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I need to put multiple regular expressions in a single string and then parse it back as separate regex. Like below
regex1<!>regex2<!>regex3
Problem is I am not sure which delimiter will be best to use to separate the expressions in place of <!> shown in example, so that I can safely split the string when parsing it back.
Constraints are, I can not make the string in multiple lines or use xml or json string. Because this string of expressions should be easily configurable.
Looking forward for any suggestion.
Edited:
Q: Why does it have to be a single string?
A: The system has a configuration manager that loads config from properties file. And properties are containing lines like
com.some.package.Class1.Field1: value
com.some.package.Class1.Expressions: exp1<!>exp2<!>exp3
There is no way to write the value in multiple lines in the properties file. That's why.
526
[] denotes a character class. () denotes a capturing group. [a-z0-9] -- One character that is in the range of a-z OR 0-9. (a-z0-9) -- Explicit capture of a-z0-9 .
$ means "Match the end of the string" (the position after the last character in the string). Both are called anchors and ensure that the entire string is matched instead of just a substring.
Regex will work faster in execution, however Regex's compile time and setup time will be more in instance creation. But if you keep your regex object ready in the beginning, reusing same regex to do split will be faster. String.
The best way would be to use invalid regex as delimiter such as ** Because if it is used in normal regex it won't work and would throw an exception{NOTE:++ is valid}
regex1+"**"+regex2
Now you can split it with this regex
(?<!\\\\)[*][*](?![*])
------- -----
| |->to avoid matching pattern like "A*"+"**"+"n+"
|->check if * is not escaped
Following is a list of invalid regex
(?<!\\\\)[*][*](?![*]))(?<!\\\\)[?][?](?![?]))While splitting you need to check if they are escaped
(?<!\\\\)delimiter
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