ladybird/AK/ByteBuffer.h

#pragma once

#include "Types.h"
#include "StdLibExtras.h"
#include <AK/Retainable.h>
#include <AK/RetainPtr.h>
#include <AK/kmalloc.h>

namespace AK {

class ByteBufferImpl : public Retainable<ByteBufferImpl> {
public:
    static Retained<ByteBufferImpl> create_uninitialized(int size);
    static Retained<ByteBufferImpl> create_zeroed(int);
    static Retained<ByteBufferImpl> copy(const void*, int);
    static Retained<ByteBufferImpl> wrap(void*, int);
    static Retained<ByteBufferImpl> adopt(void*, int);

    ~ByteBufferImpl() { clear(); }

    void clear()
    {
        if (!m_data)
            return;
        if (m_owned)
            kfree(m_data);
        m_data = nullptr;
    }

    byte& operator[](int i) { ASSERT(i < m_size); return m_data[i]; }
    const byte& operator[](int i) const { ASSERT(i < m_size); return m_data[i]; }
    bool is_empty() const { return !m_size; }
    int size() const { return m_size; }

    byte* pointer() { return m_data; }
    const byte* pointer() const { return m_data; }

    byte* offset_pointer(int offset) { return m_data + offset; }
    const byte* offset_pointer(int offset) const { return m_data + offset; }

    void* end_pointer() { return m_data + m_size; }
    const void* end_pointer() const { return m_data + m_size; }

    // NOTE: trim() does not reallocate.
    void trim(int size)
    {
        ASSERT(size <= m_size);
        m_size = size;
    }

    void grow(int size);

private:
    enum ConstructionMode { Uninitialized, Copy, Wrap, Adopt };
    explicit ByteBufferImpl(int); // For ConstructionMode=Uninitialized
    ByteBufferImpl(const void*, int, ConstructionMode); // For ConstructionMode=Copy
    ByteBufferImpl(void*, int, ConstructionMode); // For ConstructionMode=Wrap/Adopt
    ByteBufferImpl() { }

    byte* m_data { nullptr };
    int m_size { 0 };
    bool m_owned { false };
};

class ByteBuffer {
public:
    ByteBuffer() { }
    ByteBuffer(std::nullptr_t) { }
    ByteBuffer(const ByteBuffer& other)
        : m_impl(other.m_impl.copy_ref())
    {
    }
    ByteBuffer(ByteBuffer&& other)
        : m_impl(move(other.m_impl))
    {
    }
    ByteBuffer& operator=(ByteBuffer&& other)
    {
        if (this != &other)
            m_impl = move(other.m_impl);
        return *this;
    }
    ByteBuffer& operator=(const ByteBuffer& other)
    {
        m_impl = other.m_impl.copy_ref();
        return *this;
    }

    static ByteBuffer create_uninitialized(ssize_t size) { return ByteBuffer(ByteBufferImpl::create_uninitialized(size)); }
    static ByteBuffer create_zeroed(ssize_t size) { return ByteBuffer(ByteBufferImpl::create_zeroed(size)); }
    static ByteBuffer copy(const void* data, ssize_t size) { return ByteBuffer(ByteBufferImpl::copy(data, size)); }
    static ByteBuffer wrap(void* data, ssize_t size) { return ByteBuffer(ByteBufferImpl::wrap(data, size)); }
    static ByteBuffer adopt(void* data, ssize_t size) { return ByteBuffer(ByteBufferImpl::adopt(data, size)); }

    ~ByteBuffer() { clear(); }
    void clear() { m_impl = nullptr; }

    operator bool() const { return !is_null(); }
    bool operator!() const { return is_null(); }
    bool is_null() const { return m_impl == nullptr; }

    byte& operator[](ssize_t i) { ASSERT(m_impl); return (*m_impl)[i]; }
    byte operator[](ssize_t i) const { ASSERT(m_impl); return (*m_impl)[i]; }
    bool is_empty() const { return !m_impl || m_impl->is_empty(); }
    ssize_t size() const { return m_impl ? m_impl->size() : 0; }

    byte* data() { return pointer(); }
    const byte* data() const { return pointer(); }

    byte* pointer() { return m_impl ? m_impl->pointer() : nullptr; }
    const byte* pointer() const { return m_impl ? m_impl->pointer() : nullptr; }

    byte* offset_pointer(ssize_t offset) { return m_impl ? m_impl->offset_pointer(offset) : nullptr; }
    const byte* offset_pointer(ssize_t offset) const { return m_impl ? m_impl->offset_pointer(offset) : nullptr; }

    void* end_pointer() { return m_impl ? m_impl->end_pointer() : nullptr; }
    const void* end_pointer() const { return m_impl ? m_impl->end_pointer() : nullptr; }

    // NOTE: trim() does not reallocate.
    void trim(ssize_t size)
    {
        if (m_impl)
            m_impl->trim(size);
    }

    ByteBuffer slice(ssize_t offset, ssize_t size) const
    {
        if (is_null())
            return { };
        if (offset >= this->size())
            return { };
        if (offset + size >= this->size())
            size = this->size() - offset;
        return copy(offset_pointer(offset), size);
    }

    void grow(ssize_t size)
    {
        if (!m_impl)
            m_impl = ByteBufferImpl::create_uninitialized(size);
        else
            m_impl->grow(size);
    }

    void append(const void* data, int data_size)
    {
        int old_size = size();
        grow(size() + data_size);
        memcpy(pointer() + old_size, data, data_size);
    }

private:
    explicit ByteBuffer(RetainPtr<ByteBufferImpl>&& impl)
        : m_impl(move(impl))
    {
    }

    RetainPtr<ByteBufferImpl> m_impl;
};

inline ByteBufferImpl::ByteBufferImpl(int size)
    : m_size(size)
{
    m_data = static_cast<byte*>(kmalloc(size));
    m_owned = true;
}

inline ByteBufferImpl::ByteBufferImpl(const void* data, int size, ConstructionMode mode)
    : m_size(size)
{
    ASSERT(mode == Copy);
    m_data = static_cast<byte*>(kmalloc(size));
    memcpy(m_data, data, size);
    m_owned = true;
}

inline ByteBufferImpl::ByteBufferImpl(void* data, ssize_t size, ConstructionMode mode)
    : m_data(static_cast<byte*>(data))
    , m_size(size)
{
    if (mode == Adopt) {
        m_owned = true;
    } else if (mode == Wrap) {
        m_owned = false;
    }
}

inline void ByteBufferImpl::grow(ssize_t size)
{
    ASSERT(size > m_size);
    ASSERT(m_owned);
    byte* new_data = static_cast<byte*>(kmalloc(size));
    memcpy(new_data, m_data, m_size);
    byte* old_data = m_data;
    m_data = new_data;
    m_size = size;
    kfree(old_data);
}

inline Retained<ByteBufferImpl> ByteBufferImpl::create_uninitialized(int size)
{
    return ::adopt(*new ByteBufferImpl(size));
}

inline Retained<ByteBufferImpl> ByteBufferImpl::create_zeroed(int size)
{
    auto buffer = ::adopt(*new ByteBufferImpl(size));
    memset(buffer->pointer(), 0, size);
    return buffer;
}

inline Retained<ByteBufferImpl> ByteBufferImpl::copy(const void* data, int size)
{
    return ::adopt(*new ByteBufferImpl(data, size, Copy));
}

inline Retained<ByteBufferImpl> ByteBufferImpl::wrap(void* data, int size)
{
    return ::adopt(*new ByteBufferImpl(data, size, Wrap));
}

inline Retained<ByteBufferImpl> ByteBufferImpl::adopt(void* data, int size)
{
    return ::adopt(*new ByteBufferImpl(data, size, Adopt));
}

}

using AK::ByteBuffer;