debug.clj

;; even more enhanced version with that allows ret val override and better prompt

;; Slightly enhanced version of Alex Osborne's debug-repl (http://gist.github.com/252421)
;; Typing () quits the debug REPL, making it possible to continue without terminating the
;; input stream by typing Ctrl-D.

;; Inspired by George Jahad's version: http://georgejahad.com/clojure/debug-repl.html

(ns clojure.contrib.debug
  [:require clojure.main])

(defmacro local-bindings
  "Produces a map of the names of local bindings to their values."
  []
  (let [symbols (map key @clojure.lang.Compiler/LOCAL_ENV)]
    (zipmap (map (fn [sym] `(quote ~sym)) symbols) symbols)))

(declare *locals*)
(defn eval-with-locals
  "Evals a form with given locals. The locals should be a map of symbols to
values."
  [locals form]
  (binding [*locals* locals]
    (eval
     `(let ~(vec (mapcat #(list % `(*locals* '~%)) (keys locals)))
        ~form))))

(defn dr-read
  [request-prompt request-exit]
  (let [input (clojure.main/repl-read request-prompt request-exit)]
    (if (= input '())
      request-exit
      input)))

(def level 0)
(def counter (atom 1000))
(defn inc-counter []
  (swap! counter inc))

(def element (atom nil))

(def quit-dr-exception
     (proxy [Exception java.util.Enumeration] []
       (nextElement [] @element)))

(defn quit-dr [ & form]
  (reset! element (first form))
  (throw quit-dr-exception))

(defn caught [exc]
  (if (= (.getCause exc) quit-dr-exception)
    (throw quit-dr-exception)
    (clojure.main/repl-caught exc)))

(defmacro debug-repl
  "Starts a REPL with the local bindings available."
  ([]
     '(debug-repl nil))
  ([form]
     `(let [counter# (inc-counter)
            eval-fn# (partial eval-with-locals (local-bindings))]
        (try
         (binding [level (inc level)]
           (clojure.main/repl
            :prompt #(print (str "dr-" level "-" counter# " => "))
            :eval eval-fn#
            :read dr-read
            :caught caught))
         (catch Exception e#
           (if (= e# quit-dr-exception)
             (if-let [new-form# (.nextElement quit-dr-exception)]
               (eval-fn# new-form#)
               (eval-fn# ~form))
             (throw e#)))))))

 
(comment
  ;;
  ;; Some examples
  ;;
 
  (let [c 1
        locals (local-bindings)
        d 2]
    locals)
  ;; => {fn__5310 #<user$eval__5309 user$eval__5309@1a65a18>, c 1}
 
  (let [c 1
        d 2]
    (defn a [b c]
      (debug-repl)
      d))
  (a "foo" "bar")
  ;; dr => c
  ;; "bar"
  ;; dr => d
  ;; 2
  ;; dr => *locals*
  ;; {fn__20 #<user$eval__19 user$eval__19@955cd5>,
  ;; c "bar",
  ;; d 2,
  ;; fn__22 #<user$eval__19$a__21 user$eval__19$a__21@59fb21>,
  ;; b "foo"}


 
(comment
  ;;
  ;; Some examples
  ;;
 
  (let [c 1
        locals (local-bindings)
        d 2]
    locals)
  ;; => {fn__5310 #<user$eval__5309 user$eval__5309@1a65a18>, c 1}
 
  (let [c 1
        d 2]
    (defn a [b c]
      (debug-repl)
      d))
  (a "foo" "bar")
  ;; dr => c
  ;; "bar"
  ;; dr => d
  ;; 2
  ;; dr => *locals*
  ;; {fn__20 #<user$eval__19 user$eval__19@955cd5>,
  ;; c "bar",
  ;; d 2,
  ;; fn__22 #<user$eval__19$a__21 user$eval__19$a__21@59fb21>,
  ;; b "foo"}
  )
 
 
user=> (let [a 10] (debug-repl (* a a)))
dr-1-1006 => (quit-dr)
100

user=> (let [a 10] (debug-repl (* a a)))
dr-1-1007 => (quit-dr 99)
99

  )