diff options
Diffstat (limited to 'genwrite.scm')
| -rw-r--r-- | genwrite.scm | 264 |
1 files changed, 264 insertions, 0 deletions
diff --git a/genwrite.scm b/genwrite.scm new file mode 100644 index 0000000..0bb4e56 --- /dev/null +++ b/genwrite.scm @@ -0,0 +1,264 @@ +;;"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 (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) + + (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 (make-string 1 #\newline) 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 (make-string 1 #\newline) (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)) |