;;;; -*-scheme-*-
;;;;
;;;; 	Copyright (C) 2001 Free Software Foundation, Inc.
;;;; 
;;;; This program is free software; you can redistribute it and/or modify
;;;; it under the terms of the GNU General Public License as published by
;;;; the Free Software Foundation; either version 2, or (at your option)
;;;; any later version.
;;;; 
;;;; This program is distributed in the hope that it will be useful,
;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;;;; GNU General Public License for more details.
;;;; 
;;;; You should have received a copy of the GNU General Public License
;;;; along with this software; see the file COPYING.  If not, write to
;;;; the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
;;;; Boston, MA 02110-1301 USA
;;;;
;;;; As a special exception, the Free Software Foundation gives permission
;;;; for additional uses of the text contained in its release of GUILE.
;;;;
;;;; The exception is that, if you link the GUILE library with other files
;;;; to produce an executable, this does not by itself cause the
;;;; resulting executable to be covered by the GNU General Public License.
;;;; Your use of that executable is in no way restricted on account of
;;;; linking the GUILE library code into it.
;;;;
;;;; This exception does not however invalidate any other reasons why
;;;; the executable file might be covered by the GNU General Public License.
;;;;
;;;; This exception applies only to the code released by the
;;;; Free Software Foundation under the name GUILE.  If you copy
;;;; code from other Free Software Foundation releases into a copy of
;;;; GUILE, as the General Public License permits, the exception does
;;;; not apply to the code that you add in this way.  To avoid misleading
;;;; anyone as to the status of such modified files, you must delete
;;;; this exception notice from them.
;;;;
;;;; If you write modifications of your own for GUILE, it is your choice
;;;; whether to permit this exception to apply to your modifications.
;;;; If you do not wish that, delete this exception notice.
;;;; 
(define-module (ice-9 pretty-print)
  :export (pretty-print))

;; From SLIB.

;;"genwrite.scm" generic write used by pretty-print and truncated-print.
;; Copyright (c) 1991, Marc Feeley
;; Author: Marc Feeley (feeley@iro.umontreal.ca)
;; Distribution restrictions: none

(define genwrite:newline-str (make-string 1 #\newline))

(define (generic-write obj display? width output)

  (define (read-macro? l)
    (define (length1? l) (and (pair? l) (null? (cdr l))))
    (let ((head (car l)) (tail (cdr l)))
      (case head
        ((quote quasiquote unquote unquote-splicing) (length1? tail))
        (else                                        #f))))

  (define (read-macro-body l)
    (cadr l))

  (define (read-macro-prefix l)
    (let ((head (car l)) (tail (cdr l)))
      (case head
        ((quote)            "'")
        ((quasiquote)       "`")
        ((unquote)          ",")
        ((unquote-splicing) ",@"))))

  (define (out str col)
    (and col (output str) (+ col (string-length str))))

  (define (wr obj col)
    (cond ((and (pair? obj)
		(read-macro? obj))
	   (wr (read-macro-body obj)
	       (out (read-macro-prefix obj) col)))
	  (else
	   (out (object->string obj (if display? display write)) col))))

  (define (pp obj col)

    (define (spaces n col)
      (if (> n 0)
        (if (> n 7)
          (spaces (- n 8) (out "        " col))
          (out (substring "        " 0 n) col))
        col))

    (define (indent to col)
      (and col
           (if (< to col)
             (and (out genwrite:newline-str col) (spaces to 0))
             (spaces (- to col) col))))

    (define (pr obj col extra pp-pair)
      (if (or (pair? obj) (vector? obj)) ; may have to split on multiple lines
        (let ((result '())
              (left (min (+ (- (- width col) extra) 1) max-expr-width)))
          (generic-write obj display? #f
            (lambda (str)
              (set! result (cons str result))
              (set! left (- left (string-length str)))
              (> left 0)))
          (if (> left 0) ; all can be printed on one line
            (out (reverse-string-append result) col)
            (if (pair? obj)
              (pp-pair obj col extra)
              (pp-list (vector->list obj) (out "#" col) extra pp-expr))))
        (wr obj col)))

    (define (pp-expr expr col extra)
      (if (read-macro? expr)
        (pr (read-macro-body expr)
            (out (read-macro-prefix expr) col)
            extra
            pp-expr)
        (let ((head (car expr)))
          (if (symbol? head)
            (let ((proc (style head)))
              (if proc
                (proc expr col extra)
                (if (> (string-length (symbol->string head))
                       max-call-head-width)
                  (pp-general expr col extra #f #f #f pp-expr)
                  (pp-call expr col extra pp-expr))))
            (pp-list expr col extra pp-expr)))))

    ; (head item1
    ;       item2
    ;       item3)
    (define (pp-call expr col extra pp-item)
      (let ((col* (wr (car expr) (out "(" col))))
        (and col
             (pp-down (cdr expr) col* (+ col* 1) extra pp-item))))

    ; (item1
    ;  item2
    ;  item3)
    (define (pp-list l col extra pp-item)
      (let ((col (out "(" col)))
        (pp-down l col col extra pp-item)))

    (define (pp-down l col1 col2 extra pp-item)
      (let loop ((l l) (col col1))
        (and col
             (cond ((pair? l)
                    (let ((rest (cdr l)))
                      (let ((extra (if (null? rest) (+ extra 1) 0)))
                        (loop rest
                              (pr (car l) (indent col2 col) extra pp-item)))))
                   ((null? l)
                    (out ")" col))
                   (else
                    (out ")"
                         (pr l
                             (indent col2 (out "." (indent col2 col)))
                             (+ extra 1)
                             pp-item)))))))

    (define (pp-general expr col extra named? pp-1 pp-2 pp-3)

      (define (tail1 rest col1 col2 col3)
        (if (and pp-1 (pair? rest))
          (let* ((val1 (car rest))
                 (rest (cdr rest))
                 (extra (if (null? rest) (+ extra 1) 0)))
            (tail2 rest col1 (pr val1 (indent col3 col2) extra pp-1) col3))
          (tail2 rest col1 col2 col3)))

      (define (tail2 rest col1 col2 col3)
        (if (and pp-2 (pair? rest))
          (let* ((val1 (car rest))
                 (rest (cdr rest))
                 (extra (if (null? rest) (+ extra 1) 0)))
            (tail3 rest col1 (pr val1 (indent col3 col2) extra pp-2)))
          (tail3 rest col1 col2)))

      (define (tail3 rest col1 col2)
        (pp-down rest col2 col1 extra pp-3))

      (let* ((head (car expr))
             (rest (cdr expr))
             (col* (wr head (out "(" col))))
        (if (and named? (pair? rest))
          (let* ((name (car rest))
                 (rest (cdr rest))
                 (col** (wr name (out " " col*))))
            (tail1 rest (+ col indent-general) col** (+ col** 1)))
          (tail1 rest (+ col indent-general) col* (+ col* 1)))))

    (define (pp-expr-list l col extra)
      (pp-list l col extra pp-expr))

    (define (pp-LAMBDA expr col extra)
      (pp-general expr col extra #f pp-expr-list #f pp-expr))

    (define (pp-IF expr col extra)
      (pp-general expr col extra #f pp-expr #f pp-expr))

    (define (pp-COND expr col extra)
      (pp-call expr col extra pp-expr-list))

    (define (pp-CASE expr col extra)
      (pp-general expr col extra #f pp-expr #f pp-expr-list))

    (define (pp-AND expr col extra)
      (pp-call expr col extra pp-expr))

    (define (pp-LET expr col extra)
      (let* ((rest (cdr expr))
             (named? (and (pair? rest) (symbol? (car rest)))))
        (pp-general expr col extra named? pp-expr-list #f pp-expr)))

    (define (pp-BEGIN expr col extra)
      (pp-general expr col extra #f #f #f pp-expr))

    (define (pp-DO expr col extra)
      (pp-general expr col extra #f pp-expr-list pp-expr-list pp-expr))

    ; define formatting style (change these to suit your style)

    (define indent-general 2)

    (define max-call-head-width 5)

    (define max-expr-width 50)

    (define (style head)
      (case head
        ((lambda let* letrec define) pp-LAMBDA)
        ((if set!)                   pp-IF)
        ((cond)                      pp-COND)
        ((case)                      pp-CASE)
        ((and or)                    pp-AND)
        ((let)                       pp-LET)
        ((begin)                     pp-BEGIN)
        ((do)                        pp-DO)
        (else                        #f)))

    (pr obj col 0 pp-expr))

  (if width
    (out genwrite:newline-str (pp obj 0))
    (wr obj 0))
  ;; Return `unspecified'
  (if #f #f))

; (reverse-string-append l) = (apply string-append (reverse l))

(define (reverse-string-append l)

  (define (rev-string-append l i)
    (if (pair? l)
      (let* ((str (car l))
             (len (string-length str))
             (result (rev-string-append (cdr l) (+ i len))))
        (let loop ((j 0) (k (- (- (string-length result) i) len)))
          (if (< j len)
            (begin
              (string-set! result k (string-ref str j))
              (loop (+ j 1) (+ k 1)))
            result)))
      (make-string i)))

  (rev-string-append l 0))

;"pp.scm" Pretty-Print
(define (pretty-print obj . opt)
  (let ((port (if (pair? opt) (car opt) (current-output-port))))
    (generic-write obj #f 79
		   (lambda (s) (display s port) #t))))

