docs/05-changelog.markdown @ 884333cfb6fb v1.3.2

Detect *all* cycles during topological sort

Previously the cycle detection was limited to detecting when we hit
a currently-being-visited node during a traversal.  So something like this would
be correctly found:

    A --> B --> C
          ^     |
          |     |
          +-----+

We start at the root (A), go to B, then to C, then to B, and detect that we're
still working on B and signal the error.

But this doesn't find all cycles, because we *start* at the root nodes, and if
a cycle doesn't have any outcropping branches we'll never reach it at all.  For
example:

    A --> B
    ^     |
    |     |
    +-----+

This graph has no roots, so we incorrectly ignore the cycle.

This patch fixes the problem by keeping a count of visited nodes and and making
sure it matches the digraph's size at the end.

Fixes https://github.com/sjl/cl-digraph/issues/4

Changelog
=========

Here's the list of changes in each released version.

[TOC]

v1.3.2
------

[Fixed a bug](https://github.com/sjl/cl-digraph/issues/4) where certain kinds of
cycles were not correctly detected during topological sorting.

v1.3.1
------

[Fixed a bug](https://github.com/sjl/cl-digraph/pull/3) for recent SBCL versions
when creating a digraph without a custom hash function.

v1.3.0
------

Added the `arbitrary-vertex` function to return an arbitrary vertex of
a digraph.

v1.2.1
------

Fixed a bug in `copy-digraph`.

v1.2.0
------

Added `rootp` and `leafp` predicates to check whether a vertex is a root/leaf in
a digraph.

v1.1.0
------

Minor internal cleanup.

If you pass an invalid `strategy` argument to `reachablep` there will now be
a restart available to supply a new value, instead of just crashing and burning.

v1.0.0
------

Initial version.