| // Copyright 2021 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 <algorithm> |
| #include <array> |
| #include <bit> |
| #include <cstddef> |
| #include <cstring> |
| #include <span> |
| #include <string_view> |
| |
| #include "pw_assert/assert.h" |
| #include "pw_bytes/endian.h" |
| #include "pw_bytes/span.h" |
| #include "pw_protobuf/config.h" |
| #include "pw_protobuf/wire_format.h" |
| #include "pw_status/status.h" |
| #include "pw_status/try.h" |
| #include "pw_stream/memory_stream.h" |
| #include "pw_stream/stream.h" |
| #include "pw_varint/varint.h" |
| |
| namespace pw::protobuf { |
| |
| // Provides a size estimate to help with sizing buffers passed to |
| // StreamEncoder and MemoryEncoder objects. |
| // |
| // Args: |
| // max_message_size: For MemoryEncoder objects, this is the max expected size |
| // of the final proto. For StreamEncoder objects, this should be the max |
| // size of any nested proto submessage that will be built with this encoder |
| // (recursively accumulating the size from the root submessage). If your |
| // proto will encode many large submessages, this value should just be the |
| // size of the largest one. |
| // max_nested_depth: The max number of nested submessage encoders that are |
| // expected to be open simultaneously to encode this proto message. |
| static constexpr size_t MaxScratchBufferSize(size_t max_message_size, |
| size_t max_nested_depth) { |
| return max_message_size + max_nested_depth * config::kMaxVarintSize; |
| } |
| |
| // Write a varint value to the writer. |
| // |
| // Args: |
| // value: The value of the varint to write |
| // writer: The writer for writing to output. |
| // |
| // Returns: |
| // OK - varint is written successfully |
| // |
| // Errors encountered by the `writer` will be returned as it is. |
| inline Status WriteVarint(uint64_t value, stream::Writer& writer) { |
| std::array<std::byte, varint::kMaxVarint64SizeBytes> varint_encode_buffer; |
| const size_t varint_size = |
| pw::varint::EncodeLittleEndianBase128(value, varint_encode_buffer); |
| return writer.Write(std::span(varint_encode_buffer).first(varint_size)); |
| } |
| |
| // Write the field key and length prefix for a length-delimited field. It is |
| // up to the caller to ensure that this will be followed by an exact number |
| // of bytes written for the field in order to form a valid proto message. |
| // |
| // Args: |
| // field_number: The field number for the field. |
| // payload_size: The size of the payload. |
| // writer: The output writer to write to |
| // |
| // |
| // Returns: |
| // OK - Field key is written successfully |
| // |
| // Errors encountered by the `writer` will be returned as it is. |
| // |
| // Precondition: The field_number must be a ValidFieldNumber. |
| // Precondition: `data_size_bytes` must be smaller than |
| // std::numeric_limits<uint32_t>::max() |
| inline Status WriteLengthDelimitedKeyAndLengthPrefix(uint32_t field_number, |
| size_t payload_size, |
| stream::Writer& writer) { |
| PW_TRY(WriteVarint(FieldKey(field_number, WireType::kDelimited), writer)); |
| return WriteVarint(payload_size, writer); |
| } |
| |
| // Forward declaration. StreamEncoder and MemoryEncoder are very tightly |
| // coupled. |
| class MemoryEncoder; |
| |
| // A protobuf encoder that encodes serialized proto data to a |
| // pw::stream::Writer. |
| class StreamEncoder { |
| public: |
| // The StreamEncoder will serialize proto data to the pw::stream::Writer |
| // provided through the constructor. The scratch buffer provided is for |
| // internal use ONLY and should not be considered valid proto data. |
| // |
| // If a StreamEncoder object will be writing nested proto messages, it must |
| // provide a scratch buffer large enough to hold the largest submessage some |
| // additional overhead incurred by the encoder's implementation. It's a good |
| // idea to be generous when sizing this buffer. MaxScratchBufferSize() can be |
| // helpful in providing an estimated size for this buffer. The scratch buffer |
| // must exist for the lifetime of the StreamEncoder object. |
| // |
| // StreamEncoder objects that do not write nested proto messages can |
| // provide a zero-length scratch buffer. |
| constexpr StreamEncoder(stream::Writer& writer, ByteSpan scratch_buffer) |
| : status_(OkStatus()), |
| parent_(nullptr), |
| nested_field_number_(0), |
| memory_writer_(scratch_buffer), |
| writer_(writer) {} |
| |
| // Precondition: Encoder has no active child encoder. |
| // |
| // Postcondition: If this encoder is a nested one, the parent encoder is |
| // unlocked and proto encoding may resume on the parent. |
| ~StreamEncoder(); |
| |
| // Disallow copy/assign to avoid confusion about who owns the buffer. |
| StreamEncoder& operator=(const StreamEncoder& other) = delete; |
| StreamEncoder(const StreamEncoder& other) = delete; |
| |
| // It's not safe to move an encoder as it could cause another encoder's |
| // parent_ pointer to become invalid. |
| StreamEncoder& operator=(StreamEncoder&& other) = delete; |
| |
| // Forwards the conservative write limit of the underlying |
| // pw::stream::Writer. |
| // |
| // Precondition: Encoder has no active child encoder. |
| size_t ConservativeWriteLimit() const { |
| PW_ASSERT(!nested_encoder_open()); |
| return writer_.ConservativeWriteLimit(); |
| } |
| |
| // Creates a nested encoder with the provided field number. Once this is |
| // called, the parent encoder is locked and not available for use until the |
| // nested encoder is finalized (either explicitly or through destruction). |
| // |
| // Precondition: Encoder has no active child encoder. |
| // |
| // Postcondition: Until the nested child encoder has been destroyed, this |
| // encoder cannot be used. |
| StreamEncoder GetNestedEncoder(uint32_t field_number); |
| |
| // Returns the current encoder's status. |
| // |
| // Precondition: Encoder has no active child encoder. |
| Status status() const { |
| PW_ASSERT(!nested_encoder_open()); |
| return status_; |
| } |
| |
| // Writes a proto uint32 key-value pair. |
| // |
| // Precondition: Encoder has no active child encoder. |
| Status WriteUint32(uint32_t field_number, uint32_t value) { |
| return WriteUint64(field_number, value); |
| } |
| |
| // Writes a repeated uint32 using packed encoding. |
| // |
| // Precondition: Encoder has no active child encoder. |
| Status WritePackedUint32(uint32_t field_number, |
| std::span<const uint32_t> values) { |
| return WritePackedVarints(field_number, values, VarintEncodeType::kNormal); |
| } |
| |
| // Writes a proto uint64 key-value pair. |
| // |
| // Precondition: Encoder has no active child encoder. |
| Status WriteUint64(uint32_t field_number, uint64_t value) { |
| return WriteVarintField(field_number, value); |
| } |
| |
| // Writes a repeated uint64 using packed encoding. |
| // |
| // Precondition: Encoder has no active child encoder. |
| Status WritePackedUint64(uint64_t field_number, |
| std::span<const uint64_t> values) { |
| return WritePackedVarints(field_number, values, VarintEncodeType::kNormal); |
| } |
| |
| // Writes a proto int32 key-value pair. |
| // |
| // Precondition: Encoder has no active child encoder. |
| Status WriteInt32(uint32_t field_number, int32_t value) { |
| return WriteUint64(field_number, value); |
| } |
| |
| // Writes a repeated int32 using packed encoding. |
| // |
| // Precondition: Encoder has no active child encoder. |
| Status WritePackedInt32(uint32_t field_number, |
| std::span<const int32_t> values) { |
| return WritePackedVarints( |
| field_number, |
| std::span(reinterpret_cast<const uint32_t*>(values.data()), |
| values.size()), |
| VarintEncodeType::kNormal); |
| } |
| |
| // Writes a proto int64 key-value pair. |
| // |
| // Precondition: Encoder has no active child encoder. |
| Status WriteInt64(uint32_t field_number, int64_t value) { |
| return WriteUint64(field_number, value); |
| } |
| |
| // Writes a repeated int64 using packed encoding. |
| // |
| // Precondition: Encoder has no active child encoder. |
| Status WritePackedInt64(uint32_t field_number, |
| std::span<const int64_t> values) { |
| return WritePackedVarints( |
| field_number, |
| std::span(reinterpret_cast<const uint64_t*>(values.data()), |
| values.size()), |
| VarintEncodeType::kNormal); |
| } |
| |
| // Writes a proto sint32 key-value pair. |
| // |
| // Precondition: Encoder has no active child encoder. |
| Status WriteSint32(uint32_t field_number, int32_t value) { |
| return WriteUint64(field_number, varint::ZigZagEncode(value)); |
| } |
| |
| // Writes a repeated sint32 using packed encoding. |
| // |
| // Precondition: Encoder has no active child encoder. |
| Status WritePackedSint32(uint32_t field_number, |
| std::span<const int32_t> values) { |
| return WritePackedVarints( |
| field_number, |
| std::span(reinterpret_cast<const uint32_t*>(values.data()), |
| values.size()), |
| VarintEncodeType::kZigZag); |
| } |
| |
| // Writes a proto sint64 key-value pair. |
| // |
| // Precondition: Encoder has no active child encoder. |
| Status WriteSint64(uint32_t field_number, int64_t value) { |
| return WriteUint64(field_number, varint::ZigZagEncode(value)); |
| } |
| |
| // Writes a repeated sint64 using packed encoding. |
| // |
| // Precondition: Encoder has no active child encoder. |
| Status WritePackedSint64(uint32_t field_number, |
| std::span<const int64_t> values) { |
| return WritePackedVarints( |
| field_number, |
| std::span(reinterpret_cast<const uint64_t*>(values.data()), |
| values.size()), |
| VarintEncodeType::kZigZag); |
| } |
| |
| // Writes a proto bool key-value pair. |
| // |
| // Precondition: Encoder has no active child encoder. |
| Status WriteBool(uint32_t field_number, bool value) { |
| return WriteUint32(field_number, static_cast<uint32_t>(value)); |
| } |
| |
| // Writes a proto fixed32 key-value pair. |
| // |
| // Precondition: Encoder has no active child encoder. |
| Status WriteFixed32(uint32_t field_number, uint32_t value) { |
| std::array<std::byte, sizeof(value)> data = |
| bytes::CopyInOrder(std::endian::little, value); |
| return WriteFixed(field_number, data); |
| } |
| |
| // Writes a repeated fixed32 field using packed encoding. |
| // |
| // Precondition: Encoder has no active child encoder. |
| Status WritePackedFixed32(uint32_t field_number, |
| std::span<const uint32_t> values) { |
| return WritePackedFixed( |
| field_number, std::as_bytes(values), sizeof(uint32_t)); |
| } |
| |
| // Writes a proto fixed64 key-value pair. |
| // |
| // Precondition: Encoder has no active child encoder. |
| Status WriteFixed64(uint32_t field_number, uint64_t value) { |
| std::array<std::byte, sizeof(value)> data = |
| bytes::CopyInOrder(std::endian::little, value); |
| return WriteFixed(field_number, data); |
| } |
| |
| // Writes a repeated fixed64 field using packed encoding. |
| // |
| // Precondition: Encoder has no active child encoder. |
| Status WritePackedFixed64(uint32_t field_number, |
| std::span<const uint64_t> values) { |
| return WritePackedFixed( |
| field_number, std::as_bytes(values), sizeof(uint64_t)); |
| } |
| |
| // Writes a proto sfixed32 key-value pair. |
| // |
| // Precondition: Encoder has no active child encoder. |
| Status WriteSfixed32(uint32_t field_number, int32_t value) { |
| return WriteFixed32(field_number, static_cast<uint32_t>(value)); |
| } |
| |
| // Writes a repeated sfixed32 field using packed encoding. |
| // |
| // Precondition: Encoder has no active child encoder. |
| Status WritePackedSfixed32(uint32_t field_number, |
| std::span<const int32_t> values) { |
| return WritePackedFixed( |
| field_number, std::as_bytes(values), sizeof(int32_t)); |
| } |
| |
| // Writes a proto sfixed64 key-value pair. |
| // |
| // Precondition: Encoder has no active child encoder. |
| Status WriteSfixed64(uint32_t field_number, int64_t value) { |
| return WriteFixed64(field_number, static_cast<uint64_t>(value)); |
| } |
| |
| // Writes a repeated sfixed64 field using packed encoding. |
| // |
| // Precondition: Encoder has no active child encoder. |
| Status WritePackedSfixed64(uint32_t field_number, |
| std::span<const int64_t> values) { |
| return WritePackedFixed( |
| field_number, std::as_bytes(values), sizeof(int64_t)); |
| } |
| |
| // Writes a proto float key-value pair. |
| // |
| // Precondition: Encoder has no active child encoder. |
| Status WriteFloat(uint32_t field_number, float value) { |
| static_assert(sizeof(float) == sizeof(uint32_t), |
| "Float and uint32_t are not the same size"); |
| uint32_t integral_value; |
| std::memcpy(&integral_value, &value, sizeof(value)); |
| std::array<std::byte, sizeof(value)> data = |
| bytes::CopyInOrder(std::endian::little, integral_value); |
| return WriteFixed(field_number, data); |
| } |
| |
| // Writes a repeated float field using packed encoding. |
| // |
| // Precondition: Encoder has no active child encoder. |
| Status WritePackedFloat(uint32_t field_number, |
| std::span<const float> values) { |
| return WritePackedFixed(field_number, std::as_bytes(values), sizeof(float)); |
| } |
| |
| // Writes a proto double key-value pair. |
| // |
| // Precondition: Encoder has no active child encoder. |
| Status WriteDouble(uint32_t field_number, double value) { |
| static_assert(sizeof(double) == sizeof(uint64_t), |
| "Double and uint64_t are not the same size"); |
| uint64_t integral_value; |
| std::memcpy(&integral_value, &value, sizeof(value)); |
| std::array<std::byte, sizeof(value)> data = |
| bytes::CopyInOrder(std::endian::little, integral_value); |
| return WriteFixed(field_number, data); |
| } |
| |
| // Writes a repeated double field using packed encoding. |
| // |
| // Precondition: Encoder has no active child encoder. |
| Status WritePackedDouble(uint32_t field_number, |
| std::span<const double> values) { |
| return WritePackedFixed( |
| field_number, std::as_bytes(values), sizeof(double)); |
| } |
| |
| // Writes a proto `bytes` field as a key-value pair. This can also be used to |
| // write a pre-encoded nested submessage directly without using a nested |
| // encoder. |
| // |
| // Precondition: Encoder has no active child encoder. |
| Status WriteBytes(uint32_t field_number, ConstByteSpan value) { |
| return WriteLengthDelimitedField(field_number, value); |
| } |
| |
| // Writes a proto 'bytes' field from the stream bytes_reader. |
| // |
| // The payload for the value is provided through the stream::Reader |
| // `bytes_reader`. The method reads a chunk of the data from the reader using |
| // the `stream_pipe_buffer` and writes it to the encoder. |
| // |
| // Precondition: The stream_pipe_buffer.byte_size() >= 1 |
| // Precondition: Encoder has no active child encoder. |
| // |
| // Returns: |
| // OK - Bytes field is written successfully. |
| // RESOURCE_EXHAUSTED - Exceeds write limits. |
| // OUT_OF_RANGE - `bytes_reader` is exhausted before `num_bytes` of |
| // bytes is read. |
| // |
| // Other errors encountered by the writer will be returned as it is. |
| Status WriteBytesFromStream(uint32_t field_number, |
| stream::Reader& bytes_reader, |
| size_t num_bytes, |
| ByteSpan stream_pipe_buffer) { |
| return WriteLengthDelimitedFieldFromStream( |
| field_number, bytes_reader, num_bytes, stream_pipe_buffer); |
| } |
| |
| // Writes a proto string key-value pair. |
| // |
| // Precondition: Encoder has no active child encoder. |
| Status WriteString(uint32_t field_number, std::string_view value) { |
| return WriteBytes(field_number, std::as_bytes(std::span(value))); |
| } |
| |
| // Writes a proto string key-value pair. |
| // |
| // Precondition: Encoder has no active child encoder. |
| Status WriteString(uint32_t field_number, const char* value, size_t len) { |
| return WriteBytes(field_number, std::as_bytes(std::span(value, len))); |
| } |
| |
| // Writes a proto 'string' field from the stream bytes_reader. |
| // |
| // The payload for the value is provided through the stream::Reader |
| // `bytes_reader`. The method reads a chunk of the data from the reader using |
| // the `stream_pipe_buffer` and writes it to the encoder. |
| // |
| // Precondition: The stream_pipe_buffer.byte_size() >= 1 |
| // Precondition: Encoder has no active child encoder. |
| // |
| // Returns: |
| // OK - String field is written successfully. |
| // RESOURCE_EXHAUSTED - Exceeds write limits. |
| // OUT_OF_RANGE - `bytes_reader` is exhausted before `num_bytes` of |
| // bytes is read. |
| // |
| // Other errors encountered by the writer will be returned as it is. |
| Status WriteStringFromStream(uint32_t field_number, |
| stream::Reader& bytes_reader, |
| size_t num_bytes, |
| ByteSpan stream_pipe_buffer) { |
| return WriteBytesFromStream( |
| field_number, bytes_reader, num_bytes, stream_pipe_buffer); |
| } |
| |
| protected: |
| // Specialized move constructor used only for codegen. |
| // |
| // Postcondition: The other encoder is invalidated and cannot be used as it |
| // acts like a parent encoder with an active child encoder. |
| constexpr StreamEncoder(StreamEncoder&& other) |
| : status_(other.status_), |
| parent_(other.parent_), |
| nested_field_number_(other.nested_field_number_), |
| memory_writer_(std::move(other.memory_writer_)), |
| writer_(&other.writer_ == &other.memory_writer_ ? memory_writer_ |
| : other.writer_) { |
| PW_ASSERT(nested_field_number_ == 0); |
| // Make the nested encoder look like it has an open child to block writes |
| // for the remainder of the object's life. |
| other.nested_field_number_ = kFirstReservedNumber; |
| other.parent_ = nullptr; |
| } |
| |
| private: |
| friend class MemoryEncoder; |
| |
| enum class VarintEncodeType { |
| kNormal, |
| kZigZag, |
| }; |
| |
| constexpr StreamEncoder(StreamEncoder& parent, ByteSpan scratch_buffer) |
| : status_(scratch_buffer.empty() ? Status::ResourceExhausted() |
| : OkStatus()), |
| parent_(&parent), |
| nested_field_number_(0), |
| memory_writer_(scratch_buffer), |
| writer_(memory_writer_) {} |
| |
| bool nested_encoder_open() const { return nested_field_number_ != 0; } |
| |
| // CloseNestedMessage() is called on the parent encoder as part of the nested |
| // encoder destructor. |
| void CloseNestedMessage(StreamEncoder& nested); |
| |
| // Implementation for encoding all varint field types. |
| Status WriteVarintField(uint32_t field_number, uint64_t value); |
| |
| // Implementation for encoding all length-delimited field types. |
| Status WriteLengthDelimitedField(uint32_t field_number, ConstByteSpan data); |
| |
| // Encoding of length-delimited field where payload comes from `bytes_reader`. |
| Status WriteLengthDelimitedFieldFromStream(uint32_t field_number, |
| stream::Reader& bytes_reader, |
| size_t num_bytes, |
| ByteSpan stream_pipe_buffer); |
| |
| // Implementation for encoding all fixed-length integer types. |
| Status WriteFixed(uint32_t field_number, ConstByteSpan data); |
| |
| // Encodes a base-128 varint to the buffer. This function assumes the caller |
| // has already checked UpdateStatusForWrite() to ensure the writer's |
| // conservative write limit indicates the Writer has sufficient buffer space. |
| Status WriteVarint(uint64_t value) { |
| PW_TRY(status_); |
| status_.Update(::pw::protobuf::WriteVarint(value, writer_)); |
| return status_; |
| } |
| |
| Status WriteZigzagVarint(int64_t value) { |
| return WriteVarint(varint::ZigZagEncode(value)); |
| } |
| |
| // Writes a list of varints to the buffer in length-delimited packed encoding. |
| template <typename T, typename = std::enable_if_t<std::is_integral<T>::value>> |
| Status WritePackedVarints(uint32_t field_number, |
| std::span<T> values, |
| VarintEncodeType encode_type) { |
| static_assert(std::is_same<T, const uint32_t>::value || |
| std::is_same<T, const int32_t>::value || |
| std::is_same<T, const uint64_t>::value || |
| std::is_same<T, const int64_t>::value, |
| "Packed varints must be of type uint32_t, int32_t, uint64_t, " |
| "or int64_t"); |
| |
| size_t payload_size = 0; |
| for (T val : values) { |
| if (encode_type == VarintEncodeType::kZigZag) { |
| int64_t integer = |
| static_cast<int64_t>(static_cast<std::make_signed_t<T>>(val)); |
| payload_size += varint::EncodedSize(varint::ZigZagEncode(integer)); |
| } else { |
| uint64_t integer = static_cast<uint64_t>(val); |
| payload_size += varint::EncodedSize(integer); |
| } |
| } |
| |
| if (!UpdateStatusForWrite(field_number, WireType::kDelimited, payload_size) |
| .ok()) { |
| return status_; |
| } |
| |
| WriteVarint(FieldKey(field_number, WireType::kDelimited)) |
| .IgnoreError(); // TODO(pwbug/387): Handle Status properly |
| WriteVarint(payload_size) |
| .IgnoreError(); // TODO(pwbug/387): Handle Status properly |
| for (T value : values) { |
| if (encode_type == VarintEncodeType::kZigZag) { |
| WriteZigzagVarint(static_cast<std::make_signed_t<T>>(value)) |
| .IgnoreError(); // TODO(pwbug/387): Handle Status properly |
| } else { |
| WriteVarint(value) |
| .IgnoreError(); // TODO(pwbug/387): Handle Status properly |
| } |
| } |
| |
| return status_; |
| } |
| |
| // Writes a list of fixed-size types to the buffer in length-delimited |
| // packed encoding. Only float, double, uint32_t, int32_t, uint64_t, and |
| // int64_t are permitted |
| Status WritePackedFixed(uint32_t field_number, |
| std::span<const std::byte> values, |
| size_t elem_size); |
| |
| // Checks if a write is invalid or will cause the encoder to enter an error |
| // state, and preemptively sets this encoder's status to that error to block |
| // the write. Only the first error encountered is tracked. |
| // |
| // Precondition: Encoder has no active child encoder. |
| // |
| // Returns: |
| // InvalidArgument: The field number provided was invalid. |
| // ResourceExhausted: The requested write would have exceeded the |
| // stream::Writer's conservative write limit. |
| // Other: If any Write() operations on the stream::Writer caused an error, |
| // that error will be repeated here. |
| Status UpdateStatusForWrite(uint32_t field_number, |
| WireType type, |
| size_t data_size); |
| |
| // The current encoder status. This status is only updated to reflect the |
| // first error encountered. Any further write operations are blocked when the |
| // encoder enters an error state. |
| Status status_; |
| |
| // If this is a nested encoder, this points to the encoder that created it. |
| // For user-created MemoryEncoders, parent_ points to this object as an |
| // optimization for the MemoryEncoder and nested encoders to use the same |
| // underlying buffer. |
| StreamEncoder* parent_; |
| |
| // If an encoder has a child encoder open, this is the field number of that |
| // submessage. Otherwise, this is 0 to indicate no child encoder is open. |
| uint32_t nested_field_number_; |
| |
| // This memory writer is used for staging proto submessages to the |
| // scratch_buffer. |
| stream::MemoryWriter memory_writer_; |
| |
| // All proto encode operations are directly written to this writer. |
| stream::Writer& writer_; |
| }; |
| |
| // A protobuf encoder that writes directly to a provided buffer. |
| // |
| // Example: |
| // |
| // // Writes a proto response to the provided buffer, returning the encode |
| // // status and number of bytes written. |
| // StatusWithSize WriteProtoResponse(ByteSpan response) { |
| // // All proto writes are directly written to the `response` buffer. |
| // MemoryEncoder encoder(response); |
| // encoder.WriteUint32(kMagicNumberField, 0x1a1a2b2b); |
| // encoder.WriteString(kFavoriteFood, "cookies"); |
| // return StatusWithSize(encoder.status(), encoder.size()); |
| // } |
| // |
| // Note: Avoid using a MemoryEncoder reference as an argument for a function. |
| // The StreamEncoder is more generic. |
| class MemoryEncoder : public StreamEncoder { |
| public: |
| constexpr MemoryEncoder(ByteSpan dest) : StreamEncoder(*this, dest) {} |
| |
| // Precondition: Encoder has no active child encoder. |
| // |
| // Postcondition: If this encoder is a nested one, the parent encoder is |
| // unlocked and proto encoding may resume on the parent. |
| ~MemoryEncoder() = default; |
| |
| // Disallow copy/assign to avoid confusion about who owns the buffer. |
| MemoryEncoder(const MemoryEncoder& other) = delete; |
| MemoryEncoder& operator=(const MemoryEncoder& other) = delete; |
| |
| // It's not safe to move an encoder as it could cause another encoder's |
| // parent_ pointer to become invalid. |
| MemoryEncoder& operator=(MemoryEncoder&& other) = delete; |
| |
| const std::byte* data() const { return memory_writer_.data(); } |
| size_t size() const { return memory_writer_.bytes_written(); } |
| |
| protected: |
| // This is needed by codegen. |
| MemoryEncoder(MemoryEncoder&& other) = default; |
| }; |
| |
| } // namespace pw::protobuf |
