rence between the two arrays.
	 */
	public static function deep_assoc_array_diff( array $array1, array $array2, bool $strict = true ): array {
		return self::deep_compute_or_compare_array_diff( $array1, $array2, false, $strict );
	}

	/**
	 * Helper method to compare to compute difference between two arrays. Comparison is done recursively.
	 *
	 * @param array $array1 First array.
	 * @param array $array2 Second array.
	 * @param bool  $compare Whether to compare the arrays. If true, then function will return false on first difference, in order to be slightly more efficient.
	 * @param bool  $strict Whether to do string comparison.
	 *
	 * @return array|bool The difference between the two arrays, or if array are same, depending upon $compare param.
	 */
	private static function deep_compute_or_compare_array_diff( array $array1, array $array2, bool $compare, bool $strict = true ) {
		$diff = array();
		foreach ( $array1 as $key => $value ) {
			if ( is_array( $value ) ) {
				if ( ! array_key_exists( $key, $array2 ) || ! is_array( $array2[ $key ] ) ) {
					if ( $compare ) {
						return true;
					}
					$diff[ $key ] = $value;
					continue;
				}
				$new_diff = self::deep_assoc_array_diff( $value, $array2[ $key ], $strict );
				if ( ! empty( $new_diff ) ) {
					if ( $compare ) {
						return true;
					}
					$diff[ $key ] = $new_diff;
				}
			} elseif ( $strict ) {
				if ( ! array_key_exists( $key, $array2 ) || $value !== $array2[ $key ] ) {
					if ( $compare ) {
						return true;
					}
					$diff[ $key ] = $value;
				}
            // phpcs:ignore Universal.Operators.StrictComparisons.LooseNotEqual -- Intentional when $strict is false.
			} elseif ( ! array_key_exists( $key, $array2 ) || $value != $array2[ $key ] ) {
				if ( $compare ) {
					return true;
				}
				$diff[ $key ] = $value;
			}
		}

		return $compare ? false : $diff;
	}

	/**
	 * Push a value to an array, but only if the value isn't in the array already.
	 *
	 * @param array $items The array.
	 * @param mixed $value The value to maybe push.
	 * @return bool True if the value has been added to the array, false if the value was already in the array.
	 */
	public static function push_once( array &$items, $value ): bool {
		if ( in_array( $value, $items, true ) ) {
			return false;
		}

		$items[] = $value;
		return true;
	}

	/**
	 * Ensure that an associative array has a given key, and if not, set the key to an empty array.
	 *
	 * @param array  $items The array to check.
	 * @param string $key The key to check.
	 * @param bool   $throw_if_existing_is_not_array If true, an exception will be thrown if the key already exists in the array but the value is not an array.
	 * @return bool True if the key has been added to the array, false if not (the key already existed).
	 * @throws \Exception The key already exists in the array but the value is not an array.
	 */
	public static function ensure_key_is_array( array &$items, string $key, bool $throw_if_existing_is_not_array = false ): bool {
		if ( ! isset( $items[ $key ] ) ) {
			$items[ $key ] = array();
			return true;
		}

		if ( $throw_if_existing_is_not_array && ! is_array( $items[ $key ] ) ) {
			$type = is_object( $items[ $key ] ) ? get_class( $items[ $key ] ) : gettype( $items[ $key ] );
            // phpcs:ignore WordPress.Security.EscapeOutput.ExceptionNotEscaped
			throw new \Exception( "Array key exists but it's not an array, it's a {$type}" );
		}

		return false;
	}

	/**
	 * Given an array of associative arrays, all having a shared key name ("column"), generates a new array in which
	 * keys are the distinct column values found, and values are arrays with all the matches found
	 * (or only the last matching array found, if $single_values is true).
	 * See ArrayUtilTest for examples.
	 *
	 * @param array  $items The array to process.
	 * @param string $column The name of the key to group by.
	 * @param bool   $single_values True to only return the last suitable array found for each column value.
	 * @return array The grouped array.
	 */
	public static function group_by_column( array $items, string $column, bool $single_values = false ): array {
		if ( $single_values ) {
			return array_combine( array_column( $items, $column ), array_values( $items ) );
		}

		$distinct_column_values = array_unique( array_column( $items, $column ), SORT_REGULAR );
		$result                 = array_fill_keys( $distinct_column_values, array() );

		foreach ( $items as $value ) {
			$result[ $value[ $column ] ][] = $value;
		}

		return $result;
	}
}