📄 vectoronfile.h
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//////////////////////////////////////////////////////////////////////////// Copyright (c) 2000, Yusuke Miyao/// You may distribute under the terms of the Artistic License.////// <id>$Id: VectorOnFile.h,v 1.4 2002/12/18 08:47:44 yusuke Exp $</id>/// <collection>Maximum Entropy Estimator</collection>/// <name>VectorOnFile.h</name>/// <overview>Implementation of a vector class on a file</overview>/////////////////////////////////////////////////////////////////////////#ifndef Amis_VectorOnFile_h_#define Amis_VectorOnFile_h_#include <amis/configure.h>#include <amis/ErrorBase.h>#include <amis/objstream.h>#include <amis/StringStream.h>#include <vector>#include <cstdio>AMIS_NAMESPACE_BEGIN///////////////////////////////////////////////////////////////////////// <classdef>/// <name>VectorOnFileError</name>/// <overview>A vector class on a file</overview>/// <desc>/// Only one element is accessible at the same time/// </desc>/// <body>class VectorOnFileError : public ErrorBase { public: VectorOnFileError( const std::string& s ) : ErrorBase( s ) {} /// Initialize with an error message VectorOnFileError( char* s ) : ErrorBase( s ) {} /// Initialize with an error message};/// </body>/// </classdef>///////////////////////////////////////////////////////////////////////// <classdef>/// <name>VectorOnFile</name>/// <overview>A vector class on a file</overview>/// Only one element is accessible at the same time/// <body>template < class T >class VectorOnFile {public: static const int DEFAULT_CHUNK_SIZE = 512 * 1024 * 1024; // 512 MBprivate: std::string stream_base_name; std::vector<objstream*> stream_v; std::vector<objstream*> event2stream_v; std::vector<std::streampos> event2pos_v; int last_stream_no; std::streampos last_pos; mutable T* tmp_object;protected: void readObject( int i ) const { /* if ( stream == NULL ) { throw VectorOnFileError( "Stream is not set to `VectorOnFile'" ); } */ if ( tmp_object != NULL ) delete tmp_object; // support multiple stream objstream* stream = event2stream_v[i]; stream->seekg( event2pos_v[i] ); /* if ( ! *stream ) { throw VectorOnFileError( "Cannot seek a read position in a stream" ); } */ tmp_object = new T(); tmp_object->readObject( *stream ); // Delete: since "!" predicts the success of the next action, // not the previous action. // The following code does not work on platform such as Mac OS X. // (misrports the fail of the read) /* if ( ! *stream ) { throw VectorOnFileError( "Cannot read an object from a stream" ); } */ } void pushObject( const T& t ) { /* if ( stream == NULL ) { throw VectorOnFileError( "Stream is not set to `VectorOnFile'" ); } */ objstream* stream = stream_v[last_stream_no]; stream->seekg( last_pos ); event2stream_v.push_back(stream); event2pos_v.push_back(last_pos); if ( ! *stream ) { throw VectorOnFileError( "Cannot seek a write position in a stream" ); } t.writeObject( *stream ); last_pos = stream->tellp(); if( last_pos > DEFAULT_CHUNK_SIZE ){ last_stream_no++; OStringStream os; os << stream_base_name << '.' << last_stream_no; std::string fname = os.str(); AMIS_PROF_MESSAGE( "Creating a new temporary event file on " << fname << '\n' ); stream_v.push_back(new objstream(fname)); last_pos = 0; } if ( ! *stream ) { throw VectorOnFileError( "Cannot write an object to a stream" ); } }public: VectorOnFile( void ) { stream_base_name = "amis.vector_on_file.tmp"; stream_v.push_back(new objstream(stream_base_name)); tmp_object = NULL; last_stream_no = 0; last_pos = 0; } VectorOnFile( objstream* s ) { stream_base_name = s->fileName(); stream_v.push_back(s); tmp_object = NULL; last_stream_no = 0; last_pos = 0; } virtual ~VectorOnFile() { if ( tmp_object != NULL ) { delete tmp_object; } } void setStream( objstream* s ) { stream_v[0] = s; // ?? is this useful } int size( void ) const { return event2pos_v.size(); } const T& operator[]( int i ) const { readObject( i ); return *tmp_object; } void push_back( const T& t ) { pushObject( t ); }};AMIS_NAMESPACE_END#endif // VectorOnFile_h_// end of VectorOnFile.h⌨️ 快捷键说明
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