C++学习|Config Class whitespace|iterator|file|iostream|co

//Config.h #pragma once#include #include #include #include #include/* * \brief Generic configuration Class * */ class Config { // Data protected: std::string m_Delimiter; //!< separator between key and value std::string m_Comment; //!< separator between value and comments std::map m_Contents; //!< extracted keys and valuestypedef std::map::iterator mapi; typedef std::map::const_iterator mapci; // Methods public:Config( std::string filename,std::string delimiter = "=",std::string comment = "#" ); Config(); template T Read( const std::string& in_key ) const; //! template T Read( const std::string& in_key, const T& in_value ) const; template bool ReadInto( T& out_var, const std::string& in_key ) const; template bool ReadInto( T& out_var, const std::string& in_key, const T& in_value ) const; bool FileExist(std::string filename); void ReadFile(std::string filename,std::string delimiter = "=",std::string comment = "#" ); // Check whether key exists in configuration bool KeyExists( const std::string& in_key ) const; // Modify keys and values template void Add( const std::string& in_key, const T& in_value ); void Remove( const std::string& in_key ); // Check or change configuration syntax std::string GetDelimiter() const { return m_Delimiter; } std::string GetComment() const { return m_Comment; } std::string SetDelimiter( const std::string& in_s ) { std::string old = m_Delimiter; m_Delimiter = in_s; return old; } std::string SetComment( const std::string& in_s ) { std::string old = m_Comment; m_Comment =in_s; return old; }// Write or read configuration friend std::ostream& operator<<( std::ostream& os, const Config& cf ); friend std::istream& operator>>( std::istream& is, Config& cf ); protected: template static std::string T_as_string( const T& t ); template static T string_as_T( const std::string& s ); static void Trim( std::string& inout_s ); // Exception types public: struct File_not_found { std::string filename; File_not_found( const std::string& filename_ = std::string() ) : filename(filename_) {} }; struct Key_not_found {// thrown only by T read(key) variant of read() std::string key; Key_not_found( const std::string& key_ = std::string() ) : key(key_) {} }; }; /* static */ template std::string Config::T_as_string( const T& t ) { // Convert from a T to a string // Type T must support << operator std::ostringstream ost; ost << t; return ost.str(); }/* static */ template T Config::string_as_T( const std::string& s ) { // Convert from a string to a T // Type T must support >> operator T t; std::istringstream ist(s); ist >> t; return t; }/* static */ template<> inline std::string Config::string_as_T( const std::string& s ) { // Convert from a string to a string // In other words, do nothing return s; }/* static */ template<> inline bool Config::string_as_T( const std::string& s ) { // Convert from a string to a bool // Interpret "false", "F", "no", "n", "0" as false // Interpret "true", "T", "yes", "y", "1", "-1", or anything else as true bool b = true; std::string sup = s; for( std::string::iterator p = sup.begin(); p != sup.end(); ++p ) *p = toupper(*p); // make string all caps if( sup==std::string("FALSE") || sup==std::string("F") || sup==std::string("NO") || sup==std::string("N") || sup==std::string("0") || sup==std::string("NONE") ) b = false; return b; }template T Config::Read( const std::string& key ) const { // Read the value corresponding to key mapci p = m_Contents.find(key); if( p == m_Contents.end() ) throw Key_not_found(key); return string_as_T( p->second ); }template T Config::Read( const std::string& key, const T& value ) const { // Return the value corresponding to key or given default value // if key is not found mapci p = m_Contents.find(key); if( p == m_Contents.end() ) return value; return string_as_T( p->second ); }template bool Config::ReadInto( T& var, const std::string& key ) const { // Get the value corresponding to key and store in var // Return true if key is found // Otherwise leave var untouched mapci p = m_Contents.find(key); bool found = ( p != m_Contents.end() ); if( found ) var = string_as_T( p->second ); return found; }template bool Config::ReadInto( T& var, const std::string& key, const T& value ) const { // Get the value corresponding to key and store in var // Return true if key is found // Otherwise set var to given default mapci p = m_Contents.find(key); bool found = ( p != m_Contents.end() ); if( found ) var = string_as_T( p->second ); else var = value; return found; }template void Config::Add( const std::string& in_key, const T& value ) { // Add a key with given value std::string v = T_as_string( value ); std::string key=in_key; trim(key); trim(v); m_Contents[key] = v; return; }

// Config.cpp#include "Config.h"using namespace std; Config::Config( string filename, string delimiter, string comment ) : m_Delimiter(delimiter), m_Comment(comment) { // Construct a Config, getting keys and values from given filestd::ifstream in( filename.c_str() ); if( !in ) throw File_not_found( filename ); in >> (*this); }Config::Config() : m_Delimiter( string(1,'=') ), m_Comment( string(1,'#') ) { // Construct a Config without a file; empty }bool Config::KeyExists( const string& key ) const { // Indicate whether key is found mapci p = m_Contents.find( key ); return ( p != m_Contents.end() ); }/* static */ void Config::Trim( string& inout_s ) { // Remove leading and trailing whitespace static const char whitespace[] = " \n\t\v\r\f"; inout_s.erase( 0, inout_s.find_first_not_of(whitespace) ); inout_s.erase( inout_s.find_last_not_of(whitespace) + 1U ); }std::ostream& operator<<( std::ostream& os, const Config& cf ) { // Save a Config to os for( Config::mapci p = cf.m_Contents.begin(); p != cf.m_Contents.end(); ++p ) { os << p->first << " " << cf.m_Delimiter << " "; os << p->second << std::endl; } return os; }void Config::Remove( const string& key ) { // Remove key and its value m_Contents.erase( m_Contents.find( key ) ); return; }std::istream& operator>>( std::istream& is, Config& cf ) { // Load a Config from is // Read in keys and values, keeping internal whitespace typedef string::size_type pos; const string& delim= cf.m_Delimiter; // separator const string& comm= cf.m_Comment; // comment const pos skip = delim.length(); // length of separatorstring nextline = ""; // might need to read ahead to see where value ends while( is || nextline.length() > 0 ) { // Read an entire line at a time string line; if( nextline.length() > 0 ) { line = nextline; // we read ahead; use it now nextline = ""; } else { std::getline( is, line ); }// Ignore comments line = line.substr( 0, line.find(comm) ); // Parse the line if it contains a delimiter pos delimPos = line.find( delim ); if( delimPos < string::npos ) { // Extract the key string key = line.substr( 0, delimPos ); line.replace( 0, delimPos+skip, "" ); // See if value continues on the next line // Stop at blank line, next line with a key, end of stream, // or end of file sentry bool terminate = false; while( !terminate && is ) { std::getline( is, nextline ); terminate = true; string nlcopy = nextline; Config::Trim(nlcopy); if( nlcopy == "" ) continue; nextline = nextline.substr( 0, nextline.find(comm) ); if( nextline.find(delim) != string::npos ) continue; nlcopy = nextline; Config::Trim(nlcopy); if( nlcopy != "" ) line += "\n"; line += nextline; terminate = false; }// Store key and value Config::Trim(key); Config::Trim(line); cf.m_Contents[key] = line; // overwrites if key is repeated } }return is; } bool Config::FileExist(std::string filename) { bool exist= false; std::ifstream in( filename.c_str() ); if( in ) exist = true; return exist; }void Config::ReadFile( string filename, string delimiter, string comment ) { m_Delimiter = delimiter; m_Comment = comment; std::ifstream in( filename.c_str() ); if( !in ) throw File_not_found( filename ); in >> (*this); }

【C++学习|Config Class】