This expression throws a "Server error"

(?:(?:\r\n)?[ \t])*(?:(?:(?:[^()<>@,;:\\".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\["()<>@,;:\\".\[\]]))|"(?:[^\"\r\\]|\\.|(?:(?:\r\n)?[ \t]))*"(?:(?:\r\n)?[ \t])*)(?:\.(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\["()<>@,;:\\".\[\]]))|"(?:[^\"\r\\]|\\.|(?:(?:\r\n)?[ \t]))*"(?:(?:\r\n)?[ \t])*))*@(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\["()<>@,;:\\".\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*)(?:\.(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\["()<>@,;:\\".\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*))*|(?:[^()<>@,;:\\".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\["()<>@,;:\\".\[\]]))|"(?:[^\"\r\\]|\\.|(?:(?:\r\n)?[ \t]))*"(?:(?:\r\n)?[ \t])*)*\<(?:(?:\r\n)?[ \t])*(?:@(?:[^()<>@,;:\\".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\["()<>@,;:\\".\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*)(?:\.(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\["()<>@,;:\\".\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*))*(?:,@(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\["()<>@,;:\\".\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*)(?:\.(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\["()<>@,;:\\".\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*))*)*:(?:(?:\r\n)?[ \t])*)?(?:[^()<>@,;:\\".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\["()<>@,;:\\".\[\]]))|"(?:[^\"\r\\]|\\.|(?:(?:\r\n)?[ \t]))*"(?:(?:\r\n)?[ \t])*)(?:\.(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\["()<>@,;:\\".\[\]]))|"(?:[^\"\r\\]|\\.|(?:(?:\r\n)?[ \t]))*"(?:(?:\r\n)?[ \t])*))*@(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\["()<>@,;:\\".\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*)(?:\.(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\["()<>@,;:\\".\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*))*\>(?:(?:\r\n)?[ \t])*)|(?:[^()<>@,;:\\".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\["()<>@,;:\\".\[\]]))|"(?:[^\"\r\\]|\\.|(?:(?:\r\n)?[ \t]))*"(?:(?:\r\n)?[ \t])*)*:(?:(?:\r\n)?[ \t])*(?:(?:(?:[^()<>@,;:\\".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\["()<>@,;:\\".\[\]]))|"(?:[^\"\r\\]|\\.|(?:(?:\r\n)?[ \t]))*"(?:(?:\r\n)?[ \t])*)(?:\.(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\["()<>@,;:\\".\[\]]))|"(?:[^\"\r\\]|\\.|(?:(?:\r\n)?[ \t]))*"(?:(?:\r\n)?[ \t])*))*@(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\["()<>@,;:\\".\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*)(?:\.(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\["()<>@,;:\\".\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*))*|(?:[^()<>@,;:\\".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\["()<>@,;:\\".\[\]]))|"(?:[^\"\r\\]|\\.|(?:(?:\r\n)?[ \t]))*"(?:(?:\r\n)?[ \t])*)*\<(?:(?:\r\n)?[ \t])*(?:@(?:[^()<>@,;:\\".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\["()<>@,;:\\".\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*)(?:\.(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\["()<>@,;:\\".\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*))*(?:,@(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\["()<>@,;:\\".\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*)(?:\.(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\["()<>@,;:\\".\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*))*)*:(?:(?:\r\n)?[ \t])*)?(?:[^()<>@,;:\\".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\["()<>@,;:\\".\[\]]))|"(?:[^\"\r\\]|\\.|(?:(?:\r\n)?[ \t]))*"(?:(?:\r\n)?[ \t])*)(?:\.(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\["()<>@,;:\\".\[\]]))|"(?:[^\"\r\\]|\\.|(?:(?:\r\n)?[ \t]))*"(?:(?:\r\n)?[ \t])*))*@(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\["()<>@,;:\\".\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*)(?:\.(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\["()<>@,;:\\".\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*))*\>(?:(?:\r\n)?[ \t])*)(?:,\s*(?:(?:[^()<>@,;:\\".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\["()<>@,;:\\".\[\]]))|"(?:[^\"\r\\]|\\.|(?:(?:\r\n)?[ \t]))*"(?:(?:\r\n)?[ \t])*)(?:\.(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\["()<>@,;:\\".\[\]]))|"(?:[^\"\r\\]|\\.|(?:(?:\r\n)?[ \t]))*"(?:(?:\r\n)?[ \t])*))*@(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\["()<>@,;:\\".\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*)(?:\.(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\["()<>@,;:\\".\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*))*|(?:[^()<>@,;:\\".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\["()<>@,;:\\".\[\]]))|"(?:[^\"\r\\]|\\.|(?:(?:\r\n)?[ \t]))*"(?:(?:\r\n)?[ \t])*)*\<(?:(?:\r\n)?[ \t])*(?:@(?:[^()<>@,;:\\".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\["()<>@,;:\\".\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*)(?:\.(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\["()<>@,;:\\".\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*))*(?:,@(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\["()<>@,;:\\".\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*)(?:\.(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\["()<>@,;:\\".\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*))*)*:(?:(?:\r\n)?[ \t])*)?(?:[^()<>@,;:\\".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\["()<>@,;:\\".\[\]]))|"(?:[^\"\r\\]|\\.|(?:(?:\r\n)?[ \t]))*"(?:(?:\r\n)?[ \t])*)(?:\.(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\["()<>@,;:\\".\[\]]))|"(?:[^\"\r\\]|\\.|(?:(?:\r\n)?[ \t]))*"(?:(?:\r\n)?[ \t])*))*@(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\["()<>@,;:\\".\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*)(?:\.(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\["()<>@,;:\\".\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*))*\>(?:(?:\r\n)?[ \t])*))*)?;\s*)

When you hover over a part of the diagram you could highlight the part of the text that is responsible for that section of the diagram.

At least have regexper.com forward to www.regexper.com. Bad to spit an error at folks

var s = "123, 12 1 2"
var p = /1 | 2/
s.match(p)

['1 ']

in regexper, the white space not display

Any signed letter like "á" or non-ASCII character like "ñ" breaks the thing and get a Server error

In my uses, messages like "5 times" and "1...5" are displayed to {5} and {1,5} quantifiers, but not for another quantifiers.

This is a feature will be can add?

Consider the following regex:

[^[a-z]]*

The following output is produced:

Notice the closing bracket is caught in a "0 or more" loop.

The site raise this error
My regexp = ((,+[\w\s.ñáéíóú]+,)|(,[\w\s.ñáéíóú]+))
Error page
Expected one of ?, (, [, ., , $, |, ) at line 1, column 5 (byte 5) after ((,
But in this page really works http://rubular.com/r/r9CF35OgNZ

It would be really useful to be able to test out the regex on sample data as well. E.g., for a regex of "\d+", perhaps I might throw the following sample data at it:

• "a"
• ""
• "0"
• "235"
• "aslfj235"

A really cool thing to do with this would be to highlight the path through the state machine that is taken when evaluating a piece of sample data.

Expression /^(\d{,2})$/ should be parsed as string, not as quantifier

See https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions#special-quantifier-range

Following regex throw a server error:

(([A-Z]+))?

Just a simple list of expressions to demonstrate with. Probably best to wait until after #7 is complete.

http://ex-parrot.com/~pdw/Mail-RFC822-Address.html

Looking at the code it seems to me the bulk of the work is done by the the TreeTop - the ruby PEG parser.
There are a few PEG parsers for javascript, so it may be possible to do the entire processing in the client side (javascript) entirely.

This will allow instant feedback (ie. render every keyup event), and also some super cool plugin for IDEs which support javascript plugins.

Fast clicks on "Display" button cause multiple render.
Views in attachments

A formated source of an regexp with your comments would be nice, so it can be copied direct into a js-file.

Example:

\/\/#[\[\(]hi world[\]\)]\/\/#[\[\(]test[\]\)]

output (for js):

'\/\/#'
+ '[\[\(]' // One of: "[", "("
+ 'hi world'
+ '[\]\)]' // One of: "]", ")"
+ '\/\/#'
+ '[\[\(]' // One of: "[", "("
+ 'test'
+ '[\]\)]'; // One of: "]", ")"

Same comments you use in your graphic.

Or exists a fork with that?

These two regular expression work differently
yes their images are the same.
\d+(?:.\d+?)? and
\d+(?:.\d+)?

• The "Fork me on github" image overlays most of the display button.
  
• The Textbox runs behind the display button

This can be verified by entering longer regex statements:

/^((([a-z]|\d|[!#\$%&'\*\+\-\/=\?\^_{|}~]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])+(.([a-z]|\d|[!#$%&'*+-/=?^_{\|}~]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])+)*)|((\x22)((((\x20|\x09)*(\x0d\x0a))?(\x20|\x09)+)?(([\x01-\x08\x0b\x0c\x0e-\x1f\x7f]|\x21|[\x23-\x5b]|[\x5d-\x7e]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(\\([\x01-\x09\x0b\x0c\x0d-\x7f]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF]))))*(((\x20|\x09)*(\x0d\x0a))?(\x20|\x09)+)?(\x22)))@((([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])*([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])))\.)+(([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])([a-z]|\d|-|\.| _|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])*([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])))\.?$/

^^$$

[
 {
  "type": "basic_RE",
  "value": "^^$$",
  "childs": [
   {
    "type": "start-of-line",
    "value": "^"
   },
   {
    "type": "char",
    "value": "^"
   },
   {
    "type": "char",
    "value": "$"
   },
   {
    "type": "end-of-line",
    "value": "$"
   }
  ]
 }
]

This throws a server error:

(((a*)))

Please add a Favicon for the site so that it is easily recognizable in the bookmarks bar. Right Now it looks like this: http://i.imgur.com/xhQ2pVL.png , and is indistinguishable from the other sites without favicons.

Two options, strip the beginning and trailing slashes if they are present (and not properly escaped) or support parsing them.

[a-z] is described as 'one of'
[a-z]+ is described as 'one of'

[a-z]+ should be described as "at least one of" or "one or more"

Same issue for zero or more quantifier.

Thanks for the nice webpage! Just discovered it.

http://www.regular-expressions.info/named.html

eg. exports to png/svg..
this will be grateful
because some time we need save the results

The app is great, really, but it lacks the ability to share regular expression visualizations.

Do something better when the regexp encounters an error.

e.g. Show the compiled regexp up to the point of the error.

Perhaps something like: If compilation fails, insert an "error" token at the point of the error, close any groups, recompile. Now you can at least display the regex up to the point of error.

The license this work is released under is extremely restrictive. Specifically, it prohibits the use of this work in any commercial product, and forces any work that is built on top of this code to be non-commercial as well.

Would you be prepared to release it under a less restrictive license, such as MIT or BSD. I'm happy to continue to include attribution for the original work you did, but I want to make the work available for people to use in more interesting (and helpful) scenarios.

(..csproj$)|(..sln$)

any string that ends in either .csproj or .sln (the "." in the regex visualizer is considered as "any character")

Unicode characters can be matched with \uFFFF (or \u{FFFF} depending the engine) and those are supported by regexper.

But we can also refers to Unicode characters in others way:

• \X
• \p{L}
• \p{Lu}
• \p{M}
• \p{Z}
• \p{S}
• \p{N}
• \p{P}
• \p{C}
• and much more...

More are available on this website http://www.regular-expressions.info/unicode.html, with explanation and examples.

So, the regex /^[\p{L}\s]+$/ will match a space or any Unicode letter, one or more times.

Not a code issue, but http://regexper.com/ cannot be accessed.

Since this app emphasizes readability, it would be nice to observe proper grammar if a regex is specifying that something should only repeat once. Consider:

[a-z]{1}

Regexper will describe that as repeating "1 times". There should be conditional formatting on line 54 of repetition.js.

Something like this would do the trick:

loop_desc = repeat_count + ' time' + ((repeat_count === 1) ? "" : "s");

Or even:

loop_desc = ((repeat_count === 1) ? "once" : repeat_count + " times");

Great work though!

If you have whitespace at the end or beginning of a regular expression, it comes back as an error: invalid regular expression. Submissions should be trimmed before processing.

in pattern '[every]' the 'e' while show twice,is this a problem ?

Sometimes when searching for single or double quotes, the rendering of the query is hard to read because the value is itself quoted.

e.g.
"'" (single quote)
""" (double quote)

A subtle change in color of the quotes or even the string values will help differentiate the content

I'd like to see “[no linefeed]” instead of “none of [[linefeed]]” for the RegEx [^\n], and “[" "]” (or similar) instead of “One of [[" "]]” for the regex [ ].

(Brackets stand for node frames)

This regex

(?<!\+)\+(?!http)

produces error

Expected ? at line 1, column 3 (byte 3) after (?

but I believe is valid because it is parsed elsewhere http://rick.measham.id.au/paste/explain.pl?regex=%28%3F%3C%21%5C%2B%29%5C%2B%28%3F%21http%29

It would be nice if I could enter an expression, then get a link to a page that will display that expression to others.

Don't know how to express this visually yet, but expressions that use a non-greedy repetition (*?, +?, ??, {x,y}?) should be rendered to indicate that the repetition is not greedy.

This regexp throws server error:

^\s_([(){}[]?.,:;'"~#@`]|={1,3}|/(_(jslint|properties|property|members?|globals?)?|=|/)?|*[/=]?|+(?:=|++)?|-(?:=|-+)?|[^%]=?|&[&=]?||[|=]?|>{1,3}=?|<(?:[/=!]|!([|--)?|<=?)?|!(!|==?)?|[a-zA-Z_$][a-zA-Z0-9_$]|[0-9]+(?:[xX][0-9a-fA-F]+|.[0-9])?(?:[eE][+-]?[0-9]+)?)

Loading the page with a current hash or changing the hash will trigger a display of the regexp in the URL.