ladybird/AK/DisjointChunks.h

397 lines
12 KiB
C
Raw Normal View History

/*
* Copyright (c) 2021, Ali Mohammad Pur <mpfard@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/AllOf.h>
#include <AK/Forward.h>
#include <AK/Span.h>
#include <AK/StdLibExtras.h>
namespace AK {
template<typename ChunkType, bool IsConst>
struct DisjointIterator {
struct EndTag {
};
using ReferenceType = Conditional<IsConst, AddConst<Vector<ChunkType>>, Vector<ChunkType>>&;
DisjointIterator(ReferenceType chunks)
: m_chunks(chunks)
{
}
DisjointIterator(ReferenceType chunks, EndTag)
: m_chunk_index(chunks.size())
, m_index_in_chunk(0)
, m_chunks(chunks)
{
}
DisjointIterator& operator++()
{
if (m_chunk_index >= m_chunks.size())
return *this;
auto& chunk = m_chunks[m_chunk_index];
if (m_index_in_chunk + 1 >= chunk.size()) {
++m_chunk_index;
m_index_in_chunk = 0;
} else {
++m_index_in_chunk;
}
if (m_chunk_index < m_chunks.size()) {
while (m_chunks[m_chunk_index].is_empty())
++m_chunk_index;
}
return *this;
}
bool operator==(DisjointIterator const& other) const
{
return &other.m_chunks == &m_chunks && other.m_index_in_chunk == m_index_in_chunk && other.m_chunk_index == m_chunk_index;
}
auto& operator*() requires(!IsConst) { return m_chunks[m_chunk_index][m_index_in_chunk]; }
auto* operator->() requires(!IsConst) { return &m_chunks[m_chunk_index][m_index_in_chunk]; }
auto const& operator*() const { return m_chunks[m_chunk_index][m_index_in_chunk]; }
auto const* operator->() const { return &m_chunks[m_chunk_index][m_index_in_chunk]; }
private:
size_t m_chunk_index { 0 };
size_t m_index_in_chunk { 0 };
ReferenceType m_chunks;
};
template<typename T>
class DisjointSpans {
public:
DisjointSpans() = default;
~DisjointSpans() = default;
DisjointSpans(DisjointSpans const&) = default;
DisjointSpans(DisjointSpans&&) = default;
explicit DisjointSpans(Vector<Span<T>> spans)
: m_spans(move(spans))
{
}
DisjointSpans& operator=(DisjointSpans&&) = default;
DisjointSpans& operator=(DisjointSpans const&) = default;
bool operator==(DisjointSpans const& other) const
{
if (other.size() != size())
return false;
auto it = begin();
auto other_it = other.begin();
for (; it != end(); ++it, ++other_it) {
if (*it != *other_it)
return false;
}
return true;
}
T& operator[](size_t index) { return at(index); }
T const& operator[](size_t index) const { return at(index); }
T const& at(size_t index) const { return const_cast<DisjointSpans&>(*this).at(index); }
T& at(size_t index)
{
auto value = find(index);
VERIFY(value != nullptr);
return *value;
}
T* find(size_t index)
{
auto span_and_offset = span_around(index);
if (span_and_offset.offset >= span_and_offset.span.size())
return nullptr;
return &span_and_offset.span.at(span_and_offset.offset);
}
T const* find(size_t index) const
{
return const_cast<DisjointSpans*>(this)->find(index);
}
size_t size() const
{
size_t size = 0;
for (auto& span : m_spans)
size += span.size();
return size;
}
bool is_empty() const
{
return all_of(m_spans, [](auto& span) { return span.is_empty(); });
}
DisjointSpans slice(size_t start, size_t length) const
{
DisjointSpans spans;
for (auto& span : m_spans) {
if (length == 0)
break;
if (start >= span.size()) {
start -= span.size();
continue;
}
auto sliced_length = min(length, span.size() - start);
spans.m_spans.append(span.slice(start, sliced_length));
start = 0;
length -= sliced_length;
}
// Make sure that we weren't asked to make a slice larger than possible.
VERIFY(length == 0);
return spans;
}
DisjointSpans slice(size_t start) const { return slice(start, size() - start); }
DisjointSpans slice_from_end(size_t length) const { return slice(size() - length, length); }
DisjointIterator<Span<T>, false> begin() { return { m_spans }; }
DisjointIterator<Span<T>, false> end() { return { m_spans, {} }; }
DisjointIterator<Span<T>, true> begin() const { return { m_spans }; }
DisjointIterator<Span<T>, true> end() const { return { m_spans, {} }; }
private:
struct SpanAndOffset {
Span<T>& span;
size_t offset;
};
SpanAndOffset span_around(size_t index)
{
size_t offset = 0;
for (auto& span : m_spans) {
if (span.is_empty())
continue;
auto next_offset = span.size() + offset;
if (next_offset <= index) {
offset = next_offset;
continue;
}
return { span, index - offset };
}
return { m_spans.last(), index - (offset - m_spans.last().size()) };
}
Vector<Span<T>> m_spans;
};
template<typename T, typename ChunkType = Vector<T>>
class DisjointChunks {
public:
DisjointChunks() = default;
~DisjointChunks() = default;
DisjointChunks(DisjointChunks const&) = default;
DisjointChunks(DisjointChunks&&) = default;
DisjointChunks& operator=(DisjointChunks&&) = default;
DisjointChunks& operator=(DisjointChunks const&) = default;
void append(ChunkType&& chunk) { m_chunks.append(chunk); }
void extend(DisjointChunks&& chunks) { m_chunks.extend(move(chunks.m_chunks)); }
void extend(DisjointChunks const& chunks) { m_chunks.extend(chunks.m_chunks); }
ChunkType& first_chunk() { return m_chunks.first(); }
ChunkType& last_chunk() { return m_chunks.last(); }
ChunkType const& first_chunk() const { return m_chunks.first(); }
ChunkType const& last_chunk() const { return m_chunks.last(); }
void ensure_capacity(size_t needed_capacity)
{
m_chunks.ensure_capacity(needed_capacity);
}
void insert(size_t index, T value)
{
if (m_chunks.size() == 1)
return m_chunks.first().insert(index, value);
auto chunk_and_offset = chunk_around(index);
if (!chunk_and_offset.chunk) {
m_chunks.empend();
chunk_and_offset.chunk = &m_chunks.last();
}
chunk_and_offset.chunk->insert(chunk_and_offset.offset, move(value));
}
void clear() { m_chunks.clear(); }
T& operator[](size_t index) { return at(index); }
T const& operator[](size_t index) const { return at(index); }
T const& at(size_t index) const { return const_cast<DisjointChunks&>(*this).at(index); }
T& at(size_t index)
{
auto value = find(index);
VERIFY(value != nullptr);
return *value;
}
T* find(size_t index)
{
if (m_chunks.size() == 1) {
if (m_chunks.first().size() > index)
return &m_chunks.first().at(index);
return nullptr;
}
auto chunk_and_offset = chunk_around(index);
if (!chunk_and_offset.chunk || chunk_and_offset.offset >= chunk_and_offset.chunk->size())
return nullptr;
return &chunk_and_offset.chunk->at(chunk_and_offset.offset);
}
T const* find(size_t index) const
{
return const_cast<DisjointChunks*>(this)->find(index);
}
size_t size() const
{
size_t sum = 0;
for (auto& chunk : m_chunks)
sum += chunk.size();
return sum;
}
bool is_empty() const
{
return all_of(m_chunks, [](auto& chunk) { return chunk.is_empty(); });
}
DisjointSpans<T> spans() const&
{
Vector<Span<T>> spans;
spans.ensure_capacity(m_chunks.size());
for (auto& chunk : m_chunks)
spans.unchecked_append(const_cast<ChunkType&>(chunk).span());
return DisjointSpans<T> { move(spans) };
}
bool operator==(DisjointChunks const& other) const
{
if (other.size() != size())
return false;
auto it = begin();
auto other_it = other.begin();
for (; it != end(); ++it, ++other_it) {
if (*it != *other_it)
return false;
}
return true;
}
DisjointChunks release_slice(size_t start, size_t length) & { return move(*this).slice(start, length); }
DisjointChunks release_slice(size_t start) & { return move(*this).slice(start); }
DisjointChunks slice(size_t start, size_t length) &&
{
DisjointChunks result;
for (auto& chunk : m_chunks) {
if (length == 0)
break;
if (start >= chunk.size()) {
start -= chunk.size();
continue;
}
auto sliced_length = min(length, chunk.size() - start);
if (start == 0 && sliced_length == chunk.size()) {
// Happy path! move the chunk itself.
result.m_chunks.append(move(chunk));
} else {
// Shatter the chunk, we were asked for only a part of it :(
auto wanted_slice = chunk.span().slice(start, sliced_length);
ChunkType new_chunk;
if constexpr (IsTriviallyConstructible<T>) {
new_chunk.resize(wanted_slice.size());
TypedTransfer<T>::move(new_chunk.data(), wanted_slice.data(), wanted_slice.size());
} else {
new_chunk.ensure_capacity(wanted_slice.size());
for (auto& entry : wanted_slice)
new_chunk.unchecked_append(move(entry));
}
result.m_chunks.append(move(new_chunk));
chunk.remove(start, sliced_length);
}
start = 0;
length -= sliced_length;
}
m_chunks.remove_all_matching([](auto& chunk) { return chunk.is_empty(); });
// Make sure that we weren't asked to make a slice larger than possible.
VERIFY(length == 0);
return result;
}
DisjointChunks slice(size_t start) && { return move(*this).slice(start, size() - start); }
DisjointChunks slice_from_end(size_t length) && { return move(*this).slice(size() - length, length); }
void flatten()
{
if (m_chunks.is_empty())
return;
auto size = this->size();
auto& first_chunk = m_chunks.first();
first_chunk.ensure_capacity(size);
bool first = true;
for (auto& chunk : m_chunks) {
if (first) {
first = false;
continue;
}
first_chunk.extend(move(chunk));
}
m_chunks.remove(1, m_chunks.size() - 1);
}
DisjointIterator<ChunkType, false> begin() { return { m_chunks }; }
DisjointIterator<ChunkType, false> end() { return { m_chunks, {} }; }
DisjointIterator<ChunkType, true> begin() const { return { m_chunks }; }
DisjointIterator<ChunkType, true> end() const { return { m_chunks, {} }; }
private:
struct ChunkAndOffset {
ChunkType* chunk;
size_t offset;
};
ChunkAndOffset chunk_around(size_t index)
{
if (m_chunks.is_empty())
return { nullptr, index };
size_t offset = 0;
for (auto& chunk : m_chunks) {
if (chunk.is_empty())
continue;
auto next_offset = chunk.size() + offset;
if (next_offset <= index) {
offset = next_offset;
continue;
}
return { &chunk, index - offset };
}
return { &m_chunks.last(), index - (offset - m_chunks.last().size()) };
}
Vector<ChunkType> m_chunks;
};
}
using AK::DisjointChunks;
using AK::DisjointSpans;