Add repl_ln.clj, a repl that supports line numbers

src/clojure/contrib/repl_ln.clj

@@ -0,0 +1,198 @@
+;;  Copyright (c) Stephen C. Gilardi. All rights reserved. The use and
+;;  distribution terms for this software are covered by the Common Public
+;;  License 1.0 (http://opensource.org/licenses/cpl.php) which can be found
+;;  in the file CPL.TXT at the root of this distribution. By using this
+;;  software in any fashion, you are agreeing to be bound by the terms of
+;;  this license. You must not remove this notice, or any other, from this
+;;  software.
+;;
+;;  A repl with a custom "read" hook that provides support for line
+;;  numbers.
+;;
+;;  scgilardi (gmail)
+;;  Created 28 November 2008
+
+(ns clojure.contrib.repl-ln
+  (:import (clojure.lang Compiler LineNumberingPushbackReader RT Var)
+           (java.io InputStreamReader OutputStreamWriter PrintWriter)
+           (java.util Date))
+  (:use clojure.contrib.def))
+
+;; Private
+
+(defstruct- repl-info
+  :name :started :name-fmt :prompt-fmt :serial :thread :depth)
+
+(defvar- +name-formats+
+  {"%S" "%1$d" "%T" "%2$d" "%D" "%3$d"}
+  "For set-name, maps our dynamic value codes to arg positions in
+  the call to format in repl-name")
+
+(defvar- +prompt-formats+
+  {"%S" "%1$d" "%T" "%2$d" "%D" "%3$d" "%L" "%4$d" "%N" "%5$s"}
+  "For set-prompt, maps our dynamic value codes to arg positions in
+  the call to format in repl-prompt")
+
+(defvar- +info-format+
+  ["Name:       %s"
+   "Started:    %s"
+   "Name-fmt:   \"%s\""
+   "Prompt-fmt: \"%s\""
+   "Serial:     %d"
+   "Thread:     %d"
+   "Depth:      %d"
+   "Line:       %d"])
+
+(defvar- +info-defaults+
+  (struct-map repl-info
+    :name-fmt "repl-%S"
+    :prompt-fmt "%S:%L %N=> "
+    :depth 0)
+  "Default/root values for repl info")
+
+(defonce- *serial-number* (ref 0)
+  "Serial number counter")
+
+(defonce- *info* +info-defaults+
+  "Info for this repl")
+
+(defn- set-info!
+  "Replaces the value thread-locally bound to *info* with a new map with
+  updated values. Args are sequential inline key value pairs."
+  [& args]
+  (set! *info* (apply assoc *info* args)))
+
+(defn- repl-name
+  "Returns the repl name based on *info*"
+  []
+  (let [{:keys [name-fmt-internal serial thread depth]} *info*]
+    (format name-fmt-internal serial thread depth)))
+
+(defn- repl-prompt
+  "Returns the repl prompt based on *info*, line number, and namespace"
+  []
+  (let [{:keys [prompt-fmt-internal serial thread depth]} *info*
+        line (.getLineNumber *in*)
+        namespace (ns-name *ns*)]
+    (format prompt-fmt-internal serial thread depth line namespace)))
+
+(defn- skip-whitespace
+  "Reads and skips whitespace characters from stream s. Returns :eos on end
+  of stream, :eol on end of line, or false on non-whitespace."
+  [s]
+  (loop [c (.read s)]
+    (cond (= c -1) :eos
+          (#{\return \newline} (char c)) :eol
+          (or (Character/isWhitespace c) (= c \,)) (recur (.read s))
+          :else (do (.unread s c) false))))
+
+(defn- read-hook
+  "Read hook that keeps the compiler's line number in sync with that of our
+  input stream, prompts only when there is nothing remaining to read on the
+  previous input line, and calls the Clojure reader only when there's
+  something to read on the current line."
+  [eof]
+  (loop [c (skip-whitespace *in*)]
+    (cond (= c :eos) eof
+          (= c :eol)
+          (do
+            (print (repl-prompt))
+            (flush)
+            (var-set Compiler/LINE (.getLineNumber *in*))
+            (recur (skip-whitespace *in*)))
+          :else (read *in* false eof))))
+
+;; Public
+
+(defn set-repl-name
+  "Sets the repl name. Include the following codes in the name to make the
+  corresponding dynamic values part of it:
+
+    %S - repl serial number
+    %T - thread id
+    %D - nesting depth in this thread
+
+  The default name is \"repl-%S\""
+  [name-fmt]
+  (set-info! :name-fmt name-fmt)
+  (loop [[[code fmt] & more] (seq +name-formats+)
+         name-fmt name-fmt]
+    (if code
+      (recur more (.replace name-fmt code fmt))
+      (set-info! :name-fmt-internal name-fmt)))
+  (let [name (repl-name)]
+    (set-info! :name name)
+    (var-set Compiler/SOURCE name))
+  nil)
+
+(defn set-repl-prompt
+  "Sets the repl prompt. Include the following codes in the prompt to make
+  the corresponding dynamic values part of it:
+
+    %S - repl serial number
+    %T - thread id
+    %D - nesting depth in this thread
+    %L - input line number
+    %N - namespace name
+
+  The default prompt is \"%S:%L %N=> \""
+  [prompt-fmt]
+  (set-info! :prompt-fmt prompt-fmt)
+  (loop [[[code fmt] & more] (seq +prompt-formats+)
+         prompt-fmt prompt-fmt]
+    (if code
+      (recur more (.replace prompt-fmt code fmt))
+      (set-info! :prompt-fmt-internal prompt-fmt)))
+  nil)
+
+(defn repl-info
+  "Returns a map of info about the current repl"
+  []
+  (let [line (.getLineNumber *in*)]
+    (dissoc (assoc *info* :line line)
+            :name-fmt-internal :prompt-fmt-internal)))
+
+(defn print-repl-info
+  "Prints info about the current repl"
+  []
+  (let [{:keys [name started name-fmt prompt-fmt serial thread depth line]}
+        (repl-info)]
+    (printf
+     (apply str (interleave +info-format+ (repeat "\n")))
+     name started name-fmt prompt-fmt serial thread depth line)))
+
+(defn repl
+  "A repl that supports line numbers. The default prompt displays repl
+  serial number, line number, and namespace. The default repl name contains
+  the repl serial number. Thrown exceptions display the repl name and line
+  number; metadata for defs made at the repl identify their origin by repl
+  name and line number. Use set-repl-name and set-repl-prompt to customize
+  the repl name and prompt"
+  ([]
+     (repl System/in System/out System/err RT/UTF8))
+  ([in out err encoding]
+     (try
+      (Var/pushThreadBindings
+       {RT/IN (LineNumberingPushbackReader.
+               (InputStreamReader. in encoding))
+        RT/OUT (OutputStreamWriter. out encoding)
+        RT/ERR (PrintWriter. (OutputStreamWriter. err encoding) true)
+        Compiler/SOURCE (var-get Compiler/SOURCE)
+        Compiler/LINE (var-get Compiler/LINE)
+        (var *info*) *info*})
+      (set-info!
+       :started (Date.)
+       :serial (dosync (alter *serial-number* inc))
+       :thread (.getId (Thread/currentThread))
+       :depth (inc (:depth *info*)))
+      (set-repl-name (:name-fmt *info*))
+      (set-repl-prompt (:prompt-fmt *info*))
+      ;; unread newline to enable first prompt
+      (.unread *in* (int \newline))
+      (clojure.main/repl
+       :prompt #()
+       :flush #()
+       :read read-hook)
+      (finally
+       (Var/popThreadBindings)
+       (prn)))))