You are looking at historical revision 20170 of this page. It may differ significantly from its current revision.

## binary-heap

Binary heap.

## Usage

(require-extension binary-heap)

## Documentation

The `binary-heap` library is based on the Ocaml heap implementation by Jean-Christophe Filliatre.

Heaps are encoded as binary trees that have the heap property, namely the value of any node is greater or equal than the nodes in its left and right subtrees.

A binary-heap object is created by procedure `make-binary-heap`, the only user-visible procedure defined in this egg:

*[procedure]*

`make-binary-heap:: KEY-COMPARE-PROC -> SELECTOR`

where KEY-COMPARE-PROC is a user-supplied function that takes two keys and returns a negative, positive, or zero number depending on how the first key compares to the second.

The returned selector procedure can take one of the following arguments:

'get-max | returns a (key . value) pair for an association in the heap with the largest key. If the heap is empty, an error is signalled. |

'delete-max | removes the max key and the corresponding association from the heap. Returns a (key . value) pair of the removed association. If the heap is empty, an error is signalled. |

'empty? | returns #t if the heap is empty |

'size | returns the size (the number of associations) in the heap |

'put | pure variant of PUT!; it returns a new heap object that contains the given association, while the original heap object is unmodified. |

'for-each | returns a procedure LAMBDA PROC that will apply the given procedure PROC to each (key . value) association of the heap, from the one with the smallest key all the way to the one with the max key, in an ascending order of keys. |

'fold | returns a procedure LAMBDA PROC INITIAL such that, given the associations in the heap ordered by the descending order of keys: (key-n . value-n) ... (key-2 . value-2) (key-1 . value-1) the procedure returns the result of the successive function applications (PROC value-1 (PROC value-2 ... (PROC value-n INITIAL). |

## Examples

## About this egg

### Author

### Version history

- 1.1
- Documentation converted to wiki format
- 1.0
- Initial release

### License

Copyright 2007-2010 Ivan Raikov. This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. A full copy of the GPL license can be found at <http://www.gnu.org/licenses/>.