Table of Contents

Pattern

Patterns are declared from a class that extends UserDefinedPattern. Each concrete subclass of UserDefinedPattern declares a user-defined pattern, where the term “user-defined” distinguishes such a pattern from built-in patterns of the XL programming language. The signature (number and types of parameters) of a user-defined pattern is given by a special method named signature which has no further purpose. The @In and @Out annotations in the signature are needed when textually neighboring patterns are connected.

In XL

Custom patterns can be created in XL with the simple syntax: 

class patternName(@In Node a, @Out Node b) (
    // some patterns
    )

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In Java

The minimal format to declare a pattern as java object is: 

class X extends Node {
    static class Pattern extends UserDefinedPattern {
        private static void signature(@In @Out X node) {}
        public Matcher createMatcher(Graph graph, XBitSet bound,
             IntList requiredAsBound) {...}
    }
}