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<?php
// This file is part of Moodle - http://moodle.org/
//
// Moodle 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.
//
// Moodle 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 Moodle. If not, see <http://www.gnu.org/licenses/>.
/**
* This class represent one XMLDB Index
*
* @package core_xmldb
* @copyright 1999 onwards Martin Dougiamas http://dougiamas.com
* 2001-3001 Eloy Lafuente (stronk7) http://contiento.com
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
defined('MOODLE_INTERNAL') || die();
class xmldb_index extends xmldb_object {
/** @var bool is unique? */
protected $unique;
/** @var array index fields */
protected $fields;
/** @var array index hints */
protected $hints;
/**
* Note:
* - MySQL: MyISAM has a limit of 1000 bytes for any key including composed, InnoDB has limit 3500 bytes.
*
* @const max length of composed indexes, one utf-8 char is 3 bytes in the worst case
*/
const INDEX_COMPOSED_MAX_BYTES = 999;
/**
* Note:
* - MySQL: InnoDB limits size of index on single column to 767bytes (256 chars)
*
* @const single column index length limit, one utf-8 char is 3 bytes in the worst case
*/
const INDEX_MAX_BYTES = 765;
/**
* Creates one new xmldb_index
*
* @param string $name
* @param string $type XMLDB_INDEX_UNIQUE, XMLDB_INDEX_NOTUNIQUE
* @param array $fields an array of fieldnames to build the index over
* @param array $hints an array of optional hints
*/
public function __construct($name, $type=null, $fields=array(), $hints=array()) {
$this->unique = false;
$this->fields = array();
$this->hints = array();
parent::__construct($name);
$this->set_attributes($type, $fields, $hints);
}
/**
* Set all the attributes of one xmldb_index
*
* @param string type XMLDB_INDEX_UNIQUE, XMLDB_INDEX_NOTUNIQUE
* @param array fields an array of fieldnames to build the index over
* @param array $hints array of optional hints
*/
public function set_attributes($type, $fields, $hints = array()) {
$this->unique = !empty($type) ? true : false;
$this->fields = $fields;
$this->hints = $hints;
}
/**
* Get the index unique
* @return bool
*/
public function getUnique() {
return $this->unique;
}
/**
* Set the index unique
* @param bool $unique
*/
public function setUnique($unique = true) {
$this->unique = $unique;
}
/**
* Set the index fields
* @param array $fields
*/
public function setFields($fields) {
$this->fields = $fields;
}
/**
* Get the index fields
* @return array
*/
public function getFields() {
return $this->fields;
}
/**
* Set optional index hints.
* @param array $hints
*/
public function setHints($hints) {
$this->hints = $hints;
}
/**
* Returns optional index hints.
* @return array
*/
public function getHints() {
return $this->hints;
}
/**
* Load data from XML to the index
* @param $xmlarr array
* @return bool
*/
public function arr2xmldb_index($xmlarr) {
$result = true;
// Debug the table
// traverse_xmlize($xmlarr); //Debug
// print_object ($GLOBALS['traverse_array']); //Debug
// $GLOBALS['traverse_array']=""; //Debug
// Process key attributes (name, unique, fields, comment, previous, next)
if (isset($xmlarr['@']['NAME'])) {
$this->name = trim($xmlarr['@']['NAME']);
} else {
$this->errormsg = 'Missing NAME attribute';
$this->debug($this->errormsg);
$result = false;
}
if (isset($xmlarr['@']['UNIQUE'])) {
$unique = strtolower(trim($xmlarr['@']['UNIQUE']));
if ($unique == 'true') {
$this->unique = true;
} else if ($unique == 'false') {
$this->unique = false;
} else {
$this->errormsg = 'Incorrect UNIQUE attribute (true/false allowed)';
$this->debug($this->errormsg);
$result = false;
}
} else {
$this->errormsg = 'Undefined UNIQUE attribute';
$this->debug($this->errormsg);
$result = false;
}
if (isset($xmlarr['@']['FIELDS'])) {
$fields = strtolower(trim($xmlarr['@']['FIELDS']));
if ($fields) {
$fieldsarr = explode(',',$fields);
if ($fieldsarr) {
foreach ($fieldsarr as $key => $element) {
$fieldsarr [$key] = trim($element);
}
} else {
$this->errormsg = 'Incorrect FIELDS attribute (comma separated of fields)';
$this->debug($this->errormsg);
$result = false;
}
} else {
$this->errormsg = 'Empty FIELDS attribute';
$this->debug($this->errormsg);
$result = false;
}
} else {
$this->errormsg = 'Missing FIELDS attribute';
$this->debug($this->errormsg);
$result = false;
}
// Finally, set the array of fields
$this->fields = $fieldsarr;
if (isset($xmlarr['@']['HINTS'])) {
$this->hints = array();
$hints = strtolower(trim($xmlarr['@']['HINTS']));
if ($hints !== '') {
$hints = explode(',', $hints);
$this->hints = array_map('trim', $hints);
}
}
if (isset($xmlarr['@']['COMMENT'])) {
$this->comment = trim($xmlarr['@']['COMMENT']);
}
// Set some attributes
if ($result) {
$this->loaded = true;
}
$this->calculateHash();
return $result;
}
/**
* This function calculate and set the hash of one xmldb_index
* @retur nvoid, changes $this->hash
*/
public function calculateHash($recursive = false) {
if (!$this->loaded) {
$this->hash = null;
} else {
$key = $this->unique . implode (', ', $this->fields) . implode (', ', $this->hints);
$this->hash = md5($key);
}
}
/**
*This function will output the XML text for one index
* @return string
*/
public function xmlOutput() {
$o = '';
$o.= ' <INDEX NAME="' . $this->name . '"';
if ($this->unique) {
$unique = 'true';
} else {
$unique = 'false';
}
$o.= ' UNIQUE="' . $unique . '"';
$o.= ' FIELDS="' . implode(', ', $this->fields) . '"';
if ($this->hints) {
$o.= ' HINTS="' . implode(', ', $this->hints) . '"';
}
if ($this->comment) {
$o.= ' COMMENT="' . htmlspecialchars($this->comment) . '"';
}
$o.= '/>' . "\n";
return $o;
}
/**
* This function will set all the attributes of the xmldb_index object
* based on information passed in one ADOindex
* @param array
* @return void
*/
public function setFromADOIndex($adoindex) {
// Set the unique field
$this->unique = false;
// Set the fields, converting all them to lowercase
$fields = array_flip(array_change_key_case(array_flip($adoindex['columns'])));
$this->fields = $fields;
// Some more fields
$this->loaded = true;
$this->changed = true;
}
/**
* Returns the PHP code needed to define one xmldb_index
* @return string
*/
public function getPHP() {
$result = '';
// The type
$unique = $this->getUnique();
if (!empty($unique)) {
$result .= 'XMLDB_INDEX_UNIQUE, ';
} else {
$result .= 'XMLDB_INDEX_NOTUNIQUE, ';
}
// The fields
$indexfields = $this->getFields();
if (!empty($indexfields)) {
$result .= "['". implode("', '", $indexfields) . "']";
} else {
$result .= 'null';
}
// Hints
$hints = $this->getHints();
if (!empty($hints)) {
$result .= ", ['". implode("', '", $hints) . "']";
}
// Return result
return $result;
}
/**
* Shows info in a readable format
* @return string
*/
public function readableInfo() {
$o = '';
// unique
if ($this->unique) {
$o .= 'unique';
} else {
$o .= 'not unique';
}
// fields
$o .= ' (' . implode(', ', $this->fields) . ')';
if ($this->hints) {
$o .= ' [' . implode(', ', $this->hints) . ']';
}
return $o;
}
/**
* Validates the index restrictions.
*
* The error message should not be localised because it is intended for developers,
* end users and admins should never see these problems!
*
* @param xmldb_table $xmldb_table optional when object is table
* @return string null if ok, error message if problem found
*/
public function validateDefinition(xmldb_table $xmldb_table=null) {
if (!$xmldb_table) {
return 'Invalid xmldb_index->validateDefinition() call, $xmldb_table is required.';
}
$total = 0;
foreach ($this->getFields() as $fieldname) {
if (!$field = $xmldb_table->getField($fieldname)) {
// argh, we do not have the fields loaded yet, this should not happen during install
continue;
}
switch ($field->getType()) {
case XMLDB_TYPE_INTEGER:
$total += 8; // big int
break;
case XMLDB_TYPE_NUMBER:
$total += 12; // this is just a guess
break;
case XMLDB_TYPE_FLOAT:
$total += 8; // double precision
break;
case XMLDB_TYPE_CHAR:
if ($field->getLength() > self::INDEX_MAX_BYTES / 3) {
return 'Invalid index definition in table {'.$xmldb_table->getName(). '}: XMLDB_TYPE_CHAR field "'.$field->getName().'" can not be indexed because it is too long.'
.' Limit is '.(self::INDEX_MAX_BYTES/3).' chars.';
}
$total += ($field->getLength() * 3); // the most complex utf-8 chars have 3 bytes
break;
case XMLDB_TYPE_TEXT:
return 'Invalid index definition in table {'.$xmldb_table->getName(). '}: XMLDB_TYPE_TEXT field "'.$field->getName().'" can not be indexed';
break;
case XMLDB_TYPE_BINARY:
return 'Invalid index definition in table {'.$xmldb_table->getName(). '}: XMLDB_TYPE_BINARY field "'.$field->getName().'" can not be indexed';
break;
case XMLDB_TYPE_DATETIME:
$total += 8; // this is just a guess
break;
case XMLDB_TYPE_TIMESTAMP:
$total += 8; // this is just a guess
break;
}
}
if ($total > self::INDEX_COMPOSED_MAX_BYTES) {
return 'Invalid index definition in table {'.$xmldb_table->getName(). '}: the composed index on fields "'.implode(',', $this->getFields()).'" is too long.'
.' Limit is '.self::INDEX_COMPOSED_MAX_BYTES.' bytes / '.(self::INDEX_COMPOSED_MAX_BYTES/3).' chars.';
}
return null;
}
}