Catastrophic backtracking; regular expression for extracting values in nested brackets

Question

I would like to extract aaa, bb b={{b}}bb bbb and {ccc} ccc from the following string using regular expression:

zyx={aaa}, yzx={bb b={{b}}bb bbb}, xyz={{ccc} ccc}

Note: aaa represents an arbitrary sequence of any number of characters, hence no determined length or pattern. For instance, {ccc} ccc could be {cccccccccc}cc {cc} cccc cccc, or any other combination),

I have written the following regular expression:

(?<a>[^{}]*)\s*=\s*{((?<v>[^{}]+)*)},*

This expression extracts aaa, but fails to parse the rest of the input with catastrophic backtracking failure, because of the nested curly-brackets.

Any thoughts on how I can update the regex to process the nested brackets correctly?

(Just in case, I am using C# .NET Core 3.0, if you need engine-specific options. Also, I rather not doing any magics on the code, but work with the regex pattern only.)

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Similar question

The question regular expression to match balanced parentheses is similar to this question, with one difference that here the parenthesis are not necessarily balanced, rather they follow x={y} pattern.

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Update 1

Inputs such as the following are also possible:

yzx={bb b={{b}},bb bbb,}, 

Note , after {{b}} and bbb.

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Update 2

I wrote the following patter, this can match anything but aaa from the first example:

(?<A>[^{}]*)\s*=\s*{(?<V>(?<S>([^{}]?)\{(?:[^}{]+|(?&S))+\}))}(,|$)

Answer 1

Regex.Matches, pretty good

"={(.*?)}(, |$)" could work.

string input = "zyx={aaa}, yzx={bb b={{b}}bb bbb}, yzx={bb b={{b}},bb bbb,}, xyz={{ccc} ccc}";

string pattern = "={(.*?)}(, |$)";

var matches = Regex.Matches(input, pattern)
        .Select(m => m.Groups[1].Value)
        .ToList();

foreach (var m in matches) Console.WriteLine(m);

Output

aaa
bb b={{b}}bb bbb
bb b={{b}},bb bbb,
{ccc} ccc

Regex.Split, really good

I think for this job Regex.Split may be a better tool.

tring input = "zyx={aaa}, yzx={bb b={{b}}bb bbb}, yzx={bb b={{b}},bb bbb,}, ttt={nasty{t, }, }, xyz={{ccc} ccc}, zzz={{{{{{{huh?}";
var matches2 = Regex.Split(input, "(^|, )[a-zA-Z]+=", RegexOptions.ExplicitCapture); // Or "(?:^|, )[a-zA-Z]+=" without the flag


Console.WriteLine("-------------------------"); // Adding this to show the empty element (see note below)
foreach (var m in matches2) Console.WriteLine(m);
Console.WriteLine("-------------------------");

-------------------------

{aaa}
{bb b={{b}}bb bbb}
{bb b={{b}},bb bbb,}
{nasty{t, }, }
{{ccc} ccc}
{{{{{{{huh?}
-------------------------

Note: The empty element is there because:

If a match is found at the beginning or the end of the input string, an empty string is included at the beginning or the end of the returned array.

Case 3

string input = "AAA={aaa}, BBB={bbb, bb{{b}}, bbb{b}}, CCC={ccc}, DDD={ddd}, EEE={00-99} ";
var matches2 = Regex.Split(input, "(?:^|, )[a-zA-Z]+="); // Or drop '?:' and use RegexOptions.ExplicitCapture

foreach (var m in matches2) Console.WriteLine(m);

{aaa}
{bbb, bb{{b}}, bbb{b}}
{ccc}
{ddd}
{00-99}