96 lines
3.4 KiB
Scheme
96 lines
3.4 KiB
Scheme
;; (interact* task [input-filter output-filter])
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;;
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(define (interact* task . args)
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(let-optionals args ((input-filter (lambda (k x) x))
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(output-filter (lambda (k x) x)))
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(let ((ivec (make-vector 2))
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(ivec0 (current-input-port))
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(ivec1 (task:in task))
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(out0 (current-output-port))
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(out1 (task:out task)))
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(call-with-current-continuation
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(lambda (k)
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(with-errno-handler
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((e p) ((errno/io) #f)) ;; TODO: eof in input/output
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(let lp ()
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(vector-set! ivec 0 ivec0)
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(vector-set! ivec 1 ivec1)
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(select! ivec '#() '#())
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(if (char-ready? ivec0)
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(let ((str (input-filter k (read-string/partial 256 ivec0))))
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(if str (write-string str out1))))
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(if (char-ready? ivec1)
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(let ((str (output-filter k (read-string/partial 256 ivec1))))
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(if str (write-string str out0))))
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(lp))))))))
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(define (interact/char* task . args)
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(let-optionals args ((input-filter #f)
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(output-filter #f))
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(interact* task
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(lambda (k str)
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(if input-filter
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;; TODO: does this preserve correct order?
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(let ((chars (filter (lambda (c) (input-filter k c))
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(string->list str))))
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(list->string chars))
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str))
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(lambda (k str)
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(if output-filter
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(let ((chars (filter (lambda (c) (output-filter k c))
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(string->list str))))
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(list->string chars))
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str)))))
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;; syntax
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;;;; Allow user to interact with program (sometimes there's just no other way)
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;;;; (interact task) simply switches the user into interact mode with the task.
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;;;;
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;;;; (interact task clause ...) filters the input. The clause can either be a
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;;;; character clause (character continuation-variable exp ...) or a filter
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;;;; clause (filter proc). A character clause matches the character given,
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;;;; links the continuation variable to the continuation out of the
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;;;; interaction, and runs the expressions. A filter clause runs the given
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;;;; filter-function with two arguments: the character entered and the
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;;;; continuation out of the interaction. In both cases, if the filter returns
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;;;; true, the expression falls through. If the expression falls through to
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;;;; the bottom, the character is printed. Note that the interaction will
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;;;; continue anyway, unless the continuation was explicitly called.
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(define-syntax interact-input-clauses
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(syntax-rules (filter eof)
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((interact-input-clauses break char)
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#t)
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((interact-input-clauses break char (eof k body ...) clause2 ...)
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(if (eof-object? char)
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(let ((k break))
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(begin body ...))
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(interact-input-clauses break char clause2 ...)))
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((interact-input-clauses break char (test-char k body ...) clause2 ...)
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(if (eq? char test-char)
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(let ((k break))
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(begin body ...))
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(interact-input-clauses break char clause2 ...)))
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((interact-input-clauses break char (filter proc) clause2 ...)
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(and (filter break char)
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(interact-input-clauses break char clause2 ...)))))
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(define-syntax interact-output-clauses
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(syntax-rules (filter eof)
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((interact-output-clauses break char)
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#t)
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((interact-output-clauses break char clause ...)
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#t)))
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(define-syntax interact
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(syntax-rules ()
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((interact task)
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(interact* task))
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((interact task clause ...)
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(interact/char* task
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(lambda (k c)
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(interact-input-clauses k c clause ...))
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(lambda (k c)
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(interact-output-clauses k c clause ...))))))
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