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current-input-port et al are srfi-39 parameters
* libguile/ports.c (scm_init_ports): Export the port fluids to Scheme, temporarily. * module/ice-9/boot-9.scm (fluid->parameter): Turn `current-input-port' et al into srfi-39 parameters, backed by the exported fluids, then remove the fluids from the guile module. (%cond-expand-features): Add srfi-39. * module/srfi/srfi-39.scm: Re-export features from boot-9. * test-suite/tests/parameters.test: Add tests.
This commit is contained in:
Andy Wingo
parent
4eb286127c
commit
9670f238d4
4 changed files with 106 additions and 94 deletions
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@ -2582,6 +2582,11 @@ scm_init_ports ()
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(scm_from_int ((int) SCM_FAILED_CONVERSION_QUESTION_MARK)));
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scm_conversion_strategy_init = 1;
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/* These bindings are used when boot-9 turns `current-input-port' et
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al into parameters. They are then removed from the guile module. */
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scm_c_define ("%current-input-port-fluid", cur_inport_fluid);
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scm_c_define ("%current-output-port-fluid", cur_outport_fluid);
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scm_c_define ("%current-error-port-fluid", cur_errport_fluid);
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}
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/*
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@ -2913,6 +2913,36 @@ module '(ice-9 q) '(make-q q-length))}."
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...)
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body body* ...)))))))
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;;;
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;;; Current ports as parameters.
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;;;
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(let ((fluid->parameter
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(lambda (fluid conv)
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(make-struct <parameter> 0
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(case-lambda
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(() (fluid-ref fluid))
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((x) (let ((prev (fluid-ref fluid)))
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(fluid-set! fluid (conv x))
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prev)))
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fluid conv))))
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(define-syntax-rule (port-parameterize! binding fluid predicate msg)
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(begin
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(set! binding (fluid->parameter (module-ref (current-module) 'fluid)
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(lambda (x)
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(if (predicate x) x
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(error msg x)))))
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(module-remove! (current-module) 'fluid)))
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(port-parameterize! current-input-port %current-input-port-fluid
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input-port? "expected an input port")
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(port-parameterize! current-output-port %current-output-port-fluid
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output-port? "expected an output port")
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(port-parameterize! current-error-port %current-error-port-fluid
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output-port? "expected an output port"))
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;;;
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;;; Warnings.
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@ -3657,8 +3687,9 @@ module '(ice-9 q) '(make-q q-length))}."
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srfi-4 ;; homogenous numeric vectors
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srfi-6 ;; open-input-string etc, in the guile core
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srfi-13 ;; string library
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srfi-23 ;; `error` procedure
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srfi-14 ;; character sets
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srfi-23 ;; `error` procedure
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srfi-39 ;; parameterize
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srfi-55 ;; require-extension
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srfi-61 ;; general cond clause
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))
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@ -35,104 +35,19 @@
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;;; Code:
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(define-module (srfi srfi-39)
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#:use-module (srfi srfi-16)
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#:export (make-parameter)
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#:export-syntax (parameterize)
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;; helper procedure not in srfi-39.
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#:export (with-parameters*)
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#:replace (current-input-port current-output-port current-error-port))
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#:re-export (make-parameter
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parameterize
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current-input-port current-output-port current-error-port))
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;; Make 'srfi-39 available as a feature identifiere to `cond-expand'.
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;;
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(cond-expand-provide (current-module) '(srfi-39))
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(define make-parameter
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(case-lambda
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((val) (make-parameter/helper val (lambda (x) x)))
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((val conv) (make-parameter/helper val conv))))
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(define get-fluid-tag (lambda () 'get-fluid)) ;; arbitrary unique (as per eq?) value
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(define get-conv-tag (lambda () 'get-conv)) ;; arbitrary unique (as per eq?) value
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(define (make-parameter/helper val conv)
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(let ((fluid (make-fluid (conv val))))
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(case-lambda
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(()
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(fluid-ref fluid))
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((new-value)
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(cond
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((eq? new-value get-fluid-tag) fluid)
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((eq? new-value get-conv-tag) conv)
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(else (fluid-set! fluid (conv new-value))))))))
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(define-syntax-rule (parameterize ((?param ?value) ...) ?body ...)
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(with-parameters* (list ?param ...)
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(list ?value ...)
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(lambda () ?body ...)))
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(define current-input-port
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(case-lambda
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(()
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((@ (guile) current-input-port)))
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((new-value)
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(set-current-input-port new-value))))
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(define current-output-port
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(case-lambda
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(()
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((@ (guile) current-output-port)))
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((new-value)
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(set-current-output-port new-value))))
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(define current-error-port
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(case-lambda
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(()
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((@ (guile) current-error-port)))
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((new-value)
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(set-current-error-port new-value))))
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(define port-list
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(list current-input-port current-output-port current-error-port))
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;; There are no fluids behind current-input-port etc, so those parameter
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;; objects are picked out of the list and handled separately with a
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;; dynamic-wind to swap their values to and from a location (the "value"
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;; variable in the swapper procedure "let").
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;;
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;; current-input-port etc are already per-dynamic-root, so this arrangement
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;; works the same as a fluid. Perhaps they could become fluids for ease of
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;; implementation here.
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;;
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;; Notice the use of a param local variable for the swapper procedure. It
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;; ensures any application changes to the PARAMS list won't affect the
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;; winding.
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;;
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(define (with-parameters* params values thunk)
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(let more ((params params)
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(values values)
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(fluids '()) ;; fluids from each of PARAMS
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(convs '()) ;; VALUES with conversion proc applied
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(swapper noop)) ;; wind/unwind procedure for ports handling
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(convs '())) ;; VALUES with conversion proc applied
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(if (null? params)
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(if (eq? noop swapper)
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(with-fluids* fluids convs thunk)
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(dynamic-wind
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swapper
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(lambda ()
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(with-fluids* fluids convs thunk))
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swapper))
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(if (memq (car params) port-list)
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(more (cdr params) (cdr values)
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fluids convs
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(let ((param (car params))
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(value (car values))
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(prev-swapper swapper))
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(lambda ()
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(set! value (param value))
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(prev-swapper))))
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(more (cdr params) (cdr values)
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(cons ((car params) get-fluid-tag) fluids)
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(cons (((car params) get-conv-tag) (car values)) convs)
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swapper)))))
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(with-fluids* fluids convs thunk)
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(more (cdr params) (cdr values)
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(cons (parameter-fluid (car params)) fluids)
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(cons ((parameter-converter (car params)) (car values)) convs)))))
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@ -67,3 +67,64 @@
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(lambda ()
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(parameterize ((inside? #t))
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(raise 'some-exception)))))))))
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(let ()
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(define (test-ports param new-port new-port-2)
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(let ((old-port (param)))
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(pass-if "new value"
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(parameterize ((param new-port))
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(eq? (param) new-port)))
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(pass-if "set value"
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(parameterize ((param old-port))
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(param new-port)
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(eq? (param) new-port)))
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(pass-if "old restored"
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(parameterize ((param new-port))
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#f)
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(eq? (param) old-port))
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(pass-if "throw exit"
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(catch 'bail
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(lambda ()
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(parameterize ((param new-port))
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(throw 'bail)))
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(lambda args #f))
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(eq? (param) old-port))
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(pass-if "call/cc re-enter"
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(let ((cont #f)
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(count 0)
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(port #f)
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(good #t))
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(parameterize ((param new-port))
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(call/cc (lambda (k) (set! cont k)))
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(set! count (1+ count))
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(set! port (param))
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(if (= 1 count) (param new-port-2)))
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(set! good (and good (eq? (param) old-port)))
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(case count
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((1)
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(set! good (and good (eq? port new-port)))
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;; re-entering should give new-port-2 left there last time
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(cont))
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((2)
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(set! good (and good (eq? port new-port-2)))))
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good))
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(pass-if "original unchanged"
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(eq? (param) old-port))))
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(with-test-prefix "current-input-port"
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(test-ports current-input-port
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(open-input-string "xyz") (open-input-string "xyz")))
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(with-test-prefix "current-output-port"
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(test-ports current-output-port
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(open-output-string) (open-output-string)))
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(with-test-prefix "current-error-port"
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(test-ports current-error-port
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(open-output-string) (open-output-string))))
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