49 lines
1.8 KiB
Factor
49 lines
1.8 KiB
Factor
! Copyright (C) 2009 Doug Coleman.
|
|
! See http://factorcode.org/license.txt for BSD license.
|
|
USING: help.markup help.syntax kernel quotations math.order
|
|
sequences ;
|
|
IN: sorting.slots
|
|
|
|
HELP: compare-slots
|
|
{ $values
|
|
{ "obj1" object }
|
|
{ "obj2" object }
|
|
{ "sort-specs" "a sequence of accessors ending with a comparator" }
|
|
{ "<=>" { $link +lt+ } " " { $link +eq+ } " or " { $link +gt+ } }
|
|
}
|
|
{ $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." } ;
|
|
|
|
HELP: sort-by
|
|
{ $values
|
|
{ "seq" sequence } { "sort-specs" "a sequence of accessors ending with a comparator" }
|
|
{ "seq'" sequence }
|
|
}
|
|
{ $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." }
|
|
{ $examples
|
|
"Sort by slot a, then b descending:"
|
|
{ $example
|
|
"USING: accessors math.order prettyprint sorting.slots ;"
|
|
"IN: scratchpad"
|
|
"TUPLE: sort-me a b ;"
|
|
"{"
|
|
" T{ sort-me f 2 3 } T{ sort-me f 3 2 }"
|
|
" T{ sort-me f 4 3 } T{ sort-me f 2 1 }"
|
|
"}"
|
|
"{ { a>> <=> } { b>> >=< } } sort-by ."
|
|
"{\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}"
|
|
}
|
|
} ;
|
|
|
|
ARTICLE: "sorting.slots" "Sorting by slots"
|
|
"The " { $vocab-link "sorting.slots" } " vocabulary can sort tuples by slot in ascending or descending order, using subsequent slots as tie-breakers." $nl
|
|
"Comparing two objects by a sequence of slots:"
|
|
{ $subsections compare-slots }
|
|
"Sorting a sequence of tuples by a slot/comparator pairs:"
|
|
{ $subsections
|
|
sort-by
|
|
sort-keys-by
|
|
sort-values-by
|
|
} ;
|
|
|
|
ABOUT: "sorting.slots"
|