112 lines
3.0 KiB
PHP
112 lines
3.0 KiB
PHP
<?php
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// Utilities for flatfile functions
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/** Constant to indicating a column holding floating point numbers */
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define('FLOAT_COL', 'float');
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/** Constant to indicating a column holding integers */
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define('INT_COL', 'int');
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/** Constant to indicating a column holding strings */
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define('STRING_COL', 'string');
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/** Constant to indicating a column holding unix timestamps */
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define('DATE_COL', 'date');
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/** EXPERIMENTAL: Encapsulates info about a column in a flatfile DB */
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class Column
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{
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/**
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* Create a new column object
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*/
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function Column($index, $type)
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{
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$this->index = $index;
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$this->type = $type;
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}
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}
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/** EXPERIMENTAL: Represent a column that is a foreign key. Used for temporarily building tables array */
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class JoinColumn
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{
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function JoinColumn($index, $tablename, $columnname)
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{
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$this->index = $index;
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$this->tablename = $tablename;
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$this->columnname = $columnname;
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}
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}
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/**
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* EXPERIMENTAL: Utilities for handling definitions of tables.
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*/
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class TableUtils
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{
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/**
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* Finds JoinColumns in an array of tables, and adds 'type' fields by looking up the columns
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*
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* @param tables This should be an associative array containing 'tablename' => tabledefinition
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* tabledefinition is itself an associativive array of 'COLUMN_NAME_CONSTANT' => columndefintion
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* COLUMN_NAME_CONSTANT should be a unique constant within the table, and
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* column definition should be a Column object or JoinColumn object
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*/
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function resolveJoins(&$tables)
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{
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foreach ($tables as $tablename => $discard)
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{
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// PHP4 compatible: can't do : foreach ($tables as $tablename => &$tabledef)
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// and strangely, if we do
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// foreach ($tables as $tablename => &$tabledef)
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// $tabledef =& $tables[$tablename];
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// then we get bugs
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$tabledef =& $tables[$tablename];
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foreach ($tabledef as $colname => $discard)
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{
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$coldef =& $tabledef[$colname]; // PHP4 compatible
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if (is_a($coldef, 'JoinColumn') or is_subclass_of($coldef, 'JoinColumn'))
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{
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TableUtils::resolveColumnJoin($coldef, $tables);
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}
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}
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}
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}
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/** @access private */
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function resolveColumnJoin(&$columndef, &$tables)
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{
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// Doesn't work if the column it is joined to is also
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// a JoinColumn, but I can't think of ever wanting to do that
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$columndef->type = $tables[$columndef->tablename][$columndef->columnname]->type;
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}
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/** Uses 'define' to create global constants for all the column names */
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function createDefines(&$tables)
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{
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foreach ($tables as $tablename => $discard)
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{
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$tabledef = &$tables[$tablename]; // PHP4 compatible
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foreach ($tabledef as $colname => $discard)
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{
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$coldef = &$tabledef[$colname];
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define(strtoupper($tablename) . '_' . $colname, $coldef->index);
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}
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}
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}
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/**
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* Creates a 'row schema' for a given table definition.
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*
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* A row schema is just an array of the column types for a table,
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* using the constants defined above.
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*/
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function createRowSchema(&$tabledef)
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{
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$row_schema = array();
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foreach ($tabledef as $colname => $coldef)
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{
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$row_schema[$coldef->index] = $coldef->type;
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}
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return $row_schema;
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}
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}
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?>
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