Numerous approaches based on metrics, token sequence pattern-matching, abstract syntax tree (AST) or program dependency graph (PDG) analysis have already been proposed to highlight similarities in source code: in this paper we present a simple and scalable architecture based on AST fingerprinting. Thanks to a study of several hashing strategies reducing false-positive collisions, we propose a framework that efficiently indexes AST representations in a database, that quickly detects exact (w.r.t source code abstraction) clone clusters and that easily retrieves their corresponding ASTs. Our aim is to allow further processing of neighboring exact matches in order to identify the larger approximate matches, dealing with the common modification patterns seen in the intra-project copy-pastes and in the plagiarism cases.

In Java, method implementations are chosen at runtime by late-binding with respect to the runtime class of just the receiver argument. However, in order to simplify many programming designs, late-binding with respect to the dynamic type of all arguments is sometimes desirable. This behavior, usually provided by multimethods, is known as multipolymorphism. This work presents a new multimethod implementation based on the standard Java reflection mechanism. Provided as a package, it does not require any language extension or any virtual machine modification. The design issues of this reflective implementation are presented together with a new and simple multimethod dispatch algorithm that efficiently supports class loading at runtime. This implementation provides a practicable and fully portable multimethod solution.