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330 lines
6.8 KiB
C++
330 lines
6.8 KiB
C++
//
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// Buffer.h
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//
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// Library: Foundation
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// Package: Core
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// Module: Buffer
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//
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// Definition of the Buffer class.
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//
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// Copyright (c) 2012, Applied Informatics Software Engineering GmbH.
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// and Contributors.
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//
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// SPDX-License-Identifier: BSL-1.0
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//
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#ifndef Foundation_Buffer_INCLUDED
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#define Foundation_Buffer_INCLUDED
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#include "Poco/Foundation.h"
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#include "Poco/Exception.h"
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#include <cstring>
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#include <cstddef>
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namespace Poco {
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template <class T>
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class Buffer
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/// A buffer class that allocates a buffer of a given type and size
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/// in the constructor and deallocates the buffer in the destructor.
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///
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/// This class is useful everywhere where a temporary buffer
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/// is needed.
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{
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public:
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Buffer(std::size_t capacity):
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_capacity(capacity),
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_used(capacity),
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_ptr(0),
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_ownMem(true)
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/// Creates and allocates the Buffer.
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{
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if (capacity > 0)
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{
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_ptr = new T[capacity];
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}
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}
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Buffer(T* pMem, std::size_t length):
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_capacity(length),
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_used(length),
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_ptr(pMem),
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_ownMem(false)
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/// Creates the Buffer. Length argument specifies the length
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/// of the supplied memory pointed to by pMem in the number
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/// of elements of type T. Supplied pointer is considered
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/// blank and not owned by Buffer, so in this case Buffer
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/// only acts as a wrapper around externally supplied
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/// (and lifetime-managed) memory.
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{
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}
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Buffer(const T* pMem, std::size_t length):
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_capacity(length),
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_used(length),
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_ptr(0),
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_ownMem(true)
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/// Creates and allocates the Buffer; copies the contents of
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/// the supplied memory into the buffer. Length argument specifies
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/// the length of the supplied memory pointed to by pMem in the
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/// number of elements of type T.
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{
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if (_capacity > 0)
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{
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_ptr = new T[_capacity];
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std::memcpy(_ptr, pMem, _used * sizeof(T));
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}
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}
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Buffer(const Buffer& other):
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/// Copy constructor.
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_capacity(other._used),
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_used(other._used),
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_ptr(0),
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_ownMem(true)
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{
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if (_used)
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{
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_ptr = new T[_used];
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std::memcpy(_ptr, other._ptr, _used * sizeof(T));
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}
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}
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Buffer& operator = (const Buffer& other)
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/// Assignment operator.
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{
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if (this != &other)
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{
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Buffer tmp(other);
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swap(tmp);
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}
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return *this;
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}
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~Buffer()
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/// Destroys the Buffer.
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{
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if (_ownMem) delete [] _ptr;
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}
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void resize(std::size_t newCapacity, bool preserveContent = true)
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/// Resizes the buffer capacity and size. If preserveContent is true,
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/// the content of the old buffer is copied over to the
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/// new buffer. The new capacity can be larger or smaller than
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/// the current one; if it is smaller, capacity will remain intact.
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/// Size will always be set to the new capacity.
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///
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/// Buffers only wrapping externally owned storage can not be
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/// resized. If resize is attempted on those, IllegalAccessException
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/// is thrown.
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{
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if (!_ownMem) throw Poco::InvalidAccessException("Cannot resize buffer which does not own its storage.");
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if (newCapacity > _capacity)
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{
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T* ptr = new T[newCapacity];
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if (preserveContent)
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{
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std::memcpy(ptr, _ptr, _used * sizeof(T));
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}
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delete [] _ptr;
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_ptr = ptr;
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_capacity = newCapacity;
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}
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_used = newCapacity;
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}
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void setCapacity(std::size_t newCapacity, bool preserveContent = true)
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/// Sets the buffer capacity. If preserveContent is true,
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/// the content of the old buffer is copied over to the
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/// new buffer. The new capacity can be larger or smaller than
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/// the current one; size will be set to the new capacity only if
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/// new capacity is smaller than the current size, otherwise it will
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/// remain intact.
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///
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/// Buffers only wrapping externally owned storage can not be
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/// resized. If resize is attempted on those, IllegalAccessException
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/// is thrown.
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{
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if (!_ownMem) throw Poco::InvalidAccessException("Cannot resize buffer which does not own its storage.");
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if (newCapacity != _capacity)
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{
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T* ptr = 0;
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if (newCapacity > 0)
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{
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ptr = new T[newCapacity];
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if (preserveContent)
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{
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std::size_t newSz = _used < newCapacity ? _used : newCapacity;
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std::memcpy(ptr, _ptr, newSz * sizeof(T));
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}
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}
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delete [] _ptr;
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_ptr = ptr;
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_capacity = newCapacity;
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if (newCapacity < _used) _used = newCapacity;
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}
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}
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void assign(const T* buf, std::size_t sz)
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/// Assigns the argument buffer to this buffer.
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/// If necessary, resizes the buffer.
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{
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if (0 == sz) return;
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if (sz > _capacity) resize(sz, false);
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std::memcpy(_ptr, buf, sz * sizeof(T));
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_used = sz;
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}
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void append(const T* buf, std::size_t sz)
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/// Resizes this buffer and appends the argument buffer.
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{
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if (0 == sz) return;
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resize(_used + sz, true);
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std::memcpy(_ptr + _used - sz, buf, sz * sizeof(T));
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}
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void append(T val)
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/// Resizes this buffer by one element and appends the argument value.
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{
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resize(_used + 1, true);
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_ptr[_used - 1] = val;
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}
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void append(const Buffer& buf)
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/// Resizes this buffer and appends the argument buffer.
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{
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append(buf.begin(), buf.size());
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}
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std::size_t capacity() const
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/// Returns the allocated memory size in elements.
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{
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return _capacity;
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}
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std::size_t capacityBytes() const
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/// Returns the allocated memory size in bytes.
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{
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return _capacity * sizeof(T);
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}
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void swap(Buffer& other)
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/// Swaps the buffer with another one.
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{
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using std::swap;
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swap(_ptr, other._ptr);
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swap(_capacity, other._capacity);
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swap(_used, other._used);
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}
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bool operator == (const Buffer& other) const
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/// Compare operator.
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{
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if (this != &other)
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{
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if (_used == other._used)
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{
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if (std::memcmp(_ptr, other._ptr, _used * sizeof(T)) == 0)
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{
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return true;
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}
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}
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return false;
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}
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return true;
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}
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bool operator != (const Buffer& other) const
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/// Compare operator.
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{
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return !(*this == other);
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}
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void clear()
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/// Sets the contents of the buffer to zero.
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{
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std::memset(_ptr, 0, _used * sizeof(T));
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}
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std::size_t size() const
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/// Returns the used size of the buffer in elements.
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{
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return _used;
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}
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std::size_t sizeBytes() const
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/// Returns the used size of the buffer in bytes.
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{
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return _used * sizeof(T);
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}
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T* begin()
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/// Returns a pointer to the beginning of the buffer.
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{
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return _ptr;
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}
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const T* begin() const
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/// Returns a pointer to the beginning of the buffer.
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{
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return _ptr;
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}
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T* end()
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/// Returns a pointer to end of the buffer.
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{
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return _ptr + _used;
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}
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const T* end() const
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/// Returns a pointer to the end of the buffer.
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{
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return _ptr + _used;
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}
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bool empty() const
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/// Return true if buffer is empty.
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{
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return 0 == _used;
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}
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T& operator [] (std::size_t index)
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{
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poco_assert (index < _used);
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return _ptr[index];
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}
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const T& operator [] (std::size_t index) const
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{
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poco_assert (index < _used);
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return _ptr[index];
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}
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private:
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Buffer();
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std::size_t _capacity;
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std::size_t _used;
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T* _ptr;
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bool _ownMem;
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};
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} // namespace Poco
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#endif // Foundation_Buffer_INCLUDED
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