#!/bin/sh	# -*- mode: gauche -*-
:; exec rlwrap -c --break-chars "'"'(){}[].,#@;|`"' gosh "$@" -- "$0"
;;;
;;;  igosh - inferior gauche
;;;
;;; Copyright (c) 2007 OOHASHI, Daichi,
;;; All rights reserved.
;;;
;;; Redistribution and use in source and binary forms, with or without
;;; modification, are permitted provided that the following conditions
;;; are met:
;;;
;;; 1. Redistributions of source code must retain the above copyright
;;;    notice, this list of conditions and the following disclaimer.
;;;
;;; 2. Redistributions in binary form must reproduce the above copyright
;;;    notice, this list of conditions and the following disclaimer in the
;;;    documentation and/or other materials provided with the distribution.
;;;
;;; 3. Neither the name of the authors nor the names of its contributors
;;;    may be used to endorse or promote products derived from this
;;;    software without specific prior written permission.
;;;
;;; THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
;;; "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
;;; LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
;;; A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
;;; OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
;;; SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
;;; TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
;;; PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
;;; LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
;;; NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
;;; SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
;;;

(define-module iutil
  (use srfi-1)
  (use gauche.parameter)
  (export *history-size* repl/history href))

(select-module iutil)

(define ids #f)

(define history #f)

(define *history-size*
  (make-parameter 10
    (lambda (n)
      (set! history (make-vector n))
      (set! ids (apply circular-list (iota n)))
      n)))

(define (repl/history)
  (read-eval-print-loop #f eval/history #f prompt/id))

(define (eval/history expr env)
  (receive vals (eval expr env)
    (vector-set! history (car ids) vals)
    (pop! ids)
    (apply values vals)))

(define (prompt/id)
  (format #t "gosh:~A> " (car ids))
  (flush))

(define (href i)
  (let1 j (car ids)
    (cond
     ((and (negative? i)
	   (<= (abs i) (*history-size*)))
      (href (modulo (+ j i) (*history-size*))))
     ((< (- j (*history-size*) 1) i j)
      (apply values (vector-ref history (modulo i (*history-size*)))))
     (else
      (errorf "index out of bounds: ~A" i)))))

(provide "iutil")

(select-module user)

(import iutil)

(define (main args)
  (repl/history)
  0)