Given that:
You have some Key-Value data that can be modified
Modification is done via by applying filters to the data. Filters that control what gets changed are created by non-technical people
The filters are setup using regular expressions. An example of a rule described as part of a filter may be "If a key matches some regex, replace value with some other value"
How would you:
If filters are to be produced by business people, who can't create regular expressions, in what form would you have them submit their input that would be easily translated to regex?
Agent Ransack contains a GUI editor for creating regular expressions from plain English, I would suggest taking a look at that and implementing your own variation of it.
See the screenshot for an example:
If it works, I would go for "wildcard only" support - ie the asterisk * is the only special character allowed and you translate that to the regex .*? in code.
Most non-technical people can grasp * meaning "anything".
Related
So I read a lot about Negation in Regex but can't solve my problem in MS Word 2016.
How do I exclude a String, Word, Number(s) from being found?
Example:
<[A-Z]{2}[A-Z0-9]{9;11}> to search a String like XY123BBT22223
But how to exclude for example a specefic one like SEDWS12WW04?
Well it depends on what you need to achieve or is this a matter of curiosity... RegEx is not the same as the built-in Advanced Find with Wildcards; for that you need VBA.
Depending on your need, without using VBA, you could make use of space and return characters - something like this will work for the strings provided: [ ^13][A-Z]{2}[0-9]{1,}[A-Z]{1,}[0-9]{1,}[ ^13] (assuming you use normal carriage returns and spaces in your document)
Anyway, this is a good article on wildcard searches in MS Word: https://wordmvp.com/FAQs/General/UsingWildcards.htm
EDIT:
In light of your further comments you will probably want to look at section 8 of the linked article which explains grouping. For my proposed search you can use this to your advantage by creating 3 groups in your 'find' and only modifying the middle group, if indeed you do intend to modify. Using groups the search would look something like:
([ ^13])([A-Z]{2}[0-9]{1,}[A-Z]{1,}[0-9]{1,})([ ^13])
and the replace might look like this:
\1 SOMETHING \3
Note also: compared to a RegEx solution my suggestion is kinda lame, mainly because compared to RegEx, MS-Words find and replace (good as it is, and really it is) is kinda lame... it's hacky but it might work for you (although you might need to do a few searches).
BUT... if it really is REGEX that you want, well you can get access to this via VBA: How to Use/Enable (RegExp object) Regular Expression using VBA (MACRO) in word
And... then you will be able to use proper RegEx for find and replace, well almost - I'm under the impression that the VBA RegEx still has some quirks...
As already noted by others, this is not possible in Microsoft Word's flavor of regular expressions.
Instead, you should use standard regular expressions. It is actually possible to use standard regular expressions in MS Word if you use a special tool that integrates into Microsoft Word called Multiple Find & Replace (see http://www.translatortools.net/products/transtoolsplus/word-multiplefindreplace). This tool opens as a pane to the right of the document window and works just like the Advanced Find & Replace dialog. However, in addition to Word's existing search functionality, it can use the standard regular expressions syntax to search and replace any text within a Word document.
In your particular case, I would use this:
\b[A-Z]{2}[A-Z0-9]{9,11}\b(?<!\bSEDWS12WW04)
To explain, this searches for a word boundary + ID + word boundary, and then it looks back to make sure that the preceding string does not match [word boundary + excluded ID]. In a similar vein, you can do something like
(?<!\bSEDWS12WW04|\bSEDWS12WW05|\bSEDWS12WW05)
to exlude several IDs.
Multiple Find & Replace is quite powerful: you can add any number of expressions (either using regular expressions or using Word's standard search syntax) to a list and then search the document for all of them, replace everything, display all matches in a list and replace only specific matches, and a few more things.
I created this tool for translators and editors, but it is great for any advanced search/replace operations in Word, and I am sure you will find it very useful.
Best regards, Stanislav
The online service Kimono provides a GUI for a user to select
page elements and then uses the selected elements to create a regex which will match those selections. This regex can then be used to extract information from the same page at different points in time. The service is useful because you dont have to generate the regex query yourself and instead provide a set of example query matches which are then compiled into a query regex expression. The company was acquired and so the service is no longer available.
However the problem seems like an interesting problem and so my question is this: what algorithm is capable of turning a number of examples (both positive and negative are needed) in a large document into a regex which when applied will then match those examples?
Regular expressions are typically implemented with NFAs and DFAs.
https://en.wikipedia.org/wiki/Nondeterministic_finite_automaton
https://en.wikipedia.org/wiki/Deterministic_finite_automaton
The process of finding the smallest DFA to represent a particular DFA is known as minimization.
https://en.wikipedia.org/wiki/DFA_minimization
This needs to be converted back into a regular expression.
https://cs.stackexchange.com/questions/2016/how-to-convert-finite-automata-to-regular-expressions
I'm looking to have the (admin) user enter some pattern matching string, to give different users of my website access to different database rows, depending on if the text in a particular field of the row matches the pattern matching string against that user.
I decided on Regex because it is trivial to integrate into the MySQL statements directly.
I don't really know where to start with validating that a string is a valid regular expression, with a regular expression.
I did some searching for similar questions, couldn't see one. Google produced the comical answer, sadly not so helpful.
Do people do this in the wild, or avoid it?
Is it able to be done with a simple regex, or will the set of all valid regex need to be limited to a usable subset?
Validating a regex is an incredibly complex task. A regex would not be able to do it.
A simple approach would be to catch any errors that occur when you try to run the SQL statement, then report an appropriate error back to the user.
I am assuming that the 'admin' is a trusted user here. It is quite dangerous to give a non-trusted user the ability to enter regexes, because it is easy to attack your system with a regex that is constructed to take a really long time to execute. And that is before you even start to worry about the Bobby Tables problems.
in javascript:
input = "hello**";
try{
RegExp(input);
// sumbit the regex
}catch(err){
// regex is not valid
}
You cannot validate that a string contains a valid regular expression with a regular expression. But you might be able to compromise.
If you only need to know that only characters which are valid in regular expressions were used in the string, you can use the regex:
^[\d\w \-\}\{\)\(\+\*\?\|\.\$\^\[\]\\]*$
This might be enough depending on the application.
I need to enhance the search functionality on a page listing user accounts. Rather than have multiple search boxes for each possible field, or a drop down menu where the user can only search against one field, I'd like a single search box and to use a gmail like syntax. That's the best way I can describe it, and what I mean by a gmail like search syntax is being able to type the following into the input box:
username:bbaggins type:admin "made up plc"
When the form is submitted, the search string should be split into it's separate parts, which will allow me to construct a SQL query. So for example, type:admin would form part of the WHERE clause so that it would find any record where the field type is equal to admin and the same for username. The text in quotes may be a free text search, but I'm not sure on that yet.
I'm thinking that a regular expression or two would be the best way to do this, but that's something I'm really not good at. Can anyone help to construct a regular expression which could be used for this purpose? I've searched around for some pointers but either I don't know what to search for or it's not out there as I couldn't find anything obvious. Maybe if I understood regular expressions better it would be easier :-)
Cheers,
Adam
No, you would not use regular expressions for this. Just split the string on spaces in whatever language you're using.
You don't necessarily have to use a regex. Regexes are powerful, but in many cases also slow. Regex also does not handle nested parameters very well. It would be easier for you to write a script that uses string manipulation to split the string and extract the keywords and the field names.
If you want to experiment with Regex, try the online REGex tester. Find a tutorial and play around, it's fun, and you should quickly be able to produce useful regexes that find any words before or after a : character, or any sentences between " quotation marks.
thanks for the answers...I did start doing it without regex and just wondered if a regex would be simpler. Sounds like it wouldn't though, so I'll go back to the way I was doing it and test it again.
Good old Mr Bilbo is my go to guy for any naming needs :-)
Cheers,
Adam
I'm not sure if Jeff coined it but it's the joke/saying that people who say "oh, I know I'll use regular expressions!" now have two problems. I've always taken this to mean that people use regular expressions in very inappropriate contexts.
However, under what circumstances are regular expressions really the best answer? What problems are they really the best or maybe only way to solve a situation?
RexExprs are good for:
Text Format Validations (email, url, numbers)
Text searchs/substitution.
Mappings (e.g. url pattern to function call)
Filtering some texts (related to substitution)
Lexical analysis during parsing.
They can be used to validate anything that have a pattern like :
Social Security Number
Telephone Number ( 555-555-5555 )
Email Address (something#example.com)
IP Address (but it's more complex to make sure it's valid)
All those have patterns and are easily verifiable by RegEx.
They are difficultly used for entry that have a logic instead of a pattern like a credit card number but they still can be used to do some client validation.
So the best ways?
To sanitize data entry on the client
side before sanitizing them on the
server.
To make "Search and Replace" of some
strings that contains pattern
I'm sure I am missing a lot of other cases.
Regular expressions are a great way to parse text that doesn't already have a parser (i.e. XML) I have used it to create a parser for the mod_rewrite syntax in the .htaccess file or in my URL Rewriter project http://www.codeplex.com/urlrewriter for example
they are really good when you want to be more specific than "*" or "?" like "3 letters then 2 numbers then a $ sign then a period"
The quote is from an anti-Perl rant from Jamie Zawinski. I think Perl used to do regex really badly but now it seems to be a standard engine for a lot of programs.
But the same sentiment still applies. If you don't know how to use regex, you better not try something real fancy other wise you get one of these tags too (see bronze list) ;o)
https://stackoverflow.com/users/730/keng
They are good for matching or finding text that takes a very specific and simple format. By "simple" I mean not nested and smaller than the entire html spec, for example.
They are primarily of value for highly structured text parsing. If you used named groups (and option in most mature regex systems), you have a phenomenally powerful and crisp way to handle the strings.
Here's an example. Consider that netstat in its various iterations on different linux OSes, and versions of netstat can return different results. Sometimes there is an extra column, sometimes there is a shift if the date/time format. Regexes give you a powerful way to handle that with a single expression. Couple that with named groups, and you can retrieve the data without hacks like:
1) split on spaces
2) ok, the netstat version is X so add I need to add 1 to all array references past column 5.
3) ok, the netstat version is Y so I need to make sure that I use multiple array references for the date info.
YUCK. Simple to fix in a Regex :-)