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|
#!r6rs
;;; FILE "format.sls"
;;; IMPLEMENTS SRFI-48: Intermediary format strings
;;; http://srfi.schemers.org/srfi-48/srfi-48.html
;;; AUTHOR Ken Dickey
;;; UPDATED Syntax updated for R6RS February 2008 by Ken Dickey
;;; LANGUAGE R6RS
;;;Copyright (C) Kenneth A Dickey (2003). All Rights Reserved.
;;;
;;;Permission is hereby granted, free of charge, to any person
;;;obtaining a copy of this software and associated documentation
;;;files (the "Software"), to deal in the Software without
;;;restriction, including without limitation the rights to use,
;;;copy, modify, merge, publish, distribute, sublicense, and/or
;;;sell copies of the Software, and to permit persons to whom
;;;the Software is furnished to do so, subject to the following
;;;conditions:
;;;
;;;The above copyright notice and this permission notice shall
;;;be included in all copies or substantial portions of the Software.
;;;
;;;THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
;;;EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
;;;OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
;;;NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
;;;HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
;;;WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
;;;FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
;;;OTHER DEALINGS IN THE SOFTWARE.
;; Ikarus specific
(library (format) ;; (srfi format)
(export format)
(import (rnrs)
(rnrs io ports (6))
(implementation-dependent)
; dont-print
; open-output-string get-output-string
; write-with-shared-structure
; pretty-print
)
;; FORMAT
(define (format . args)
(cond
[(null? args)
(error 'format "required format-string argument is missing")
]
[(string? (car args))
(apply format (cons #f args))
]
[(< (length args) 2)
(error 'format "too few arguments" (cons 'format args))
]
[else
(let ( [output-port (car args)]
[format-string (cadr args)]
[args (cddr args)]
)
(letrec ( [port
(cond [(output-port? output-port) output-port]
[(eq? output-port #t) (current-output-port)]
[(eq? output-port #f) (open-output-string)]
[else (error 'format "bad output-port argument"
output-port)])
]
[return-value
(if (eq? output-port #f) ;; if format into a string
(lambda () (get-output-string port)) ;; then return the string
(lambda () dont-print)) ;; else do something harmless
]
)
(define (string-index str c)
(let ( [len (string-length str)] )
(let loop ( [i 0] )
(cond ((= i len) #f)
((eqv? c (string-ref str i)) i)
(else (loop (+ i 1)))))))
(define (string-grow str len char)
(let ( [off (- len (string-length str))] )
(if (positive? off)
(string-append (make-string off char) str)
str)))
(define (compose-with-digits digits pre-str frac-str exp-str)
(let ( [frac-len (string-length frac-str)] )
(cond
[(< frac-len digits) ;; grow frac part, pad with zeros
(string-append pre-str "."
frac-str (make-string (- digits frac-len) #\0)
exp-str)
]
[(= frac-len digits) ;; frac-part is exactly the right size
(string-append pre-str "."
frac-str
exp-str)
]
[else ;; must round to shrink it
(let* ( [first-part (substring frac-str 0 digits)]
[last-part (substring frac-str digits frac-len)]
[temp-str
(number->string
(round (string->number
(string-append first-part "." last-part))))]
[dot-pos (string-index temp-str #\.)]
[carry?
(and (> dot-pos digits)
(> (round (string->number
(string-append "0." frac-str)))
0))]
[new-frac
(substring temp-str 0 digits)]
)
(string-append
(if carry? (number->string (+ 1 (string->number pre-str))) pre-str)
"."
new-frac
exp-str))]
) ) )
(define (format-fixed number-or-string width digits) ; returns a string
(cond
[(string? number-or-string)
(string-grow number-or-string width #\space)
]
[(number? number-or-string)
(let ( [real (real-part number-or-string)]
[imag (imag-part number-or-string)]
)
(cond
[(not (zero? imag))
(string-grow
(string-append (format-fixed real 0 digits)
(if (negative? imag) "" "+")
(format-fixed imag 0 digits)
"i")
width
#\space)
]
[digits
(let* ( [num-str (number->string (exact real))]
[dot-index (string-index num-str #\.)]
[exp-index (string-index num-str #\e)]
[length (string-length num-str)]
[pre-string
(cond
(exp-index
(if dot-index
(substring num-str 0 dot-index)
(substring num-str 0 (+ exp-index 1)))
)
(dot-index
(substring num-str 0 dot-index)
)
(else
num-str))
]
[exp-string
(if exp-index (substring num-str exp-index length) "")
]
[frac-string
(if exp-index
(substring num-str (+ dot-index 1) exp-index)
(substring num-str (+ dot-index 1) length))
]
)
(string-grow
(if dot-index
(compose-with-digits digits
pre-string
frac-string
exp-string)
(string-append pre-string exp-string))
width
#\space)
)]
[else ;; no digits
(string-grow (number->string real) width #\space)])
)]
[else
(error 'format "~F requires a number or a string" number-or-string)])
)
(define documentation-string
"(format [<port>] <format-string> [<arg>...]) -- <port> is #t, #f or an output-port
OPTION [MNEMONIC] DESCRIPTION -- Implementation Assumes ASCII Text Encoding
~H [Help] output this text
~A [Any] (display arg) for humans
~S [Slashified] (write arg) for parsers
~W [WriteCircular] like ~s but outputs circular and recursive data structures
~~ [tilde] output a tilde
~T [Tab] output a tab character
~% [Newline] output a newline character
~& [Freshline] output a newline character if the previous output was not a newline
~D [Decimal] the arg is a number which is output in decimal radix
~X [heXadecimal] the arg is a number which is output in hexdecimal radix
~O [Octal] the arg is a number which is output in octal radix
~B [Binary] the arg is a number which is output in binary radix
~w,dF [Fixed] the arg is a string or number which has width w and d digits after the decimal
~C [Character] charater arg is output by write-char
~_ [Space] a single space character is output
~Y [Yuppify] the list arg is pretty-printed to the output
~? [Indirection] recursive format: next 2 args are format-string and list of arguments
~K [Indirection] same as ~?
"
)
(define (require-an-arg args)
(when (null? args)
(error 'format "too few arguments"))
)
(define (format-help format-strg arglist)
(letrec (
[length-of-format-string (string-length format-strg)]
[anychar-dispatch
(lambda (pos arglist last-was-newline)
(if (>= pos length-of-format-string)
arglist ; return unused args
(let ( [char (string-ref format-strg pos)] )
(cond
[(eqv? char #\~)
(tilde-dispatch (+ pos 1) arglist last-was-newline)]
[else
(write-char char port)
(anychar-dispatch (+ pos 1) arglist #f)
])
)))
] ; end anychar-dispatch
[has-newline?
(lambda (whatever last-was-newline)
(or (eqv? whatever #\newline)
(and (string? whatever)
(let ( [len (string-length whatever)] )
(if (zero? len)
last-was-newline
(eqv? #\newline (string-ref whatever (- len 1)))))))
)] ; end has-newline?
[tilde-dispatch
(lambda (pos arglist last-was-newline)
(cond
((>= pos length-of-format-string)
(write-char #\~ port) ; tilde at end of string is just output
arglist ; return unused args
)
(else
(case (char-upcase (string-ref format-strg pos))
((#\A) ; Any -- for humans
(require-an-arg arglist)
(let ( [whatever (car arglist)] )
(display whatever port)
(anychar-dispatch (+ pos 1)
(cdr arglist)
(has-newline? whatever last-was-newline))
))
((#\S) ; Slashified -- for parsers
(require-an-arg arglist)
(let ( [whatever (car arglist)] )
(write whatever port)
(anychar-dispatch (+ pos 1)
(cdr arglist)
(has-newline? whatever last-was-newline))
))
((#\W)
(require-an-arg arglist)
(let ( [whatever (car arglist)] )
(write-with-shared-structure whatever port) ;; srfi-38
(anychar-dispatch (+ pos 1)
(cdr arglist)
(has-newline? whatever last-was-newline))
))
((#\D) ; Decimal
(require-an-arg arglist)
(display (number->string (car arglist) 10) port)
(anychar-dispatch (+ pos 1) (cdr arglist) #f)
)
((#\X) ; HeXadecimal
(require-an-arg arglist)
(display (number->string (car arglist) 16) port)
(anychar-dispatch (+ pos 1) (cdr arglist) #f)
)
((#\O) ; Octal
(require-an-arg arglist)
(display (number->string (car arglist) 8) port)
(anychar-dispatch (+ pos 1) (cdr arglist) #f)
)
((#\B) ; Binary
(require-an-arg arglist)
(display (number->string (car arglist) 2) port)
(anychar-dispatch (+ pos 1) (cdr arglist) #f)
)
((#\C) ; Character
(require-an-arg arglist)
(write-char (car arglist) port)
(anychar-dispatch (+ pos 1)
(cdr arglist)
(eqv? (car arglist) #\newline))
)
((#\~) ; Tilde
(write-char #\~ port)
(anychar-dispatch (+ pos 1) arglist #f)
)
((#\%) ; Newline
(newline port)
(anychar-dispatch (+ pos 1) arglist #t)
)
((#\&) ; Freshline
(if (not last-was-newline) ;; (unless last-was-newline ..
(newline port))
(anychar-dispatch (+ pos 1) arglist #t)
)
((#\_) ; Space
(write-char #\space port)
(anychar-dispatch (+ pos 1) arglist #f)
)
((#\T) ; Tab
(write-char #\tab port)
(anychar-dispatch (+ pos 1) arglist #f)
)
((#\Y) ; Pretty-print
(pretty-print (car arglist) port) ;; IMPLEMENTATION DEPENDENT
(anychar-dispatch (+ pos 1) (cdr arglist) #f)
)
((#\F)
(require-an-arg arglist)
(display (format-fixed (car arglist) 0 #f) port)
(anychar-dispatch (+ pos 1) (cdr arglist) #f)
)
((#\0 #\1 #\2 #\3 #\4 #\5 #\6 #\7 #\8 #\9)
;; gather "~w[,d]F" w and d digits
(let loop ( [index (+ pos 1)]
[w-digits (list (string-ref format-strg pos))]
[d-digits '()]
[in-width? #t]
)
(if (>= index length-of-format-string)
(error 'format
"improper numeric format directive" format-strg)
(let ( [next-char (string-ref format-strg index)] )
(cond
[(char-numeric? next-char)
(if in-width?
(loop (+ index 1)
(cons next-char w-digits)
d-digits
in-width?)
(loop (+ index 1)
w-digits
(cons next-char d-digits)
in-width?))
]
[(char=? next-char #\F)
(let ( [width
(string->number
(list->string (reverse w-digits)))]
[digits
(if (zero? (length d-digits))
#f
(string->number
(list->string (reverse d-digits))))]
)
(display
(format-fixed (car arglist) width digits)
port)
(anychar-dispatch (+ index 1) (cdr arglist) #f))
]
[(char=? next-char #\,)
(if in-width?
(loop (+ index 1)
w-digits
d-digits
#f)
(error 'format
"too many commas in directive"
format-strg))
]
[else
(error 'format "~w,dF directive ill-formed"
format-strg)])))
))
((#\? #\K) ; indirection -- take next arg as format string
(cond ; and following arg as list of format args
((< (length arglist) 2)
(error 'format
"less arguments than specified for ~?" arglist)
)
((not (string? (car arglist)))
(error 'format "~? requires a string" (car arglist))
)
(else
(format-help (car arglist) (cadr arglist))
(anychar-dispatch (+ pos 1) (cddr arglist) #f)
)))
((#\H) ; Help
(display documentation-string port)
(anychar-dispatch (+ pos 1) arglist #t)
)
(else
(error 'format "unknown tilde escape"
(string-ref format-strg pos)))
)))
)] ; end tilde-dispatch
) ; end letrec
; format-help main
(anychar-dispatch 0 arglist #f)
)) ; end format-help
; format main
(let ( [unused-args (format-help format-string args)] )
(if (not (null? unused-args))
(error 'format "unused arguments" unused-args)
(return-value)))
)) ; end letrec
]) ; end else, cond
) ; end format
)
;; --- E O F --- ;;
|