AutoExcerpt

[sudo] gem install auto_excerpt

Creates excerpts of html formatted text.

AutoExcerpt.new("<span>This is <strong>some</strong> fancy html formatted text homie</span>", {:words => 5}) 
    #   => "<span>This is <strong>some</strong> fancy html...</span>"

Features

There are 4 different ways to limit the length of an excerpt: characters, words, sentences, paragraphs
If the excerpt would be shorter than the limit that is set, the entire text will be shown.
If limiting by characters the gem will ensure that the excerpt does not cutoff in the middle of a word.
HTML can be stripped. You can also set specific tags that you don’t want stripped.
HTML tags are automatically closed.

Options

:characters
The number of characters to display from the text.
Default: 150 (does not need to be set to 0 if you choose another option)

If you need to be 100% accurate in your character count, then remove the :ending

AutoExcerpt.new("<h1>Hello World!</h1>", {:characters => 5, :ending => nil}) 
     # => <h1>Hello</h1>

:words, :sentences, :paragraphs
The number of [which] to display from the text.

:ending
The text that will be displayed at the end of the excerpt when generating the excerpt by length or words. Set to nil if you don’t want it.
Default: “…”

AutoExcerpt.new("This is cool stuff man!", :ending => ". Srsly!", :words => 3)
    # => "This is cool. Srsly!"

:strip_html
Strips HTML tags from the excerpt that is displayed.
Default: false

:allowed_tags
If using :strip_html then this setting will allow the listed tags to be shown.
default: []

AutoExcerpt.new("<p>This <em>is</em> some <strong>formatted</strong> html</p>", {:strip_html => true, :allowed_tags => %w(p em)})
    # => "<p>This <em>is</em> some formatted html</p>"

:strip_paragraphs
Strip all paragraph tags from the html.
Default: false

:skip_words, :skip_sentences, :skip_paragraphs
The number of [which] to skip at the beginning of the html when returned.
Default: 0

Command Line

new: v0.7.1 Run auto_excerpt from the command line with all of the options shown above!
$ auto_excerpt --words 10 "<p>Some html string</p>"

Help out on Github!

Fork the project.
Make your feature addition or bug fix.
Commit, do not mess with Rakefile, Version, or LICENSE.
Send me a pull request :)
Thanks for helping out!

Credits

This is based on the rss_auto_excerpt plugin for Textpattern by the great Rob Sable.