50 lines
2.1 KiB
Factor
50 lines
2.1 KiB
Factor
! Copyright (C) 2009 Doug Coleman.
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! See http://factorcode.org/license.txt for BSD license.
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USING: help.markup help.syntax kernel quotations math.order
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sequences ;
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IN: sorting.slots
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HELP: compare-slots
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{ $values
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{ "sort-specs" "a sequence of accessors ending with a comparator" }
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{ "<=>" { $link +lt+ } " " { $link +eq+ } " or " { $link +gt+ } }
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}
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{ $description "Compares two objects using a chain of intrinsic linear orders such that if two objects are " { $link +eq+ } ", then the next comparator is tried. The comparators are slot-name/comparator pairs." } ;
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HELP: sort-by-slots
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{ $values
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{ "seq" sequence } { "sort-specs" "a sequence of accessors ending with a comparator" }
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{ "seq'" sequence }
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}
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{ $description "Sorts a sequence of tuples by the sort-specs in " { $snippet "sort-spec" } ". A sort-spec is a sequence of slot accessors ending in a comparator." }
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{ $examples
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"Sort by slot c, then b descending:"
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{ $example
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"USING: accessors math.order prettyprint sorting.slots ;"
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"IN: scratchpad"
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"TUPLE: sort-me a b ;"
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"{"
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" T{ sort-me f 2 3 } T{ sort-me f 3 2 }"
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" T{ sort-me f 4 3 } T{ sort-me f 2 1 }"
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"}"
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"{ { a>> <=> } { b>> >=< } } sort-by-slots ."
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"{\n T{ sort-me { a 2 } { b 3 } }\n T{ sort-me { a 2 } { b 1 } }\n T{ sort-me { a 3 } { b 2 } }\n T{ sort-me { a 4 } { b 3 } }\n}"
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}
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} ;
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HELP: split-by-slots
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{ $values
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{ "accessor-seqs" "a sequence of sequences of tuple accessors" }
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{ "quot" quotation }
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}
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{ $description "Splits a sequence of tuples into a sequence of slices of tuples that have the same values in all slots in the accessor sequence. This word is only useful for splitting a sorted sequence, but is more efficient than partitioning in such a case." } ;
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ARTICLE: "sorting.slots" "Sorting by slots"
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"The " { $vocab-link "sorting.slots" } " vocabulary can sort tuples by slot in ascending or descending order, using subsequent slots as tie-breakers." $nl
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"Comparing two objects by a sequence of slots:"
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{ $subsection compare-slots }
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"Sorting a sequence by a sequence of slots:"
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{ $subsection sort-by-slots } ;
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ABOUT: "sorting.slots"
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