ConfigFile.h

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// ConfigFile.h
// Class for reading named values from configuration files
// Richard J. Wagner  v2.1  24 May 2004  wagnerr@umich.edu
// Copyright (c) 2004 Richard J. Wagner
// 
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to
// deal in the Software without restriction, including without limitation the
// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
// sell copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// 
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
// IN THE SOFTWARE.

// Typical usage
// -------------
// 
// Given a configuration file "settings.inp":
//   atoms  = 25
//   length = 8.0  # nanometers
//   name = Reece Surcher
// 
// Named values are read in various ways, with or without default values:
//   ConfigFile config( "settings.inp" );
//   int atoms = config.read<int>( "atoms" );
//   double length = config.read( "length", 10.0 );
//   string author, title;
//   config.readInto( author, "name" );
//   config.readInto( title, "title", std::string("Untitled") );
// 
// See file example.cpp for more examples.

#ifndef CONFIGFILE_H
#define CONFIGFILE_H

#include <string>
#include <map>
#include <iostream>
#include <fstream>
#include <sstream>
#include <vector>

class ConfigFile {
// Data
protected:
    std::string myDelimiter;  // separator between key and value
    std::string myComment;    // separator between value and comments
    std::string mySentry;     // optional std::string to signal end of file
    std::map<std::string,std::string> myContents;  // extracted keys and values
    
    typedef std::map<std::string,std::string>::iterator mapi;
    typedef std::map<std::string,std::string>::const_iterator mapci;

// Methods
public:
    ConfigFile( std::string filename,
                std::string delimiter = "=",
                std::string comment = "#",
                std::string sentry = "EndConfigFile" );
    ConfigFile();
    
    // Search for key and read value or optional default value
    template<class T> T read( const std::string& key ) const;  // call as read<T>
    template<class T> T read( const std::string& key, const T& value ) const;
    template<class T> bool readInto( T& var, const std::string& key ) const;
    template<class T> bool readInto( T& var, const std::string& key, const T& value ) const;
    
//  template<class T> std::vector<T> readvec( const std::string& key ) const;   
    
    // Modify keys and values
    template<class T> void add( std::string key, const T& value );
    void remove( const std::string& key );
    
    // Check whether key exists in configuration
    bool keyExists( const std::string& key ) const;
    
    // Check or change configuration syntax
    std::string getDelimiter() const { return myDelimiter; }
    std::string getComment() const { return myComment; }
    std::string getSentry() const { return mySentry; }
    std::string setDelimiter( const std::string& s )
        { std::string old = myDelimiter;  myDelimiter = s;  return old; }  
    std::string setComment( const std::string& s )
        { std::string old = myComment;  myComment = s;  return old; }
    
    // Write or read configuration
    friend std::ostream& operator<<( std::ostream& os, const ConfigFile& cf );
    friend std::istream& operator>>( std::istream& is, ConfigFile& cf );
    
protected:
    template<class T> static std::string T_as_string( const T& t );
    template<class T> static T string_as_T( const std::string& s );
    static void trim( std::string& 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<class T>
std::string ConfigFile::T_as_string( const T& t )
{
    // Convert from a T to a std::string
    // Type T must support << operator
    std::ostringstream ost;
    ost << t;
    return ost.str();
}


/* static */
template<class T>
T ConfigFile::string_as_T( const std::string& s )
{
    // Convert from a std::string to a T
    // Type T must support >> operator
    T t;
    std::istringstream ist(s);
    ist >> t;
    return t;
}


/* static */
template<>
inline std::string ConfigFile::string_as_T<std::string>( const std::string& s )
{
    // Convert from a std::string to a std::string
    // In other words, do nothing
    return s;
}


/* static */
template<>
inline bool ConfigFile::string_as_T<bool>( const std::string& s )
{
    // Convert from a std::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 std::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<class T>
T ConfigFile::read( const std::string& key ) const
{
    // Read the value corresponding to key
    mapci p = myContents.find(key);
    if( p == myContents.end() ) throw key_not_found(key);
    return string_as_T<T>( p->second );
}


template<class T>
T ConfigFile::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 = myContents.find(key);
    if( p == myContents.end() ) return value;
    return string_as_T<T>( p->second );
}

// CTA -------------------------------------------------------------------
//template<class T>
//std::vector<T> ConfigFile::readvec( const std::string& key ) const
//{
//  std::vector<int> t;
//  t.push_back(0);
//  t.push_back(3);  
//  return t;
//}
// CTA -------------------------------------------------------------------

template<class T>
bool ConfigFile::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 = myContents.find(key);
    bool found = ( p != myContents.end() );
    if( found ) var = string_as_T<T>( p->second );
    return found;
}


template<class T>
bool ConfigFile::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 = myContents.find(key);
    bool found = ( p != myContents.end() );
    if( found )
        var = string_as_T<T>( p->second );
    else
        var = value;
    return found;
}


template<class T>
void ConfigFile::add( std::string key, const T& value )
{
    // Add a key with given value
    std::string v = T_as_string( value );
    trim(key);
    trim(v);
    myContents[key] = v;
    return;
}

#endif  // CONFIGFILE_H

// Release notes:
// v1.0  21 May 1999
//   + First release
//   + Template read() access only through non-member readConfigFile()
//   + ConfigurationFileBool is only built-in helper class
// 
// v2.0  3 May 2002
//   + Shortened name from ConfigurationFile to ConfigFile
//   + Implemented template member functions
//   + Changed default comment separator from % to #
//   + Enabled reading of multiple-line values
// 
// v2.1  24 May 2004
//   + Made template specializations inline to avoid compiler-dependent linkage
//   + Allowed comments within multiple-line values
//   + Enabled blank line termination for multiple-line values
//   + Added optional sentry to detect end of configuration file
//   + Rewrote messy trimWhitespace() function as elegant trim()