I have some 100 files in which I need to replace:
Eval("something") with Eval("something").ToEncodedString()
Eval("something").ToString() with Eval("something").ToEncodedString()
I'm writing a small C# application that can automate this. But unable to form the regular expression. Would somebody help me please?
You can use this pattern: #"\bEval\(""(?<Value>.+?)""\)(?:\.ToString\(\))?"
Breakdown:
\bEval: match a word-boundary to ensure we match "Eval" as a whole word and not as part of another word
\("": literal opening parenthesis and double quotes (the double quotes appear twice since that's how they're escaped when using a verbatim string literal, i.e., the # symbol preceding the string)
(?<Value>.+?): named capture group of "Value" which is a non-greedy match of any character (will stop at double quotes)
""\): closing double quotes and closing parenthesis
(?:\.ToString\(\))?: the (?:...) bit is a non-capturing group, then we match .ToString() literally with appropriate escaping, and the final ? makes this group optional
The replacement pattern is #"Eval(""${Value}"").ToEncodedString()", which is easy to understand. The important part is that the named capture group, "Value," is referenced by using ${Value}.
Example code:
string[] inputs =
{
#"Eval(""something"")",
#"Eval(""hello"").ToString()"
};
string pattern = #"\bEval\(""(?<Value>.+?)""\)(?:\.ToString\(\))?";
string replacement = #"Eval(""${Value}"").ToEncodedString()";
foreach (var input in inputs)
{
Console.WriteLine(Regex.Replace(input, pattern, replacement));
}
Related
I need to be able to remove a pair of double quotes around words, without removing single instances of double quotes.
Ie. in the below examples, the regex should only match around "hello" and "bounce", without removing the word itself.
3.5" hdd
"hello"
"cool
"bounce"
single sentence with out quotes.
Closest regex i've found so far is this one below, but this highlights the entire "bounce" word which is not acceptable as I need to retain the word.
"([^\\"]|\\")*"
Other close regex I've found in my research:
1.
\"*\"
but this highlights the single quotes.
and Unsuccessful Method 2
This needs to be usable in C# code.
I've been using RegexStorm to test my regex: http://regexstorm.net/reference
Your first regex seems fine but lacks an outer capturing group. It would be better if we transform this into a linear regex, avoiding alternation.
"([^\\"\r\n]*(?:\\.[^\\"\r\n]*)*)"
I included carriage return \r and \n in character class to prevent regex from going more than one line in regex, you may not need them however. You then replace whole match with $1 (a back-reference to first capturing group saved data). To escape a " in C# use double quote "".
Live demo
C# code:
string pattern = #"""([^\\""\r\n]*(?:\\.[^\\""\r\n]*)*)""";
string input = #"3.5"" hdd
""hello""
""cool
""bounce""
single sentence with out quotes.";
Regex regex = new Regex(pattern);
Console.WriteLine(regex.Replace(input, #"$1"));
I'm having a hard time with this one. First off, here is the difficult part of the string I'm matching against:
"a \"b\" c"
What I want to extract from this is the following:
a \"b\" c
Of course, this is just a substring from a larger string, but everything else works as expected. The problem is making the regex ignore the quotes that are escaped with a backslash.
I've looked into various ways of doing it, but nothing has gotten me the correct results. My most recent attempt looks like this:
"((\"|[^"])+?)"
In various test online, this works the way it should - but when I build my ASP.NET page, it cuts off at the first ", leaving me with just the a-letter, white space and a backslash.
The logic behind the pattern above is to capture all instances of \" or something that is not ". I was hoping this would search for \", making sure to find those first - but I got the feeling that this is overridden by the second part of the expression, which is only 1 single character. A single backslash does not match 2 characters (\"), but it will match as a non-". And from there, the next character will be a single ", and the matching is completed. (This is just my hypothesis on why my pattern is failing.)
Any pointers on this one? I have tried various combinations with "look"-methods in regex, but I didn't really get anywhere. I also get the feeling that is what I need.
ORIGINAL ANSWER
To match a string like a \"b\" c, you need to use following regex declaration:
(?:\\"|[^"])+
var rx = Regex(#"(?:\\""|[^""])+");
See RegexStorm demo
Here is an IDEONE demo:
var str = "a \\\"b\\\" c";
Console.WriteLine(str);
var rx = new Regex(#"(?:\\""|[^""])+");
Console.WriteLine(rx.Match(str).Value);
Please note the # in front of the string literal that lets us use verbatim string literals where we have to double quotes to match literal quotes and use single escape slashes instead of double. This makes regexps easier to read and maintain.
If you want to match any escaped entities in your input string, you can use:
var rx = new Regex(#"[^""\\]*(?:\\.[^""\\]*)*");
See demo on RegexStorm
UPDATE
To match the quoted strings, just add quotes around the pattern:
var rx = new Regex(#"""(?<res>[^""\\]*(?:\\.[^""\\]*)*)""");
This pattern yields much better performance than Tim Long's suggested regex, see RegexHero test resuls:
The following expression worked for me:
"(?<Result>(\\"|.)*)"
The expression matches as follows:
An opening quote (literal ")
A named capture (?<name>pattern) consisting of:
Zero or more occurences * of literal \" or (|) any single character (.)
A final closing quote (literal ")
Note that the * (zero or more) quantifier is non-greedy so the final quote is matched by the literal " and not the "any single character" . part.
I used ReSharper 9's built-in Regular Expression validator to develop the expression and verify the results:
I have used the "Explicit Capture" option to reduce cruft in the output (RegexOptions.ExplicitCapture).
One thing to note is that I am matching the whole string, but I am only capturing the substring, using a named capture. Using named captures is a really useful way to get at the results you want. In code, it might look something like this:
static string MatchQuotedString(string input)
{
const string pattern = #"""(?<Result>(\\""|.)*)""";
const RegexOptions options = RegexOptions.ExplicitCapture;
Regex regex = new Regex(pattern, options);
var matches = regex.Match(input);
var substring = matches.Groups["Result"].Value;
return substring;
}
Optimization: If you are planning on using the regex a lot, you could factor it out into a field and use the RegexOptions.Compiled option, this pre-compiles the expression and gives you faster throughput at the expense of longer initialization.
How do I make Regex stop the search after "Target This"?
HeaderText="Target This" AnotherAttribute="Getting Picked Up"
This is what i've tried
var match = Regex.Match(string1, #"(?<=HeaderText=\").*(?=\")");
The quantifier * is eager, which means it will consume as many characters as it can while still getting a match. You want the lazy quantifier, *?.
As an aside, rather than using look-around expressions as you have done here, you may find it in general easier to use capturing groups:
var match = Regex.Match(string1, "HeaderText=\"(.*?)\"");
^ ^ these make a capturing group
Now the match matches the whole thing, but match.Groups[1] is just the value in the quotes.
Plain regex pattern
(?<=HeaderText=").*?(?=")
or as string
string pattern = "(?<=HeaderText=\").*?(?=\")";
or using a verbatim string
string pattern = #"(?<=HeaderText="").*?(?="")";
The trick is the question mark after .*. It means "as few as possible", making it stop after the first end-quotes it encounters.
Note that verbatim strings (introduced with #) do not recognize the backslash \ as escape character. Escape the double quotes by doubling them.
Note for others interested in regex: The search pattern used finds a postion between a prefix and a suffix:
(?<=prefix)find(?=suffix)
Try this:
var match = Regex.Match(string1, "HeaderText=\"([^\"]+)");
var val = match.Groups[1].Value; //Target This
UPDATE
if there possibilities have double quotes in target,change the regex to:
HeaderText=\"(.+?)\"\\s+\\w
Note: it's not right way to do this, if it's a XML, check out System.XML otherwise,HtmlAgilityPack / How to use HTML Agility pack.
I'm trying to write a regular expression that finds C#-style unescaped strings, such as
string x = #"hello
world";
The problem I'm having is how to write a rule that handles double quotes within the string correctly, like in this example
string x = #"before quote ""junk"" after quote";
This should be an easy one, right?
Try this one:
#".*?(""|[^"])"([^"]|$)
The first parantheses mean 'If there is an " before the finishing quote, it better be two of them', the second parantheses mean 'After the finishing quote, there sould ether be not a quote, or the end of the line'.
How 'bout the regex #\"([^\"]|\"\")*\"(?=[^\"])
Due to greedy matching, the final lookahead clause is likely not to be needed in your regex engine, although it is more specific.
If I remember correctly, you have to use \"" - the double-double quotes to hash it for C# and the backslash to hash it for regex.
Try this:
#"[^"]*?(""[^"]*?)*";
It looks for the starting characters #", for the ending characters "; (you can leave the semicolon out if you need to) and in between it can have any characters except quotes, or if there are quotes they have to be doubled.
#"(?:""|[^"])*"(?!")
is the right regex for this job. It matches the #, a quote, then either two quotes in a row or any non-quote character, repeating this up unto the next quote (that isn't doubled).
"^#(""|[^"])*$" is the regex you want, looking for first an at-sign and a double-quote, then a sequence of any characters (except double-quotes) or double double-quotes, and finally a double-quote.
As a string literal in C#, you'd have to write it string regex = "^#\"(\"\"|[^\"])*\"$"; or string regex = #"^#""(""""|[^""])*""$";. Choose your poison.
Greetings, I have file with the following strings:
string.Format("{0},{1}", "Having \"Two\" On The Same Line".Localize(), "Is Tricky For regex".Localize());
my goal is to get a match set with the two strings:
Having \"Two\" On The Same Line
Is Tricky For regex
My current regex looks like this:
private Regex CSharpShortRegex = new Regex("\"(?<constant>[^\"]+?)\".Localize\\(\\)");
My problem is with the escaped quotes in the first line I end up stopping at the quote and I get:
On The Same Line
Is Tricky For This Style Too
however attempting to ignore the escaped quotes is not working out because it makes the Regex greedy and I get
Having \"Two\" On The Same Line".Localize(), "Is Tricky For regex"
We seem to be caught between maximum and minimum munge. Is there any hope? I have some backup plans. Can you Regex backwards? that would make it easier because I can start with the "()ezilacoL."
EDIT:
To clarify. This is my lone edge case. Most of the time the string sits alone like:
var myString = "Hot Patootie".Localize()
This one works for me:
\"((?:[^\\"]|(?:\\\"))*)\"\.Localize\(\)
Tested on http://www.regexplanet.com/simple/index.html against a number of strings with various escaped quotes.
Looks like most of us who answered this one had the same rough idea, so let me explain the approach (comments after #s):
\" # We're looking for a string delimited by quotation marks
( # Capture the contents of the quotation marks
(?: # Start a non-capturing group
[^\\"] # Either read a character that isn't a quote or a slash
|(?:\\\") # Or read in a slash followed by a quote.
)* # Keep reading
) # End the capturing group
\" # The string literal ends in a quotation mark
\.Localize\(\) # and ends with the literal '.Localize()', escaping ., ( and )
For C# you'll need to escape the slashes twice (messy):
\"((?:[^\\\\\"]|(?:\\\\\"))*)\"\\.Localize\\(\\)
Mark correctly points out that this one doesn't match escaped characters other than quotation marks. So here's a better version:
\"((?:[^\\"]|(?:\\")|(?:\\.))*)\"\.Localize\(\)
And its slashed-up equivalent:
\"((?:[^\\\\\"]|(?:\\\\\")|(?:\\\\.))*)\"\\.Localize\\(\\)
Works the same way, except it has a special case that if encounters a slash but it can't match \", it just consumes the slash and the following character and moves on.
Thinking about it, it's better to just consume two characters at every slash, which is effectively Mark's answer so I won't repeat it.
Here's the regular expression you need:
#"""(?<constant>(\\.|[^""])*)""\.Localize\(\)"
A test program:
using System;
using System.Text.RegularExpressions;
using System.IO;
class Program
{
static void Main()
{
Regex CSharpShortRegex =
new Regex(#"""(?<constant>(\\.|[^""])*)""\.Localize\(\)");
foreach (string line in File.ReadAllLines("input.txt"))
foreach (Match match in CSharpShortRegex.Matches(line))
Console.WriteLine(match.Groups["constant"].Value);
}
}
Output:
Having \"Two\" On The Same Line
Is Tricky For regex
Hot Patootie
Notice that I have used #"..." to avoid having to escape backslashes inside the regular expression. I think this makes it easier to read.
Update:
My original answer (below the horizontal rule) has a bug: regular-expression matchers attempt alternatives in left-to-right order. Having [^"] as the first alternative allows it to consume the backslash, but then the next character to be matched is a quote, which prevents the match from proceeding.
Incompatibility note: Given the pattern below, perl backtracks to the other alternative (the escaped quote) and successfully finds a match for the Having \"Two\" On The Same Line case.
The fix is to try an escaped quote first and then a non-quote:
var CSharpShortRegex =
new Regex("\"(?<constant>(\\\\\"|[^\"])*)\"\\.Localize\\(\\)");
or if you prefer the at-string form:
var CSharpShortRegex =
new Regex(#"""(?<constant>(\\""|[^""])*)""\.Localize\(\)");
Allow for escapes:
private Regex CSharpShortRegex =
new Regex("\"(?<constant>([^\"]|\\\\\")*)\"\\.Localize\\(\\)");
Applying one level of escaping to make the pattern easier to read, we get
"(?<constant>([^"]|\\")*)"\.Localize\(\)
That is, a string starts and ends with " characters, and everything between is either a non-quote or an escaped quote.
Looks like you're trying to parse code so one approach might be to evaluate the code on the fly:
var cr = new CSharpCodeProvider().CompileAssemblyFromSource(
new CompilerParameters { GenerateInMemory = true },
"class x { public static string e() { return " + input + "}}");
var result = cr.CompiledAssembly.GetType("x")
.GetMethod("e").Invoke(null, null) as string;
This way you could handle all kinds of other special cases (e.g. concatenated or verbatim strings) that would be extremely difficult to handle with regex.
new Regex(#"((([^#]|^|\n)""(?<constant>((\\.)|[^""])*)"")|(#""(?<constant>(""""|[^""])*)""))\s*\.\s*Localize\s*\(\s*\)", RegexOptions.Compiled);
takes care of both simple and #"" strings. It also takes into account escape sequences.