sequences.rotated: adding rotated virtual sequences.

diff --git a/extra/sequences/rotated/authors.txt b/extra/sequences/rotated/authors.txt
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+John Benediktsson

diff --git a/extra/sequences/rotated/rotated-tests.factor b/extra/sequences/rotated/rotated-tests.factor
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+++ b/extra/sequences/rotated/rotated-tests.factor
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+! Copyright (C) 2012 John Benediktsson
+! See http://factorcode.org/license.txt for BSD license
+USING: strings tools.test ;
+IN: sequences.rotated
+
+{ "fasd" } [ "asdf" -1 <rotated> >string ] unit-test
+{ "sdfa" } [ "asdf" 1 <rotated> >string ] unit-test
+{ "asdf" } [ "asdf" 0 <rotated> >string ] unit-test
+{ "asdf" } [ "asdf" 4 <rotated> >string ] unit-test
+{ "asdf" } [ "asdf" -4 <rotated> >string ] unit-test

diff --git a/extra/sequences/rotated/rotated.factor b/extra/sequences/rotated/rotated.factor
new file mode 100644 (file)
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+++ b/extra/sequences/rotated/rotated.factor
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+! Copyright (C) 2012 John Benediktsson
+! See http://factorcode.org/license.txt for BSD license
+USING: accessors circular kernel math sequences ;
+IN: sequences.rotated
+
+TUPLE: rotated
+{ circular circular read-only }
+{ n integer read-only } ;
+
+: <rotated> ( seq n -- rotated )
+    [ <circular> ] dip rotated boa ;
+
+M: rotated length circular>> length ;
+
+M: rotated virtual@ [ n>> + ] [ circular>> ] bi ;
+
+M: rotated virtual-exemplar circular>> ;
+
+INSTANCE: rotated virtual-sequence

diff --git a/extra/sequences/rotated/summary.txt b/extra/sequences/rotated/summary.txt
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+Rotated virtual sequences