bin/scimindent.rkt
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#! /usr/bin/env racket
#lang racket/base
;Dorai Sitaram
;Oct 8, 1999
;last change 2020-11-14
;This script takes lines of Scheme or Lisp code from its
;stdin and produces an indented version thereof on its
;stdout.
(define *lisp-keywords* '())
(define (set-lisp-indent-number sym num-of-subforms-to-be-indented-wide)
(let* ((x (symbol->string sym))
(c (assf (lambda (a) (string-ci=? x a)) *lisp-keywords*)))
(unless c
(set! c (cons x (box 0)))
(set! *lisp-keywords* (cons c *lisp-keywords*)))
(set-box! (cdr c) num-of-subforms-to-be-indented-wide)))
(define (read-home-lispwords)
(let ([init-file (or (getenv "LISPWORDS")
(build-path (find-system-path 'home-dir) ".lispwords"))])
(when (file-exists? init-file)
(call-with-input-file init-file
(lambda (i)
(let loop ()
(let ([w (read i)])
(unless (eof-object? w)
(let ([a (car w)])
(cond [(number? a)
(for-each (lambda (x) (set-lisp-indent-number x a)) (cdr w))]
[(list? a)
(let ([n (cadr w)])
(for-each (lambda (x) (set-lisp-indent-number x n)) a))]
[else
(set-lisp-indent-number a (cadr w))]))
(loop)))))))))
(define (past-next-atom s i n)
(let loop ((i i))
(if (>= i n) n
(let ((c (string-ref s i)))
(cond ((char=? c #\\) (loop (+ i 2)))
((memv c '(#\space #\tab #\( #\) #\[ #\] #\" #\' #\` #\, #\;))
i)
(else (loop (+ i 1))))))))
(define (get-lisp-indent-number s)
(let ((c (assf (lambda (a) (string-ci=? s a)) *lisp-keywords*)))
(cond (c (unbox (cdr c)))
((and (>= (string-length s) 3)
(string-ci=? (substring s 0 3) "def")) 0)
(else -1))))
(define (literal-token? s)
(let ((x (let ((i (open-input-string s)))
(begin0 (read i) (close-input-port i)))))
(or (char? x) (number? x) (string? x))))
(define (calc-subindent s i n)
(let* ((j (past-next-atom s i n))
(lisp-indent-num -1)
(delta-indent
(if (= j i) 0
(let ((w (substring s i j)))
(if (and (>= i 2)
(memv (string-ref s (- i 2)) '(#\' #\`)))
0
(begin
(set! lisp-indent-num (get-lisp-indent-number w))
(case lisp-indent-num
((-2) 0)
((-1) (if (< j n) (+ (- j i) 1) 1))
(else 1))))))))
(values delta-indent lisp-indent-num j)))
(define (num-leading-spaces s)
(let ((n (string-length s)))
(let loop ((i 0) (j 0))
(if (>= i n) 0
(case (string-ref s i)
((#\space) (loop (+ i 1) (+ j 1)))
((#\tab) (loop (+ i 1) (+ j 8)))
(else j))))))
(define (string-trim-blanks s)
(let ((n (string-length s)))
(let ((j (let loop ((j 0))
(if (or (>= j n)
(not (char-whitespace? (string-ref s j))))
j
(loop (+ j 1))))))
(if (>= j n) ""
(let ((k (let loop ((k (- n 1)))
(if (or (< k 0)
(not (char-whitespace? (string-ref s k))))
(+ k 1)
(loop (- k 1))))))
(substring s j k))))))
(define-struct lparen
(spaces-before lisp-indent-num num-finished-subforms)
#:mutable)
(define (indent-lines)
(let ((default-left-i -1) (left-i 0) (paren-stack '()) (inside-string? #f))
(let line-loop ()
(let ((curr-line (read-line)))
(unless (eof-object? curr-line)
(let* ((leading-spaces (num-leading-spaces curr-line))
(curr-left-i
(cond (inside-string? leading-spaces)
((null? paren-stack)
(when (= left-i 0)
(when (= default-left-i -1)
(set! default-left-i leading-spaces))
(set! left-i default-left-i))
left-i)
(else (let* ((lp (car paren-stack))
(lin (lparen-lisp-indent-num lp))
(nfs (lparen-num-finished-subforms lp))
(extra-w 0))
(when (< nfs lin)
(set! extra-w 2))
(+ (lparen-spaces-before lp) extra-w))))))
(set! curr-line (string-trim-blanks curr-line))
(unless (string=? curr-line "")
(do ((i 0 (+ i 1)))
((= i curr-left-i))
(write-char #\space))
(display curr-line))
(newline)
;
(let ((n (string-length curr-line))
(escape? #f)
(token-interstice? #f))
(let ((incr-finished-subforms (lambda ()
(unless token-interstice?
(cond ((and (pair? paren-stack)
(car paren-stack)) =>
(lambda (lp)
(let ((nfs (lparen-num-finished-subforms lp)))
(set-lparen-num-finished-subforms!
lp (+ nfs 1))))))
(set! token-interstice? #t)))))
(let loop ((i 0))
(unless (>= i n)
(let ((c (string-ref curr-line i)))
(cond (escape? (set! escape? #f) (loop (+ i 1)))
((char=? c #\\)
(set! token-interstice? #f)
(set! escape? #t) (loop (+ i 1)))
(inside-string?
(when (char=? c #\")
(set! inside-string? #f)
(incr-finished-subforms))
(loop (+ i 1)))
((char=? c #\;)
(incr-finished-subforms)
'break-loop)
((char=? c #\")
(incr-finished-subforms)
(set! inside-string? #t)
(loop (+ i 1)))
((memv c '(#\space #\tab))
(incr-finished-subforms)
(loop (+ i 1)))
((memv c '(#\( #\[))
(incr-finished-subforms)
(let-values (((delta-indent lisp-indent-num j)
(calc-subindent curr-line (+ i 1) n)))
(set! paren-stack
(cons (make-lparen (+ 1 i curr-left-i delta-indent)
lisp-indent-num
-1)
paren-stack))
(set! token-interstice? #t)
(let ((inext (+ i 1)))
(when (> j inext)
(set! inext j)
(set! token-interstice? #f))
(loop inext))))
((memv c '(#\) #\]))
(set! token-interstice? #f)
(cond ((pair? paren-stack)
(set! paren-stack (cdr paren-stack)))
(else (set! left-i 0)))
(loop (+ i 1)))
(else (set! token-interstice? #f)
(loop (+ i 1)))))))
(incr-finished-subforms))))
(line-loop))))))
(read-home-lispwords)
(indent-lines)
;eof
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