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author | Jim Posen <jimpo@coinbase.com> | 2018-01-23 15:59:36 -0800 |
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committer | Jim Posen <jim.posen@gmail.com> | 2018-08-25 10:02:37 -0700 |
commit | 947133dec92cd25ec2b3358c09b8614ba6fb40d4 (patch) | |
tree | 4810f825a87cf27f24708a76a5fc0273808451ba | |
parent | 021dce935af25adc17ae04a721d5f74a2ea1ca76 (diff) | |
download | bitcoin-947133dec92cd25ec2b3358c09b8614ba6fb40d4.tar.xz |
streams: Create VectorReader stream interface for vectors.
This is a read analogue for the existing CVectorWriter.
-rw-r--r-- | src/streams.h | 74 |
1 files changed, 74 insertions, 0 deletions
diff --git a/src/streams.h b/src/streams.h index 096ebfc9c2..32a7073815 100644 --- a/src/streams.h +++ b/src/streams.h @@ -139,6 +139,80 @@ private: size_t nPos; }; +/** Minimal stream for reading from an existing vector by reference + */ +class VectorReader +{ +private: + const int m_type; + const int m_version; + const std::vector<unsigned char>& m_data; + size_t m_pos = 0; + +public: + + /* + * @param[in] type Serialization Type + * @param[in] version Serialization Version (including any flags) + * @param[in] data Referenced byte vector to overwrite/append + * @param[in] pos Starting position. Vector index where reads should start. + */ + VectorReader(int type, int version, const std::vector<unsigned char>& data, size_t pos) + : m_type(type), m_version(version), m_data(data) + { + seek(pos); + } + + /* + * (other params same as above) + * @param[in] args A list of items to deserialize starting at pos. + */ + template <typename... Args> + VectorReader(int type, int version, const std::vector<unsigned char>& data, size_t pos, + Args&&... args) + : VectorReader(type, version, data, pos) + { + ::UnserializeMany(*this, std::forward<Args>(args)...); + } + + template<typename T> + VectorReader& operator>>(T& obj) + { + // Unserialize from this stream + ::Unserialize(*this, obj); + return (*this); + } + + int GetVersion() const { return m_version; } + int GetType() const { return m_type; } + + size_t size() const { return m_data.size() - m_pos; } + bool empty() const { return m_data.size() == m_pos; } + + void read(char* dst, size_t n) + { + if (n == 0) { + return; + } + + // Read from the beginning of the buffer + size_t pos_next = m_pos + n; + if (pos_next > m_data.size()) { + throw std::ios_base::failure("VectorReader::read(): end of data"); + } + memcpy(dst, m_data.data() + m_pos, n); + m_pos = pos_next; + } + + void seek(size_t n) + { + m_pos += n; + if (m_pos > m_data.size()) { + throw std::ios_base::failure("VectorReader::seek(): end of data"); + } + } +}; + /** Double ended buffer combining vector and stream-like interfaces. * * >> and << read and write unformatted data using the above serialization templates. |