Support code reflection in the cljs repl.

A few changes have been made to support runtime code reflection in a
cljs repl. These include small changes to cljs.analyzer, a separation of
the server element of cljs.repl.browser into cljs.repl.server, and the
addition of two new namespaces: cljs.repl.reflect (in src/clj) and
clojure.reflect (in src/cljs).

cljs.analyzer:
- Arbitrary metadata declared on symbols will now be added to the AST.
  This supports the addition of docstrings.
- Fix a subtle bug in cljs.analyzer/analyze-file, where an uncommon
  code-path would lead to the failed coercion of an absolute-path into a
  URL. An absolute path, including a `file://` protocol, can now be
  passed into the function successfully.

cljs.repl:
- Add function to analyze source on repl-env -setup. This is used to
  support reflection on user-defined cljs source files, as well as to
  populate the cljs.analyzer/namespaces atom on repl startup.

cljs.repl.browser:
- The server element of this namespace has been factored out into
  cljs.repl.server to support other services that may require that
  functionality.

cljs.repl.server:
- Expose a simple HTTP method and predicate dispatch system to register
  handler functions for incoming requests. (Note: this system seems to
  be relatively brittle, and future change may be warranted.)

cljs.repl.reflect:
- Registers a server handler for incoming requests to "/reflect".
- Queries cljs.analyzer/namespaces for meta information relevant to a
  symbol, responding to requests with compiled javascript.
- Can use "fixed point" macroexpansion on cljs macro forms.

clojure.reflect:
- Expose a set of simple functions for querying meta information of a
  symbol, as well as macroexpanding a cljs form.

.gitignore

@@ -9,3 +9,4 @@ closure
/coresimple.js
/out
.repl
*.swp

samples/repl/src/repl/test.cljs

@@ -7,7 +7,8 @@
;; You must not remove this notice, or any other, from this software.

(ns repl.test
  (:require [clojure.browser.repl :as repl]))
  (:require [clojure.browser.repl :as repl]
            [clojure.reflect :as reflect]))

(repl/connect "http://localhost:9000/repl")

script/browser-repl

@@ -0,0 +1,16 @@
#!/bin/sh

if [ "$CLOJURESCRIPT_HOME" = "" ]; then
  CLOJURESCRIPT_HOME="`dirname $0`/.."
fi

CLJSC_CP=''
for next in lib/*: src/clj: src/cljs: test/cljs; do
  CLJSC_CP=$CLJSC_CP$CLOJURESCRIPT_HOME'/'$next
done

java -server -cp $CLJSC_CP clojure.main -e "
(require '[cljs.repl :as r])
(require '[cljs.repl.browser :as b])
(r/repl (b/repl-env))
"

src/clj/cljs/analyzer.clj

@@ -290,6 +290,7 @@
              ([_ sym doc init] {:sym sym :doc doc :init init}))
        args (apply pfn form)
        sym (:sym args)
        sym-meta (meta sym)
        tag (-> sym meta :tag)
        protocol (-> sym meta :protocol)
        dynamic (-> sym meta :dynamic)
@@ -326,6 +327,7 @@
               (let [m (assoc (or m {}) :name name)]
                 (merge m
                   (when tag {:tag tag})
                   (when sym-meta sym-meta)
                   (when dynamic {:dynamic true})
                   (when-let [line (:line env)]
                     {:file *cljs-file* :line line})
@@ -533,7 +535,7 @@
     (when (and known-num-fields (not= known-num-fields argc))
       (warning env
         (str "WARNING: Wrong number of args (" argc ") passed to " ctor)))
     

     {:env env :op :new :form form :ctor ctorexpr :args argexprs
      :children (into [ctorexpr] argexprs)})))

@@ -677,7 +679,7 @@
                       :type true
                       :num-fields (count fields))]
               (merge m
                 {:protocols (-> tsym meta :protocols)}     
                 {:protocols (-> tsym meta :protocols)}
                 (when-let [line (:line env)]
                   {:file *cljs-file*
                    :line line})))))
@@ -935,8 +937,8 @@
        :else {:op :constant :env env :form form}))))

(defn analyze-file
  [f]
  (let [res (if (= \/ (first f)) f (io/resource f))]
  [^String f]
  (let [res (if (re-find #"^file://" f) (java.net.URL. f) (io/resource f))]
    (assert res (str "Can't find " f " in classpath"))
    (binding [*cljs-ns* 'cljs.user
              *cljs-file* (.getPath ^java.net.URL res)
@@ -950,4 +952,3 @@
              (when-not (identical? eof r)
                (analyze env r)
                (recur (read pbr false eof false))))))))))

src/clj/cljs/repl.clj

@@ -8,6 +8,7 @@

(ns cljs.repl
  (:refer-clojure :exclude [load-file])
  (:import java.io.File)
  (:require [clojure.string :as string]
            [clojure.java.io :as io]
            [cljs.compiler :as comp]
@@ -149,6 +150,15 @@
     'clojure.core/load-file load-file-fn
     'load-namespace (fn [repl-env ns] (load-namespace repl-env ns))}))

(defn analyze-source
  "Given a source directory, analyzes all .cljs files. Used to populate
  cljs.analyzer/namespaces so as to support code reflection."
  [src-dir]
  (if-let [src-dir (and (not (empty? src-dir))
                     (File. src-dir))]
    (doseq [file (comp/cljs-files-in src-dir)]
      (ana/analyze-file (str "file://" (.getAbsolutePath file))))))

(defn repl
  "Note - repl will reload core.cljs every time, even if supplied old repl-env"
  [repl-env & {:keys [verbose warn-on-undeclared special-fns]}]
@@ -166,12 +176,12 @@
        (let [{:keys [status form]} (read-next-form)]
          (cond
           (= form :cljs/quit) :quit
           

           (= status :error) (recur)
           

           (and (seq? form) (is-special-fn? (first form)))
           (do (apply (get special-fns (first form)) repl-env (rest form)) (newline) (recur))
           

           :else
           (do (eval-and-print repl-env env form) (recur)))))
      (-tear-down repl-env))))