Working better, but even the basic sedit functionality isn't right.

README.md

@@ -8,12 +8,22 @@ Preliminary, incomplete, alpha quality code. This implements a structure editor
 not a display editor in the tradition of InterLisp's DEdit. I do intend to follow up with a
 display editor, but this is exploratory proof-of-concept code.
 
+Note that to work with this, you need to start with
+
+    lein trampoline repl
+
+rather than just
+
+    lein repl
+
+I've read explanations of why this is, but I don't claim to fully understand them. Treat it as magic,
+but trust me on this.
+
 To edit an arbitrary s-expression:
 
 	(sedit sexpr)
 
-This pretty much works now; it returns an edited copy of the s-expression. Vectors are not handled
+This pretty much works now; it returns an edited copy of the s-expression. Maps are not yet handled.
-intelligently (but could be).
 
 To edit a function definition
 

project.clj

@@ -3,5 +3,6 @@
   :url "http://example.com/FIXME"
   :license {:name "Eclipse Public License"
             :url "http://www.eclipse.org/legal/epl-v10.html"}
-  :dependencies [[org.clojure/clojure "1.5.1"]]
+  :dependencies [[org.clojure/clojure "1.8.0"]
+                 [jline "2.11"]]
   :clean-targets ["classes" "bin"])

src/fedit/core.clj

@@ -1,5 +1,8 @@
 (ns fedit.core
-  (:use clojure.repl))
+  (:require [clojure.repl :refer :all]
+            [clojure.pprint :refer [pprint]])
+  (:import [jline.console ConsoleReader]))
+
 
 (defn clear-terminal
   "Clear the terminal screen - should be possible to do this by printing a \f, but
@@ -7,87 +10,137 @@
   []
   (dotimes [_ 25] (println)))
 
-(defn print-indent
-  "indent this many spaces and then print this s-expression"
-  [x spaces]
-  (dotimes [_ spaces] (print " "))
-  (println x)
-  x)
-
-(defn recursively-frob-strings 
-  "Walk this s-expression, replacing strings with quoted strings.
-
-   TODO: does not fix strings in vectors"
-  [sexpr]
-  (cond 
-    (nil? sexpr) nil
-    (symbol? sexpr) sexpr
-    (empty? sexpr) ()
-    (list? sexpr)(cons (recursively-frob-strings (first sexpr))(recursively-frob-strings (rest sexpr)))
-    (string? sexpr)(str "\"" sexpr "\"")
-    true sexpr))
-
-(defn rereadable-print-str 
-  "print-str doesn't produce a re-readable output, because it does not surround 
-   embedded strings with quotation marks. This attempts to fix this problem."
-  [sexpr]
-  (let [fixed (recursively-frob-strings sexpr)]
-    (print-str fixed))) 
-
-(defn pretty-print 
-  "Print this s-expression neatly indented. 
-
-   TODO: Does not yet handle vectors intelligently"
-  ([sexpr] (pretty-print sexpr 0))
-  ([sexpr indent]  
-  (cond 
-    (string? sexpr)
-    (let [printform (str "\"" sexpr "\"")](print-indent printform indent))
-    (list? sexpr)
-    (let [asstring (rereadable-print-str sexpr)]
-      ;; print-str isn't right here because it does not substitute in quotation marks around strings
-      ;; need to write a new function of my own.
-      (cond 
-        (< (+ indent (count asstring)) 80) (print-indent asstring indent)
-              true (do 
-                    (let [firstline (str "(" (rereadable-print-str (first sexpr)))] 
-                      (print-indent firstline indent))
-                    (doall (map (fn [x] (pretty-print x (+ indent 2))) (rest sexpr)))
-                    (print-indent ")" indent))))
-    true (print-indent sexpr indent))
-  sexpr))
 
 (defn read-char
-  "Ultimately this will read a single character, probably requiring some Java hackery; but for now
+  "Read from standard input a single character which is one of these targets return it."
-   just read"
+  [targets]
-  []
+  (let [cr (ConsoleReader.)
-  (read))
+        keyint (.readCharacter cr)
+        key (char keyint)]
+    (if
+      (some #(= % key) targets)
+      key
+      (recur targets))))
+
+
+(def symbol-menu
+  {\r "Return"
+   \s "Substitute"
+   \x "eXcise"})
+
+
+(def sequence-menu
+  {\a "cAr"
+   \d "cDr"
+   \r "Return"
+   \s "Substitute"
+   \x "eXcise"})
+
 
 (defn prompt-and-read
   "Show a prompt, and read a form from the input
    TODO: the read should be on the same line as the prompt - again, possibly some hackery needed."
   [prompt]
   ;; print, on its own, does not flush the buffer.
-  (println prompt)
+  (print (str prompt " "))
-  (read))
+  (flush)
+  (read-string
+    (read-line)))
+
+
+(defn print-menu
+  "Print this menu."
+  [menu]
+  (println
+    (apply
+      str
+      (cons
+        "Enter one character: "
+        (map
+          #(str " \t" % ": " (menu %))
+          (keys menu))))))
+
+
+(defn- prepare-screen
+  "Prepare the screen for editing this s-expression"
+  [sexpr menu]
+  (clear-terminal)
+  (pprint sexpr)
+  (print-menu menu))
+
+
+(defn- sedit-list
+  "Edit something believed to be a list."
+  [l]
+  (if
+    (list? l)
+    (do
+      (prepare-screen l sequence-menu)
+      (let [key (read-char (keys sequence-menu))]
+        (case key
+          \x nil
+          \s (sedit (prompt-and-read "==?"))
+          \a (sedit (let [[car & cdr] l] (cons (sedit car) cdr)))
+          \d (sedit (let [[car & cdr] l] (cons car (sedit cdr))))
+          \r l
+          (sedit l))))
+    l))
+
+
+(defn- sedit-vector
+  "Edit something believed to be a vector. Different from
+  sedit-list, since vectors are recomposed differently."
+  [v]
+  (if
+    (vector? v)
+    (do
+      (prepare-screen v sequence-menu)
+      (let [key (read-char (keys sequence-menu))]
+        (case key
+          \x nil
+          \s (sedit (prompt-and-read "==?"))
+          \a (sedit (let [[car & cdr] v] (apply vector (cons (sedit car) cdr))))
+          \d (sedit (let [[car & cdr] v] (apply vector (cons car (sedit cdr)))))
+          \r v
+          (sedit v))))
+    v))
+
+
+(defn- sedit-token
+  "Edit something which from our point of view is a single token
+  (which for now includes strings)."
+  [token]
+  (prepare-screen token symbol-menu)
+  (let [key (read-char (keys symbol-menu))]
+    (case key
+      \x nil
+      \s (sedit (prompt-and-read "==?"))
+      \r token
+      (sedit token))))
+
+
+(defn cons?
+  "Return true if this sexpr is either a cons or a list.
+   Bizarrely, in Clojure, a cons cell is not a list."
+  [sexpr]
+  (or
+    (list? sexpr)
+    (instance? clojure.lang.Cons sexpr)))
+
 
 (defn sedit
   "Edit an S-Expression, and return a modified version of it"
   [sexpr]
-  (clear-terminal)
+  (cond
-  (pretty-print sexpr)
+    (nil? sexpr) (sedit-token sexpr)
-  (cond (list? sexpr) (println "Enter one character: a:CAR; d:CDR; s:Substitute; x:Cut; r:Return")
+    (cons? sexpr) (sedit-list sexpr)
-    true (println "Enter one character: s:Substitute; x:Cut; r:Return"))
+    (vector? sexpr) (sedit-vector sexpr)
-  (let [key (read-char)]
+    (or
-    (cond
+      (symbol? sexpr)
-      (= key 'x) nil
+      (number? sexpr)
-      (= key 's) (prompt-and-read "==?")
+      (string? sexpr)) (sedit-token sexpr)
-      (and (= key 'a)(list? sexpr)(> (count sexpr) 0)) 
+    true (println (str "Unexpected: " (type sexpr)))))
-      (let [car (sedit (first sexpr)) cdr (rest sexpr)](sedit (cons car cdr)))
+
-      (and (= key 'd)(list? sexpr)) 
-      (let [car (first sexpr) cdr (sedit (rest sexpr))](sedit (cons car cdr)))
-      (= key 'r) sexpr
-      true (sedit sexpr))))
 
 (defn fedit
   "Edit a named function or macro, and recompile the result.