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## graph-cycles

Enumerate the simple cycles of a graph.

## Usage

(require-extension graph-cycles)

## Documentation

The `graph-cycles` library enumerates all simple cycles in a graph, where the graph object follows the API of e.g. the digraph egg.

### Procedures

*[procedure]*

`graph-cycles-fold:: G F INITIAL -> STATE`

graph cycles iterator; every cycle is reprensented as a list of edges. Adjacent edges are adjacent in the list; the cycles are folded together using the user-supplied function `F`, which is of the form `LAMBDA CYCLE STATE`

## Examples

;; example adapted from graph example in the Boost library documentation (require-extension srfi-1) (require-extension digraph) (require-extension graph-cycles) (define g (make-digraph 'depgraph "dependency graph")) (define used-by (list (cons 'dax_h 'foo_cpp) (cons 'dax_h 'bar_cpp) (cons 'dax_h 'yow_h) (cons 'yow_h 'bar_cpp) (cons 'yow_h 'zag_cpp) (cons 'boz_h 'bar_cpp) (cons 'boz_h 'zig_cpp) (cons 'boz_h 'zag_cpp) (cons 'zow_h 'foo_cpp) (cons 'foo_cpp 'foo_o) (cons 'foo_o 'libfoobar_a) (cons 'bar_cpp 'bar_o) (cons 'bar_o 'libfoobar_a) (cons 'libfoobar_a 'libzigzag_a) (cons 'zig_cpp 'zig_o) (cons 'zig_o 'libzigzag_a) (cons 'libfoobar_a 'dax_h) (cons 'zag_cpp 'zag_o) (cons 'zag_o 'libzigzag_a) (cons 'libzigzag_a 'killerapp))) (define node-list (delete-duplicates (concatenate (list (map car used-by) (map cdr used-by))))) (define node-ids (list-tabulate (length node-list) values)) (for-each (lambda (i n) ((g 'add-node!) i n)) node-ids node-list) (define node-map (zip node-list node-ids)) (for-each (lambda (e) (match e ((ni . nj) (let ((i (car (alist-ref ni node-map))) (j (car (alist-ref nj node-map)))) ((g 'add-edge!) (list i j (format "~A->~A" ni nj))))) (else (error "invalid edge " e)))) used-by) (define roots (map car ((g 'roots)))) ;; accumulate all cycles in a list (graph-cycles-fold g (lambda (cycle ax) (cons cycle ax)) (list))

## About this egg

### Author

### Version history

- 1.9
- Documentation converted to wiki format
- 1.8
- Ported to Chicken 4
- 1.7
- Now using matchable extension
- 1.6
- Updated unit tests to use testbase
- 1.5
- Build script updated for better cross-platform compatibility
- 1.4
- eggdoc documentation fix
- 1.3
- License upgrade to GPL v3
- 1.2
- Added support for chicken-setup -test
- 1.1
- Corrected a mistake in the documentation title
- 1.0
- Initial release

### License

Copyright 2007-2010 Ivan Raikov and the Okinawa Institute of Science and Technology 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/>.