revert accidental checkin of repl_ln.clj

1 files changed, 87 insertions, 22 deletions

diff --git a/src/clojure/contrib/repl_ln.clj b/src/clojure/contrib/repl_ln.clj
index 372eb3ff..7e72a836 100644
--- a/src/clojure/contrib/repl_ln.clj
+++ b/src/clojure/contrib/repl_ln.clj
@@ -54,6 +54,14 @@
     :depth 0)
   "Default/root values for repl info")
 
+(defvar- +special-character+
+  { (int \return)  :eol
+    (int \newline) :eol
+    (int \,)       :ws
+    (int \;)       :cte
+    -1             :eos }
+  "Maps interesting character codes to keywords representing their type")
+
 (defonce- *serial-number* (atom 0)
   "Serial number counter")
 
@@ -76,11 +84,65 @@
         {:keys [serial thread depth]} *info*]
     (format name-fmt serial thread depth)))
 
-(defn- prompt-hook
-  []
-  (let [prompt (*private* :prompt)]
-    (var-set Compiler/LINE (.getLineNumber *in*))
-    (prompt)))
+(defn- next-char
+  "Reads the next character in s and either returns it or one of the
+  following keywords if the character is of the corresponding type:
+    :ws  whitespace
+    :eol end-of-line
+    :eos end-of-stream
+    :cte comment-to-end character"
+  [s]
+  (let [c (.read s)]
+    (cond-let [type]
+      (+special-character+ c) type
+      (Character/isWhitespace c) :ws
+      :else c)))
+
+(defn- skip-to-end
+  "Skips characters on stream s until an end of stream or end of line"
+  [s]
+  (loop [c (next-char s)]
+    (if (#{:eol :eos} c)
+      c
+      (recur (next-char s)))))
+
+(defn- find-readable-this-line
+  "Skips characters on stream s until end of stream, end of line, or a
+  character of interest to the Reader. Returns :eos on end of stream, :eol
+  on end of line, :eol or :eos after skipping to end of line or end of
+  stream on semicolon, or :readable otherwise. Before returning :readable,
+  the readable character is pushed back onto the stream."
+  [s]
+  (loop [c (next-char s)]
+    (case c
+     :eol c
+     :eos c
+     :cte (skip-to-end s)
+     :ws (recur (next-char s))
+     (do
+       (.unread s c)
+       :readable))))
+
+(defn- read-hook
+  "Read hook for clojure.main/repl that keeps the compiler's line number in
+  sync with that of our input stream, prompts only when there is nothing
+  interesting remaining to read on the previous input line, and calls the
+  Reader only when there's something interesting to read on the current
+  line."
+  [eof]
+  (let [{:keys [prompt flush read]} *private*]
+    (loop [c (find-readable-this-line *in*)]
+      (case c
+       :eos eof
+       :eol
+       (do
+         (prompt)
+         (flush)
+         (recur (find-readable-this-line *in*)))
+       :readable
+       (do
+         (var-set Compiler/LINE (.getLineNumber *in*))
+         (read eof))))))
 
 (defn- process-inits
   "Processes initial pairs of args of the form:
@@ -206,20 +268,19 @@
        - :prompt-fmt, Prompt format string
          default: the prompt-fmt of the parent repl, or \"%S:%L %N=> \""
   [& options]
-  (let [{:keys [init need-prompt prompt flush read eval print caught in out err
+  (let [{:keys [init prompt flush read eval print caught in out err
                 encoding name-fmt prompt-fmt]
-         :or {init        #()
-              prompt      #(clojure.core/print (repl-prompt))
-              need-prompt #(.atLineStart *in*)
-              flush       flush
-              read        read
-              eval        eval
-              print       prn
-              caught      #(.println *err* (clojure.main/repl-exception %))
-              in          System/in
-              out         System/out
-              err         System/err
-              encoding    RT/UTF8}}
+         :or {init       #()
+              prompt     #(clojure.core/print (repl-prompt))
+              flush      flush
+              read       #(read *in* false %)
+              eval       eval
+              print      prn
+              caught     #(.println *err* (clojure.main/repl-exception %))
+              in         System/in
+              out        System/out
+              err        System/err
+              encoding   RT/UTF8}}
         (apply hash-map options)]
     (try
      (Var/pushThreadBindings
@@ -237,14 +298,18 @@
              :thread (.getId (Thread/currentThread))
              :depth (inc (:depth *info*)))
      (assoc! *private*
-             :prompt prompt)
+             :prompt prompt
+             :flush flush
+             :read read)
      (set-repl-name (or name-fmt (:name-fmt *info*)))
      (set-repl-prompt (or prompt-fmt (:prompt-fmt *info*)))
+     ;; unread newline to enable first prompt
+     (.unread *in* (int \newline))
      (clojure.main/repl
       :init init
-      :prompt prompt-hook
-      :flush flush
-      :read read
+      :prompt #()
+      :flush #()
+      :read read-hook
       :eval eval
       :print print
       :caught caught)