/**
	 * Parses the request to find the correct WordPress query.
	 *
	 * Sets up the query variables based on the request. There are also many
	 * filters and actions that can be used to further manipulate the result.
	 *
	 * @since 2.0.0
	 * @since 6.0.0 A return value was added.
	 *
	 * @global WP_Rewrite $wp_rewrite WordPress rewrite component.
	 *
	 * @param array|string $extra_query_vars Set the extra query variables.
	 * @return bool Whether the request was parsed.
	 */
	public function parse_request( $extra_query_vars = '' ) {
		global $wp_rewrite;

		/**
		 * Filters whether to parse the request.
		 *
		 * @since 3.5.0
		 *
		 * @param bool         $bool             Whether or not to parse the request. Default true.
		 * @param WP           $wp               Current WordPress environment instance.
		 * @param array|string $extra_query_vars Extra passed query variables.
		 */
		if ( ! apply_filters( 'do_parse_request', true, $this, $extra_query_vars ) ) {
			return false;
		}

		$this->query_vars     = array();
		$post_type_query_vars = array();

		if ( is_array( $extra_query_vars ) ) {
			$this->extra_query_vars = & $extra_query_vars;
		} elseif ( ! empty( $extra_query_vars ) ) {
			parse_str( $extra_query_vars, $this->extra_query_vars );
		}
		// Process PATH_INFO, REQUEST_URI, and 404 for permalinks.

		// Fetch the rewrite rules.
		$rewrite = $wp_rewrite->wp_rewrite_rules();

		if ( ! empty( $rewrite ) ) {
			// If we match a rewrite rule, this will be cleared.
			$error               = '404';
			$this->did_permalink = true;

			$pathinfo         = isset( $_SERVER['PATH_INFO'] ) ? $_SERVER['PATH_INFO'] : '';
			list( $pathinfo ) = explode( '?', $pathinfo );
			$pathinfo         = str_replace( '%', '%25', $pathinfo );

			list( $req_uri ) = explode( '?', $_SERVER['REQUEST_URI'] );
			$self            = $_SERVER['PHP_SELF'];

			$home_path       = parse_url( home_url(), PHP_URL_PATH );
			$home_path_regex = '';
			if ( is_string( $home_path ) && '' !== $home_path ) {
				$home_path       = trim( $home_path, '/' );
				$home_path_regex = sprintf( '|^%s|i', preg_quote( $home_path, '|' ) );
			}

			/*
			 * Trim path info from the end and the leading home path from the front.
			 * For path info requests, this leaves us with the requesting filename, if any.
			 * For 404 requests, this leaves us with the requested permalink.
			 */
			$req_uri  = str_replace( $pathinfo, '', $req_uri );
			$req_uri  = trim( $req_uri, '/' );
			$pathinfo = trim( $pathinfo, '/' );
			$self     = trim( $self, '/' );

			if ( ! empty( $home_path_regex ) ) {
				$req_uri  = preg_replace( $home_path_regex, '', $req_uri );
				$req_uri  = trim( $req_uri, '/' );
				$pathinfo = preg_replace( $home_path_regex, '', $pathinfo );
				$pathinfo = trim( $pathinfo, '/' );
				$self     = preg_replace( $home_path_regex, '', $self );
				$self     = trim( $self, '/' );
			}

			// The requested permalink is in $pathinfo for path info requests and $req_uri for other requests.
			if ( ! empty( $pathinfo ) && ! preg_match( '|^.*' . $wp_rewrite->index . '$|', $pathinfo ) ) {
				$requested_path = $pathinfo;
			} else {
				// If the request uri is the index, blank it out so that we don't try to match it against a rule.
				if ( $req_uri === $wp_rewrite->index ) {
					$req_uri = '';
				}

				$requested_path = $req_uri;
			}

			$requested_file = $req_uri;

			$this->request = $requested_path;

			// Look for matches.
			$request_match = $requested_path;
			if ( empty( $request_match ) ) {
				// An empty request could only match against ^$ regex.
				if ( isset( $rewrite['$'] ) ) {
					$this->matched_rule = '$';
					$query              = $rewrite['$'];
					$matches            = array( '' );
				}
			} else {
				foreach ( (array) $rewrite as $match => $query ) {
					// If the requested file is the anchor of the match, prepend it to the path info.
					if ( ! empty( $requested_file )
						&& str_starts_with( $match, $requested_file )
						&& $requested_file !== $requested_path
					) {
						$request_match = $requested_file . '/' . $requested_path;
					}

					if ( preg_match( "#^$match#", $request_match, $matches )
						|| preg_match( "#^$match#", urldecode( $request_match ), $matches )
					) {

						if ( $wp_rewrite->use_verbose_page_rules
							&& preg_match( '/pagename=\$matches\[([0-9]+)\]/', $query, $varmatch )
						) {
							// This is a verbose page match, let's check to be sure about it.
							$page = get_page_by_path( $matches[ $varmatch[1] ] );

							if ( ! $page ) {
								continue;
							}

							$post_status_obj = get_post_status_object( $page->post_status );

							if ( ! $post_status_obj->public && ! $post_status_obj->protected
								&& ! $post_status_obj->private && $post_status_obj->exclude_from_search
							) {
								continue;
							}
						}

						// Got a match.
						$this->matched_rule = $match;
						break;
					}
				}
			}

			if ( ! empty( $this->matched_rule ) ) {
				// Trim the query of everything up to the '?'.
				$query = preg_replace( '!^.+\?!', '', $query );

				// Substitute the substring matches into the query.
				$query = addslashes( WP_MatchesMapRegex::apply( $query, $matches ) );

				$this->matched_query = $query;

				// Parse the query.
				parse_str( $query, $perma_query_vars );

				// If we're processing a 404 request, clear the error var since we found something.
				if ( '404' === $error ) {
					unset( $error, $_GET['error'] );
				}
			}

			// If req_uri is empty or if it is a request for ourself, unset error.
			if ( empty( $requested_path ) || $requested_file === $self
				|| str_contains( $_SERVER['PHP_SELF'], 'wp-admin/' )
			) {
				unset( $error, $_GET['error'] );

				if ( isset( $perma_query_vars ) && str_contains( $_SERVER['PHP_SELF'], 'wp-admin/' ) ) {
					unset( $perma_query_vars );
				}

				$this->did_permalink = false;
			}
		}

		/**
		 * Filters the query variables allowed before processing.
		 *
		 * Allows (publicly allowed) query vars to be added, removed, or changed prior
		 * to executing the query. Needed to allow custom rewrite rules using your own arguments
		 * to work, or any other custom query variables you want to be publicly available.
		 *
		 * @since 1.5.0
		 *
		 * @param string[] $public_query_vars The array of allowed query variable names.
		 */
		$this->public_query_vars = apply_filters( 'query_vars', $this->public_query_vars );

		foreach ( get_post_types( array(), 'objects' ) as $post_type => $t ) {
			if ( is_post_type_viewable( $t ) && $t->query_var ) {
				$post_type_query_vars[ $t->query_var ] = $post_type;
			}
		}

		foreach ( $this->public_query_vars as $wpvar ) {
			if ( isset( $this->extra_query_vars[ $wpvar ] ) ) {
				$this->query_vars[ $wpvar ] = $this->extra_query_vars[ $wpvar ];
			} elseif ( isset( $_GET[ $wpvar ] ) && isset( $_POST[ $wpvar ] )
				&& $_GET[ $wpvar ] !== $_POST[ $wpvar ]
			) {
				wp_die(
					__( 'A variable mismatch has been detected.' ),
					__( 'Sorry, you are not allowed to view this item.' ),
					400
				);
			} elseif ( isset( $_POST[ $wpvar ] ) ) {
				$this->query_vars[ $wpvar ] = $_POST[ $wpvar ];
			} elseif ( isset( $_GET[ $wpvar ] ) ) {
				$this->query_vars[ $wpvar ] = $_GET[ $wpvar ];
			} elseif ( isset( $perma_query_vars[ $wpvar ] ) ) {
				$this->query_vars[ $wpvar ] = $perma_query_vars[ $wpvar ];
			}

			if ( ! empty( $this->query_vars[ $wpvar ] ) ) {
				if ( ! is_array( $this->query_vars[ $wpvar ] ) ) {
					$this->query_vars[ $wpvar ] = (string) $this->query_vars[ $wpvar ];
				} else {
					foreach ( $this->query_vars[ $wpvar ] as $vkey => $v ) {
						if ( is_scalar( $v ) ) {
							$this->query_vars[ $wpvar ][ $vkey ] = (string) $v;
						}
					}
				}

				if ( isset( $post_type_query_vars[ $wpvar ] ) ) {
					$this->query_vars['post_type'] = $post_type_query_vars[ $wpvar ];
					$this->query_vars['name']      = $this->query_vars[ $wpvar ];
				}
			}
		}

		// Convert urldecoded spaces back into '+'.
		foreach ( get_taxonomies( array(), 'objects' ) as $taxonomy => $t ) {
			if ( $t->query_var && isset( $this->query_vars[ $t->query_var ] ) ) {
				$this->query_vars[ $t->query_var ] = str_replace( ' ', '+', $this->query_vars[ $t->query_var ] );
			}
		}

		// Don't allow non-publicly queryable taxonomies to be queried from the front end.
		if ( ! is_admin() ) {
			foreach ( get_taxonomies( array( 'publicly_queryable' => false ), 'objects' ) as $taxonomy => $t ) {
				/*
				 * Disallow when set to the 'taxonomy' query var.
				 * Non-publicly queryable taxonomies cannot register custom query vars. See register_taxonomy().
				 */
				if ( isset( $this->query_vars['taxonomy'] ) && $taxonomy === $this->query_vars['taxonomy'] ) {
					unset( $this->query_vars['taxonomy'], $this->query_vars['term'] );
				}
			}
		}

		// Limit publicly queried post_types to those that are 'publicly_queryable'.
		if ( isset( $this->query_vars['post_type'] ) ) {
			$queryable_post_types = get_post_types( array( 'publicly_queryable' => true ) );

			if ( ! is_array( $this->query_vars['post_type'] ) ) {
				if ( ! in_array( $this->query_vars['post_type'], $queryable_post_types, true ) ) {
					unset( $this->query_vars['post_type'] );
				}
			} else {
				$this->query_vars['post_type'] = array_intersect( $this->query_vars['post_type'], $queryable_post_types );
			}
		}

		// Resolve conflicts between posts with numeric slugs and date archive queries.
		$this->query_vars = wp_resolve_numeric_slug_conflicts( $this->query_vars );

		foreach ( (array) $this->private_query_vars as $var ) {
			if ( isset( $this->extra_query_vars[ $var ] ) ) {
				$this->query_vars[ $var ] = $this->extra_query_vars[ $var ];
			}
		}

		if ( isset( $error ) ) {
			$this->query_vars['error'] = $error;
		}

		/**
		 * Filters the array of parsed query variables.
		 *
		 * @since 2.1.0
		 *
		 * @param array $query_vars The array of requested query variables.
		 */
		$this->query_vars = apply_filters( 'request', $this->query_vars );

		/**
		 * Fires once all query variables for the current request have been parsed.
		 *
		 * @since 2.1.0
		 *
		 * @param WP $wp Current WordPress environment instance (passed by reference).
		 */
		do_action_ref_array( 'parse_request', array( &$this ) );

		return true;
	}

---

上述代码是WordPress核心类WP中parse_request方法的详细实现。这个方法负责解析传入的URL或请求，以确定应执行哪个WordPress查询。以下是对此方法的作用和工作方式的解释，分解为其关键组件：

parse_request的目的

parse_request方法旨在根据传入请求设置查询变量。它确定请求应如何处理——无论是渲染文章、页面、类别列表还是处理404错误。

关键步骤和操作

1. 过滤提前退出：方法首先检查是否应继续解析请求，使用do_parse_request过滤器。插件可以使用此过滤器来跳过解析过程。
2. 初始化：

• 清除任何之前的查询变量。
• 初始化本地变量以处理URL的不同组件。

1. 处理额外的查询变量：如果提供了任何额外的查询变量，它们将被整合到查询处理中。
2. 应用重写规则：

• 从$wp_rewrite检索WordPress重写规则。
• 处理请求URI和路径信息，去除家庭URL路径，留下将与重写规则匹配的相对路径或查询字符串。

1. 与重写规则匹配：

• 迭代重写规则以找到与处理后的请求路径的匹配项。
• 如果找到匹配，相应的WordPress查询变量将根据重写规则设置。

1. 文章类型和分类法处理：

• 将与文章类型或分类法相关的任何查询变量映射到其相应的查询。
• 确保只能查询公开可查询的文章类型和分类法。

1. 安全和清洁：

• 处理GET和POST请求之间潜在的变量冲突。
• 过滤查询变量以确保最终查询中只包含允许的键。

1. 最终查询变量准备：

• 应用过滤器以修改或验证查询变量列表。
• 解决URL中的数字slug冲突。

1. 动作钩子：

• 执行操作，允许插件在解析查询变量后执行操作。

结论

parse_request函数是WordPress解释和响应URL的能力的核心部分。它使用重写规则将URL映射到查询变量，处理来自GET和POST请求的传入变量，并确保只执行允许的查询。这个方法对于确保WordPress可以为不同的URL提供正确的内容至关重要，无论这些URL指向文章、页面、存档还是自定义文章类型和分类法。

开发中的使用

开发人员可以使用提供的钩子（do_parse_request、query_vars、request和parse_request）来扩展或修改这种行为，以定制WordPress对不同请求的响应，这对于需要专门路由的自定义插件或主题特别有用。