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authorJim Posen <jimpo@coinbase.com>2018-01-23 15:59:36 -0800
committerJim Posen <jim.posen@gmail.com>2018-08-25 10:02:37 -0700
commit947133dec92cd25ec2b3358c09b8614ba6fb40d4 (patch)
tree4810f825a87cf27f24708a76a5fc0273808451ba /src/streams.h
parent021dce935af25adc17ae04a721d5f74a2ea1ca76 (diff)
streams: Create VectorReader stream interface for vectors.
This is a read analogue for the existing CVectorWriter.
Diffstat (limited to 'src/streams.h')
-rw-r--r--src/streams.h74
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.