RegEx

Description

A regular expression (or regex) is a compact language that can be used to recognize strings that follow a specific pattern, such as URLs, email addresses, complete sentences, etc. For example, a regex of ab[0-9] would find any string that is ab followed by any number from 0 to 9. For a more in-depth look, you can easily find various tutorials and detailed explanations on the Internet. To begin, the RegEx object needs to be compiled with the search pattern using compile() before it can be used.

		var regex = RegEx.new()
		regex.compile("\\w-(\\d+)")
		

The search pattern must be escaped first for GDScript before it is escaped for the expression. For example, compile("\\d+") would be read by RegEx as \d+. Similarly, compile("\"(?:\\\\.|[^\"])*\"") would be read as "(?:\\.|[^"])*". In GDScript, you can also use raw string literals (r-strings). For example, compile(r'"(?:\\.|[^"])*"') would be read the same. Using search(), you can find the pattern within the given text. If a pattern is found, RegExMatch is returned and you can retrieve details of the results using methods such as RegExMatch.get_string() and RegExMatch.get_start().

		var regex = RegEx.new()
		regex.compile("\\w-(\\d+)")
		var result = regex.search("abc n-0123")
		if result:
			print(result.get_string()) # Prints "n-0123"
		

The results of capturing groups () can be retrieved by passing the group number to the various methods in RegExMatch. Group 0 is the default and will always refer to the entire pattern. In the above example, calling result.get_string(1) would give you 0123. This version of RegEx also supports named capturing groups, and the names can be used to retrieve the results. If two or more groups have the same name, the name would only refer to the first one with a match.

		var regex = RegEx.new()
		regex.compile("d(?<digit>[0-9]+)|x(?<digit>[0-9a-f]+)")
		var result = regex.search("the number is x2f")
		if result:
			print(result.get_string("digit")) # Prints "2f"
		

If you need to process multiple results, search_all() generates a list of all non-overlapping results. This can be combined with a for loop for convenience.

		# Prints "01 03 0 3f 42"
		for result in regex.search_all("d01, d03, d0c, x3f and x42"):
			print(result.get_string("digit"))
		

Example: Split a string using a RegEx:

		var regex = RegEx.new()
		regex.compile("\\S+") # Negated whitespace character class.
		var results = []
		for result in regex.search_all("One  Two \n\tThree"):
			results.push_back(result.get_string())
		print(results) # Prints ["One", "Two", "Three"]
		

Note: Redot's regex implementation is based on the PCRE2 library. You can view the full pattern reference here. Tip: You can use Regexr to test regular expressions online.

Methods