DB Class

<?php

class DB {
    var $host = '127.0.0.1',
        $database = 'roystonvasey',
        $username = 'root',
        $password = '',
        $charset = 'utf8',
        $tablePrefix = 'rv_',
        $logFile = 'sql_errors.log',
        $db;

    function __construct() {
        @$this->db = new mysqli($this->host, $this->username, $this->password, $this->database);
        if ($this->db->connect_error) {
            die("сant't connect to db.");
        }
        $this->db->set_charset($this->charset);
    }

    static function getInstance() {
        static $instance;
        if (!$instance) {
            $instance = new self;
        }
        return $instance;
    }

    function log($err) {
        $fp = fopen($this->logFile, 'a+');
        flock($fp, LOCK_EX);
        fwrite($fp, date('d.m.Y H:i:s') . "\t" . $_SERVER['REMOTE_ADDR'] . "\t" . $_SERVER['REQUEST_URI'] . "\t" . $err . "\r\n");
        flock($fp, LOCK_UN);
        fclose($fp);
    }

    function raw($sql) {
        if (!(@$res = $this->db->query($sql))) {
            $err = $this->db->error;
            $this->log($err);
            die("bad sql query: $err.");
        }
        return $res;
    }

    function escape($str) {
        return $this->db->real_escape_string($str);
    }

    function quote($str) {
        return "'" . $this->escape($str) . "'";
    }

    function quoteIndent($str) {
        return '`' . str_replace('`', '``', $str) . '`';
    }

    function getFullTableName($table) {
        return $this->quoteIndent($this->tablePrefix . $table);
    }

    function sanitize($data) {
        foreach ($data as &$v) {
            $v = gettype($v) == 'string' ? $this->quote($v) : var_export($v, 1);
        }
        return $data;
    }

    function array2str($data) {
        return implode(',', $this->sanitize($data));
    }

    function assoc2str($data) {
        $data = $this->sanitize($data);
        $arr = array();
        foreach ($data as $k => $v) {
            $arr[] =  $this->quoteIndent($k) . '=' . $v;
        }
        return implode(',', $arr);
    }

    function _query($args) {
        $parts = preg_split('/\?([_aAbfis]?)/', $args[0], -1, PREG_SPLIT_DELIM_CAPTURE);
        $total = count($parts);
        $cur = 1;
        for ($i = 1; $i < $total; $i += 2) {
            $part = &$parts[$i];
            if ($part == '_') {
                $part = $this->tablePrefix;
            }
            else {
                $val = $args[$cur++];
                switch ($part) {
                    case 'a':
                        $part = $this->array2str($val);
                        break;

                    case 'A':
                        $part = $this->assoc2str($val);
                        break;

                    case 'b':
                        $part = $val ? 'true' : 'false';
                        break;

                    case 'f':
                        $part = (float) $val;
                        break;

                    case 'i':
                        $part = (int) $val;
                        break;

                    default:
                        $part = $this->quote($val);
                }
            }
        }
        $sql = implode('', $parts);
        // echo $sql;
        return $this->raw($sql);
    }

    /**
     * $db->query($sql, $val1, $val2, ...);
     * Плейсхолдеры:
     * ?_ - преффикс для таблиц
     * ?a - простой массив (значения через запятую)
     * ?A - ассоциативный массив (field1=val1, field2=val2, ...)
     * ?b - булев
     * ?f - число с плавающей точкой
     * ?i - целое число
     * ?, ?s - строка в кавычках
     *
     * @return mysqli_result
     */
    function query() {
        $args = func_get_args();
        // var_dump($args);
        return $this->_query($args);
    }

    function one() {
        $args = func_get_args();
        $res = $this->_query($args);
        $row = $res->fetch_row();
        return $row[0];
    }

    function row() {
        $args = func_get_args();
        $res = $this->_query($args);
        return $res->fetch_assoc();
    }

    function rows() {
        $args = func_get_args();
        $res = $this->_query($args);
        return $res->fetch_all(MYSQLI_ASSOC);
    }

    function assoc() {
        $args = func_get_args();
        $res = $this->_query($args);
        $arr = $res->fetch_all(MYSQLI_NUM);
        $total = count($arr);
        $ret = array();
        for ($i = 0; $i < $total; ++$i) {
            $ret[$arr[$i][0]] = $arr[$i][1];
        }
        return $ret;
    }

    function insert($table, $data) {
        $sql = 'INSERT INTO' . $this->getFullTableName($table);
        $values = array_values($data);
        if ($values != $data) {
            $fields = array_keys($data);
            $sql .= '(' . implode(',', array_map(array($this, 'quoteIndent'), $fields)) . ')';
        }
        $sql .= 'VALUES(' . $this->array2str($values) . ')';
        $this->raw($sql);
        return $this->db->insert_id;
    }

    function update($table, $data, $id) {
        $this->raw('UPDATE' . $this->getFullTableName($table) . ' SET ' . $this->assoc2str($data) . ' WHERE id=' . intval($id));
        return $this->db->affected_rows;
    }

    function delete($table, $id) {
        $this->raw('DELETE FROM' . $this->getFullTableName($table) . ' WHERE id=' . intval($id));
        return $this->db->affected_rows;
    }
}