;;;; -*- coding: utf-8; mode: scheme -*-
;;;;
;;;; Copyright (C) 2001, 2004, 2006, 2009, 2010,
;;;; 2012, 2014 Free Software Foundation, Inc.
;;;;
;;;; This library is free software; you can redistribute it and/or
;;;; modify it under the terms of the GNU Lesser General Public
;;;; License as published by the Free Software Foundation; either
;;;; version 3 of the License, or (at your option) any later version.
;;;;
;;;; This library 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
;;;; Lesser General Public License for more details.
;;;;
;;;; You should have received a copy of the GNU Lesser General Public
;;;; License along with this library; if not, write to the Free Software
;;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
;;;;
(define-module (ice-9 pretty-print)
#:use-module (ice-9 match)
#:use-module (srfi srfi-1)
#:use-module (rnrs bytevectors)
#:export (pretty-print
truncated-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 max-expr-width per-line-prefix 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)))
(case head
((quote) "'")
((quasiquote) "`")
((unquote) ",")
((unquote-splicing) ",@"))))
(define (out str col)
(and col (output str) (+ col (string-length str))))
(define (wr obj col)
(let loop ((obj obj)
(col col))
(match obj
(((or 'quote 'quasiquote 'unquote 'unquote-splicing) body)
(wr body (out (read-macro-prefix obj) col)))
((head . (rest ...))
;; A proper list: do our own list printing so as to catch read
;; macros that appear in the middle of the list.
(let ((col (loop head (out "(" col))))
(out ")"
(fold (lambda (i col)
(loop i (out " " col)))
col rest))))
(_
(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)
(out per-line-prefix 0)
(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 max-expr-width ""
(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 (pp-SYNTAX-CASE expr col extra)
(pp-general expr col extra #t pp-expr-list #f pp-expr))
; define formatting style (change these to suit your style)
(define indent-general 2)
(define max-call-head-width 5)
(define (style head)
(case head
((lambda lambda* let* letrec define define* define-public
define-syntax let-syntax letrec-syntax with-syntax)
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)
((syntax-rules) pp-LAMBDA)
((syntax-case) pp-SYNTAX-CASE)
(else #f)))
(pr obj col 0 pp-expr))
(out per-line-prefix 0)
(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))
(define* (pretty-print obj #:optional port*
#:key
(port (or port* (current-output-port)))
(width 79)
(max-expr-width 50)
(display? #f)
(per-line-prefix ""))
"Pretty-print OBJ on PORT, which is a keyword argument defaulting to
the current output port. Formatting can be controlled by a number of
keyword arguments: Each line in the output is preceded by the string
PER-LINE-PREFIX, which is empty by default. The output lines will be
at most WIDTH characters wide; the default is 79. If DISPLAY? is
true, display rather than write representation will be used.
Instead of with a keyword argument, you can also specify the output
port directly after OBJ, like (pretty-print OBJ PORT)."
(generic-write obj display?
(- width (string-length per-line-prefix))
max-expr-width
per-line-prefix
(lambda (s) (display s port) #t)))
;; `truncated-print' was written in 2009 by Andy Wingo, and is not from
;; genwrite.scm.
(define* (truncated-print x #:optional port*
#:key
(port (or port* (current-output-port)))
(width 79)
(display? #f)
(breadth-first? #f))
"Print @var{x}, truncating the output, if necessary, to make it fit
into @var{width} characters. By default, @var{x} will be printed using
@code{write}, though that behavior can be overriden via the
@var{display?} keyword argument.
The default behaviour is to print depth-first, meaning that the entire
remaining width will be available to each sub-expression of @var{x} --
e.g., if @var{x} is a vector, each member of @var{x}. One can attempt to
\"ration\" the available width, trying to allocate it equally to each
sub-expression, via the @var{breadth-first?} keyword argument."
;; Make sure string ports are created with the right encoding.
(with-fluids ((%default-port-encoding (port-encoding port)))
(define ellipsis
;; Choose between `HORIZONTAL ELLIPSIS' (U+2026) and three dots, depending
;; on the encoding of PORT.
(let ((e "…"))
(catch 'encoding-error
(lambda ()
(with-fluids ((%default-port-conversion-strategy 'error))
(with-output-to-string
(lambda ()
(display e)))))
(lambda (key . args)
"..."))))
(let ((ellipsis-width (string-length ellipsis)))
(define (print-sequence x width len ref next)
(let lp ((x x)
(width width)
(i 0))
(if (> i 0)
(display #\space))
(cond
((= i len)) ; catches 0-length case
((and (= i (1- len)) (or (zero? i) (> width 1)))
(print (ref x i) (if (zero? i) width (1- width))))
((<= width (+ 1 ellipsis-width))
(display ellipsis))
(else
(let ((str
(with-fluids ((%default-port-encoding (port-encoding port)))
(with-output-to-string
(lambda ()
(print (ref x i)
(if breadth-first?
(max 1
(1- (floor (/ width (- len i)))))
(- width (+ 1 ellipsis-width)))))))))
(display str)
(lp (next x) (- width 1 (string-length str)) (1+ i)))))))
(define (print-tree x width)
;; width is >= the width of # . #, which is 5
(let lp ((x x)
(width width))
(cond
((or (not (pair? x)) (<= width 4))
(display ". ")
(print x (- width 2)))
(else
;; width >= 5
(let ((str (with-output-to-string
(lambda ()
(print (car x)
(if breadth-first?
(floor (/ (- width 3) 2))
(- width 4)))))))
(display str)
(display " ")
(lp (cdr x) (- width 1 (string-length str))))))))
(define (truncate-string str width)
;; width is < (string-length str)
(let lp ((fixes '(("#<" . ">")
("#(" . ")")
("(" . ")")
("\"" . "\""))))
(cond
((null? fixes)
"#")
((and (string-prefix? (caar fixes) str)
(string-suffix? (cdar fixes) str)
(>= (string-length str)
width
(+ (string-length (caar fixes))
(string-length (cdar fixes))
ellipsis-width)))
(format #f "~a~a~a~a"
(caar fixes)
(substring str (string-length (caar fixes))
(- width (string-length (cdar fixes))
ellipsis-width))
ellipsis
(cdar fixes)))
(else
(lp (cdr fixes))))))
(define (print x width)
(cond
((<= width 0)
(error "expected a positive width" width))
((list? x)
(cond
((>= width (+ 2 ellipsis-width))
(display "(")
(print-sequence x (- width 2) (length x)
(lambda (x i) (car x)) cdr)
(display ")"))
(else
(display "#"))))
((vector? x)
(cond
((>= width (+ 3 ellipsis-width))
(display "#(")
(print-sequence x (- width 3) (vector-length x)
vector-ref identity)
(display ")"))
(else
(display "#"))))
((bytevector? x)
(cond
((>= width 9)
(format #t "#~a(" (array-type x))
(print-sequence x (- width 6) (array-length x)
array-ref identity)
(display ")"))
(else
(display "#"))))
((pair? x)
(cond
((>= width (+ 4 ellipsis-width))
(display "(")
(print-tree x (- width 2))
(display ")"))
(else
(display "#"))))
(else
(let* ((str (with-output-to-string
(lambda () (if display? (display x) (write x)))))
(len (string-length str)))
(display (if (<= (string-length str) width)
str
(truncate-string str width)))))))
(with-output-to-port port
(lambda ()
(print x width))))))