/**
* Traverses a DataTable tree using an array of labels and returns the row
* it finds or `false` if it cannot find one. The number of path segments that
* were successfully walked is also returned.
*
* If `$missingRowColumns` is supplied, the specified path is created. When
* a subtable is encountered w/o the required label, a new row is created
* with the label, and a new subtable is added to the row.
*
* Read [http://en.wikipedia.org/wiki/Tree_(data_structure)#Traversal_methods](http://en.wikipedia.org/wiki/Tree_(data_structure)#Traversal_methods)
* for more information about tree walking.
*
* @param array $path The path to walk. An array of label values. The first element
* refers to a row in this DataTable, the second in a subtable of
* the first row, the third a subtable of the second row, etc.
* @param array|bool $missingRowColumns The default columns to use when creating new rows.
* If this parameter is supplied, new rows will be
* created for path labels that cannot be found.
* @param int $maxSubtableRows The maximum number of allowed rows in new subtables. New
* subtables are only created if `$missingRowColumns` is provided.
* @return array First element is the found row or `false`. Second element is
* the number of path segments walked. If a row is found, this
* will be == to `count($path)`. Otherwise, it will be the index
* of the path segment that we could not find.
*/
public function walkPath($path, $missingRowColumns = false, $maxSubtableRows = 0)
{
$pathLength = count($path);
$table = $this;
$next = false;
for ($i = 0; $i < $pathLength; ++$i) {
$segment = $path[$i];
$next = $table->getRowFromLabel($segment);
if ($next === false) {
// if there is no table to advance to, and we're not adding missing rows, return false
if ($missingRowColumns === false) {
return array(false, $i);
} else {
// if we're adding missing rows, add a new row
$row = new DataTableSummaryRow();
$row->setColumns(array('label' => $segment) + $missingRowColumns);
$next = $table->addRow($row);
if ($next !== $row) {
// if the row wasn't added, the table is full
// Summary row, has no metadata
$next->deleteMetadata();
return array($next, $i);
}
}
}
$table = $next->getSubtable();
if ($table === false) {
// if the row has no table (and thus no child rows), and we're not adding
// missing rows, return false
if ($missingRowColumns === false) {
return array(false, $i);
} elseif ($i != $pathLength - 1) {
// create subtable if missing, but only if not on the last segment
$table = new DataTable();
$table->setMaximumAllowedRows($maxSubtableRows);
$table->metadata[self::COLUMN_AGGREGATION_OPS_METADATA_NAME] = $this->getMetadata(self::COLUMN_AGGREGATION_OPS_METADATA_NAME);
$next->setSubtable($table);
// Summary row, has no metadata
$next->deleteMetadata();
}
}
}
return array($next, $i);
}
