(ns de.clojure-buch.api-search
  (use [clojure.walk :only (postwalk)])
  (use [clojure.repl :only (source-fn)]))

(defn source-as-sexpr [sym]
  (let [src (source-fn sym)]
    (binding [*read-eval* false]
      (if (nil? src) '() (read-string src)))))

(defn walk-source [sym-to-scan sym]
  (let [found-symbol (atom false)]
    (postwalk
     (fn [x]
       (if (= sym x)
         (swap! found-symbol #(or % true))) x)
     (source-as-sexpr sym-to-scan))
    (when @found-symbol sym-to-scan)))

(defn- symbol-usage [sym syms-to-scan-seq]
  (filter identity (pmap #(walk-source % sym)
                         syms-to-scan-seq)))

;; Alternative ohne Parallelisierung
;; (defn- symbol-usage [sym syms-to-scan-seq]
;;   (filter #(walk-source % sym) syms-to-scan-seq))

(defn find-usage-in-ns
  ([^Symbol s]
     (symbol-usage s (keys (ns-publics 'clojure.core))))
  ([^Symbol ns #^Symbol s]
     (require ns)
     (symbol-usage s (keys (ns-publics ns)))))