75 lines
2.5 KiB
Factor
75 lines
2.5 KiB
Factor
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! Copyright (C) 2006 Chris Double.
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!
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! Redistribution and use in source and binary forms, with or without
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! modification, are permitted provided that the following conditions are met:
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!
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! 1. Redistributions of source code must retain the above copyright notice,
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! this list of conditions and the following disclaimer.
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!
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! 2. Redistributions in binary form must reproduce the above copyright notice,
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! this list of conditions and the following disclaimer in the documentation
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! and/or other materials provided with the distribution.
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!
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! THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
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! INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
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! FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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! DEVELOPERS AND CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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! SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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! PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
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! OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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! WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
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! OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
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! ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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!
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! Based on Scheme code for bshift and breset from:
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! http://groups.google.com/group/comp.lang.scheme/msg/9f0d61da01540816
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!
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IN: continuations
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USING: kernel io math prettyprint inspector lists arrays sequences namespaces ;
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SYMBOL: mark
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SYMBOL: mark-old
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: set-mark ( cc -- )
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0 mark get set-nth ;
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: get-mark ( -- cc )
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mark get first ;
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: save-mark ( -- )
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get-mark mark-old set ;
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: restore-mark ( -- )
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mark-old get set-mark ;
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: with-mark ( quot -- )
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[ save-mark call restore-mark ] with-scope ;
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: breset ( quot -- )
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#! Marks the boundary of the partial continuation.
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#! The quotation has stack effect ( r -- v ).
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[
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[ 1array dup mark set swap call mark get first continue-with ] with-scope
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] callcc1 nip ;
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: (bshift) ( v r pcc -- )
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[
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swap mark set
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[
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[ set-mark continue-with ] callcc1 2nip
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] with-mark
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] with-scope ;
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: bshift ( r quot -- )
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#! Calls the quotation with the partial continuation
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#! on the stack. The quotation should have stack effect
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#! ( pcc -- v ). The partial continuation can be called
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#! with 'call' and has stack effect ( a -- b ).
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[
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over mark set
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[
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[ (bshift) ] cons swapd cons swap call get-mark continue-with
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] callcc1 2nip
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] with-scope ;
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