Code clone analysis

CREATED: 200701011012 Author: Katsuro Inoue

** Motivation

• Code clone as a result of ** copy and paste ** sterotype function, eg DB connection ** intentional iteration, eg for performanc enhancement
• Makes maintenance difficult
• Types of clones ** exactly the same ** similar, different identifiers etc ** semamtically the same, syntectically very different

** Methods

• Line based -> line by line
• AST based -> algorithm to compare two trees, need to be syntactically correct code
• PDG based -> algorithms to compare two subgraphs
• Metrics
• Tokens based -> CCFinder (Gemini, Aries, Libra)

** CCFinder

tokenize

normalization

suffix tree algorithms

** Application

candidates for refactoring

• visualization using metric graph
• change support
• phylogeny of software, evolution of code