Index.php

<?php
class ZendDbSchema_Db_Schema_Table_Index
    extends ZendDbSchema_Db_Schema_Table_AbstractDefinition
{
    const COLUMNS_KEY   = 'columns';
    const TYPE_KEY      = 'type';

    protected function _getSchemaKey()
    {
        return ZendDbSchema_Db_Schema_Table::INDEXES_KEY;
    }

    protected function _getDropSql()
    {
        return $this->getTable()->getGenerator()->dropIndex($this);
    }

    protected function _getAlterSql()
    {
        return $this->getTable()->getGenerator()->alterIndex($this);
    }

    protected function _getCreateSql()
    {
        return $this->getTable()->getGenerator()->createIndex($this);
    }

    public function setColumns(array $columns)
    {
        $this->__set(self::COLUMNS_KEY, array_unique($columns));
        return $this;
    }

    public function hasColumn($columnName)
    {
        return in_array($columnName, $this->getColumns());
    }

    public function addColumn($columnName)
    {
        if (!$this->hasColumn($columnName)) {
            $columns = $this->getColumns();
            $columns[] = $columnName;
            $this->setColumns($columns);
        }
        return $this;
    }

    public function getColumns()
    {
        $columns = $this->__get(self::COLUMNS_KEY);
        return is_array($columns) ? $columns : array();
    }

    public function removeColumn($columnName)
    {
        if ($this->hasColumn($columnName)) {
            $columns = array_flip($this->getColumns());
            unset($columns[$columnName]);
            $this->setColumns(array_flip($columns));
        }
        return $this;
    }
}