62 lines
1.7 KiB
Factor
62 lines
1.7 KiB
Factor
! Copyright (C) 2005 Slava Pestov.
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! See http://factor.sf.net/license.txt for BSD license.
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IN: sequences
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USING: errors generic kernel math sequences-internals vectors ;
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! A reversal of an underlying sequence.
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TUPLE: reversed ;
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C: reversed [ set-delegate ] keep ;
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: reversed@ delegate [ length swap - 1- ] keep ; inline
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M: reversed nth ( n seq -- elt ) reversed@ nth ;
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M: reversed nth-unsafe ( n seq -- elt ) reversed@ nth-unsafe ;
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M: reversed set-nth ( elt n seq -- ) reversed@ set-nth ;
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M: reversed set-nth-unsafe ( elt n seq -- )
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reversed@ set-nth-unsafe ;
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M: reversed like ( seq reversed -- seq ) delegate like ;
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M: reversed thaw ( seq -- seq ) delegate thaw ;
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! A slice of another sequence.
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TUPLE: slice seq from to ;
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: collapse-slice ( from to slice -- from to seq )
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dup slice-from swap slice-seq >r tuck + >r + r> r> ;
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: check-slice ( from to seq -- )
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pick 0 < [ "Slice begins before 0" throw ] when
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length over < [ "Slice longer than sequence" throw ] when
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> [ "Slice start is after slice end" throw ] when ;
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C: slice ( from to seq -- seq )
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#! A slice of a slice collapses.
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>r dup slice? [ collapse-slice ] when r>
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>r 3dup check-slice r>
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[ set-slice-seq ] keep
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[ set-slice-to ] keep
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[ set-slice-from ] keep ;
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M: slice length ( range -- n )
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dup slice-to swap slice-from - ;
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: slice@ ( n slice -- n seq )
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[ slice-from + ] keep slice-seq ; inline
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M: slice nth ( n slice -- obj ) slice@ nth ;
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M: slice nth-unsafe ( n slice -- obj ) slice@ nth-unsafe ;
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M: slice set-nth ( obj n slice -- ) slice@ set-nth ;
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M: slice set-nth-unsafe ( n slice -- obj ) slice@ set-nth-unsafe ;
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M: slice like ( seq slice -- seq ) slice-seq like ;
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M: slice thaw ( seq -- seq ) slice-seq thaw ;
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