001 (ns beowulf.reader.char-reader
002 "Provide sensible line editing, auto completion, and history recall.
003
004 None of what's needed here is really working yet, and a pull request with
005 a working implementation would be greatly welcomed.
006
007 ## What's needed (rough specification)
008
009 1. Carriage return **does not** cause input to be returned, **unless**
010 a. the number of open brackets `(` and closing brackets `)` match; and
011 b. the number of open square brackets `[` and closing square brackets `]` also match;
012 2. <Ctrl-D> aborts editing and returns the string `STOP`;
013 3. <Up-arrow> and <down-arrow> scroll back and forward through history, but ideally I'd like
014 this to be the Lisp history (i.e. the history of S-Expressions actually read by `READ`,
015 rather than the strings which were supplied to `READ`);
016 4. <Tab> offers potential auto-completions taken from the value of `(OBLIST)`, ideally the
017 current value, not the value at the time the session started;
018 5. <Back-arrow> and <Forward-arrow> offer movement and editing within the line.
019
020 TODO: There are multiple problems with JLine; a better solution might be
021 to start from here:
022 https://stackoverflow.com/questions/7931988/how-to-manipulate-control-characters"
023 (:require [beowulf.oblist :refer [*options* oblist]])
024 (:import [org.jline.reader.impl.completer StringsCompleter]
025 [org.jline.reader.impl DefaultParser DefaultParser$Bracket]
026 [org.jline.reader LineReaderBuilder]
027 [org.jline.terminal TerminalBuilder]
028 [org.jline.widget AutopairWidgets AutosuggestionWidgets]))
029
030 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
031 ;;;
032 ;;; Copyright (C) 2022-2023 Simon Brooke
033 ;;;
034 ;;; This program is free software; you can redistribute it and/or
035 ;;; modify it under the terms of the GNU General Public License
036 ;;; as published by the Free Software Foundation; either version 2
037 ;;; of the License, or (at your option) any later version.
038 ;;;
039 ;;; This program is distributed in the hope that it will be useful,
040 ;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
041 ;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
042 ;;; GNU General Public License for more details.
043 ;;;
044 ;;; You should have received a copy of the GNU General Public License
045 ;;; along with this program; if not, write to the Free Software
046 ;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
047 ;;;
048 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
049
050 ;; It looks from the example given [here](https://github.com/jline/jline3/blob/master/demo/src/main/java/org/jline/demo/Repl.java)
051 ;; as though JLine could be used to build a perfect line-reader for Beowulf; but it also
052 ;; looks as though you'd need a DPhil in JLine to write it, and I don't have
053 ;; the time.
054
055 (defn build-completer
056 "Build a completer which takes tokens from the oblist.
057
058 This is sort-of working, in as much as hitting <TAB> on a blank line will
059 show a table of values from the oblist, but hitting <TAB> after you've
060 started input does not show potential completions for tokens you've started."
061 []
062 (StringsCompleter. (map #(str (first %)) @oblist)))
063
064 ;; This breaks; it is not correctly resolving the Enum, although I can't work out
065 ;; why not.
066 ;; (defn build-parser
067 ;; []
068 ;; (println "Building parser")
069 ;; (let [parser (DefaultParser.)]
070 ;; (doall
071 ;; (.setEofOnUnclosedBracket
072 ;; parser DefaultParser$Bracket/ROUND))))
073
074 (def get-reader
075 "Return a reader, first constructing it if necessary.
076
077 **NOTE THAT** this is not settled API. The existence and call signature of
078 this function is not guaranteed in future versions."
079 (memoize (fn []
080 (let [term (.build (.system (TerminalBuilder/builder) true))
081 reader (-> (LineReaderBuilder/builder)
082 (.terminal term)
083 (.completer (build-completer))
084 ;; #(.parser % (build-parser))
085 (.build))
086 ;; apw (AutopairWidgets. reader false)
087 ;; asw (AutosuggestionWidgets. reader)
088 ]
089 ;; (.enable apw)
090 ;; (.enable asw)
091 reader))))
092
093 (defn read-chars
094 "A drop-in replacement for `clojure.core/read-line`, except that line editing
095 and history should be enabled.
096
097 **NOTE THAT** this does not fully work yet, but it is in the API because I
098 hope that it will work later!"
099 [prompt]
100 (let [eddie (get-reader)]
101 (loop [s (.readLine eddie (str prompt " "))]
102 (if (and (= (count (re-seq #"\(" s))
103 (count (re-seq #"\)" s)))
104 (= (count (re-seq #"\[]" s))
105 (count (re-seq #"\]" s))))
106 s
107 (recur (str s " " (.readLine eddie ":: ")))))))