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 [code]ab[0-9][/code] would find any string that is [code]ab[/code] followed by any number from [code]0[/code] to [code]9[/code]. For a more in-depth look, you can easily find various tutorials and detailed explanations on the Internet.
The search pattern must be escaped first for GDScript before it is escaped for the expression. For example, [code]compile("\\d+")[/code] would be read by RegEx as [code]\d+[/code]. Similarly, [code]compile("\"(?:\\\\.|[^\"])*\"")[/code] would be read as [code]"(?:\\.|[^"])*"[/code]. In GDScript, you can also use raw string literals (r-strings). For example, [code]compile(r'"(?:\\.|[^"])*"')[/code] would be read the same.
Using [method 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 [method RegExMatch.get_string] and [method RegExMatch.get_start].
The results of capturing groups [code]()[/code] 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 [code]result.get_string(1)[/code] would give you [code]0123[/code].
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.
If you need to process multiple results, [method search_all] generates a list of all non-overlapping results. This can be combined with a [code]for[/code] loop for convenience.
[b]Note:[/b] Godot's regex implementation is based on the [url=https://www.pcre.org/]PCRE2[/url] library. You can view the full pattern reference [url=https://www.pcre.org/current/doc/html/pcre2pattern.html]here[/url].
[b]Tip:[/b] You can use [url=https://regexr.com/]Regexr[/url] to test regular expressions online.
Compiles and assign the search pattern to use. Returns [constant OK] if the compilation is successful. If an error is encountered, details are printed to standard output and an error is returned.
Searches the text for the compiled pattern. Returns a [RegExMatch] container of the first matching result if found, otherwise [code]null[/code].
The region to search within can be specified with [param offset] and [param end]. This is useful when searching for another match in the same [param subject] by calling this method again after a previous success. Note that setting these parameters differs from passing over a shortened string. For example, the start anchor [code]^[/code] is not affected by [param offset], and the character before [param offset] will be checked for the word boundary [code]\b[/code].
Searches the text for the compiled pattern. Returns an array of [RegExMatch] containers for each non-overlapping result. If no results were found, an empty array is returned instead.
The region to search within can be specified with [param offset] and [param end]. This is useful when searching for another match in the same [param subject] by calling this method again after a previous success. Note that setting these parameters differs from passing over a shortened string. For example, the start anchor [code]^[/code] is not affected by [param offset], and the character before [param offset] will be checked for the word boundary [code]\b[/code].
Searches the text for the compiled pattern and replaces it with the specified string. Escapes and backreferences such as [code]$1[/code] and [code]$name[/code] are expanded and resolved. By default, only the first instance is replaced, but it can be changed for all instances (global replacement).
The region to search within can be specified with [param offset] and [param end]. This is useful when searching for another match in the same [param subject] by calling this method again after a previous success. Note that setting these parameters differs from passing over a shortened string. For example, the start anchor [code]^[/code] is not affected by [param offset], and the character before [param offset] will be checked for the word boundary [code]\b[/code].
