---
title: "The Reanimator - Visualize How the Regex Engine Works"
url: "https://osherove.com/blog/2006/2/28/the-reanimator-visualize-how-the-regex-engine-works.md"
canonical: "https://osherove.com/blog/2006/2/28/the-reanimator-visualize-how-the-regex-engine-works.html"
published: "2006-02-28T19:02:00"
updated: "2006-02-28T19:02:00"
tags: ["Regex"]
author: "Roy Osherove"
description: "If you're into Regular Expressions, check out the Reanimator . It provides a visual graphs of how the match was performed. \"The regular expression is compiled into a nondeterministic finite-state automaton (the first…"
usage: "Licensed under CC BY 4.0 — reuse, quote and adapt with attribution (Roy Osherove, link to the original page)."
license: "https://creativecommons.org/licenses/by/4.0/"
---

# The Reanimator - Visualize How the Regex Engine Works

By Roy Osherove February 28, 2006 In [Regex](https://osherove.com/blog/category/regex)

**Historical article** · Originally published February 28, 2006; technical details may be outdated.

If you're into Regular Expressions, check out [the Reanimator](http://osteele.com/tools/reanimator/). It provides a visual graphs of how the match was performed.

_"The regular expression is compiled into a nondeterministic finite-state automaton (the first graph). Most regular expression engines reduce this to a deterministic finite-state automaton (the second graph). This is like a board game. The input string is interpreted as a series of instructions to advance a "game counter" (the state) along the game board (the automaton). If it lands on a winning space (a final state), there's a match!"_

\[via [Addy Santo](http://blogs.msdn.com/asanto/)\]

## More in Regex

[All posts in Regex](https://osherove.com/blog/category/regex)

- Sep 10, 2006

    ### [Regulazy 1.02 is out and about](https://osherove.com/blog/2006/9/10/regulazy-102-is-out-and-about.html)

- Mar 1, 2006

    ### [The Next Regex Regulator](https://osherove.com/blog/2006/3/1/the-next-regex-regulator.html)

- Nov 26, 2005

    ### [Announcing Regex Kit: Regular Expression Visualizers for VS 2005](https://osherove.com/blog/2005/11/26/announcing-regex-kit-regular-expression-visualizers-for-vs-2.html)

- Jul 8, 2005

    ### [Sessions done at TechEd](https://osherove.com/blog/2005/7/8/sessions-done-at-teched.html)


---

## About the author

**Roy Osherove**: Senior Solutions Architect at AWS working on AI for production and AI-driven development; author of The Art of Unit Testing and Elastic Leadership, with about 20 years of consulting and training on unit testing, TDD, team leadership and continuous delivery.

### Sites

- [RobotPaper](https://robotpaper.ai/): This blog: AI patterns and anti-patterns, AI and coding agents, and engineering leadership.
- [osherove.com](https://osherove.com): Roy's personal site. Author of The Art of Unit Testing and Elastic Leadership; consulting and training on unit testing, TDD, team leadership and continuous delivery, plus about 20 years of blog posts.
- [The Art of Unit Testing](https://www.artofunittesting.com): The Art of Unit Testing, 3rd Edition (Manning): readable, maintainable, trustworthy unit tests, plus TDD workshops in C#, JavaScript, Java and Kotlin.
- [5whys.com](https://www.5whys.com): Roy's writing on software team leadership: self-organizing teams, surviving chaos, learning mode and the Elastic Leadership model.
- [Pipeline Driven](https://pipelinedriven.org): Continuous delivery and DevOps practices: build patterns, pipeline-friendly testing, DevOps metrics and enterprise DevOps.
- [Elastic Leadership](https://www.elasticleadership.com): Elastic Leadership, Roy's framework for software team leaders (survival, learning and self-organizing modes).

### Social

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### Contact

- Contact form: https://forms.gle/jQSx5KoXvrVA1JCK7

### License

Licensed under CC BY 4.0 — reuse, quote and adapt with attribution (Roy Osherove, link to the original page). License: https://creativecommons.org/licenses/by/4.0/