I am using the regex ((.*)?:)?(.*)\\/([0-9]+|[n])? to match pattern of type module:function/arity, where arity can be any number >= 0 or the string n.
Success cases should match:
foo:bar/1
bar/1
foo:bar/0
foo:bar/n
bar/n
This seems to work fine at https://regex101.com/r/AtI5Nw/3, but using the following code, I am getting only one match group for "mod:func/1".
+ (NSArray<NSTextCheckingResult *> *)matchesInString:(NSString *)string withExpression:(NSRegularExpression *)pattern {
return [pattern matchesInString:string options:0 range:NSMakeRange(0, [string length])];
}
I tried with "mod:func/1" string and I am getting only one match. How to get all matching groups as in the screenshot? I want to get the module, function and arity parts from the string.
It's been awhile since I've done this, but...
matchesInString:... returns an array of NSTextCheckingResult objects. Each object represents a single match of the entire regex within the string.
Each NSTextCheckingResult object encapsulates a number of "ranges" (see numberOfRanges property). You then use rangeAtIndex: to extract the range of each group within that match instance.
If each target is in a separate string, you don't need matchesInString:..., simply use firstMatchInString:... to obtain the one, and only, NSTextCheckingResult for your string. You can then extract each group by getting its range, then return to the original string to extract the text of that component.
Related
I have a CoreData table with a field holding a string of a series of numbers separated by commas. I want to be able to run a fetch with a predicate that will match against a given specific number.
For example if fieldName = "12,52,66,89,2,8"
And I want to search for 2, then it should match the second to last number in the string and include that record in the results.
Using the regular expression:
^2|,2,|,2
I have found it working satisfactorily for my test cases, testing it using this site for example: https://www.regexpal.com/
However, when I pass this into an NSPredicate for a NSFetchRequest, I can't get it to match
NSNumber *val = #2;
NSString *regex = [NSString stringWithFormat:#"^%#|,%#,|,%#", val, val, val];
NSPredicate *pred = [NSPredicate predicateWithFormat:#"fieldName MATCHES %#", regex];
Replacing the MATCHES with a CONTAINS val makes it work, but of course it will also incorrectly match any occurrence of the digits.
I suspect I am missing something stupid about formatting for CoreData (or regex), but I've tried many variations, and I'm hoping a kind soul reading this will put me out of my misery :)
Disclaimer: I haven't used Objective C. This answer is based on my regex knowledge and some documentation.
MATCHES
The left hand expression equals the right hand expression using a regex-style comparison according to ICU v3 (for more details see the ICU User Guide for Regular Expressions).
That sounds like how Java uses the method "matches" in which case "^2|,2,|,2" can never match the entire string. This differs from regexpal which will always search the text. The regex you would need is more like
.*\b2\b.*
(the ^$ are assumed in Java). Another option is to split the string.
I have a string with random names with an invisible decimal value as prefix . The decimal = the names length. I need to retrieve the names. Obviously they are of different length. I want the names in an array so my idea is to use stringByReplacingOccurrencesOfString:withString. I implement the word "trunk" at the beginning and end of names. Though I am having trouble accessing the index corresponding at the end of the name (decimal value), here is my code :
trimmed1 = [[trimmed1 stringByReplacingOccurrencesOfString:sp withString:#"trunk"]mutableCopy];
NSString *trunk = #"trunk%d";// add the ghost decimal at the end of prefix in order to get its value;
NSRange range =[trimmed1 rangeOfString:trunk];
int ghost= [trunk characterAtIndex:5];
NSMutableString *mu = [NSMutableString stringWithString:trimmed1];
[mu insertString : #"trunk" atIndex :range.location+range.length+ ghost];
I get the error [__NSCFString insertString:atIndex:]: Range or index out of bounds.
You are misunderstanding what %d means.
In a format used for creating a string it means "insert the value of an integer argument formatted as a string".
When matching one string against another it means "match the characters %d", I.e. it is not special in anyway.
You are getting an error as your string does not contain the characters "trunk%d". If you check the return value of rangeOfString: you will find it is returning a failure indication - read the documentation for how to test for that value.
For the simple task of matching an arbitrary decimal number trying looking at the NSString method rangeOfCharactersFromSet:.
You can also solve this problem with the classes NSScanner and NSRegularExpression.
HTH
just faced the problem of inability to write a good regex that would satisfy my needs. I've never used regex before, so that wasn't a big surprise for me.
Here are the good input examples that I'm trying to validate:
01
00:01
01:02:03
01:02:03:04 - max 3 colons possible
123,456,789 - max two commas possible
40000035
1:2:06
here are the bad ones:
,3234
134,2343,333
000:01:00
:01:03:00
:01
01:
First I tried to write one that would cover at least all the colon cases and here is what I have:
NSUInteger numberOfMatches = -1;
NSError *error = NULL;
NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:#"([([0-9]{1,2}):]{1,3})([0-9]{1,2})"
options:NSRegularExpressionCaseInsensitive
error:&error];
if (error) {
NSLog(#"error %#", error);
}
numberOfMatches = [regex numberOfMatchesInString:stringToValidate
options:0
range:NSMakeRange(0, [stringToValidate length])];
I'm also curious if NSRegularExpression has any methods to extract the validated substrings in a some sort of an array?!
For example:
12:23:63 --- would be validated and the array would contain [12,23,63]
234 --- would be validated and the array would contain [234]
123,235,653 --- would be validated and the array would contain [123235653]
basically colon separated input would be as separate values and everything else would be as one value
In order to achieve what you want, you I suggest you do one for each case for validation.
Validation
Colons:
^\d{1,2}(?::\d{1,2}){0,2}(?::\d{2})?$
Commas:
^\d{3}(?:,\d{3}){0,2}$
Just the number:
^\d+$
Then assuming you pass validation of each case, use something else for data extraction.
Data Extraction
Colons
Simply do a string split on the colons.
Commas:
Remove all occurences of , in the string.
Just the number:
Well, you have what you need here, so no need to make any changes.
I haven't used regular expressions yet in objective-c. What I'm trying to do right now is evaluate a string to see if it contains a 4 or 5 character repeating pattern - any pattern, it doesn't matter. For instance, a string like #"testA54RqA54Rq" would return a true value from the regex, while a string like #"testA54Rq" would not. Right now I'm just generating all possible 4 and 5 character substrings and matching them to each other, but obviously this is extremely inefficient. Where can I find some resources about how to start using regular expressions in objective C? If anyone's been in this situation before a small example would be nice.
-EDIT-
I would also like to have somthing like #"testQWEr30BKRe40" return true (pattern of 4 letters followed by 2 numbers). I'm not sure if this is possible.
You probably want to look at:
https://developer.apple.com/library/ios/#documentation/Foundation/Reference/NSRegularExpression_Class/Reference/Reference.html
The actual regex I believe would just be: (\\w{4,5})\\1
NSString *regexStr = #"(\\w{4,5})\\1";
NSError *error = nil;
NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:regexStr options:0 error:&error];
if ((regex==nil) && (error!=nil)) {
warn( #"Regex failed for: %#, error was: %#", string, error);
} else {
}
For exact patterns you will be able to do such validation with regex (.{4,5})\\1
If you want to do category pattern, such as 4 letters followed by 2 numbers, then you have to:
replace all letters with one constant letter (for example replace [a-zA-Z] with X)
replace all numbers with one constant number (for example replace \\d with 0)
validate such modified input with the same regex as shown above
I'm trying to get some info out of a document. I'm trying to match the info I need with regex, which matches 3 numbers within a string. It works fine, but it only matches the first occurance. I need it to match an unlimited number of times because I don't know how many times this string will occur.
NSString *regex = #"String containing data:(\\d+) and more data:(\\d+) and so on";
NSArray *captures = [document captureComponentsMatchedByRegex:regex];
for(NSString *match in captures){
NSLog(#"%#",match);
}
The above code prints out 3 strings - The entire string, the first data and the second data. All good, but now I need it to keep searching the document, because similar strings will occur n times.
How do I do this? And is there any way to group the matches into an array for each string or something like that?
Use the arrayOfCaptureComponentsMatchedByRegex: method. That will return an NSArray of NSArray objects, and each nested NSArray object will have the captures (index 0 being the string, index 1 being the first capture, etc).