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dynamic_buffer.h
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dynamic_buffer.h
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/* -*- Mode: C++; tab-width: 4; c-basic-offset: 4; indent-tabs-mode: nil -*- */
/*
* Copyright 2015 Couchbase, 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.
*/
#pragma once
#include <cstdlib>
#include <stdexcept>
#include <string>
class DynamicBuffer {
public:
DynamicBuffer()
: buffer(nullptr),
offset(0),
size(0) {
// empty
}
DynamicBuffer(const DynamicBuffer&) = delete;
~DynamicBuffer() {
clear();
}
/**
* Grow the buffer to have at least <em>needed</em> bytes
*
* @param needed the number of bytes needed in the buffer
* @return true if success, false otherwise
*/
bool grow(size_t needed);
/**
* Clear the buffer and release all allocated resources
*/
void clear();
/**
* Get the root of the buffer
*/
char *getRoot() const {
return buffer;
}
/**
* Get the "current" pointer (root + offset)
*/
char *getCurrent() const {
return buffer + offset;
}
/**
* Get the current offset in the buffer
*/
size_t getOffset() const {
return offset;
}
/**
* Move the offset in the buffer (we've just inserted more data into
* the buffer)
*/
void moveOffset(size_t num) {
offset += num;
// Validate that we've not run over the buffer size
if (offset > size) {
throw std::out_of_range("DynamicBuffer::moveOffset: offset (" +
std::to_string(offset) + ") > size (" +
std::to_string(size) + ")");
}
}
/**
* Transfer the ownership of the underlying buffer. The caller is
* responsible for freeing the underlying data
*/
void takeOwnership() {
buffer = nullptr;
size = 0;
offset = 0;
}
/**
* Get the total size of the allocated buffer. Note that the bytes in
* the range [offset, size> is not initialized or used.
*/
size_t getSize() const {
return size;
}
private:
/** Start of the allocated buffer */
char* buffer;
/** How much of the buffer has been used so far. */
size_t offset;
/** Total allocated size */
size_t size;
};