include/daemon/ConfigFile.h

Go to the documentation of this file.

// 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;

namespace dtn
{
        namespace daemon
        {
                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()

---