racket/collects/readline/pread.ss
Eli Barzilay 33f93c0d2e * Reformattings
* Avoid keeping empty history lines
* Avoid keeping repetitive history lines
* Provided (and documented) set-completion-function!
* Change sample use to a conditional `dynamic-require'
* Use raw mallocs instead of eternal for completions

svn: r4434
2006-09-25 23:30:53 +00:00

74 lines
2.7 KiB
Scheme

(module pread mzscheme
(require "readline.ss"
(lib "file.ss"))
(define MAX-HISTORY 100)
(define KEEP-DUPLICATES #f)
(define KEEP-BLANKS #f)
(define leftovers null)
(define counter 1)
(define local-history
(let ([hist (get-preference 'mzrl-history (lambda () null))])
(for-each add-history hist)
(reverse hist)))
(define (save-history)
(put-preferences '(mzrl-history) (list (reverse local-history))))
(define (readline/hist p)
(let ([s (readline p)])
(when (and (string? s)
(or KEEP-BLANKS (not (zero? (string-length s))))
(or KEEP-DUPLICATES
(null? local-history)
(not (equal? s (car local-history)))))
(add-history s)
(set! local-history (cons s local-history))
(let loop ([n MAX-HISTORY] [l local-history])
(cond [(null? l) 'done]
[(zero? n) (set-cdr! l '())]
[else (loop (sub1 n) (cdr l))])))
s))
(exit-handler (let ([old (exit-handler)])
(lambda (v)
(save-history)
(old v))))
(define (prompt-read-using-readline get-prompt)
(if (pair? leftovers)
(begin0 (car leftovers)
(set! leftovers (cdr leftovers)))
(let big-loop ()
(let loop ([s (readline/hist (get-prompt 0))] [next-pos 1] [force? #f])
(if (eof-object? s)
(begin (save-history) s)
(with-handlers ([(if force? (lambda (x) #f) exn:fail:read:eof?)
(lambda (exn)
(let ([v (readline/hist (get-prompt next-pos))])
(loop (string-append s "\n"
(if (eof-object? v) "" v))
(add1 next-pos)
(eof-object? v))))])
(let ([p (open-input-string (string-append s "\n"))])
(port-count-lines! p)
(let ([rs (let loop ()
(let ([r (parameterize ([read-accept-reader #t])
(read-syntax
(string->path
(format "repl-~a" counter))
p))])
(if (eof-object? r)
null
(cons r (loop)))))])
(if (null? rs)
(big-loop)
(begin0 (car rs)
(set! counter (add1 counter))
(set! leftovers (cdr rs))))))))))))
(provide prompt-read-using-readline))