;;"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)
(case (car l)
((quote) "'")
((quasiquote) "`")
((unquote) ",")
((unquote-splicing) ",@")))
(define (out str col)
(and col (output str) (+ col (string-length str))))
(define (wr obj col)
(define (wr-expr expr col)
(if (read-macro? expr)
(wr (read-macro-body expr) (out (read-macro-prefix expr) col))
(wr-lst expr col)))
(define (wr-lst l col)
(if (pair? l)
(let loop ((l (cdr l))
(col (and col (wr (car l) (out "(" col)))))
(cond ((not col) col)
((pair? l)
(loop (cdr l) (wr (car l) (out " " col))))
((null? l) (out ")" col))
(else (out ")" (wr l (out " . " col))))))
(out "()" col)))
(cond ((pair? obj) (wr-expr obj col))
((null? obj) (wr-lst obj col))
((vector? obj) (wr-lst (vector->list obj) (out "#" col)))
((boolean? obj) (out (if obj "#t" "#f") col))
((number? obj) (out (number->string obj) col))
((symbol? obj) (out (symbol->string obj) col))
((procedure? obj) (out "#[procedure]" col))
((string? obj) (if display?
(out obj col)
(let loop ((i 0) (j 0) (col (out "\"" col)))
(if (and col (< j (string-length obj)))
(let ((c (string-ref obj j)))
(if (or (char=? c #\\)
(char=? c #\"))
(loop j
(+ j 1)
(out "\\"
(out (substring obj i j)
col)))
(loop i (+ j 1) col)))
(out "\""
(out (substring obj i j) col))))))
((char? obj) (if display?
(out (make-string 1 obj) col)
(out (case obj
((#\space) "space")
((#\newline) "newline")
(else (make-string 1 obj)))
(out "#\\" col))))
((input-port? obj) (out "#[input-port]" col))
((output-port? obj) (out "#[output-port]" col))
((eof-object? obj) (out "#[eof-object]" col))
(else (out "#[unknown]" 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)))
;;; (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))