gistfile1.py

#!/usr/bin/python
# -*- encoding: utf-8 -*-

#   MusicLog Daemon
#
#   Copyright (c) 2008 Rafael G. Martins <rafael@rafaelmartins.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 2 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/>.

from os import path, unlink
from base64 import b64encode, b64decode

class txtDb:
    
    table_file = '/home/rafael/workspace/lastfm/src/%s.db'
    
    def __init__(self, tables):
        self.tables = tables
        
        for table in self.tables.keys():
            
            if not path.exists(self.table_file % table):
                
                if 'id' not in self.tables[table]:
                    self.tables[table] = ['id'] + self.tables[table]
                
                db = open(self.table_file % table, 'w')
                print >> db, ' '.join(self.tables[table])
                db.close()
            
            self.__parseDb(table)
        
    def __parseDb(self, table):
        db = open(self.table_file % table, 'r')
        lines = [a.strip() for a in db.readlines()]
        db.close()
        
        self.keys = {}
        self.rows = {}
        
        self.keys[table] = lines[0].split(' ')
        
        if len(lines) > 1:
            self.rows[table] = lines[1:]
    
    def __getNewId(self, table):
        self.__parseDb(table)
        
        try:
            return len(self.rows[table]) + 1
        except:
            return 1
    
    def addRow(self, table, values):
        
        new_row = []
        
        for key in self.keys[table]:
            if key == 'id':
                new_row.append(str(self.__getNewId(table)))
            elif values.has_key(key):
                if values[key] == '':
                    new_row.append('NULL')
                else:
                    new_row.append(b64encode(str(values[key])))
            else:
                new_row.append('NULL')
        
        #Add new row to database file
        db = open(self.table_file % table, 'a')
        print >> db, ' '.join(new_row)
        db.close()
    
    def getRow(self, table):
        rows = self.getRows(table)
        self.cleanTable(table)
        if len(rows) > 0:
            for row in rows[1:]:
                row.pop('id')
                self.addRow(table, row)
            return rows[0]
        else:
            return []
    
    def getRows(self, table):
        
        self.__parseDb(table)
        
        result = []
        
        if self.__getNewId(table) > 1:
            
            for row in self.rows[table]:
                row = row.split(' ')
                
                aux = {}
                
                for key in range(len(self.keys[table])):
                    
                    if row[key] != 'NULL' and self.keys[table][key] != 'id':
                        row[key] = b64decode(row[key])
                    
                    if row[key] == 'NULL':
                        row[key] = ''
                    
                    aux[self.keys[table][key]] = row[key]
                
                result.append(aux)
                
        return result

    def cleanTable(self, table):
        unlink(self.table_file % table)
        self.__init__(self.tables)

if __name__ == '__main__':
    a = txtDb({
        'teste': ['a','b'],
    })
    
    a.addRow('teste', {
        'a': '11111',
        'b': '',
    })
    
    a.addRow('teste', {
        'a': '222222',
        'b': 'ffff',
    })
    
    print a.getRow('teste')