blob: 2b9e60c742d14b728a9605f0fd0876461af586ef [file] [log] [blame]
// Copyright 2020 The Pigweed Authors
//
// 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
//
// https://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 <array>
#include <cstddef>
#include <span>
#include "pw_bytes/span.h"
#include "pw_result/result.h"
#include "pw_stream/seek.h"
#include "pw_stream/stream.h"
namespace pw::stream {
class MemoryWriter : public SeekableWriter {
public:
using difference_type = ptrdiff_t;
using reference = const std::byte&;
using const_reference = const std::byte&;
using pointer = const std::byte*;
using const_pointer = const std::byte*;
using iterator = const std::byte*;
using const_iterator = const std::byte*;
constexpr MemoryWriter(ByteSpan dest) : dest_(dest) {}
// Construct writer with prepopulated data in the buffer. The number of
// pre-written bytes is provided as `bytes_written`.
//
// Precondition: The number of pre-written bytes must not be greater than the
// size of the provided buffer.
constexpr MemoryWriter(ByteSpan dest, size_t bytes_written)
: dest_(dest), position_(bytes_written) {
PW_ASSERT(position_ <= dest.size_bytes());
}
ConstByteSpan WrittenData() const { return dest_.first(position_); }
void clear() { position_ = 0; }
std::byte* data() { return dest_.data(); }
const std::byte* data() const { return dest_.data(); }
const std::byte& operator[](size_t index) const { return dest_[index]; }
[[nodiscard]] bool empty() const { return size() == 0u; }
size_t size() const { return position_; }
size_t bytes_written() const { return size(); }
size_t capacity() const { return dest_.size(); }
const std::byte* begin() const { return dest_.begin(); }
const std::byte* end() const { return dest_.begin() + position_; }
private:
size_t ConservativeLimit(LimitType type) const override {
return type == LimitType::kWrite ? dest_.size_bytes() - position_ : 0;
}
// Implementation for writing data to this stream.
//
// If the in-memory buffer is exhausted in the middle of a write, this will
// perform a partial write and Status::ResourceExhausted() will be returned.
Status DoWrite(ConstByteSpan data) final;
Status DoSeek(ptrdiff_t offset, Whence origin) final {
return CalculateSeek(offset, origin, dest_.size(), position_);
}
size_t DoTell() const final { return position_; }
ByteSpan dest_;
size_t position_ = 0;
};
template <size_t kSizeBytes>
class MemoryWriterBuffer final : public MemoryWriter {
public:
constexpr MemoryWriterBuffer() : MemoryWriter(buffer_) {}
private:
std::array<std::byte, kSizeBytes> buffer_;
};
class MemoryReader final : public SeekableReader {
public:
constexpr MemoryReader(ConstByteSpan source)
: source_(source), position_(0) {}
size_t bytes_read() const { return position_; }
const std::byte* data() const { return source_.data(); }
private:
size_t ConservativeLimit(LimitType type) const override {
return type == LimitType::kRead ? source_.size_bytes() - position_ : 0;
}
Status DoSeek(ptrdiff_t offset, Whence origin) override {
return CalculateSeek(offset, origin, source_.size(), position_);
}
size_t DoTell() const override { return position_; }
// Implementation for reading data from this stream.
//
// If the in-memory buffer does not have enough remaining bytes for what was
// requested, this will perform a partial read and OK will still be returned.
StatusWithSize DoRead(ByteSpan dest) override;
ConstByteSpan source_;
size_t position_;
};
} // namespace pw::stream