C++ 读取配置文件 (二)

2014-11-23 19:42:28 · 作者: · 浏览: 15
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 file  
  
    std::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 separator  
  
    string 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); }
//main.cpp  
#include "Config.h"  
int main()  
{  
    int port;  
    std::string ipAddress;  
    std::string username;  
    std::string password;  
    const char ConfigFile[]= "config.txt";   
    Config configSettings(ConfigFile);  
      
    port = configSettings.Read("port", 0);  
    ipAddress = configSettings.Read("ipAddress", ipAddress);  
    username = configSettings.Read("username", username);  
    pas