113 lines
3.6 KiB
C++
113 lines
3.6 KiB
C++
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#ifndef _FC_DATASTREAM_HPP_
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#define _FC_DATASTREAM_HPP_
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#include <fc/utility.hpp>
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#include <fc/exception.hpp>
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#include <stdint.h>
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namespace fc {
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/**
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* The purpose of this datastream is to provide a fast, effecient, means
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* of calculating the amount of data "about to be written" and then
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* writing it. This means having two modes of operation, "test run" where
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* you call the entire pack sequence calculating the size, and then
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* actually packing it after doing a single allocation.
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*/
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template<typename T>
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struct datastream {
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datastream( T start, uint32_t s )
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:m_start(start),m_pos(start),m_end(start+s){};
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template<typename DATA>
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inline datastream& operator<<(const DATA& d) {
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static_assert( !fc::is_class<DATA>::value, "no serialization defined" );
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write( (const char*)&d, sizeof(d) );
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return *this;
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}
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template<typename DATA>
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inline datastream& operator>>(DATA& d) {
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static_assert( !fc::is_class<DATA>::value, "no serialization defined" );
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read((char*)&d, sizeof(d) );
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return *this;
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}
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inline void skip( uint32_t s ){ m_pos += s; }
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inline bool read( char* d, uint32_t s ) {
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if( m_end - m_pos >= (int32_t)s ) {
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memcpy( d, m_pos, s );
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m_pos += s;
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return true;
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}
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FC_THROW( "Attempt to read %d bytes beyond end of buffer of size %d", -((m_end-m_pos) - s),(m_end-m_start) );
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return false;
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}
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inline bool write( const char* d, uint32_t s ) {
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if( m_end - m_pos >= (int32_t)s ) {
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memcpy( m_pos, d, s );
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m_pos += s;
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return true;
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}
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FC_THROW( "Attempt to write %d bytes beyond end of buffer of size %d",%-((m_end-m_pos) - s),(m_end-m_start) );
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return false;
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}
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inline bool put(char c) {
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if( m_pos < m_end ) {
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*m_pos = c;
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++m_pos;
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return true;
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}
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FC_THROW( "Attempt to write %d byte beyond end of buffer of size %d", -((m_end-m_pos) - 1), (m_end-m_start) );
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return false;
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}
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inline bool get( unsigned char& c ) { return get( *(char*)&c ); }
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inline bool get( char& c ) {
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if( m_pos < m_end ) {
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c = *m_pos;
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++m_pos;
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return true;
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}
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FC_THROW( "Attempt to read %d byte beyond end of buffer of size %d", -((m_end-m_pos) - 1), (m_end-m_start) );
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++m_pos;
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return false;
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}
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T pos()const { return m_pos; }
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inline bool valid()const { return m_pos <= m_end && m_pos >= m_start; }
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inline bool seekp(uint32_t p) { m_pos = m_start + p; return m_pos <= m_end; }
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inline uint32_t tellp()const { return m_pos - m_start; }
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inline uint32_t remaining()const { return m_end - m_pos; }
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private:
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T m_start;
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T m_pos;
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T m_end;
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};
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template<>
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struct datastream<size_t> {
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datastream( size_t init_size = 0):m_size(init_size){};
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template<typename DATA>
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inline datastream& operator<<(const DATA& d) {
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static_assert( !fc::is_class<DATA>::value, "no serialzation defined" );
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m_size += sizeof(d);
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return *this;
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}
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inline bool skip( uint32_t s ) { m_size += s; return true; }
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inline bool write( const char* d, uint32_t s ) { m_size += s; return true; }
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inline bool put(char c) { ++m_size; return true; }
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inline bool valid()const { return true; }
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inline bool seekp(uint32_t p) { m_size = p; return true; }
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inline uint32_t tellp()const { return m_size; }
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inline uint32_t remaining()const { return 0; }
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private:
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uint32_t m_size;
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};
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} // namespace fc
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#endif
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