doctrine / dbal

     *

     * @return void

     */

    private function detectColumnRenamings(TableDiff $tableDifferences)

    {

        $renameCandidates = [];

        foreach ($tableDifferences->addedColumns as $addedColumnName => $addedColumn) {

            foreach ($tableDifferences->removedColumns as $removedColumn) {

                if (count($this->diffColumn($addedColumn, $removedColumn)) == 0) {

                    $renameCandidates[$addedColumn->getName()][] = [$removedColumn, $addedColumn, $addedColumnName];

                }

            }

        }

        foreach ($renameCandidates as $candidateColumns) {

            if (count($candidateColumns) == 1) {

                list($removedColumn, $addedColumn) = $candidateColumns[0];

                $removedColumnName = strtolower($removedColumn->getName());

                $addedColumnName = strtolower($addedColumn->getName());

                if ( ! isset($tableDifferences->renamedColumns[$removedColumnName])) {

                    $tableDifferences->renamedColumns[$removedColumnName] = $addedColumn;

                    unset($tableDifferences->addedColumns[$addedColumnName]);

                    unset($tableDifferences->removedColumns[$removedColumnName]);

                }

            }

        }

    }

    /**

     * Try to find indexes that only changed their name, rename operations maybe cheaper than add/drop

     *

     * @return void

     */

    private function detectIndexRenamings(TableDiff $tableDifferences)

    {

        $renameCandidates = [];

        // Gather possible rename candidates by comparing each added and removed index based on semantics.

        foreach ($tableDifferences->addedIndexes as $addedIndexName => $addedIndex) {

            foreach ($tableDifferences->removedIndexes as $removedIndex) {

                if (! $this->diffIndex($addedIndex, $removedIndex)) {

                    $renameCandidates[$addedIndex->getName()][] = [$removedIndex, $addedIndex, $addedIndexName];

                }

            }

        }

        foreach ($renameCandidates as $candidateIndexes) {

            // If the current rename candidate contains exactly one semantically equal index,

            // we can safely rename it.

            // Otherwise it is unclear if a rename action is really intended,

            // therefore we let those ambiguous indexes be added/dropped.

            if (count($candidateIndexes) === 1) {

                list($removedIndex, $addedIndex) = $candidateIndexes[0];

                $removedIndexName = strtolower($removedIndex->getName());

                $addedIndexName = strtolower($addedIndex->getName());

                if (! isset($tableDifferences->renamedIndexes[$removedIndexName])) {

                    $tableDifferences->renamedIndexes[$removedIndexName] = $addedIndex;

                    unset($tableDifferences->addedIndexes[$addedIndexName]);

                    unset($tableDifferences->removedIndexes[$removedIndexName]);

                }

            }

        }

    }

    /**

     * @param \Doctrine\DBAL\Schema\ForeignKeyConstraint $key1