sequences.inserters: a new utility that abuses the exemplar parameter of *-as combinators to direct their output into existing growable sequences, either appending to the end of the vector (appender) or emptying the vector and replacing the contents (replacer)

extra/sequences/inserters/authors.txt

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+Joe Groff

extra/sequences/inserters/inserters-tests.factor

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+! (c)2010 Joe Groff bsd license
+USING: sequences.inserters tools.test ;
+IN: sequences.inserters.tests
+
+[ V{ 1 2 "Three" "Four" "Five" } ] [
+    { "three" "four" "five" }
+    [ >title ] V{ 1 2 } clone <back-inserter> map-as
+] unit-test
+
+[ t ] [
+    { "three" "four" "five" }
+    [ >title ] V{ 1 2 } clone [ <back-inserter> map-as ] keep eq?
+] unit-test
+
+[ V{ 1 2 "Three" "Four" "Five" } ] [
+    { { "Th" "ree" } { "Fo" "ur" } { "Fi" "ve" } }
+    [ append ] V{ 1 2 } clone <back-inserter> assoc>map
+] unit-test
+
+[ t ] [
+    { { "Th" "ree" } { "Fo" "ur" } { "Fi" "ve" } }
+    [ append ] V{ 1 2 } clone [ <back-inserter> assoc>map ] keep eq?
+] unit-test
+
+[ V{ "Three" "Four" "Five" } ] [
+    { "three" "four" "five" }
+    [ >title ] V{ 1 2 } clone <replacer> map-as
+] unit-test
+
+[ t ] [
+    { "three" "four" "five" }
+    [ >title ] V{ 1 2 } clone [ <replacer> map-as ] keep eq?
+] unit-test

extra/sequences/inserters/inserters.factor

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+! (c)2010 Joe Groff bsd license
+USING: accessors fry growable kernel locals math sequences ;
+IN: sequences.inserters
+
+TUPLE: offset-growable { underlying read-only } { offset read-only } ;
+C: <offset-growable> offset-growable
+INSTANCE: offset-growable virtual-sequence
+M: offset-growable length
+    [ underlying>> length ] [ offset>> ] bi - ; inline
+M: offset-growable virtual-exemplar
+    underlying>> ; inline
+M: offset-growable virtual@
+    [ offset>> + ] [ underlying>> ] bi ; inline
+M: offset-growable set-length
+    [ offset>> + ] [ underlying>> ] bi set-length ; inline
+
+MIXIN: inserter
+M: inserter like
+    nip underlying>> ; inline
+M: inserter new-resizable
+    [ drop 0 ] dip new-sequence ; inline
+M: inserter length
+    drop 0 ; inline
+
+TUPLE: back-inserter { underlying read-only } ;
+C: <back-inserter> back-inserter
+
+INSTANCE: back-inserter inserter
+
+M:: back-inserter new-sequence ( len inserter -- sequence )
+    inserter underlying>> :> underlying
+    underlying length :> old-length
+    old-length len + :> new-length
+    new-length underlying set-length
+    underlying old-length <offset-growable> ; inline
+
+TUPLE: replacer { underlying read-only } ;
+C: <replacer> replacer
+
+INSTANCE: replacer inserter
+
+M: replacer new-sequence
+    underlying>> [ set-length ] keep ; inline
+

extra/sequences/inserters/summary.txt

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+Direct the output of map-as, filter-as, etc. combinators into existing growable sequences