如何编写这个 clojure enlive 程序以便它可以解析多个 url？

Question

这是一个解析一些网站的程序。第一个站点是site1。解析该特定站点的所有逻辑都位于 (-> config :site1)

(ns program.core
    (require [net.cgrand.enlive-html :as html])) 

(def config 
    {:site1   
        {:site-url 
            ["http://www.site1.com/page/1"
             "http://www.site1.com/page/2"
                 "http://www.site1.com/page/3"
             "http://www.site1.com/page/4"]
        :url-encoding "iso-8859-1"
        :parsing-index
            {:date
                {:selector 
                    [[:td.PadMed (html/nth-of-type 1)] :table [:tr (html/nth-of-type 2)] 
                    [:td (html/nth-of-type 3)] [:span]]
                :trimming-fn
                    (comp first :content) ; (first) to remove extra parenthese
                }
            :title 
                {:selector
                    [[:td.PadMed (html/nth-of-type 1)] :table :tr [:td (html/nth-of-type 2)] [:a]]
                :trimming-fn
                    (comp first :content first :content)
                }
            :url 
                {:selector
                    [[:td.PadMed (html/nth-of-type 1)] :table :tr [:td (html/nth-of-type 2)] [:a]]
                :trimming-fn 
                    #(str "http://www.site.com" (:href (:attrs %)))
                }
            }
        }})
    ;=== Fetch fn ===;

    (defn fetch-encoded-url 
        ([url] (fetch-encoded-url url "utf-8"))
        ([url encoding] (-> url java.net.URL. 
                    .getContent 
                    (java.io.InputStreamReader. encoding)
                    html/html-resource)))

现在我要解析 (-> config :site1 :site-url) 中包含的页面所有的网址？

(defn parse-element [element]
    (into [] (map (-> config :site1 :parsing-index element :trimming-fn)
            (html/select 
              (fetch-encoded-url
                (-> config :site1 :site-url first)
                (-> config :site1 :url-encoding))
              (-> config :site1 :parsing-index element :selector)))))

(def element-lists
    (apply map vector
        (map parse-element (-> config :site1 :parsing-index keys))))

(def tagged-lists
    (into [] (for [element-list element-lists]
           (zipmap [:date :title :url] element-list))))

;==== Fn call ====
    (println tagged-lists)

Answer 1

将:site1 作为参数传递给parse-element 和elements-list。

(defn parse-element [site element]
    (into [] (map (-> config site :parsing-index element :trimming-fn)
        (html/select 
          (fetch-encoded-url
            (-> config site :site-url first)
            (-> config site :url-encoding))
          (-> config site :parsing-index element :selector)))))

(def element-lists [site]
    (apply map vector
        (map (partial parse-element site) (-> config site :parsing-index keys))))

然后映射到:site1 :site2…键。

---

附录以回答 cmets 中的进一步问题。

您可以将html/select 包裹在map 中，覆盖:site-urls。比如：

(defn parse-element [site element]
  (let [site-urls (-> config site :site-url)]  
    (into [] (map (-> config site :parsing-index element :trimming-fn)
       map
        #(html/select 
          (fetch-encoded-url
            %
            (-> config site :url-encoding))
          (-> config site :parsing-index element :selector)))
        site-urls)))

（我希望我的括号是正确的。）

然后您可能需要检查 :trimming-fn，以便它处理嵌套。 apply 就足够了。