Source

File: wp-includes/class-wp-query.php

public function get_queried_object() {
		if ( isset( $this->queried_object ) ) {
			return $this->queried_object;
		}

		$this->queried_object    = null;
		$this->queried_object_id = null;

		if ( $this->is_category || $this->is_tag || $this->is_tax ) {
			if ( $this->is_category ) {
				if ( $this->get( 'cat' ) ) {
					$term = get_term( $this->get( 'cat' ), 'category' );
				} elseif ( $this->get( 'category_name' ) ) {
					$term = get_term_by( 'slug', $this->get( 'category_name' ), 'category' );
				}
			} elseif ( $this->is_tag ) {
				if ( $this->get( 'tag_id' ) ) {
					$term = get_term( $this->get( 'tag_id' ), 'post_tag' );
				} elseif ( $this->get( 'tag' ) ) {
					$term = get_term_by( 'slug', $this->get( 'tag' ), 'post_tag' );
				}
			} else {
				// For other tax queries, grab the first term from the first clause.
				if ( ! empty( $this->tax_query->queried_terms ) ) {
					$queried_taxonomies = array_keys( $this->tax_query->queried_terms );
					$matched_taxonomy   = reset( $queried_taxonomies );
					$query              = $this->tax_query->queried_terms[ $matched_taxonomy ];

					if ( ! empty( $query['terms'] ) ) {
						if ( 'term_id' === $query['field'] ) {
							$term = get_term( reset( $query['terms'] ), $matched_taxonomy );
						} else {
							$term = get_term_by( $query['field'], reset( $query['terms'] ), $matched_taxonomy );
						}
					}
				}
			}

			if ( ! empty( $term ) && ! is_wp_error( $term ) ) {
				$this->queried_object    = $term;
				$this->queried_object_id = (int) $term->term_id;

				if ( $this->is_category && 'category' === $this->queried_object->taxonomy ) {
					_make_cat_compat( $this->queried_object );
				}
			}
		} elseif ( $this->is_post_type_archive ) {
			$post_type = $this->get( 'post_type' );
			if ( is_array( $post_type ) ) {
				$post_type = reset( $post_type );
			}
			$this->queried_object = get_post_type_object( $post_type );
		} elseif ( $this->is_posts_page ) {
			$page_for_posts          = get_option( 'page_for_posts' );
			$this->queried_object    = get_post( $page_for_posts );
			$this->queried_object_id = (int) $this->queried_object->ID;
		} elseif ( $this->is_singular && ! empty( $this->post ) ) {
			$this->queried_object    = $this->post;
			$this->queried_object_id = (int) $this->post->ID;
		} elseif ( $this->is_author ) {
			$this->queried_object_id = (int) $this->get( 'author' );
			$this->queried_object    = get_userdata( $this->queried_object_id );
		}

		return $this->queried_object;
	}