Priority queue: Difference between revisions

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=={{header|Logtalk}}==

Logtalk comes with a [https://github.com/LogtalkDotOrg/logtalk3/tree/master/library/heaps heap implementation] out of the box. As such it by definition also has a priority queue. It can be used at the toplevel like this (with some formatting changes for clarity, and '%' marking comments that would not be in the output):

Logtalk comes with a [https://github.com/LogtalkDotOrg/logtalk3/tree/master/library/heaps heap implementation] out of the box. As such it by definition also has a priority queue. It can be used at the toplevel like this (with some formatting changes for clarity, and <code>%</code> marking comments that would not be in the output):

<syntaxhighlight lang="logtalk">?- logtalk_load(heaps(loader)). % also `{heaps(loader)}.` on most back-ends

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heap(<)::top(H4, K4, V4). % K4=2, V4='Tax return'</syntaxhighlight>

Since `heap` is a parametrized object in Logtalk, with the parameter being the ordering predicate, we actually use `heap(<)` object to get min ordering. There are two objects provided in Logtalk that eliminate the unnecessary replication of the two most common orderings:

Since <code>heap(Ordering)</code> is a parametrized object in Logtalk, with the parameter being the ordering predicate, we actually use <code>heap(<)</code> object to get min ordering. There are two objects provided in Logtalk that eliminate the unnecessary replication of the two most common orderings:

<syntaxhighlight lang="logtalk">:- object(minheap,

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:- end_object.</syntaxhighlight>

Given the presence of these two objects, all of the example code above could have `heap(<)` replaced with `minheap` for identical results (including identical performance). It also illustrates how quickly and easily other orderings could be provided at need.

Given the presence of these two objects, all of the example code above could have <code>heap(<)</code> replaced with <code>minheap</code> for identical results (including identical performance). It also illustrates how quickly and easily other orderings could be provided at need.

=={{header|Lua}}==