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", 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>

using std::string;

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

// Methods
public:
        ConfigFile( string filename,
                    string delimiter = "=",
                    string comment = "#",
                                string sentry = "EndConfigFile" );
        ConfigFile();
        
        // Search for key and read value or optional default value
        template<class T> T read( const string& key ) const;  // call as read<T>
        template<class T> T read( const string& key, const T& value ) const;
        template<class T> bool readInto( T& var, const string& key ) const;
        template<class T>
        bool readInto( T& var, const string& key, const T& value ) const;
        
        // Modify keys and values
        template<class T> void add( string key, const T& value );
        void remove( const string& key );
        
        // Check whether key exists in configuration
        bool keyExists( const string& key ) const;
        
        // Check or change configuration syntax
        string getDelimiter() const { return myDelimiter; }
        string getComment() const { return myComment; }
        string getSentry() const { return mySentry; }
        string setDelimiter( const string& s )
                { string old = myDelimiter;  myDelimiter = s;  return old; }  
        string setComment( const string& s )
                { 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 string T_as_string( const T& t );
        template<class T> static T string_as_T( const string& s );
        static void trim( string& s );


// Exception types
public:
        struct file_not_found {
                string filename;
                file_not_found( const string& filename_ = string() )
                        : filename(filename_) {} };
        struct key_not_found {  // thrown only by T read(key) variant of read()
                string key;
                key_not_found( const string& key_ = string() )
                        : key(key_) {} };
};


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


/* static */
template<>
inline bool ConfigFile::string_as_T<bool>( const 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;
        string sup = s;
        for( string::iterator p = sup.begin(); p != sup.end(); ++p )
                *p = toupper(*p);  // make string all caps
        if( sup==string("FALSE") || sup==string("F") ||
            sup==string("NO") || sup==string("N") ||
            sup==string("0") || sup==string("NONE") )
                b = false;
        return b;
}


template<class T>
T ConfigFile::read( const 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 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 );
}


template<class T>
bool ConfigFile::readInto( T& var, const 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 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( string key, const T& value )
{
        // Add a key with given value
        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()