wip: config reader, reading input

[physics.git] / src / config / reader.cpp

/*
 *  Copyright (C) 2008 Patrik Gornicz, Gornicz_P (at) hotmail (dot) com.
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "reader.h"
#include "../debug.h"

#include <iostream>
#include <fstream>
#include <string>

using std::ifstream;
using std::string;

char* configDir = "../configs/";

/// ***** Private Method Headers *****

void processLine(const string& str, keyMap* map);
bool extractLine(const string& str, string* name, string* value);

/// ***** Private Variables *****

/// ***** Public Methods *****

void readConfigs(keyMap* map)
{
    char fileName[64];

    strcpy(fileName, configDir);
    strcat(fileName, "test.cfg");

    ifstream file(fileName);

    if( !file.is_open() )
    {
        cerr << "Unable to open file " << fileName << "." << endl;
        exit(1);
    }

    while(true)
    {
        string line;
        getline(file, line);

        if(file.eof())
            break;

        processLine(line, map);
    }

    file.close();
}

/// ***** Private Methods *****

void processLine(const string& str, keyMap* map)
{
    string name;
    string value;

    bool extracted;

    extracted = extractLine(str, &name, &value);

    if(extracted)
    {
        cout << name << endl;
        cout << value << endl;
    }
}

/*
 * Return true iff the string str, had a name and value extracted and saved in
 * name and value. Otherwise return false and leave name and value alone.
 */
bool extractLine(const string& str, string* name, string* value)
{
    /*
     * state    := 0 if eating leading name whitespace
     *          := 1 if saving name
     *          := 2 if eating trailing name whitespace
     *          := 3 if eating leading value whitespace
     *          := 4 if saving value
     *          := 5 if all is done and well
     */
    int state = 0;

    int char_pos = 0;

    int name_start;
    int name_end;

    int value_start;
    int value_end;

    const char* c_str = str.c_str();

    while(true)
    {
        if(c_str[char_pos] == 0 && state != 4)
            return false;

        switch (state)
        {
            case 0:
                if(c_str[char_pos] != ' '
                && c_str[char_pos] != '\t')
                {
                    state++;
                    name_start = char_pos;
                }
                break;
            case 1:
                if(c_str[char_pos] == ' '
                || c_str[char_pos] == '\t'
                || c_str[char_pos] == '=')
                {
                    state++;
                    name_end = char_pos;
                }
                if(c_str[char_pos] == '=')
                    char_pos--; // decrement to stay on this char
                break;
            case 2:
                if(c_str[char_pos] == '=')
                {
                    state++;
                }
                break;
            case 3:
                if(c_str[char_pos] != ' '
                && c_str[char_pos] != '\t')
                {
                    state++;
                    value_start = char_pos;
                }
                break;
            case 4:
                if(c_str[char_pos] == ' '
                || c_str[char_pos] == '\t'
                || c_str[char_pos] == 0)
                {
                    state++;
                    value_end = char_pos;
                }
                break;
        }

        if(state == 5)
            break;

        char_pos++;
    }

    name->clear();
    value->clear();

    name->replace(0, 0, c_str, name_start, name_end-name_start);
    value->replace(0, 0, c_str, value_start, value_end-value_start);

    return true;
}