If matches regex¤

Description¤

The ifMatchesRegex plugin uses a regular expression as a matching condition in order to distinguish which input to take.

This plugin is a conditional transformer plugin. This means that a regular expression is used as a matching condition, i.e. it is used in order to answer the question “does the regular expression match the provided text?”. If it does match, then the next input is taken as output. Otherwise, the last input is taken as output, provided it exists. If it doesn’t, the output is empty.

Creating and calling the conditional transformer¤

For creating an instance of this transformer, we need to give it a regular expression with the parameter regex and, optionally, tell with the parameter negate whether we will take or exclude the second input value upon calling it (by default, we take it). In other words: the negate parameter tells us which ‘way’ we want to go after the comparison.

For calling this transformer, we need to give it two or three values as its input. The first input value is what the regular expression should match (or not, depending on negate), and the following values are the branches of the condition, i.e. the output if the regex matches the first input value, and the alternative if it doesn’t.

The following list summarizes the creation and the behavior of the conditional transformer:

The regular condition within the transformer is used as a matching condition on the first input.
If it matches, then the second input is returned.
If it doesn’t match, then the third input is returned, provided it exists.
If the third input doesn’t exist, an empty sequence is returned.

Notes on regular expressions¤

The most commonly used examples of regular expressions are "\\s*" for representing whitespace characters, [^0-9]* for numbers, and [a-z]* for the usual English characters between a and z. The star (*) represents an arbitrary number of occurrences (zero included), whereas the plus sign (+) indicates a strictly positive number of occurrences (zero excluded).

An uppercase version of the predefined character classes means negation, such as "\\S*" for non-whitespace characters, or "\\D*" for non-digits. Similarly, the hat sign ^ can be used for negating (arbitrary) character classes, such as [^xyz] for any character except x, y or z.

Attention: Slashes in regular expressions have to be escaped, e.g. instead of \s we need to escape it as \\s.

Note for advanced users¤

A compilation of the available constructs for building regular expressions is available in the API of the Java Pattern.

Relation to other plugins¤

Additionally to the ifMatchesRegex plugin, there are related plugins such as validateRegex, regexReplace and regexExtract.

The distinctive feature of each of these plugins lies in what happens whenever the regular expression matches the input value(s): the ifMatchesRegex plugin is useful for conditionally distinguishing which input to take, validateRegex is used for validating the input, regexReplace replaces all occurrences, and regexExtract extracts them.

Examples¤

Notation: List of values are represented via square brackets. Example: [first, second] represents a list of two values “first” and “second”.

returns the second input if the regex matches the first input:

Parameters
- regex: [abc]{2}
- negate: false
Input values:
1. [black]
2. [should be taken]
3. [last value should be left]
Returns: [should be taken]

returns the third input if the regex does not match the first input:

Parameters
- regex: [abc]{2}
- negate: false
Input values:
1. [xyz]
2. [should be left]
3. [last value should be taken]
Returns: [last value should be taken]

returns an empty value if the regex does not match the first input:

Parameters
- regex: [abc]{2}
- negate: false
Input values:
1. [xyz]
2. [should be left]
Returns: []

Parameter¤

Regex¤

No description

ID: regex
Datatype: string
Default Value: None

Negate¤