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#ifndef STRING_STORE_HPP
#define STRING_STORE_HPP
/*
Copyright 2012 Jochen Topf <jochen@topf.org>.
This file is part of Tagstats.
Tagstats is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
Tagstats 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with Tagstats. If not, see <http://www.gnu.org/licenses/>.
*/
#include <list>
#include <stdexcept>
#include <new>
#include <cstring>
/**
* class StringStore
*
* Storage of lots of strings (const char *). Memory is allocated in chunks.
* If a string is added and there is no space in the current chunk, a new
* chunk will be allocated.
*
* All memory is released when the destructor is called. There is no other way
* to release all or part of the memory.
*
*/
class StringStore {
int chunk_size;
// number of bytes that are available in the current chunk
int current_rest_length;
// pointer where the next string is stored
char *current_ptr;
// list of chunks
std::list<void *> chunks;
const char *_add_chunk() {
current_ptr = (char *) malloc(chunk_size);
if (! current_ptr) {
throw std::bad_alloc();
}
current_rest_length = chunk_size;
chunks.push_back(current_ptr);
return current_ptr;
}
bool _add(const char *string) {
if (current_rest_length <= 1) {
_add_chunk();
}
char *next_ptr = (char *) memccpy(current_ptr, string, 0, current_rest_length);
if (next_ptr) {
current_rest_length -= (next_ptr - current_ptr);
current_ptr = next_ptr;
return true;
}
return false;
}
public:
StringStore(int chunk_size) : chunk_size(chunk_size) {
_add_chunk();
}
~StringStore() {
while (! chunks.empty()) {
free(chunks.back());
chunks.pop_back();
}
}
/**
* Add a null terminated string to the store. This will
* automatically get more memory if we are out.
* Returns a pointer to the copy of the string we have
* allocated.
*
* Throws std::length_error if the string we want to
* add is longer then the chunk size.
*/
const char *add(const char *string) {
const char *string_ptr = current_ptr;
if (! _add(string)) {
string_ptr = _add_chunk();
if (! _add(string)) {
throw std::length_error("strings added to StringStore must be shorter than chunk_size");
}
}
return string_ptr;
}
// These functions get you some idea how much memory was
// used.
int get_chunk_size() const {
return chunk_size;
}
int get_chunk_count() const {
return chunks.size();
}
int get_used_bytes_in_last_chunk() const {
return chunk_size - current_rest_length;
}
};
#endif // STRING_STORE_HPP
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