Structured Review of the Evidence for Effects of Code Duplication on Software Quality

This report presents the detailed steps and results of a structured review of code clone literature. The aim of the review is to investigate the evidence for the claim that code duplication has a negative effect on code changeability. This report contains only the details of the review for which there is not enough place to include them in the companion paper published at a conference (Hordijk, Ponisio et al. 2009 - Harmfulness of Code Duplication - A Structured Review of the Evidence)

An Extended Stable Marriage Problem Algorithm for Clone Detection

Code cloning negatively affects industrial software and threatens intellectual property. This paper presents a novel approach to detecting cloned software by using a bijective matching technique. The proposed approach focuses on increasing the range of similarity measures and thus enhancing the precision of the detection. This is achieved by extending a well-known stable-marriage problem (SMP) and demonstrating how matches between code fragments of different files can be expressed. A prototype of the proposed approach is provided using a proper scenario, which shows a noticeable improvement in several features of clone detection such as scalability and accuracy.Comment: 20 pages, 10 figures, 6 table

Syntax tree fingerprinting: a foundation for source code similarity detection

Plagiarism detection and clone refactoring in software depend on one common concern: nding similar source chunks across large repositories. However, since code duplication in software is often the result of copy-paste behaviors, only minor modi cations are expected between shared codes. On the contrary, in a plagiarism detection context, edits are more extensive and exact matching strategies show their limits. Among the three main representations used by source code similarity detection tools, namely the linear token sequences, the Abstract Syntax Tree (AST) and the Program Depen- dency Graph (PDG), we believe that the AST could e ciently support the program analysis and transformations required for the advanced similarity detection process. In this paper we present a simple and scalable architecture based on syntax tree nger- printing. Thanks to a study of several hashing strategies reducing false-positive collisions, we propose a framework that e ciently 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 modi cation patterns seen in the intra-project copy-pastes and in the plagiarism cases

Structured Review of Code Clone Literature

This report presents the results of a structured review of code clone literature. The aim of the review is to assemble a conceptual model of clone-related concepts which helps us to reason about clones. This conceptual model unifies clone concepts from a wide range of literature, so that findings about clones can be compared with each other

Clone Detection and Elimination for Haskell

Duplicated code is a well known problem in software maintenance and refactoring. Code clones tend to increase program size and several studies have shown that duplicated code makes maintenance and code understanding more complex and time consuming. This paper presents a new technique for the detection and removal of duplicated Haskell code. The system is implemented within the refactoring framework of the Haskell Refactorer (HaRe), and uses an Abstract Syntax Tree (AST) based approach. Detection of duplicate code is automatic, while elimination is semi-automatic, with the user managing the clone removal. After presenting the system, an example is given to show how it works in practice

A comparative analysis of web-based GIS applications using usability metrics

With the rapid expansion of the internet, Web-based Geographic Information System (WGIS) applications have gained popularity, despite the interface of the WGIS application being difficult to learn and understand because special functions are needed to manipulate the maps. Hence, it is essential to evaluate the usability of WGIS applications. Usability is an important factor in ensuring the development of quality, usable software products. On the other hand, there are a number of standards and models in the literature, each of which describes usability in terms of various set of attributes. These models are vague and difficult to understand. Therefore, the primary purpose of this study is to compare five common usability models (Shackel, Nielsen, ISO 9241 P-11, ISO 9126-1 and QUIM) to identify usability metrics that have most frequently used in the previous models. The questionnaire method and the automated usability evaluation method by using Loop11 tool were used, in order to evaluate the usability metrics for three case studies of commonly used WGIS applications as Google maps, Yahoo maps, and MapQuest. Finally, those case studies were compared and analysed based on usability metrics that have been identified. Based on a comparative study, four usability metrics (Effectiveness, Efficiency, Satisfaction and Learnability) were identified. Those usability metrics were characterized by consistent, comprehensive, not vaguely and proper to evaluate the usability of WGIS applications. In addition, there was a positive correlation between these usability metrics. The comparative analysis indicates that Effectiveness, Satisfaction and Learnability were higher, and the Efficiency was lesser by using the Loop11 tool compared to questionnaire method for the three case studies. In addition, Yahoo Maps and MapQuest have usability metrics rate lesser than Google Maps by applying two methods. Therefore, Google Maps is more usable compared to Yahoo Maps and MapQuest

Robust Parsing of Cloned Token Sequences

Token-based clone detection techniques are known for theirscalability, high recall, and robustness against syntax errors andincomplete code. They, however, may yield clones that aresyntactically incomplete and they know very little about the syntacticstructure of their reported clones. Hence, their results cannotimmediately be used for automated refactorings or syntactic filtersfor relevance.This paper explores techniques of robust parsing to parse codefragments reported by token-based clone detectors to determine whetherthe clones are syntactically complete and what kind of syntacticelements they contain.This knowledge can be used to improve the precision of token-basedclone detection

Clone Detection via Structural Abstraction

This paper describes the design, implementation, and application of a new algorithm to detect cloned code. It operates on the abstract syntax trees formed by many compilers as an intermediate representation. It extends prior work by identifying clones even when arbitrary subtrees have been changed. On a 440,000-line code corpus, 20- 50%of the clones it detected were missed by previous methods. The method also identifies cloning in declarations, so it is somewhat more general than conventional procedural abstraction

The Survey of the Code Clone Detection Techniques and Process with Types (I, II, III and IV)

In software upgradation code clones are regularly utilized. So, we can contemplate on code location strategies goes past introductory code. In condition of-craftsmanship on clone programming study, we perceived the absence of methodical overview. We clarified the earlier research-in view of deliberate and broad database find and the hole of research for additionally think about. Software support cost is more than outlining cost. Code cloning is useful in several areas like detecting library contents, understanding program, detecting malicious program, etc. and apart from pros several serious impact of code cloning on quality, reusability and continuity of software framework. In this paper, we have discussed the code clone and its evolution and classification of code clone. Code clone is classified into 4 types namely Type I, Type II, III and IV. The exact code as well as copied code is depicted in detail for each type of code clone. Several clone detection techniques such as: Text, token, metric, hybrid based techniques were studied comparatively. Comparison of detection tools such as: clone DR, covet, Duploc, CLAN, etc. based on different techniques used are highlighted and cloning process is also explained. Code clones are identical segment of source code which might be inserted intentionally or unintentionally. Reusing code snippets via copying and pasting with or without minor alterations is general task in software development. But the existence of code clones may reduce the design structure and quality of software like changeability, readability and maintainability and hence increase the continuation charges