Package Name: gnat.heap_sort_a
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-- --
-- GNAT RUNTIME COMPONENTS --
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-- G N A T . H E A P _ S O R T _ A --
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-- S p e c --
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-- This package provides a heapsort routine that works with access to
-- subprogram parameters, so that it can be used with different types with
-- shared sorting code. See also GNAT.Heap_Sort_G, the generic version,
-- which is a little more efficient, but does not allow code sharing.
package GNAT.Heap_Sort_A is
pragma Preelaborate (Heap_Sort_A);
-- The data to be sorted is assumed to be indexed by integer values from
-- 1 to N, where N is the number of items to be sorted. In addition, the
-- index value zero is used for a temporary location used during the sort.
type Move_Procedure is access procedure (From : Natural; To : Natural);
-- A pointer to a procedure that moves the data item with index From to
-- the data item with index To. An index value of zero is used for moves
-- from and to the single temporary location used by the sort.
type Lt_Function is access function (Op1, Op2 : Natural) return Boolean;
-- A pointer to a function that compares two items and returns True if
-- the item with index Op1 is less than the item with index Op2, and False
-- if the Op1 item is greater than or equal to the Op2 item.
procedure Sort (N : Positive; Move : Move_Procedure; Lt : Lt_Function);
-- This procedures sorts items indexed from 1 to N into ascending order
-- making calls to Lt to do required comparisons, and Move to move items
-- around. Note that, as described above, both Move and Lt use a single
-- temporary location with index value zero. This sort is not stable,
-- i.e. the order of equal elements in the input is not preserved.
end GNAT.Heap_Sort_A;