I have the following regex:
#"{thing:(?:((\w)\2*)([^}]*?))+}"
I'm using it to find matches within a string:
MatchCollection matches = regex.Matches(string);
IEnumerable formatTokens = matches[0].Groups[3].Captures
.OfType<Capture>()
.Where(i => i.Length > 0)
.Select(i => i.Value)
.Concat(matches[0].Groups[1].Captures.OfType<Capture>().Select(i => i.Value));
This used to yield the results I wanted; however, my goal has since changed. This is the desired behavior now:
Suppose the string entered is 'stuff/{thing:aa/bb/cccc}{thing:cccc}'
I want formatTokens to be:
formatTokens[0] == "aa/bb/cccc"
formatTokens[1] == "cccc"
Right now, this is what I get:
formatTokens[0] == "/"
formatTokens[1] == "/"
formatTokens[2] == "cccc"
formatTokens[3] == "bb"
formatTokens[4] == "aa"
Note especially that "cccc" does not appear twice even though it was entered twice.
I think the problems are 1) the recapture in the regex and 2) the concat configuration (which is from when I wanted everything separated), but so far I haven't been able to find a combination that yields what I want. Can someone shed some light on the proper regex/concat combination to yield the desired results above?
You may use
Regex.Matches(s, #"{thing:([^}]*)}")
.Cast<Match>()
.Select(x => x.Groups[1].Value)
.ToList()
See the regex demo
Details
{thing: - a literal {thing: substring
([^}]*) - Capturing group #1 (when a match is obtained, its value can be accessed via match.Groups[1].Value): 0+ chars other than }
} - a } char.
This way, you find multiple matches and only collect Group 1 values in the resulting list/array.
Mod update
I'm not sure why you settled for Stringnuts regex because it matches
anything inside braces {}.
The meek on SO will not get the satisfaction of deep knowledge,
so that may be your real problem.
Lets analyze your regex.
{thing:
(?:
( # (1 start)
( \w ) # (2)
\2*
) # (1 end)
( [^}]*? ) # (3)
)+
}
This reduces to this
{thing:
(?: \w [^}]*? )+
}
The only constraint is that right after {thing: there must be a word.
After which there can be anything else, because this clause [^}]*? accepts
anything.
Also, even though that clause is not greedy, the surrounding cluster will only run one iteration (?: )+
So, basically, it does almost nothing except for the single word requirement.
Your regex can be used as is to get convoluted matches,
and because you've captured all the parts in Capture Collections,
with each match you can piece that together using the code below.
I would try to understand regex a little better, before you go on to other stuff since it is likely much more important than the
language tricks used to extract data.
Here is how you would piece it all together using your unaltered regex.
Regex regex = new Regex(#"{thing:(?:((\w)\2*)([^}]*?))+}");
string str = "stuff/{thing:aa/bb/cccc}{thing:cccc}";
foreach (Match match in regex.Matches(str))
{
CaptureCollection cc1 = match.Groups[1].Captures;
CaptureCollection cc3 = match.Groups[3].Captures;
string token = "";
for (int i = 0; i < cc1.Count; i++)
token += cc1[i].Value + cc3[i].Value;
Console.WriteLine("{0}", token);
}
Output
aa/bb/cccc
cccc
Note that for example, your regex will match almost anything inside
of the braces as long as the first character is a word.
For example, it matches {thing:Z,,,*()(((asgassgasg,asgfasgafg\/\=99.239 }
You may want to think about the requirements of what actually is allowed
inside the braces.
Good Luck!
Related
The Enum I want to extract is like following:
...
other code
...
enum A
{
a,
b=2,
c=3,
d//{x}
}
...
More Enums like the above.
...
First, I have tried using the Option Singleline with Regex:
enum\s*\w+\s*{.*?\}
However, since the comments have brackets.The regex doesn't work. It will stop when it runs to the bracket in comments.
So I tried excluding the bracket after comments. Based on what I have searched so far,it seems I need Negative look ahead with grouping construct Multiline.
Then I tried parsing the brackets without comments ahead.
The substep is to find brackets after comments:
(?m:^.*?//.*?}.*?$).
However, it seems the . still match anychar including newline even in inline multiline mode.
Then I tried using multiline in the first place. Since the main problem is the brackets in comments.I tried:
(?!//.*)}
Negative look ahead doesn't work the way I expected.
Here is a csharp-regex-test-link for you to test.
To summarize, I need parse enum from a csharp source code file.
The main problem to me is the brackets in comments.
Edit:
To clarify
1.brackets in comments are in pairs. For example:
xxx=xxx; //{xx}
2.comments are only in the form of //
3.I can't rely on indentations.
You may use
#"\benum\s*\w+\s*{(?>[^{}]+|(?<o>){|(?<-o>)})*(?(o)(?!)|)}"
See the regex demo
Details
\benum - a whole word enum
\s* - 0+ whitespaces
\w+ - 1+ word chars
\s* - 0+ whitespaces
{ - a { char
(?>[^{}]+|(?<o>){|(?<-o>)})* - either 1+ chars other than { and }, or a { with an empty string pushed onto the Group o stack, or } with a value popped from Group o stack
(?(o)(?!)|) - a conditional yes-no construct that fails the match and makes the regex engine backtrack at the current location if Group o still has any items left on the stack
} - a } char.
I don't think it is possible to do your task with a single regex. What if you have a string that looks like
var notEnum = "enum A {a, b, c}";
Hovewer you can capture your enums with few passes. Take a look at this algorithm
Clear strings content
Drop singleline comments
Drop muliline comments
Use you original regex
Example:
var code = ...
var stringLiterals = new Regex("\"[^\"\\\\]*(?:\\\\.[^\"\\\\]*)*\"", RegexOptions.Compiled);
var multilineComments = new Regex("/\\*.*?\\*/", RegexOptions.Compiled | RegexOptions.Singleline);
var singlelineComments = new Regex("//.*$", RegexOptions.Compiled | RegexOptions.Multiline);
var #enum = new Regex("enum\\s*\\w+\\s*{.*?}", RegexOptions.Compiled | RegexOptions.Singleline);
code = stringLiterals.Replace(code, m => "\"\"");
code = multilineComments.Replace(code, m => "");
code = singlelineComments.Replace(code, m => "");
var enums = #enum.Matches(code).Cast<Match>().ToArray();
foreach (var match in enums)
Console.WriteLine(match.Value);
I'm reading from a file, and need to find a string that is encapsulated by two identical non-ascii values/control seperators, in this case 'RS'
How would I go about doing this? Would I need some form of regex?
RS stands for Record Separator, and it has a value of 30 (or 0x1E in hexadecimal). You can use this regular expression:
\x1E([\w\s]*?)\x1E
That matches the RS, then matches any letter, number or space, and then again the RS. The ? is to make the regex match as less characters as possible, in case there are more RS characters afterwards.
If you prefer not to match numbers, you could use [a-zA-Z\s] instead of [\w\s].
Example:
string fileContents = "Something \u001Eyour string\u001E more things \u001Eanother text\u001E end.";
MatchCollection matches = Regex.Matches(fileContents, #"\x1E([\w\s]*?)\x1E");
if (matches.Count == 0)
return; // Not found, display an error message and exit.
foreach (Match match in matches)
{
if (match.Groups.Count > 1)
Console.WriteLine(match.Groups[1].Value);
}
As you can see, you get a collection of Match, and each match.Value will have the whole matched string including the separators. match.Groups will have all matched groups, being the first one again the whole matched string (that's by default) and then each of your groups (those between parenthesis). In this case, you only have one in your regex, so you just need the second one on that list.
Using regex you can do something like this:
string pattern = string.Format("{0}(.*){1}",firstString,secondString);
var matches = Regex.Matches(myString, pattern);
foreach (Match match in matches)
{
foreach (Capture capture in match.Captures)
{
//Do stuff, with the current you should remove firstString and secondString from the capture.Value
}
}
After that use Regex.match to find the string that match with the pattern built before.
Remember to escape all the special char for regex.
You can use Regex.Matches, I'm using X as the separator in this example:
var fileContents = "Xsomething1X Xsomething2X Xsomething3X";
var results = Regex.Matches(fileContents, #"(X).*?(\1)");
The you can loop on results to do anything you want with the matches.
The \1 in the regex means "reference first group". I've put X between () so it is going to be group 1, the I use \1 to say that the match in this place should be exactly the same as the group 1.
You don't need a regular expression for that.
Read the contents of the file (File.ReadAllText).
Split on the separator character (String.Split).
If you know there's only one occurrence of your string, take the second array element (result[1]). Otherwise, take every other entry (result.Where((x, i) => i % 2 == 1)).
I'm struggling to get this regex pattern exactly right, and am open to other options outside of regex if someone has a better alternative.
The situation:
I'm basically looking to parse a T-SQL "in" clause against a text column in C#. So, I need to take a string value like this:
"'don''t', 'do', 'anything', 'stupid'"
And interpret that as a list of values (I'll take care of the double single quotes later):
"don''t"
"do"
"anything"
"stupid"
I have a regex that works for most cases, but I'm struggling to generalize it to the point where it will accept any character OR a doubled-up single quote inside my group: (?:')([a-z0-9\s(?:'(?='))]+)(?:')[,\w]*
I'm fairly experienced with regexes, but have rarely, if ever, found a need for look-arounds (so downgrade my assessment of my regex experience accordingly).
So, to put this another way, I'm wanting to take a string of comma-delimited values, each enclosed in single quotes but can contain doubled single quotes, and output each such value.
EDIT
Here's a non-working example with my current regex (my problem is I need to handle all characters in my grouping and stop when I encounter a single quote not followed by a second single quote):
"'don''t', 'do?', 'anything!', '#stupid$'"
If you still think about a regex-based solution, you can use the following regex:
'(?:''|[^'])*'
Or an "un-rolled" version suggested by #sln:
'[^']*(?:''[^']*)*'
See demo
It is fairly simple, it captures double single quotation marks OR anything that is not a single quotation mark. No need using any look-behinds or look-aheads. It does not take care of any escaped entities, but I do not see this requirement in your question.
Moreover, this regex will return matches that are easy to access and deal with:
var text = "'don''t', 'do', 'anything', 'stupid'";
var re = new Regex(#"'[^']*(?:''[^']*)*'"); // Updated thanks to #sln, previous (#"'(?:''|[^'])*'");
var match_values = re.Matches(text).Cast<Match>().Select(p => p.Value).ToList();
Output:
If you want to use the Capture Collection feature, you can grab them all in a
single pass.
# #"""\s*(?:'([^']*(?:''[^']*)*)'\s*(?:,\s*|(?="")))+"""
"
\s*
(?:
'
( # (1 start)
[^']*
(?:
'' [^']*
)*
) # (1 end)
'
\s*
(?:
, \s*
| (?= " )
)
)+
"
C# code:
string strSrc = "\"'don''t', 'do', 'anything', 'stupid'\"";
Regex rx = new Regex(#"""\s*(?:'([^']*(?:''[^']*)*)'\s*(?:,\s*|(?="")))+""");
Match srcMatch = rx.Match(strSrc);
if (srcMatch.Success)
{
CaptureCollection cc = srcMatch.Groups[1].Captures;
for (int i = 0; i < cc.Count; i++)
Console.WriteLine("{0} = '{1}'", i, cc[i].Value);
}
Output:
0 = 'don''t'
1 = 'do'
2 = 'anything'
3 = 'stupid'
Press any key to continue . . .
Why don't you split on ', ':
Regex regex = new Regex(#"'\s*,\s*'");
string[] substrings = regex.Split(str);
And then take care of the extra single quotes by Trimming
Looks to me like you're over-thinking the problem. A quoted string with an escaped quote looks just like two strings without escaped quotes, one right after the other (not even spaces between them).
(?:'[^']*')+
Of course, you'll have to remove the enclosing quotes, but you probably had to do some post-processing anyway, to unescape the escaped quotes.
Also note that I'm not trying to validate the input or work around possible errors; for example, I don't bother matching the commas between the strings. If the input is well formed, this regex should be all you need.
In the interest of maintainability, I decided against a regex and followed the advice of using a state machine. Here's the crux of my implementation:
string currentTerm = string.Empty;
State currentState = State.BetweenTerms;
foreach (char c in valueToParse)
{
switch (currentState)
{
// if between terms, only need to do something if we encounter a single quote, signalling to start a new term
// encloser is client-specified char to look for (e.g. ')
case State.BetweenTerms:
if (c == encloser)
{
currentState = State.InTerm;
}
break;
case State.InTerm:
if (c == encloser)
{
if (valueToParse.Length > index + 1 && valueToParse[index + 1] == encloser && valueToParse.Length > index + 2)
{
// if next character is also encloser then add it and move on
currentTerm += c;
}
else if (currentTerm.Length > 0 && currentTerm[currentTerm.Length - 1] != encloser)
{
// on an encloser and didn't just add encloser, so we are done
// converterFunc is a client-specified Func<string,T> to return terms in the specified type (to allow for converting to int, for example)
yield return converterFunc(currentTerm);
currentTerm = string.Empty;
currentState = State.BetweenTerms;
}
}
else
{
currentTerm += c;
}
break;
}
index++;
}
if (currentTerm.Length > 0)
{
yield return converterFunc(currentTerm);
}
I tried to find a method to count a specific word in a string, and I found this.
using System.Text.RegularExpressions;
MatchCollection matches = Regex.Matches("hi, hi, everybody.", ",");
int cnt = matches.Count;
Console.WriteLine(cnt);
It worked fine, and the result shows 2.
But when I change "," to ".", it shows 18, not the expected 1. Why?
MatchCollection matches = Regex.Matches("hi, hi, everybody.", ".");
and when I change "," to "(", it shows me an error!
the error reads:
SYSTEM.ARGUMENTEXCEPTION - THERE ARE TOO MANY (...
I don't understand why this is happening
MatchCollection matches = Regex.Matches("hi( hi( everybody.", "(");
Other cases seem to work fine but I need to count "(".
The first instance, with the ., is using a special character which has a different meaning in regular expressions. It is matching ALL of the characters you have; hence you getting a result of 18.
http://www.regular-expressions.info/dot.html
To match an actual "." character, you'll need to "escape" it so that it is read as a full-stop and not a special character.
MatchCollection matches = Regex.Matches("hi, hi, everybody.", "\.");
The same exists for the ( character. It's a special character that has a different meaning in terms of regular expressions and you will need to escape it.
MatchCollection matches = Regex.Matches("hi( hi( everybody.", "\(");
Looks like you're new to regular expressions so I'd suggest reading, the link I posted above is a good start.
HOWEVER!
If you are looking to just count ocurences in a string, you don't need regex.
How would you count occurrences of a string within a string?
If you're using .NET 3.5 you can do this in a one-liner with LINQ:
int cnt = source.Count(f => f == '(');
If you don't want to use LINQ you can do it with:
int cnt = source.Split('(').Length - 1;
The second parameter represents a pattern, not necessarily just a character to search for in your string, and the ( by itself is an invalid pattern.
You don't need Regex to count occurrences of a character. Just use LINQ's Count():
var input = "hi( hi( everybody.";
var occurrences = input.Count(x => x == '('); // 2
( character is a special character which means start of a group. If you need to use ( as literal you need to escape it with \(. That should solve your problem.
I need to create a regex that can match multiple strings. For example, I want to find all the instances of "good" or "great". I found some examples, but what I came up with doesn't seem to work:
\b(good|great)\w*\b
Can anyone point me in the right direction?
Edit: I should note that I don't want to just match whole words. For example, I may want to match "ood" or "reat" as well (parts of the words).
Edit 2: Here is some sample text: "This is a really great story."
I might want to match "this" or "really", or I might want to match "eall" or "reat".
If you can guarantee that there are no reserved regex characters in your word list (or if you escape them), you could just use this code to make a big word list into #"(a|big|word|list)". There's nothing wrong with the | operator as you're using it, as long as those () surround it. It sounds like the \w* and the \b patterns are what are interfering with your matches.
String[] pattern_list = whatever;
String regex = String.Format("({0})", String.Join("|", pattern_list));
(good)*(great)*
after your edit:
\b(g*o*o*d*)*(g*r*e*a*t*)*\b
I think you are asking for smth you dont really mean
if you want to search for any Part of the word, you litterally searching letters
e.g. Search {Jack, Jim} in "John and Shelly are cool"
is searching all letters in the names {J,a,c,k,i,m}
*J*ohn *a*nd Shelly *a*re
and for that you don't need REG-EX :)
in my opinion,
A Suffix Tree can help you with that
http://en.wikipedia.org/wiki/Suffix_tree#Functionality
enjoy.
I don't understand the problem correctly:
If you want to match "great" or "reat" you can express this by a pattern like:
"g?reat"
This simply says that the "reat"-part must exist and the "g" is optional.
This would match "reat" and "great" but not "eat", because the first "r" in "reat" is required.
If you have the too words "great" and "good" and you want to match them both with an optional "g" you can write this like this:
(g?reat|g?ood)
And if you want to include a word-boundary like:
\b(g?reat|g?ood)
You should be aware that this would not match anything like "breat" because you have the "reat" but the "r" is not at the word boundary because of the "b".
So if you want to match whole words that contain a substring link "reat" or "ood" then you should try:
"\b\w*?(reat|ood)\w+\b"
This reads:
1. Beginning with a word boundary begin matching any number word-characters, but don't be gready.
2. Match "reat" or "ood" enshures that only those words are matched that contain one of them.
3. Match any number of word characters following "reat" or "ood" until the next word boundary is reached.
This will match:
"goodness", "good", "ood" (if a complete word)
It can be read as: Give me all complete words that contain "ood" or "reat".
Is that what you are looking for?
I'm not entirely sure that regex alone offers a solution for what you're trying to do. You could, however, use the following code to create a regex expression for a given word. Although, the resulting regex pattern has the potential to become very long and slow:
function wordPermutations( $word, $minLength = 2 )
{
$perms = array( );
for ($start = 0; $start < strlen( $word ); $start++)
{
for ($end = strlen( $word ); $end > $start; $end--)
{
$perm = substr( $word, $start, ($end - $start));
if (strlen( $perm ) >= $minLength)
{
$perms[] = $perm;
}
}
}
return $perms;
}
Test Code:
$perms = wordPermutations( 'great', 3 ); // get all permutations of "great" that are 3 or more chars in length
var_dump( $perms );
echo ( '/\b('.implode( '|', $perms ).')\b/' );
Example Output:
array
0 => string 'great' (length=5)
1 => string 'grea' (length=4)
2 => string 'gre' (length=3)
3 => string 'reat' (length=4)
4 => string 'rea' (length=3)
5 => string 'eat' (length=3)
/\b(great|grea|gre|reat|rea|eat)\b/
Just check for the boolean that Regex.IsMatch() returns.
if (Regex.IsMatch(line, "condition") && Regex.IsMatch(line, "conditition2"))
The line will have both regex, right.