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Per pastaruosius metus, lankstaus programavimo metodikos sulaukė daug dėmesio. Programų kodo pertvarkymas tapo viena iš labiausiai naudojamų praktikų, ypač ekstremaliame programavime. Todėl poreikis turėti programos kodo pertvarkymų įrankį išaugo iki tokio lygio, kad pertvarkymo įrankiai tapo reikalaujama priemone šiuolaikinėse programų kūrimo aplinkose. Tyrimo sritis – abstrakčios sintaksės medžių pertvarkymo algoritmai. Tyrimo objektas – abstrakčios sintaksės medžių pertvarkymo procesai skirtingose programavimo kalbose (C++ ir Java). Šio darbo tikslas – ištirti, kaip efektyviai būtų galima vykdyti pertvarkymus bendriniam AST, tam sukuriant pertvarkymų biblioteką ir atliekant eksperimentus įvairių kalbų atvejais. / Over the past years, agile development methodologies have attracted a lot of attention. Refactoring has become one of the most heavily used practices, especially in Extreme Programming. Therefore the need to have powerful refactoring tools has grown to such an extent, that there is a required feature for modern-day IDEs to have implemented refactoring tools. The aim of this work is to build a refactoring library for the generic abstract syntax tree and test the algorithms for speed. Generic abstract syntax tree (GAST) is a tree structure that can store elements of several programming language. Achieving this goal required doing certain tasks that you find in this document: analysis of technologies and existing software; several algorithms for refactoring; user need and specification of requirements; library model, expressed in UML diagrams; test plan and test procedure. Experiments have shown that it is necessary to improve the refactoring algorithms. But the library and the AST structure is worth further development.

Operatorless Prolog text is LL(1) in nature and any standard LL parser generator tool can be used to parse it. However, the Prolog text that conforms to the ISO Prolog standard allows the definition of dynamic operators. Since Prolog operators can be defined at run-time, operator symbols are not present in the grammar rules of the language. Unless the parser generator allows for some flexibility in the specification of the grammar rules, it is very difficult to generate a parser for such text. In this thesis we discuss the existing parsing methods and their modified versions to parse languages with dynamic operator capabilities. Implementation details of a parser using Javacc as a parser generator tool to parse standard Prolog text is provided. The output of the parser is an “Abstract Syntax Tree” that reflects the correct precedence and associativity rules among the various operators (static and dynamic) of the language. Empirical results are provided that show that a Prolog parser that is generated by the parser generator like Javacc is comparable in efficiency to a hand-coded parser.

La duplication de code source a de nombreuses origines : copie et adaptation inter-projets ou clonage au sein d'un même projet. Rechercher des correspondances de code copié permet de le factoriser dans un projet ou de mettre en évidence des situations de plagiat. Nous étudions des méthodes statiques de recherche de similarité sur du code ayant potentiellement subi des opérations d'édition telle que l'insertion, la suppression, la transposition ainsi que la factorisation et le développement de fonctions. Des techniques d'identification de similarité génomique sont examinées et adaptées au contexte de la recherche de clones de code source sous forme lexemisée. Après une discussion sur des procédés d'alignement de lexèmes et de recherche par empreintes de n-grams, est présentée une méthode de factorisation fusionnant les graphes d'appels de fonctions de projets au sein d'un graphe unique avec introduction de fonctions synthétiques exprimant les correspondances imbriquées. Elle utilise des structures d'indexation de suffixes pour la détermination de facteurs répétés. Une autre voie d'exploration permettant de manipuler de grandes bases indexées de code par arbre de syntaxe est abordée avec la recherche de sous-arbres similaires par leur hachage et leur indexation selon des profils d'abstraction variables. Des clones exacts de sous-arbres de forte proximité dans leurs arbres d'extraction peuvent alors être consolidés afin d'obtenir des correspondances approchées et étendues. En amont et en aval de la recherche de correspondances, des métriques de similarité sont définies afin de préselectionner les zones d'examen, affiner la recherche ou mieux représenter les résultats / Several phenomenas cause source code duplication like inter-project copying and adaptation or cloning inside a same project. Looking for code matches allows to factorize them inside a project or to highlight plagiarism cases. We study statical similarity retrieval methods on source code that may be transformed via edit operations like insertion, deletion, transposition, in- or out-lining of functions. Sequence similarity retrieval methods inspired from genomics are studied and adapted to find common chunks of tokenized source. After an explanation on alignment and n-grams lookup techniques, we present a factorization method that merge function call graphs of projects to a single graph with the creation of synthetic functions modeling nested matches. It relies on the use of suffix indexation structures to find repeated token factors. Syntax tree indexation is explored to handle huge code bases allowing to lookup similar sub-trees with their hash values computed via heterogeneous abstraction profiles. Exact copies of sub-trees close in their host trees may be merged to get approximate and extended matches. Before and after match retrieval, we define similarity metrics to preselect interesting code spots, refine the search process or enhance the human understanding of results

This thesis describes the Drag language. Drag is a general purpose, gradually typed, lexically scoped, and multi-paradigm pro- gramming language. The essence of Drag is to build the abstract syntax trees of the programs directly and interactively. Our work includes the language specification and a prototype program. The language specification focuses on the syntax, the semantic model, and the type system. The prototype consists of an interactive editor and a compiler that targets several plat- forms, among which we focus on the LLVM platform in this thesis.

<p>An unavoidable amount of money is spent on maintaining existing software systems today. Software maintenance cost generally higher than development cost of the system therefore lowering maintenance cost is highly appreciated in software industry.</p><p>A significant part of maintenance activities is related to repeating the investigation of problems and applying repeated solutions several times. A software system may contain a common bug in several different places and it might take extra effort and time to fix all existences of this bug. This operation commonly increases the cost of Software Maintenance Activities.</p><p>Detecting duplicate code fragments can significantly decrease the time and effort therefore the maintenance cost. Clone code detection can be achieved via analyzing the source code of given software system. An abstract syntax tree based clone detector for java systems is designed and implemented through this study.</p><p>This master thesis examines a software engineering process to create an abstract syntax tree based clone detector for the projects implemented in Java programming language.</p>

An unavoidable amount of money is spent on maintaining existing software systems today. Software maintenance cost generally higher than development cost of the system therefore lowering maintenance cost is highly appreciated in software industry. A significant part of maintenance activities is related to repeating the investigation of problems and applying repeated solutions several times. A software system may contain a common bug in several different places and it might take extra effort and time to fix all existences of this bug. This operation commonly increases the cost of Software Maintenance Activities. Detecting duplicate code fragments can significantly decrease the time and effort therefore the maintenance cost. Clone code detection can be achieved via analyzing the source code of given software system. An abstract syntax tree based clone detector for java systems is designed and implemented through this study. This master thesis examines a software engineering process to create an abstract syntax tree based clone detector for the projects implemented in Java programming language.

Today, universities rely heavily on systems for detecting plagiarism in students’essays and reports. Code submissions however require specific tools. A numberof approaches to finding plagiarisms in code have already been tried, includingtechniques based on comparing textual transformations of code, token strings,parse trees and graph representations. In this master’s thesis, a new system, cojac,is presented which combines textual, tree and graph techniques to detect a broadspectrum of plagiarism attempts. The system finds plagiarisms in C, C++ and Adasource files. This thesis discusses the method used for obtaining parse trees fromthe source code and the abstract syntax tree analysis. For comparison of syntaxtrees, we generate sets of fingerprints, digest forms of trees, which makes thecomparison algorithm more scalable. To evaluate the method, a set of benchmarkfiles have been constructed containing plagiarism scenarios which was analyzedboth by our system and Moss, another available system for plagiarism detection incode. The results show that our abstract syntax tree analysis can effectively detectplagiarisms such as changing the format of the code and renaming of identifiersand is at least as effective as Moss for detecting plagiarisms of these kinds

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