~subsetpark/ec

ref: big ec/src/repl.janet -rw-r--r-- 2.8 KiB
3f9b6ebe — Zach Smith Support bigints (note: this does not work on account of floats being coerced to big ints) 8 months ago
                                                                                
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(import rl)
(import /src/env)
(import /src/print)
(import /src/eval)
(import /src/calc)
(import /src/parser)

(defn- env-keys
  [env]
  (let [these-keys (keys env)
        proto (table/getproto env)]
    (match proto
      nil these-keys
      proto (array/concat these-keys (env-keys proto)))))

(defn- getline
  [{:env env} prompt buf]

  (defn get-completions
    [line start end]
    (try
      (let [to-expand (string (string/slice line start end))]
        (->>
         (env-keys env)
         (filter (fn [s] (string/has-prefix? to-expand s)))))
      
      ([err f]
       (eprint "error in tab completion function:")
       (debug/stacktrace f err)
       @[])))
  
  (when-let [ln (rl/readline prompt get-completions)]
    (buffer/push-string buf ln "\n")
    buf))

(defn- prompt
  [s]
  (->> s
       (calc/peek)
       (print/p)
       (print/truncate)
       (string/format "<%s> $ ")))

(defn- handle-signal
  [input]
  (let [str (string input)]
    (when (= str "") (os/exit 0))
    str))

(defn- display
  [data]
  (print (print/p data)))

(defn- display-all
  [stack]
  (let [inner (map print/p stack)]
    (print (string/join inner " "))))

(defn- display-help
  [{:env env}]
  (each k (env-keys env)
    (when-let [v (env k)]
      (printf "%s: %s" k (string (v :type))))))

(defn- format
  [obj]
  (match obj
    @[:special char] (string char " (Special)")
    _ (string/format
       ```
       --
       %s : %s
       
       %s%s
       ```
       (print/p obj)
       (string (obj :type))
       (obj :doc)
       (match (obj :composes)
         nil ""
         words (string "\n\n(" (print/p words) ")")))))

(defn- describe-all
  [s q]
  (defn- describe
    [elem]
    (let [evaled (eval/eval s elem)]
      (print (format evaled))))
  (each item (q :data)
    (describe item)))

(defn- handle-special
  [s special]
  (case (freeze (string/trim special))
    "." (display (calc/pop s))
    "p" (display (calc/peek s))
    "s" (display-all (s :data))
    "?" (describe-all s (calc/pop s))
    "??" (display-help s)))

(defn- handle-commands
  [s input]
  (each token input
    (match token
      @[:special patt] (handle-special s patt)
      _ (eval/eval-and-push s token))))

(defn repl
  ```
  Interactive read-eval-print-loop.
  ```
  []
  (def s (env/new-env))
  (while true
    (def bak (array/slice (s :data)))
    (try (->> (getline s (prompt s) @"")
              (handle-signal)
              (parser/parse)
              (handle-commands s))

         ([err fib]
          (eprint err)
          (if (os/getenv "EC_TRACEBACK")
            (propagate err fib)
            (put s :data bak))))))

(defn handle-line
  ```
  Handle a single input line from the command line.
  ```
  [line]
  (let [s (env/new-env)]
    (->> line
         (parser/parse)
         (handle-commands s))
    (display-all (s :data))))