patterns.md

Patterns

Decycle uses a special pattern syntax that was inspired by Apache Ant for matching fully qualified class names. A typical decycle pattern looks like this: com.example.app.**

• ? matches exactly one name character (but not dots)
• * matches zero or more name characters (but not dots)
• ** matches zero or more dots and name characters
• . matches only itself (the dot)
• | separates alternatives
• ( and ) can be used to surround sub-patterns (for example alternatives)

A name character is a character that may be used in names of Java classes, i.e. usually letters, digits, the underscore _, and in particular the dollar symbol $.

Note: Decycle looks at the byte code and matches the class names created by the compiler. For example, the inner interface java.util.Map.Entry becomes java.util.Map$Entry.

Examples

• com.example.?oo matches com.example.Foo and com.example.Zoo (it doesn't match com.example.oo and com.example.bar.Taboo)
• com.example.* matches com.example.Foo and com.example.Bar (it doesn't match com.example.bar.Foo)
• com.example.B* matches com.example.B, com.example.Bar, and com.example.Bar$Inner
• com.example.** matches com.example.Foo and com.example.bar.baz.Qux
• com.example.**.Foo matches com.example.bar.Foo and com.example.bar.baz.Foo (however, it doesn't match com.example.Foo – this is different from Ant's ** handling)
• com.example.*.** matches com.example.bar.Foo and com.example.bar.baz.Foo (but it doesn't match com.example.Foo)
• com.example.(bar|baz).Foo matches only com.example.bar.Foo and com.example.baz.Foo

Slicing patterns

Patterns that are used for the configuration of slicings have an extended syntax.

A named pattern uses the form pattern=name. In this case the assigned name defines the name of the slice.

An unnamed pattern should also contain one pair of curly braces (e.g. com.example.{*}.**). The matched substring within the curly braces defines the name of the slice.