
delete delete_cb;
}
// Clear the array, calling the clear callback function if any.
// All the owned callbacks are also deleted.
// If you don't want the callbacks to be deleted, before calling clear, set
// the callback to NULL.
void clear() {
GenericVector::delete_data_pointers();
GenericVector::clear();
}
// Writes a vector of simple types to the given file. Assumes that bitwise
// read/write of T will work. Returns false in case of error.
bool Serialize(FILE* fp) const {
inT32 used = GenericVector::size_used_;
if (fwrite(&used, sizeof(used), 1, fp) != 1) return false;
for (int i = 0; i < used; ++i) {
inT8 non_null = GenericVector::data_[i] != NULL;
if (fwrite(&non_null, sizeof(non_null), 1, fp) != 1) return false;
if (non_null && !GenericVector::data_[i]->Serialize(fp)) return false;
}
return true;
}
// Reads a vector of simple types from the given file. Assumes that bitwise
// read/write will work with ReverseN according to sizeof(T).
// Also needs T::T(), as new T is used in this function.
// Returns false in case of error.
// If swap is true, assumes a big/little-endian swap is needed.
bool DeSerialize(bool swap, FILE* fp) {
inT32 reserved;
if (fread(&reserved, sizeof(reserved), 1, fp) != 1) return false;
if (swap) Reverse32(&reserved);
GenericVector::reserve(reserved);
for (int i = 0; i < reserved; ++i) {
inT8 non_null;
if (fread(&non_null, sizeof(non_null), 1, fp) != 1) return false;
T* item = NULL;
if (non_null) {
item = new T;
if (!item->DeSerialize(swap, fp)) {
delete item;
return false;
}
this->push_back(item);
} else {
// Null elements should keep their place in the vector.
this->push_back(NULL);
}
}
return true;
}
// Sorts the items pointed to by the members of this vector using
// t::operator<().
void sort() {
sort(&sort_ptr_cmp);
}
};
} // namespace tesseract
// A useful vector that uses operator== to do comparisons.
template
class GenericVectorEqEq : public GenericVector {
public:
GenericVectorEqEq() {
GenericVector::set_compare_callback(
NewPermanentTessCallback(tesseract::cmp_eq));
}
GenericVectorEqEq(int size) : GenericVector(size) {
GenericVector::set_compare_callback(
NewPermanentTessCallback(tesseract::cmp_eq));
}
};
template
void GenericVector::init(int size) {
size_used_ = 0;
size_reserved_ = 0;
data_ = 0;
clear_cb_ = 0;
compare_cb_ = 0;
reserve(size);
}
template
GenericVector::~GenericVector() {
clear();
}
// Reserve some memory. If the internal array contains elements, they are
// copied.
template
void GenericVector::reserve(int size) {
if (size_reserved_ >= size || size <= 0)
return;
T* new_array = new T[size];
for (int i = 0; i < size_used_; ++i)
new_array[i] = data_[i];
if (data_ != NULL) delete[] data_;
data_ = new_array;
size_reserved_ = size;
}
template
void GenericVector::double_the_size() {
if (size_reserved_ == 0) {
reserve(kDefaultVectorSize);
}
else {
reserve(2 * size_reserved_);
}
}
// Resizes to size and sets all values to t.
template
void GenericVector::init_to_size(int size, T t) {
reserve(size);
size_used_ = size;
for (int i = 0; i < size; ++i)
data_[i] = t;
}
// Return the object from an index.
template
T &GenericVector::get(int index) const {
ASSERT_HOST(index >= 0 && index < size_used_);
return data_[index];
}
template
T &GenericVector::operator[](int index) const {
assert(index >= 0 && index < size_used_);
return data_[index];
}
template
T &GenericVector::back() const {
ASSERT_HOST(size_used_ > 0);
return data_[size_used_ - 1];
}
// Returns the last object and removes it.
template
T GenericVector::pop_back() {
ASSERT_HOST(size_used_ > 0);
return data_[--size_used_];
}
// Return the object from an index.
template
void GenericVector::set(T t, int index) {
ASSERT_HOST(index >= 0 && index < size_used_);
data_[index] = t;
}
// Shifts the rest of the elements to the right to make
// space for the new elements and inserts the given element
// at the specified index.
template
void GenericVector::insert(T t, int index) {
ASSERT_HOST(index >= 0 && index <= size_used_);
if (size_reserved_ == size_used_)
double_the_size();
for (int i = size_used_; i > index; --i) {
data_[i] = data_[i-1];
}
data_[index] = t;
size_used_++;
}
// Removes an element at the given index and
// shifts the remaining elements to the left.
template
void GenericVector::remove(int index) {
ASSERT_HOST(index >= 0 && index < size_used_);
for (int i = index; i < size_used_ - 1; ++i) {
data_[i] = data_[i+1];
}
size_used_--;
}
// Return true if the index is valindex
template
T GenericVector::contains_index(int index) const {
return index >= 0 && index < size_used_;
}
// Return the index of the T object.
template
int GenericVector::get_index(T object) const {
for (int i = 0; i < size_used_; ++i) {
ASSERT_HOST(compare_cb_ != NULL);
if (compare_cb_->Run(object, data_[i]))
return i;
}
return -1;
}
// Return true if T is in the array
template
bool GenericVector::contains(T object) const {
return get_index(object) != -1;
}
// Add an element in the array
template
int GenericVector::push_back(T object) {
int index = 0;
if (size_used_ == size_reserved_)
double_the_size();
index = size_used_++;
data_[index] = object;
return index;
}
template
int GenericVector::push_back_new(T object) {
int index = get_index(object);
if (index >= 0)
return index;
return push_back(object);
}
// Add an element in the array (front)
template
int GenericVector::push_front(T object) {
if (size_used_ == size_reserved_)
double_the_size();
for (int i = size_used_; i > 0; --i)
data_[i] = data_[i-1];
data_[0] = object;
++size_used_;
return 0;
}
template
void GenericVector::operator+=(T t) {
push_back(t);
}
template
GenericVector &GenericVector::operator+=(const GenericVector& other) {
this->reserve(size_used_ + other.size_used_);
for (int i = 0; i < other.size(); ++i) {
this->operator+=(other.data_[i]);
}
return *this;
}
template
GenericVector &GenericVector::operator=(const GenericVector& other) {
this->truncate(0);
this->operator+=(other);
return *this;
}
// Add a callback to be called to delete the elements when the array took
// their ownership.
template
void GenericVector::set_clear_callback(TessCallback1* cb) {
clear_cb_ = cb;
}
// Add a callback to be called to delete the elements when the array took
// their ownership.
template
void GenericVector::set_compare_callback(
TessResultCallback2* cb) {
compare_cb_ = cb;
}
// Clear the array, calling the callback function if any.
template
void GenericVector::clear() {
if (size_reserved_ > 0) {
if (clear_cb_ != NULL)
for (int i = 0; i < size_used_; ++i)
clear_cb_->Run(data_[i]);
delete[] data_;
data_ = NULL;
size_used_ = 0;
size_reserved_ = 0;
}
if (clear_cb_ != NULL) {
delete clear_cb_;
clear_cb_ = NULL;
}
if (compare_cb_ != NULL) {
delete compare_cb_;
compare_cb_ = NULL;
}
}
template
void GenericVector::delete_data_pointers() {
for (int i = 0; i < size_used_; ++i)
if (data_[i]) {
delete data_[i];
}
}
template
bool GenericVector::write(
FILE* f, TessResultCallback2* cb) const {
if (fwrite(&size_reserved_, sizeof(size_reserved_), 1, f) != 1) return false;
if (fwrite(&size_used_, sizeof(size_used_), 1, f) != 1) return false;
if (cb != NULL) {
for (int i = 0; i < size_used_; ++i) {
if (!cb->Run(f, data_[i])) {
delete cb;
return false;
}
}
delete cb;
} else {
if (fwrite(data_, sizeof(T), size_used_, f) != size_used_) return false;
}
return true;
}
template
bool GenericVector::read(FILE* f,
TessResultCallback3* cb,
bool swap) {
inT32 reserved;
if (fread(&reserved, sizeof(reserved), 1, f) != 1) return false;
if (swap) Reverse32(&reserved);
reserve(reserved);
if (fread(&size_used_, sizeof(size_used_), 1, f) != 1) return false;
if (swap) Reverse32(&size_used_);
if (cb != NULL) {
for (int i = 0; i < size_used_; ++i) {
if (!cb->Run(f, data_ + i, swap)) {
delete cb;
return false;
}
}
delete cb;
} else {
if (fread(data_, sizeof(T), size_used_, f) != size_used_) return false;
if (swap) {
for (int i = 0; i < size_used_; ++i)
ReverseN(&data_[i], sizeof(T));
}
}
return true;
}
// Writes a vector of simple types to the given file. Assumes that bitwise
// read/write of T will work. Returns false in case of error.
template
bool GenericVector::Serialize(FILE* fp) const {
if (fwrite(&size_used_, sizeof(size_used_), 1, fp) != 1) return false;
if (fwrite(data_, sizeof(*data_), size_used_, fp) != size_used_) return false;
return true;
}
// Reads a vector of simple types from the given file. Assumes that bitwise
// read/write will work with ReverseN according to sizeof(T).
// Returns false in case of error.
// If swap is true, assumes a big/little-endian swap is needed.
template
bool GenericVector::DeSerialize(bool swap, FILE* fp) {
inT32 reserved;
if (fread(&reserved, sizeof(reserved), 1, fp) != 1) return false;
if (swap) Reverse32(&reserved);
reserve(reserved);
size_used_ = reserved;
if (fread(data_, sizeof(T), size_used_, fp) != size_used_) return false;
if (swap) {
for (int i = 0; i < size_used_; ++i)
ReverseN(&data_[i], sizeof(data_[i]));
}
return true;
}
// Writes a vector of classes to the given file. Assumes the existence of
// bool T::Serialize(FILE* fp) const that returns false in case of error.
// Returns false in case of error.
template
bool GenericVector::SerializeClasses(FILE* fp) const {
if (fwrite(&size_used_, sizeof(size_used_), 1, fp) != 1) return false;
for (int i = 0; i < size_used_; ++i) {
if (!data_[i].Serialize(fp)) return false;
}
return true;
}
// Reads a vector of classes from the given file. Assumes the existence of
// bool T::Deserialize(bool swap, FILE* fp) that returns false in case of
// error. Alse needs T::T() and T::T(constT&), as init_to_size is used in
// this function. Returns false in case of error.
// If swap is true, assumes a big/little-endian swap is needed.
template
bool GenericVector::DeSerializeClasses(bool swap, FILE* fp) {
uinT32 reserved;
if (fread(&reserved, sizeof(reserved), 1, fp) != 1) return false;
if (swap) Reverse32(&reserved);
T empty;
init_to_size(reserved, empty);
for (int i = 0; i < reserved; ++i) {
if (!data_[i].DeSerialize(swap, fp)) return false;
}
return true;
}
// This method clear the current object, then, does a shallow copy of
// its argument, and finally invalidates its argument.
template
void GenericVector::move(GenericVector* from) {
this->clear();
this->data_ = from->data_;
this->size_reserved_ = from->size_reserved_;
this->size_used_ = from->size_used_;
this->compare_cb_ = from->compare_cb_;
this->clear_cb_ = from->clear_cb_;
from->data_ = NULL;
from->clear_cb_ = NULL;
from->compare_cb_ = NULL;
from->size_used_ = 0;
from->size_reserved_ = 0;
}
template
void GenericVector::sort() {
sort(&tesseract::sort_cmp);
}
// Internal recursive version of choose_nth_item.
// The algorithm used comes from "Algorithms" by Sedgewick:
// http://books.google.com/books/about/Algorithms.html?id=idUdqdDXqnAC
// The principle is to choose a random pivot, and move everything less than
// the pivot to its left, and everything greater than the pivot to the end
// of the array, then recurse on the part that contains the desired index, or
// just return the answer if it is in the equal section in the middle.
// The random pivot guarantees average linear time for the same reason that
// n times vector::push_back takes linear time on average.
// target_index, start and and end are all indices into the full array.
// Seed is a seed for rand_r for thread safety purposes. Its value is
// unimportant as the random numbers do not affect the result except
// between equal answers.
template
int GenericVector::choose_nth_item(int target_index, int start, int end,
unsigned int* seed) {
// Number of elements to process.
int num_elements = end - start;
// Trivial cases.
if (num_elements <= 1)
return start;
if (num_elements == 2) {
if (data_[start] < data_[start + 1]) {
return target_index > start ? start + 1 : start;
} else {
return target_index > start ? start : start + 1;
}
}
// Place the pivot at start.
#ifndef rand_r // _MSC_VER, ANDROID
srand(*seed);
#define rand_r(seed) rand()
#endif // _MSC_VER
int pivot = rand_r(seed) % num_elements + start;
swap(pivot, start);
// The invariant condition here is that items [start, next_lesser) are less
// than the pivot (which is at index next_lesser) and items
// [prev_greater, end) are greater than the pivot, with items
// [next_lesser, prev_greater) being equal to the pivot.
int next_lesser = start;
int prev_greater = end;
for (int next_sample = start + 1; next_sample < prev_greater;) {
if (data_[next_sample] < data_[next_lesser]) {
swap(next_lesser++, next_sample++);
} else if (data_[next_sample] == data_[next_lesser]) {
++next_sample;
} else {
swap(--prev_greater, next_sample);
}
}
// Now the invariant is set up, we recurse on just the section that contains
// the desired index.
if (target_index < next_lesser)
return choose_nth_item(target_index, start, next_lesser, seed);
else if (target_index < prev_greater)
return next_lesser; // In equal bracket.
else
return choose_nth_item(target_index, prev_greater, end, seed);
}
#endif // TESSERACT_CCUTIL_GENERICVECTOR_H_
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