type string|string[] $value       Meta value or values to filter by.
	 *         @type string          $compare     MySQL operator used for comparing the $value. Accepts:
	 *                                            - '='
	 *                                            - '!='
	 *                                            - '>'
	 *                                            - '>='
	 *                                            - '<'
	 *                                            - '<='
	 *                                            - 'LIKE'
	 *                                            - 'NOT LIKE'
	 *                                            - 'IN'
	 *                                            - 'NOT IN'
	 *                                            - 'BETWEEN'
	 *                                            - 'NOT BETWEEN'
	 *                                            - 'REGEXP'
	 *                                            - 'NOT REGEXP'
	 *                                            - 'RLIKE'
	 *                                            - 'EXISTS'
	 *                                            - 'NOT EXISTS'
	 *                                            Default is 'IN' when `$value` is an array, '=' otherwise.
	 *         @type string          $type        MySQL data type that the meta_value column will be CAST to for
	 *                                            comparisons. Accepts:
	 *                                            - 'NUMERIC'
	 *                                            - 'BINARY'
	 *                                            - 'CHAR'
	 *                                            - 'DATE'
	 *                                            - 'DATETIME'
	 *                                            - 'DECIMAL'
	 *                                            - 'SIGNED'
	 *                                            - 'TIME'
	 *                                            - 'UNSIGNED'
	 *                                            Default is 'CHAR'.
	 *     }
	 * }
	 */
	public function __construct( $meta_query = false ) {
		if ( ! $meta_query ) {
			return;
		}

		if ( isset( $meta_query['relation'] ) && 'OR' === strtoupper( $meta_query['relation'] ) ) {
			$this->relation = 'OR';
		} else {
			$this->relation = 'AND';
		}

		$this->queries = $this->sanitize_query( $meta_query );
	}

	/**
	 * Ensures the 'meta_query' argument passed to the class constructor is well-formed.
	 *
	 * Eliminates empty items and ensures that a 'relation' is set.
	 *
	 * @since 4.1.0
	 *
	 * @param array $queries Array of query clauses.
	 * @return array Sanitized array of query clauses.
	 */
	public function sanitize_query( $queries ) {
		$clean_queries = array();

		if ( ! is_array( $queries ) ) {
			return $clean_queries;
		}

		foreach ( $queries as $key => $query ) {
			if ( 'relation' === $key ) {
				$relation = $query;

			} elseif ( ! is_array( $query ) ) {
				continue;

				// First-order clause.
			} elseif ( $this->is_first_order_clause( $query ) ) {
				if ( isset( $query['value'] ) && array() === $query['value'] ) {
					unset( $query['value'] );
				}

				$clean_queries[ $key ] = $query;

				// Otherwise, it's a nested query, so we recurse.
			} else {
				$cleaned_query = $this->sanitize_query( $query );

				if ( ! empty( $cleaned_query ) ) {
					$clean_queries[ $key ] = $cleaned_query;
				}
			}
		}

		if ( empty( $clean_queries ) ) {
			return $clean_queries;
		}

		// Sanitize the 'relation' key provided in the query.
		if ( isset( $relation ) && 'OR' === strtoupper( $relation ) ) {
			$clean_queries['relation'] = 'OR';
			$this->has_or_relation     = true;

			/*
			* If there is only a single clause, call the relation 'OR'.
			* This value will not actually be used to join clauses, but it
			* simplifies the logic around combining key-only queries.
			*/
		} elseif ( 1 === count( $clean_queries ) ) {
			$clean_queries['relation'] = 'OR';

			// Default to AND.
		} else {
			$clean_queries['relation'] = 'AND';
		}

		return $clean_queries;
	}

	/**
	 * Determines whether a query clause is first-order.
	 *
	 * A first-order meta query clause is one that has either a 'key' or
	 * a 'value' array key.
	 *
	 * @since 4.1.0
	 *
	 * @param array $query Meta query arguments.
	 * @return bool Whether the query clause is a first-order clause.
	 */
	protected function is_first_order_clause( $query ) {
		return isset( $query['key'] ) || isset( $query['value'] );
	}

	/**
	 * Constructs a meta query based on 'meta_*' query vars
	 *
	 * @since 3.2.0
	 *
	 * @param array $qv The query variables.
	 */
	public function parse_query_vars( $qv ) {
		$meta_query = array();

		/*
		 * For orderby=meta_value to work correctly, simple query needs to be
		 * first (so that its table join is against an unaliased meta table) and
		 * needs to be its own clause (so it doesn't interfere with the logic of
		 * the rest of the meta_query).
		 */
		$primary_meta_query = array();
		foreach ( array( 'key', 'compare', 'type', 'compare_key', 'type_key' ) as $key ) {
			if ( ! empty( $qv[ "meta_$key" ] ) ) {
				$primary_meta_query[ $key ] = $qv[ "meta_$key" ];
			}
		}

		// WP_Query sets 'meta_value' = '' by default.
		if ( isset( $qv['meta_value'] ) && '' !== $qv['meta_value'] && ( ! is_array( $qv['meta_value'] ) || $qv['meta_value'] ) ) {
			$primary_meta_query['value'] = $qv['meta_value'];
		}

		$existing_meta_query = isset( $qv['meta_query'] ) && is_array( $qv['meta_query'] ) ? $qv['meta_query'] : array();

		if ( ! empty( $primary_meta_query ) && ! empty( $existing_meta_query ) ) {
			$meta_query = array(
				'relation' => 'AND',
				$primary_meta_query,
				$existing_meta_query,
			);
		} elseif ( ! empty( $primary_meta_query ) ) {
			$meta_query = array(
				$primary_meta_query,
			);
		} elseif ( ! empty( $existing_meta_query ) ) {
			$meta_query = $existing_meta_query;
		}

		$this->__construct( $meta_query );
	}

	/**
	 * Returns the appropriate alias for the given meta type if applicable.
	 *
	 * @since 3.7.0
	 *
	 * @param string $type MySQL type to cast meta_value.
	 * @return string MySQL type.
	 */
	public function get_cast_for_type( $type = '' ) {
		if ( empty( $type ) ) {
			return 'CHAR';
		}

		$meta_type = strtoupper( $type );

		if ( ! preg_match( '/^(?:BINARY|CHAR|DATE|DATETIME|SIGNED|UNSIGNED|TIME|NUMERIC(?:\(\d+(?:,\s?\d+)?\))?|DECIMAL(?:\(\d+(?:,\s?\d+)?\))?)$/', $meta_type ) ) {
			return 'CHAR';
		}

		if ( 'NUMERIC' === $meta_type ) {
			$meta_type = 'SIGNED';
		}

		return $meta_type;
	}

	/**
	 * Generates SQL clauses to be appended to a main query.
	 *
	 * @since 3.2.0
	 *
	 * @param string $type              Type of meta. Possible values include but are not limited
	 *                                  to 'post', 'comment', 'blog', 'term', and 'user'.
	 * @param string $primary_table     Database table where the object being filtered is stored (eg wp_users).
	 * @param string $primary_id_column ID column for the filtered object in $primary_table.
	 * @param object $context           Optional. The main query object that corresponds to the type, for
	 *                                  example a `WP_Query`, `WP_User_Query`, or `WP_Site_Query`.
	 *                                  Default null.
	 * @return string[]|false {
	 *     Array containing JOIN and WHERE SQL clauses to append to the main query,
	 *     or false if no table exists for the requested meta type.
	 *
	 *     @type string $join  SQL fragment to append to the main JOIN clause.
	 *     @type string $where SQL fragment to append to the main WHERE clause.
	 * }
	 */
	public function get_sql( $type, $primary_table, $primary_id_column, $context = null ) {
		$meta_table = _get_meta_table( $type );
		if ( ! $meta_table ) {
			return false;
		}

		$this->table_aliases = array();

		$this->meta_table     = $meta_table;
		$this->meta_id_column = sanitize_key( $type . '_id' );

		$this->primary_table     = $primary_table;
		$this->primary_id_column = $primary_id_column;

		$sql = $this->get_sql_clauses();

		/*
		 * If any JOINs are LEFT JOINs (as in the case of NOT EXISTS), then all JOINs should
		 * be LEFT. Otherwise posts with no metadata will be excluded from results.
		 */
		if ( str_contains( $sql['join'], 'LEFT JOIN' ) ) {
			$sql['join'] = str_replace( 'INNER JOIN', 'LEFT JOIN', $sql['join'] );
		}

		/**
		 * Filters the meta query's generated SQL.
		 *
		 * @since 3.1.0
		 *
		 * @param string[] $sql               Array containing the query's JOIN and WHERE clauses.
		 * @param array    $queries           Array of meta queries.
		 * @param string   $type              Type of meta. Possible values include but are not limited
		 *                                    to 'post', 'comment', 'blog', 'term', and 'user'.
		 * @param string   $primary_table     Primary table.
		 * @param string   $primary_id_column Primary column ID.
		 * @param object   $context           The main query object that corresponds to the type, for
		 *                                    example a `WP_Query`, `WP_User_Query`, or `WP_Site_Query`.
		 */
		return apply_filters_ref_array( 'get_meta_sql', array( $sql, $this->queries, $type, $primary_table, $primary_id_column, $context ) );
	}

	/**
	 * Generates SQL clauses to be appended to a main query.
	 *
	 * Called by the public WP_Meta_Query::get_sql(), this method is abstracted
	 * out to maintain parity with the other Query classes.
	 *
	 * @since 4.1.0
	 *
	 * @return string[] {
	 *     Array containing JOIN and WHERE SQL clauses to append to the main query.
	 *
	 *     @type string $join  SQL fragment to append to the main JOIN clause.
	 *     @type string $where SQL fragment to append to the main WHERE clause.
	 * }
	 */
	protected function get_sql_clauses() {
		/*
		 * $queries are passed by reference to get_sql_for_query() for recursion.
		 * To keep $this->queries unaltered, pass a copy.
		 */
		$queries = $this->queries;
		$sql     = $this->get_sql_for_query( $queries );

		if ( ! empty( $sql['where'] ) ) {
			$sql['where'] = ' AND ' . $sql['where'];
		}

		return $sql;
	}

	/**
	 * Generates SQL clauses for a single query array.
	 *
	 * If nested subqueries are found, this method recurses the tree to
	 * produce the properly nested SQL.
	 *
	 * @since 4.1.0
	 *
	 * @param array $query Query to parse (passed by reference).
	 * @param int   $depth Optional. Number of tree levels deep we currently are.
	 *                     Used to calculate indentation. Default 0.
	 * @return string[] {
	 *     Array containing JOIN and WHERE SQL clauses to append to a single query array.
	 *
	 *     @type string $join  SQL fragment to append to the main JOIN clause.
	 *     @type string $where SQL fragment to append to the main WHERE clause.
	 * }
	 */
	protected function get_sql_for_query( &$query, $depth = 0 ) {
		$sql_chunks = array(
			'join'  => array(),
			'where' => array(),
		);

		$sql = array(
			'join'  => '',
			'where' => '',
		);

		$indent = '';
		for ( $i = 0; $i < $depth; $i++ ) {
			$indent .= '  ';
		}

		foreach ( $query as $key => &$clause ) {
			if ( 'relation' === $key ) {
				$relation = $query['relation'];
			} elseif ( is_array( $clause ) ) {

				// This is a first-order clause.
				if ( $this->is_first_order_clause( $clause ) ) {
					$clause_sql = $this->get_sql_for_clause( $clause, $query, $key );

					$where_count = count( $clause_sql['where'] );
					if ( ! $where_count ) {
						$sql_chunks['where'][] = '';
					} elseif ( 1 === $where_count ) {
						$sql_chunks['where'][] = $clause_sql['where'][0];
					} else {
						$sql_chunks['where'][] = '( ' . implode( ' AND ', $clause_sql['where'] ) . ' )';
					}

					$sql_chunks['join'] = array_merge( $sql_chunks['join'], $clause_sql['join'] );
					// This is a subquery, so we recurse.
				} else {
					$clause_sql = $this->get_sql_for_query( $clause, $depth + 1 );

					$sql_chunks['where'][] = $clause_sql['where'];
					$sql_chunks['join'][]  = $clause_sql['join'];
				}
			}
		}

		// Filter to remove empties.
		$sql_chunks['join']  = array_filter( $sql_chunks['join'] );
		$sql_chunks['where'] = array_filter( $sql_chunks['where'] );

		if ( empty( $relation ) ) {
			$relation = 'AND';
		}

		// Filter duplicate JOIN clauses and combine into a single string.
		if ( ! empty( $sql_chunks['join'] ) ) {
			$sql['join'] = implode( ' ', array_unique( $sql_chunks['join'] ) );
		}

		// Generate a single WHERE clause with proper brackets and indentation.
		if ( ! empty( $sql_chunks['where'] ) ) {
			$sql['where'] = '( ' . "\n  " . $indent . implode( ' ' . "\n  " . $indent . $relation . ' ' . "\n  " . $indent, $sql_chunks['where'] ) . "\n" . $indent . ')';
		}

		return $sql;
	}

	/**
	 * Generates SQL JOIN and WHERE clauses for a first-order query clause.
	 *
	 * "First-order" means that it's an array with a 'key' or 'value'.
	 *
	 * @since 4.1.0
	 *
	 * @global wpdb $wpdb WordPress database abstraction object.
	 *
	 * @param array  $clause       Query clause (passed by reference).
	 * @param array  $parent_query Parent query array.
	 * @param string $clause_key   Optional. The array key used to name the clause in the original `$meta_query`
	 *                             parameters. If not provided, a key will be generated automatically.
	 *                             Default empty string.
	 * @return array {
	 *     Array containing JOIN and WHERE SQL clauses to append to a first-order query.
	 *
	 *     @type string[] $join  Array of SQL fragments to append to the main JOIN clause.
	 *     @type string[] $where Array of SQL fragments to append to the main WHERE clause.
	 * }
	 */
	public function get_sql_for_clause( &$clause, $parent_query, $clause_key = '' ) {
		global $wpdb;

		$sql_chunks = array(
			'where' => array(),
			'join'  => array(),
		);

		if ( isset( $clause['compare'] ) ) {
			$clause['compare'] = strtoupper( $clause['compare'] );
		} else {
			$clause['compare'] = isset( $clause['value'] ) && is_array( $clause['value'] ) ? 'IN' : '=';
		}

		$non_numeric_operators = array(
			'=',
			'!=',
			'LIKE',
			'NOT LIKE',
			'IN',
			'NOT IN',
			'EXISTS',
			'NOT EXISTS',
			'RLIKE',
			'REGEXP',
			'NOT REGEXP',
		);

		$numeric_operators = array(
			'>',
			'>=',
			'<',
			'<=',
			'BETWEEN',
			'NOT BETWEEN',
		);

		if ( ! in_array( $clause['compare'], $non_numeric_operators, true ) && ! in_array( $clause['compare'], $numeric_operators, true ) ) {
			$clause['compare'] = '=';
		}

		if ( isset( $clause['compare_key'] ) ) {
			$clause['compare_key'] = strtoupper( $clause['compare_key'] );
		} else {
			$clause['compare_key'] = isset( $clause['key'] ) && is_array( $clause['key'] ) ? 'IN' : '=';
		}

		if ( ! in_array( $clause['compare_key'], $non_numeric_operators, true ) ) {
			$clause['compare_key'] = '=';
		}

		$meta_compare     = $clause['compare'];
		$meta_compare_key = $clause['compare_key'];

		// First build the JOIN clause, if one is required.
		$join = '';

		// We prefer to avoid joins if possible. Look for an existing join compatible with this clause.
		$alias = $this->find_compatible_table_alias( $clause, $parent_query );
		if ( false === $alias ) {
			$i     = count( $this->table_aliases );
			$alias = $i ? 'mt' . $i : $this->meta_table;

			// JOIN clauses for NOT EXISTS have their own syntax.
			if ( 'NOT EXISTS' === $meta_compare ) {
				$join .= " LEFT JOIN $this->meta_table";
				$join .= $i ? " AS $alias" : '';

				if ( 'LIKE' === $meta_compare_key ) {
					$join .= $wpdb->prepare( " ON ( $this->primary_table.$this->primary_id_column = $alias.$this->meta_id_column AND $alias.meta_key LIKE %s )", '%' . $wpdb->esc_like( $clause['key'] ) . '%' );
				} else {
					$join .= $wpdb->prepare( " ON ( $this->primary_table.$this->primary_id_column = $alias.$this->meta_id_column AND $alias.meta_key = %s )", $clause['key'] );
				}

				// All other JOIN clauses.
			} else {
				$join .= " INNER JOIN $this->meta_table";
				$join .= $i ? " AS $alias" : '';
				$join .= " ON ( $this->primary_table.$this->primary_id_column = $alias.$this->meta_id_column )";
			}

			$this->table_aliases[] = $alias;
			$sql_chunks['join'][]  = $join;
		}

		// Save the alias to this clause, for future siblings to find.
		$clause['alias'] = $alias;

		// Determine the data type.
		$_meta_type     = isset( $clause['type'] ) ? $clause['type'] : '';
		$meta_type      = $this->get_cast_for_type( $_meta_type );
		$clause['cast'] = $meta_type;

		// Fallback for clause keys is the table alias. Key must be a string.
		if ( is_int( $clause_key ) || ! $clause_key ) {
			$clause_key = $clause['alias'];
		}

		// Ensure unique clause keys, so none are overwritten.
		$iterator        = 1;
		$clause_key_base = $clause_key;
		while ( isset( $this->clauses[ $clause_key ] ) ) {
			$clause_key = $clause_key_base . '-' . $iterator;
			++$iterator;
		}

		// Store the clause in our flat array.
		$this->clauses[ $clause_key ] =& $clause;

		// Next, build the WHERE clause.

		// meta_key.
		if ( array_key_exists( 'key', $clause ) ) {
			if ( 'NOT EXISTS' === $meta_compare ) {
				$sql_chunks['where'][] = $alias . '.' . $this->meta_id_column . ' IS NULL';
			} else {
				/**
				 * In joined clauses negative operators have to be nested into a
				 * NOT EXISTS clause and flipped, to avoid returning records with
				 * matching post IDs but different meta keys. Here we prepare the
				 * nested clause.
				 */
				if ( in_array( $meta_compare_key, array( '!=', 'NOT IN', 'NOT LIKE', 'NOT EXISTS', 'NOT REGEXP' ), true ) ) {
					// Negative clauses may be reused.
					$i                     = count( $this->table_aliases );
					$subquery_alias        = $i ? 'mt' . $i : $this->meta_table;
					$this->table_aliases[] = $subquery_alias;

					$meta_compare_string_start  = 'NOT EXISTS (';
					$meta_compare_string_start .= "SELECT 1 FROM $wpdb->postmeta $subquery_alias ";
					$meta_compare_string_start .= "WHERE $subquery_alias.post_ID = $alias.post_ID ";
					$meta_compare_string_end    = 'LIMIT 1';
					$meta_compare_string_end   .= ')';
				}

				switch ( $meta_compare_key ) {
					case '=':
					case 'EXISTS':
						$where = $wpdb->prepare( "$alias.meta_key = %s", trim( $clause['key'] ) ); // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared
						break;
					case 'LIKE':
						$meta_compare_value = '%' . $wpdb->esc_like( trim( $clause['key'] ) ) . '%';
						$where              = $wpdb->prepare( "$alias.meta_key LIKE %s", $meta_compare_value ); // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared
						break;
					case 'IN':
						$meta_compare_string = "$alias.meta_key IN (" . substr( str_repeat( ',%s', count( $clause['key'] ) ), 1 ) . ')';
						$where               = $wpdb->prepare( $meta_compare_string, $clause['key'] ); // phpcs:ignore WordPress.DB.PreparedSQL.NotPrepared
						break;
					case 'RLIKE':
					case 'REGEXP':
						$operator = $meta_compare_key;
						if ( isset( $clause['type_key'] ) && 'BINARY' === strtoupper( $clause['type_key'] ) ) {
							$cast     = 'BINARY';
							$meta_key = "CAST($alias.meta_key AS BINARY)";
						} else {
							$cast     = '';
							$meta_key = "$alias.meta_key";
						}
						$where = $wpdb->prepare( "$meta_key $operator $cast %s", trim( $clause['key'] ) ); // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared
						break;

					case '!=':
					case 'NOT EXISTS':
						$meta_compare_string = $meta_compare_string_start . "AND $subquery_alias.meta_key = %s " . $meta_compare_string_end;
						$where               = $wpdb->prepare( $meta_compare_string, $clause['key'] ); // phpcs:ignore WordPress.DB.PreparedSQL.NotPrepared
						break;
					case 'NOT LIKE':
						$meta_compare_string = $meta_compare_string_start . "AND $subquery_alias.meta_key LIKE %s " . $meta_compare_string_end;

						$meta_compare_value = '%' . $wpdb->esc_like( trim( $clause['key'] ) ) . '%';
						$where              = $wpdb->prepare( $meta_compare_string, $meta_compare_value ); // phpcs:ignore WordPress.DB.PreparedSQL.NotPrepared
						break;
					case 'NOT IN':
						$array_subclause     = '(' . substr( str_repeat( ',%s', count( $clause['key'] ) ), 1 ) . ') ';
						$meta_compare_string = $meta_compare_string_start . "AND $subquery_alias.meta_key IN " . $array_subclause . $meta_compare_string_end;
						$where               = $wpdb->prepare( $meta_compare_string, $clause['key'] ); // phpcs:ignore WordPress.DB.PreparedSQL.NotPrepared
						break;
					case 'NOT REGEXP':
						$operator = $meta_compare_key;
						if ( isset( $clause['type_key'] ) && 'BINARY' === strtoupper( $clause['type_key'] ) ) {
							$cast     = 'BINARY';
							$meta_key = "CAST($subquery_alias.meta_key AS BINARY)";
						} else {
							$cast     = '';
							$meta_key = "$subquery_alias.meta_key";
						}

						$meta_compare_string = $meta_compare_string_start . "AND $meta_key REGEXP $cast %s " . $meta_compare_string_end;
						$where               = $wpdb->prepare( $meta_compare_string, $clause['key'] ); // phpcs:ignore WordPress.DB.PreparedSQL.NotPrepared
						break;
				}

				$sql_chunks['where'][] = $where;
			}
		}

		// meta_value.
		if ( array_key_exists( 'value', $clause ) ) {
			$meta_value = $clause['value'];

			if ( in_array( $meta_compare, array( 'IN', 'NOT IN', 'BETWEEN', 'NOT BETWEEN' ), true ) ) {
				if ( ! is_array( $meta_value ) ) {
					$meta_value = preg_split( '/[,\s]+/', $meta_value );
				}
			} elseif ( is_string( $meta_value ) ) {
				$meta_value = trim( $meta_value );
			}

			switch ( $meta_compare ) {
				case 'IN':
				case 'NOT IN':
					$meta_compare_string = '(' . substr( str_repeat( ',%s', count( $meta_value ) ), 1 ) . ')';
					$where               = $wpdb->prepare( $meta_compare_string, $meta_value );
					break;

				case 'BETWEEN':
				case 'NOT BETWEEN':
					$where = $wpdb->prepare( '%s AND %s', $meta_value[0], $meta_value[1] );
					break;

				case 'LIKE':
				case 'NOT LIKE':
					$meta_value = '%' . $wpdb->esc_like( $meta_value ) . '%';
					$where      = $wpdb->prepare( '%s', $meta_value );
					break;

				// EXISTS with a value is interpreted as '='.
				case 'EXISTS':
					$meta_compare = '=';
					$where        = $wpdb->prepare( '%s', $meta_value );
					break;

				// 'value' is ignored for NOT EXISTS.
				case 'NOT EXISTS':
					$where = '';
					break;

				default:
					$where = $wpdb->prepare( '%s', $meta_value );
					break;

			}

			if ( $where ) {
				if ( 'CHAR' === $meta_type ) {
					$sql_chunks['where'][] = "$alias.meta_value {$meta_compare} {$where}";
				} else {
					$sql_chunks['where'][] = "CAST($alias.meta_value AS {$meta_type}) {$meta_compare} {$where}";
				}
			}
		}

		/*
		 * Multiple WHERE clauses (for meta_key and meta_value) should
		 * be joined in parentheses.
		 */
		if ( 1 < count( $sql_chunks['where'] ) ) {
			$sql_chunks['where'] = array( '( ' . implode( ' AND ', $sql_chunks['where'] ) . ' )' );
		}

		return $sql_chunks;
	}

	/**
	 * Gets a flattened list of sanitized meta clauses.
	 *
	 * This array should be used for clause lookup, as when the table alias and CAST type must be determined for
	 * a value of 'orderby' corresponding to a meta clause.
	 *
	 * @since 4.2.0
	 *
	 * @return array Meta clauses.
	 */
	public function get_clauses() {
		return $this->clauses;
	}

	/**
	 * Identifies an existing table alias that is compatible with the current
	 * query clause.
	 *
	 * We avoid unnecessary table joins by allowing each clause to look for
	 * an existing table alias that is compatible with the query that it
	 * needs to perform.
	 *
	 * An existing alias is compatible if (a) it is a sibling of `$clause`
	 * (ie, it's under the scope of the same relation), and (b) the combination
	 * of operator and relation between the clauses allows for a shared table join.
	 * In the case of WP_Meta_Query, this only applies to 'IN' clauses that are
	 * connected by the relation 'OR'.
	 *
	 * @since 4.1.0
	 *
	 * @param array $clause       Query clause.
	 * @param array $parent_query Parent query of $clause.
	 * @return string|false Table alias if found, otherwise false.
	 */
	protected function find_compatible_table_alias( $clause, $parent_query ) {
		$alias = false;

		foreach ( $parent_query as $sibling ) {
			// If the sibling has no alias yet, there's nothing to check.
			if ( empty( $sibling['alias'] ) ) {
				continue;
			}

			// We're only interested in siblings that are first-order clauses.
			if ( ! is_array( $sibling ) || ! $this->is_first_order_clause( $sibling ) ) {
				continue;
			}

			$compatible_compares = array();

			// Clauses connected by OR can share joins as long as they have "positive" operators.
			if ( 'OR' === $parent_query['relation'] ) {
				$compatible_compares = array( '=', 'IN', 'BETWEEN', 'LIKE', 'REGEXP', 'RLIKE', '>', '>=', '<', '<=' );

				// Clauses joined by AND with "negative" operators share a join only if they also share a key.
			} elseif ( isset( $sibling['key'] ) && isset( $clause['key'] ) && $sibling['key'] === $clause['key'] ) {
				$compatible_compares = array( '!=', 'NOT IN', 'NOT LIKE' );
			}

			$clause_compare  = strtoupper( $clause['compare'] );
			$sibling_compare = strtoupper( $sibling['compare'] );
			if ( in_array( $clause_compare, $compatible_compares, true ) && in_array( $sibling_compare, $compatible_compares, true ) ) {
				$alias = preg_replace( '/\W/', '_', $sibling['alias'] );
				break;
			}
		}

		/**
		 * Filters the table alias identified as compatible with the current clause.
		 *
		 * @since 4.1.0
		 *
		 * @param string|false  $alias        Table alias, or false if none was found.
		 * @param array         $clause       First-order query clause.
		 * @param array         $parent_query Parent of $clause.
		 * @param WP_Meta_Query $query        WP_Meta_Query object.
		 */
		return apply_filters( 'meta_query_find_compatible_table_alias', $alias, $clause, $parent_query, $this );
	}

	/**
	 * Checks whether the current query has any OR relations.
	 *
	 * In some cases, the presence of an OR relation somewhere in the query will require
	 * the use of a `DISTINCT` or `GROUP BY` keyword in the `SELECT` clause. The current
	 * method can be used in these cases to determine whether such a clause is necessary.
	 *
	 * @since 4.3.0
	 *
	 * @return bool True if the query contains any `OR` relations, otherwise false.
	 */
	public function has_or_relation() {
		return $this->has_or_relation;
	}
}
;

		if ( ! empty( $_parsed_query['name'] ) && ! empty( $redirect['query'] ) ) {
			parse_str( $redirect['query'], $_parsed_redirect_query );

			if ( empty( $_parsed_redirect_query['name'] ) ) {
				unset( $_parsed_query['name'] );
			}
		}

		$_parsed_query = array_combine(
			rawurlencode_deep( array_keys( $_parsed_query ) ),
			rawurlencode_deep( array_values( $_parsed_query ) )
		);

		$redirect_url = add_query_arg( $_parsed_query, $redirect_url );
	}

	if ( $redirect_url ) {
		$redirect = parse_url( $redirect_url );
	}

	// www.example.com vs. example.com
	$user_home = parse_url( home_url() );

	if ( ! empty( $user_home['host'] ) ) {
		$redirect['host'] = $user_home['host'];
	}

	if ( empty( $user_home['path'] ) ) {
		$user_home['path'] = '/';
	}

	// Handle ports.
	if ( ! empty( $user_home['port'] ) ) {
		$redirect['port'] = $user_home['port'];
	} else {
		unset( $redirect['port'] );
	}

	// Trailing /index.php.
	$redirect['path'] = preg_replace( '|/' . preg_quote( $wp_rewrite->index, '|' ) . '/*?$|', '/', $redirect['path'] );

	$punctuation_pattern = implode(
		'|',
		array_map(
			'preg_quote',
			array(
				' ',
				'%20',  // Space.
				'!',
				'%21',  // Exclamation mark.
				'"',
				'%22',  // Double quote.
				"'",
				'%27',  // Single quote.
				'(',
				'%28',  // Opening bracket.
				')',
				'%29',  // Closing bracket.
				',',
				'%2C',  // Comma.
				'.',
				'%2E',  // Period.
				';',
				'%3B',  // Semicolon.
				'{',
				'%7B',  // Opening curly bracket.
				'}',
				'%7D',  // Closing curly bracket.
				'%E2%80%9C', // Opening curly quote.
				'%E2%80%9D', // Closing curly quote.
			)
		)
	);

	// Remove trailing spaces and end punctuation from the path.
	$redirect['path'] = preg_replace( "#($punctuation_pattern)+$#", '', $redirect['path'] );

	if ( ! empty( $redirect['query'] ) ) {
		// Remove trailing spaces and end punctuation from certain terminating query string args.
		$redirect['query'] = preg_replace( "#((^|&)(p|page_id|cat|tag)=[^&]*?)($punctuation_pattern)+$#", '$1', $redirect['query'] );

		// Clean up empty query strings.
		$redirect['query'] = trim( preg_replace( '#(^|&)(p|page_id|cat|tag)=?(&|$)#', '&', $redirect['query'] ), '&' );

		// Redirect obsolete feeds.
		$redirect['query'] = preg_replace( '#(^|&)feed=rss(&|$)#', '$1feed=rss2$2', $redirect['query'] );

		// Remove redundant leading ampersands.
		$redirect['query'] = preg_replace( '#^\??&*?#', '', $redirect['query'] );
	}

	// Strip /index.php/ when we're not using PATHINFO permalinks.
	if ( ! $wp_rewrite->using_index_permalinks() ) {
		$redirect['path'] = str_replace( '/' . $wp_rewrite->index . '/', '/', $redirect['path'] );
	}

	// Trailing slashes.
	if ( is_object( $wp_rewrite ) && $wp_rewrite->using_permalinks()
		&& ! $is_attachment_redirect
		&& ! is_404() && ( ! is_front_page() || is_front_page() && get_query_var( 'paged' ) > 1 )
	) {
		$user_ts_type = '';

		if ( get_query_var( 'paged' ) > 0 ) {
			$user_ts_type = 'paged';
		} else {
			foreach ( array( 'single', 'category', 'page', 'day', 'month', 'year', 'home' ) as $type ) {
				$func = 'is_' . $type;
				if ( call_user_func( $func ) ) {
					$user_ts_type = $type;
					break;
				}
			}
		}

		$redirect['path'] = user_trailingslashit( $redirect['path'], $user_ts_type );
	} elseif ( is_front_page() ) {
		$redirect['path'] = trailingslashit( $redirect['path'] );
	}

	// Remove trailing slash for robots.txt or sitemap requests.
	if ( is_robots()
		|| ! empty( get_query_var( 'sitemap' ) ) || ! empty( get_query_var( 'sitemap-stylesheet' ) )
	) {
		$redirect['path'] = untrailingslashit( $redirect['path'] );
	}

	// Strip multiple slashes out of the URL.
	if ( str_contains( $redirect['path'], '//' ) ) {
		$redirect['path'] = preg_replace( '|/+|', '/', $redirect['path'] );
	}

	// Always trailing slash the Front Page URL.
	if ( trailingslashit( $redirect['path'] ) === trailingslashit( $user_home['path'] ) ) {
		$redirect['path'] = trailingslashit( $redirect['path'] );
	}

	$original_host_low = strtolower( $original['host'] );
	$redirect_host_low = strtolower( $redirect['host'] );

	/*
	 * Ignore differences in host capitalization, as this can lead to infinite redirects.
	 * Only redirect no-www <=> yes-www.
	 */
	if ( $original_host_low === $redirect_host_low
		|| ( 'www.' . $original_host_low !== $redirect_host_low
			&& 'www.' . $redirect_host_low !== $original_host_low )
	) {
		$redirect['host'] = $original['host'];
	}

	$compare_original = array( $original['host'], $original['path'] );

	if ( ! empty( $original['port'] ) ) {
		$compare_original[] = $original['port'];
	}

	if ( ! empty( $original['query'] ) ) {
		$compare_original[] = $original['query'];
	}

	$compare_redirect = array( $redirect['host'], $redirect['path'] );

	if ( ! empty( $redirect['port'] ) ) {
		$compare_redirect[] = $redirect['port'];
	}

	if ( ! empty( $redirect['query'] ) ) {
		$compare_redirect[] = $redirect['query'];
	}

	if ( $compare_original !== $compare_redirect ) {
		$redirect_url = $redirect['scheme'] . '://' . $redirect['host'];

		if ( ! empty( $redirect['port'] ) ) {
			$redirect_url .= ':' . $redirect['port'];
		}

		$redirect_url .= $redirect['path'];

		if ( ! empty( $redirect['query'] ) ) {
			$redirect_url .= '?' . $redirect['query'];
		}
	}

	if ( ! $redirect_url || $redirect_url === $requested_url ) {
		return;
	}

	// Hex-encoded octets are case-insensitive.
	if ( str_contains( $requested_url, '%' ) ) {
		if ( ! function_exists( 'lowercase_octets' ) ) {
			/**
			 * Converts the first hex-encoded octet match to lowercase.
			 *
			 * @since 3.1.0
			 * @ignore
			 *
			 * @param array $matches Hex-encoded octet matches for the requested URL.
			 * @return string Lowercased version of the first match.
			 */
			function lowercase_octets( $matches ) {
				return strtolower( $matches[0] );
			}
		}

		$requested_url = preg_replace_callback( '|%[a-fA-F0-9][a-fA-F0-9]|', 'lowercase_octets', $requested_url );
	}

	if ( $redirect_obj instanceof WP_Post ) {
		$post_status_obj = get_post_status_object( get_post_status( $redirect_obj ) );
		/*
		 * Unset the redirect object and URL if they are not readable by the user.
		 * This condition is a little confusing as the condition needs to pass if
		 * the post is not readable by the user. That's why there are ! (not) conditions
		 * throughout.
		 */
		if (
			// Private post statuses only redirect if the user can read them.
			! (
				$post_status_obj->private &&
				current_user_can( 'read_post', $redirect_obj->ID )
			) &&
			// For other posts, only redirect if publicly viewable.
			! is_post_publicly_viewable( $redirect_obj )
		) {
			$redirect_obj = false;
			$redirect_url = false;
		}
	}

	/**
	 * Filters the canonical redirect URL.
	 *
	 * Returning false to this filter will cancel the redirect.
	 *
	 * @since 2.3.0
	 *
	 * @param string $redirect_url  The redirect URL.
	 * @param string $requested_url The requested URL.
	 */
	$redirect_url = apply_filters( 'redirect_canonical', $redirect_url, $requested_url );

	// Yes, again -- in case the filter aborted the request.
	if ( ! $redirect_url || strip_fragment_from_url( $redirect_url ) === strip_fragment_from_url( $requested_url ) ) {
		return;
	}

	if ( $do_redirect ) {
		// Protect against chained redirects.
		if ( ! redirect_canonical( $redirect_url, false ) ) {
			wp_redirect( $redirect_url, 301 );
			exit;
		} else {
			// Debug.
			// die("1: $redirect_url<br />2: " . redirect_canonical( $redirect_url, false ) );
			return;
		}
	} else {
		return $redirect_url;
	}
}

/**
 * Removes arguments from a query string if they are not present in a URL
 * DO NOT use this in plugin code.
 *
 * @since 3.4.0
 * @access private
 *
 * @param string $query_string
 * @param array  $args_to_check
 * @param string $url
 * @return string The altered query string
 */
function _remove_qs_args_if_not_in_url( $query_string, array $args_to_check, $url ) {
	$parsed_url = parse_url( $url );

	if ( ! empty( $parsed_url['query'] ) ) {
		parse_str( $parsed_url['query'], $parsed_query );

		foreach ( $args_to_check as $qv ) {
			if ( ! isset( $parsed_query[ $qv ] ) ) {
				$query_string = remove_query_arg( $qv, $query_string );
			}
		}
	} else {
		$query_string = remove_query_arg( $args_to_check, $query_string );
	}

	return $query_string;
}

/**
 * Strips the #fragment from a URL, if one is present.
 *
 * @since 4.4.0
 *
 * @param string $url The URL to strip.
 * @return string The altered URL.
 */
function strip_fragment_from_url( $url ) {
	$parsed_url = wp_parse_url( $url );

	if ( ! empty( $parsed_url['host'] ) ) {
		$url = '';

		if ( ! empty( $parsed_url['scheme'] ) ) {
			$url = $parsed_url['scheme'] . ':';
		}

		$url .= '//' . $parsed_url['host'];

		if ( ! empty( $parsed_url['port'] ) ) {
			$url .= ':' . $parsed_url['port'];
		}

		if ( ! empty( $parsed_url['path'] ) ) {
			$url .= $parsed_url['path'];
		}

		if ( ! empty( $parsed_url['query'] ) ) {
			$url .= '?' . $parsed_url['query'];
		}
	}

	return $url;
}

/**
 * Attempts to guess the correct URL for a 404 request based on query vars.
 *
 * @since 2.3.0
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @return string|false The correct URL if one is found. False on failure.
 */
function redirect_guess_404_permalink() {
	global $wpdb;

	/**
	 * Filters whether to attempt to guess a redirect URL for a 404 request.
	 *
	 * Returning a false value from the filter will disable the URL guessing
	 * and return early without performing a redirect.
	 *
	 * @since 5.5.0
	 *
	 * @param bool $do_redirect_guess Whether to attempt to guess a redirect URL
	 *                                for a 404 request. Default true.
	 */
	if ( false === apply_filters( 'do_redirect_guess_404_permalink', true ) ) {
		return false;
	}

	/**
	 * Short-circuits the redirect URL guessing for 404 requests.
	 *
	 * Returning a non-null value from the filter will effectively short-circuit
	 * the URL guessing, returning the passed value instead.
	 *
	 * @since 5.5.0
	 *
	 * @param null|string|false $pre Whether to short-circuit guessing the redirect for a 404.
	 *                               Default null to continue with the URL guessing.
	 */
	$pre = apply_filters( 'pre_redirect_guess_404_permalink', null );
	if ( null !== $pre ) {
		return $pre;
	}

	if ( get_query_var( 'name' ) ) {
		$publicly_viewable_statuses   = array_filter( get_post_stati(), 'is_post_status_viewable' );
		$publicly_viewable_post_types = array_filter( get_post_types( array( 'exclude_from_search' => false ) ), 'is_post_type_viewable' );

		/**
		 * Filters whether to perform a strict guess for a 404 redirect.
		 *
		 * Returning a truthy value from the filter will redirect only exact post_name matches.
		 *
		 * @since 5.5.0
		 *
		 * @param bool $strict_guess Whether to perform a strict guess. Default false (loose guess).
		 */
		$strict_guess = apply_filters( 'strict_redirect_guess_404_permalink', false );

		if ( $strict_guess ) {
			$where = $wpdb->prepare( 'post_name = %s', get_query_var( 'name' ) );
		} else {
			$where = $wpdb->prepare( 'post_name LIKE %s', $wpdb->esc_like( get_query_var( 'name' ) ) . '%' );
		}

		// If any of post_type, year, monthnum, or day are set, use them to refine the query.
		if ( get_query_var( 'post_type' ) ) {
			if ( is_array( get_query_var( 'post_type' ) ) ) {
				$post_types = array_intersect( get_query_var( 'post_type' ), $publicly_viewable_post_types );
				if ( empty( $post_types ) ) {
					return false;
				}
				$where .= " AND post_type IN ('" . join( "', '", esc_sql( get_query_var( 'post_type' ) ) ) . "')";
			} else {
				if ( ! in_array( get_query_var( 'post_type' ), $publicly_viewable_post_types, true ) ) {
					return false;
				}
				$where .= $wpdb->prepare( ' AND post_type = %s', get_query_var( 'post_type' ) );
			}
		} else {
			$where .= " AND post_type IN ('" . implode( "', '", esc_sql( $publicly_viewable_post_types ) ) . "')";
		}

		if ( get_query_var( 'year' ) ) {
			$where .= $wpdb->prepare( ' AND YEAR(post_date) = %d', get_query_var( 'year' ) );
		}
		if ( get_query_var( 'monthnum' ) ) {
			$where .= $wpdb->prepare( ' AND MONTH(post_date) = %d', get_query_var( 'monthnum' ) );
		}
		if ( get_query_var( 'day' ) ) {
			$where .= $wpdb->prepare( ' AND DAYOFMONTH(post_date) = %d', get_query_var( 'day' ) );
		}

		// phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared
		$post_id = $wpdb->get_var( "SELECT ID FROM $wpdb->posts WHERE $where AND post_status IN ('" . implode( "', '", esc_sql( $publicly_viewable_statuses ) ) . "')" );

		if ( ! $post_id ) {
			return false;
		}

		if ( get_query_var( 'feed' ) ) {
			return get_post_comments_feed_link( $post_id, get_query_var( 'feed' ) );
		} elseif ( get_query_var( 'page' ) > 1 ) {
			return trailingslashit( get_permalink( $post_id ) ) . user_trailingslashit( get_query_var( 'page' ), 'single_paged' );
		} else {
			return get_permalink( $post_id );
		}
	}

	return false;
}

/**
 * Redirects a variety of shorthand URLs to the admin.
 *
 * If a user visits example.com/admin, they'll be redirected to /wp-admin.
 * Visiting /login redirects to /wp-login.php, and so on.
 *
 * @since 3.4.0
 *
 * @global WP_Rewrite $wp_rewrite WordPress rewrite component.
 */
function wp_redirect_admin_locations() {
	global $wp_rewrite;

	if ( ! ( is_404() && $wp_rewrite->using_permalinks() ) ) {
		return;
	}

	$admins = array(
		home_url( 'wp-admin', 'relative' ),
		home_url( 'dashboard', 'relative' ),
		home_url( 'admin', 'relative' ),
		site_url( 'dashboard', 'relative' ),
		site_url( 'admin', 'relative' ),
	);

	if ( in_array( untrailingslashit( $_SERVER['REQUEST_URI'] ), $admins, true ) ) {
		wp_redirect( admin_url() );
		exit;
	}

	$logins = array(
		home_url( 'wp-login.php', 'relative' ),
		home_url( 'login.php', 'relative' ),
		home_url( 'login', 'relative' ),
		site_url( 'login', 'relative' ),
	);

	if ( in_array( untrailingslashit( $_SERVER['REQUEST_URI'] ), $logins, true ) ) {
		wp_redirect( wp_login_url() );
		exit;
	}
}