The duel mode is a game\u00a0where you have\u00a0to <\/b>guess a secret (hidden) regex<\/em><\/b>.<\/b> On each attempt, Rex generates strings that match or don’t match the same way as the secret regex. The game uses the ASCII range of characters, i.e. characters from code 0 to 127 and displays various automata associated to\u00a0the regexes.<\/p>\n There is a secret regex<\/em><\/strong> S<\/em> and a given regex<\/strong><\/em> R<\/em>. When you ask rex<\/strong>, a table is displayed showing (up to two) members of<\/p>\n where L(r<\/em>) denotes the set of all strings\u00a0matching a regex r. <\/em>In addition, the following automata are shown for R<\/em>:<\/p>\n All automata are displayed in symbolic<\/em> or extended<\/em> form, meaning that the labels on the transitions denote (nonempty)\u00a0sets of characters<\/em> rather than individual characters.<\/p>\n The\u00a0duel\u00a0also displays an NFA accepting L(S) minus<\/em> L(R), denoted by NFA(S-R)<\/strong>.<\/p>\n Duels\u00a0uses features of the underlying automata library (used by Rex) such as:<\/p>\n You have created your own duel!<\/em><\/b><\/p>\n Enter regexes R<\/em> and S <\/em>(note that comments (opens in new tab)<\/span><\/a>can be added to regexes) and click permalink<\/em>:<\/p>\n This particular example is the link http:\/\/www.rise4fun.com\/Rex\/abG (opens in new tab)<\/span><\/a>.When you visit the link, only R is shown<\/em>, S remains secret<\/em>: Most regex constructs are explained in .NET regexes (opens in new tab)<\/span><\/a>.<\/p>\n Regarding character classes, a less known but useful construct is subtraction<\/em><\/b> operation in character classes (opens in new tab)<\/span><\/a>:<\/p>\n When writing regexes, you can insert comments (opens in new tab)<\/span><\/a>, e.g., to provide a hint in the given regex in the duel, for solving the secret regex<\/p>\n Rex is a simple command line tool that takes a .NET regex pattern (opens in new tab)<\/span><\/a>or several regex patterns\u00a0and generates matching\u00a0string(s) for them. Rex can also be used through an API. Rex is fast, using a novel approach to solve this problem. When several regexes are provided, rex can be used to generate members that match all<\/em> the regexes. By default, rex assumes UTF16 encoding of characters, but can also be restricted to ASCII ecoding.<\/p>\n The following example generates 10 strings that start and end with a digit and have at least two characters:<\/p>\n In order to produce members that contain only ascii characters the \/e option can be used. For general instructions\u00a0regarding usage run:<\/p>\n 1) A regex pattern (or several patterns) is translated into a symbolic finite automaton<\/em><\/p>\n ^[0-9]+|[a-z]$\u00a0\u00a0 ==>\u00a0 2) The automaton is given to a constraint solver that generates members from it.<\/p>\n Try out Pex on the web (opens in new tab)<\/span><\/a>! Rex is a tool that explores .NET regexes and generates members efficiently. Try out\u00a0Rex in duel mode at http:\/\/rise4fun.com\/rex! The duel mode is a game\u00a0where you have\u00a0to guess a secret (hidden) regex. On each attempt, Rex generates strings that match or don’t match the same way as the secret regex. The game uses the ASCII […]<\/p>\n","protected":false},"featured_media":0,"template":"","meta":{"msr-url-field":"","msr-podcast-episode":"","msrModifiedDate":"","msrModifiedDateEnabled":false,"ep_exclude_from_search":false,"_classifai_error":"","footnotes":""},"research-area":[13560],"msr-locale":[268875],"msr-impact-theme":[],"msr-pillar":[],"class_list":["post-170457","msr-project","type-msr-project","status-publish","hentry","msr-research-area-programming-languages-software-engineering","msr-locale-en_us","msr-archive-status-active"],"msr_project_start":"2010-03-27","related-publications":[158730,158942,159863,165174,165785],"related-downloads":[],"related-videos":[],"related-groups":[],"related-events":[],"related-opportunities":[],"related-posts":[],"related-articles":[],"tab-content":[],"slides":[],"related-researchers":[{"type":"user_nicename","value":"jhalleux","display_name":"Peli de Halleux","author_link":"Peli de Halleux<\/a>","is_active":false,"user_id":32253,"last_first":"de Halleux, Peli","people_section":0,"alias":"jhalleux"},{"type":"user_nicename","value":"margus","display_name":"Margus Veanes","author_link":"Margus Veanes<\/a>","is_active":false,"user_id":32806,"last_first":"Veanes, Margus","people_section":0,"alias":"margus"}],"msr_research_lab":[199565],"msr_impact_theme":[],"_links":{"self":[{"href":"https:\/\/www.microsoft.com\/en-us\/research\/wp-json\/wp\/v2\/msr-project\/170457","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.microsoft.com\/en-us\/research\/wp-json\/wp\/v2\/msr-project"}],"about":[{"href":"https:\/\/www.microsoft.com\/en-us\/research\/wp-json\/wp\/v2\/types\/msr-project"}],"version-history":[{"count":2,"href":"https:\/\/www.microsoft.com\/en-us\/research\/wp-json\/wp\/v2\/msr-project\/170457\/revisions"}],"predecessor-version":[{"id":390560,"href":"https:\/\/www.microsoft.com\/en-us\/research\/wp-json\/wp\/v2\/msr-project\/170457\/revisions\/390560"}],"wp:attachment":[{"href":"https:\/\/www.microsoft.com\/en-us\/research\/wp-json\/wp\/v2\/media?parent=170457"}],"wp:term":[{"taxonomy":"msr-research-area","embeddable":true,"href":"https:\/\/www.microsoft.com\/en-us\/research\/wp-json\/wp\/v2\/research-area?post=170457"},{"taxonomy":"msr-locale","embeddable":true,"href":"https:\/\/www.microsoft.com\/en-us\/research\/wp-json\/wp\/v2\/msr-locale?post=170457"},{"taxonomy":"msr-impact-theme","embeddable":true,"href":"https:\/\/www.microsoft.com\/en-us\/research\/wp-json\/wp\/v2\/msr-impact-theme?post=170457"},{"taxonomy":"msr-pillar","embeddable":true,"href":"https:\/\/www.microsoft.com\/en-us\/research\/wp-json\/wp\/v2\/msr-pillar?post=170457"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}![\"\"](\"https:\/\/www.microsoft.com\/en-us\/research\/wp-content\/uploads\/2016\/02\/rex-rexduel.png\")
<\/span><\/h2>\nHow does the duel work?<\/h2>\n
\n
\n
\n
\n\t\t\t\t\t\t\t\t
\n
Example<\/h3>\n
![\"\"](\"https:\/\/www.microsoft.com\/en-us\/research\/wp-content\/uploads\/2016\/02\/rex-enterrexduelregexes.gif\")
<\/span><\/span><\/p>\n![\"\"](\"https:\/\/www.microsoft.com\/en-us\/research\/wp-content\/uploads\/2016\/02\/rex-createrexduelpermalink.gif\")
<\/span><\/span>When you now\u00a0ask rex<\/strong>, the following results are shown:![\"\"](\"https:\/\/www.microsoft.com\/en-us\/research\/wp-content\/uploads\/2016\/02\/rex-visitrexduelsamplelink.gif\")
<\/span><\/span><\/p>\nAbout .NET regex constructs<\/h2>\n
Using character classes<\/h3>\n
\n
Using comments<\/h3>\n
\n
Examples:<\/h3>\n
\n
> rex.exe \"^d.*d$\" \/k:10<\/pre>\n
> rex.exe \/?<\/pre>\n\t\t\t<\/div>\n\t\t<\/div>\n\t<\/li>\n\t\t
![\"\"](\"https:\/\/www.microsoft.com\/en-us\/research\/wp-content\/uploads\/2016\/02\/rex-samplesfa.jpg\")
<\/span><\/span><\/p>\nWatch the Channel9 Movie! (opens in new tab)<\/span><\/a>
![\"\"](\"https:\/\/www.microsoft.com\/en-us\/research\/wp-content\/uploads\/2016\/02\/rex-rexvideo.png\")
(opens in new tab)<\/span><\/a><\/span><\/h2>\n\t\t\t<\/div>\n\t\t<\/div>\n\t<\/li>\n\t\t\t\t\t\t<\/ul>\n\t<\/div>\n\t\n![\"Rex](\"https:\/\/www.microsoft.com\/en-us\/research\/wp-content\/uploads\/2016\/02\/rex-pexforfunverysmall.png\" "\\"Rex")
(opens in new tab)<\/span><\/a><\/span><\/span><\/p>\n","protected":false},"excerpt":{"rendered":"