Visualization and analysis of software clones

Code clones are identical or similar fragments of code in a software system. Simple copy-paste programming practices of developers, reusing existing code fragments instead of implementing from the scratch, limitations of both programming languages and developers are the primary reasons behind code cloning. Despite the maintenance implications of clones, it is not possible to conclude that cloning is harmful because there are also benefits in using them (e.g. faster and independent development). As a result, researchers at least agree that clones need to be analyzed before aggressively refactoring them. Although a large number of state-of-the-art clone detectors are available today, handling raw clone data is challenging due to the textual nature and large volume. To address this issue, we propose a framework for large-scale clone analysis and develop a maintenance support environment based on the framework called VisCad. To manage the large volume of clone data, VisCad employs the Visual Information Seeking Mantra: overview first, zoom and filter, then provide details-on-demand. With VisCad users can analyze and identify distinctive code clones through a set of visualization techniques, metrics covering different clone relations and data filtering operations. The loosely coupled architecture of VisCad allows users to work with any clone detection tool that reports source-coordinates of the found clones. This yields the opportunity to work with the clone detectors of choice, which is important because each clone detector has its own strengths and weaknesses. In addition, we extend the support for clone evolution analysis, which is important to understand the cause and effect of changes at the clone level during the evolution of a software system. Such information can be used to make software maintenance decisions like when to refactor clones. We propose and implement a set of visualizations that can allow users to analyze the evolution of clones from a coarse grain to a fine grain level. Finally, we use VisCad to extract both spatial and temporal clone data to predict changes to clones in a future release/revision of the software, which can be used to rank clone classes as another means of handling a large volume of clone data. We believe that VisCad makes clone comprehension easier and it can be used as a test-bed to further explore code cloning, necessary in building a successful clone management system

Trade Liberalisation as an Instrument for Regional Co-operation

South Asia is home to nearly 1.4 billion people, a vast part of humanity. The countries in the region vary widely in the size of the population as well as area and physiography. On one side of the scale is India with a population of more than a billion while on the other side is Maldives with a population no more than half a million. There is Bangladesh which is essentially a flat delta, island countries such as Sri Lanka and Maldives and countries full of high rise mountains such as Nepal and Bhutan. In between are India and Pakistan with some of everything. While there are several such external differences among the countries in the region and their people, these are literally only skin-deep. The people in the region share, by and large, the same basic culture. In many cases the same or a similar language is spoken across the borders. There are, of course, local variations in the general pattern. But that diversity makes it all the more interesting and attractive. It is only natural that the countries of the region will band together to show a united face to the world. This is yet to happen, though

Investigation of Holographic Lattice Theories

The Anti-de Sitter/Conformal Field theory (AdS/CFT) correspondence, also known as holography, has been the focus of a great deal of interest and research for the last two decades. It has improved our understanding of general relativity and quantum field theories simultaneously through the interplay between these two different kinds of theories. However, there are still many aspects of holography that we do not understand or demand further analysis. Perturbative quantum field theory and perturbative metric expansion techniques are not equipped to investigate holography in some of the most interesting regimes such as the strongly interacting gravitational theory in anti-de Sitter space (that potentially can have a dual field theory at the boundary with a small number of degrees of freedom, hence away from the large N limit). In this thesis, I have attempted to contribute to understanding holography in these more difficult regimes. Specifically, I have used lattice techniques in Wick-rotated Anti-de Sitter (AdS) spacetime to investigate holography. After a review of the properties of Anti-de Sitter space and some continuum results, lattice construction of the hyperbolic space and the algorithms used for analysis are discussed. Our initial attempt investigated free scalar fields in hyperbolic space in two and three spacetime dimensions. It has been demonstrated that properties of the bulk lattice geometry information are encoded in the dual CFT through mapping the mass spectrum of the bulk scalar field to the scaling dimension of the boundary CFT operators. Holography has also been investigated for the nearest-neighbor Ising spin model on a hyperbolic space at various temperatures. The principal focus has been measuring boundary correlation functions over a range of temperatures. This yields a temperature-dependent scaling exponent of the boundary operator. Scaling the magnetic susceptibility data at different lattice volumes also allows us to compute the same scaling exponent, demonstrating good agreement with the correlation function measurements. A phase transition temperature in the bulk geometry can be seen to correlate with a minimal boundary scaling dimension. Lattice simulation results are complemented with a discussion of the high-temperature expansion and the duality (in the sense of Kramers and Wannier). Finally, we show how lattice techniques can be used to probe strong fluctuations of the bulk geometry. A new relation of the scaling dimensions to the bulk mass is derived in this regime. We show that the backreaction of fermionic matter fieldscan dramatically alter the nature of the bulk space. Hyperbolic space configuration dominates the dynamically generated ensemble of simplicial manifolds in the limit of a large number of K\ ahler-Dirac fields. Apart from the apparent advantage of probing duality in this uncharted territory of strong geometry fluctuation and strongly coupled field theories in hyperbolic space, the tools developed in this thesis should allow investigation of different aspects of quantum information science and tensor network ideas

Context-Sensitive Code Completion

Developers depend extensively on software frameworks and libraries to deliver the products on time. While these frameworks and libraries support software reuse, save development time, and reduce the possibility of introducing errors, they do not come without a cost. Developers need to learn and remember Application Programming Interfaces (APIs) for effectively using those frameworks and libraries. However, APIs are difficult to learn and use. This is mostly due to APIs being large in number, they may not be properly documented, and finally there exist complex relationships between various classes and methods that make APIs difficult to learn. To support developers using those APIs, this thesis focuses on the code completion feature of modern integrated development environments (IDEs). As a developer types code, a code completion system offers a list of completion proposals through a popup menu to navigate and select. This research aims to improve the current state of code completion systems in discovering APIs. Towards this direction, a case study on tracking source code lines has been conducted to better understand capturing code context and to evaluate the benefits of using the simhash technique. Observations from the study have helped to develop a simple, context-sensitive method call completion technique, called CSCC. The technique is compared with a large number of existing code completion techniques. The notion of context proposed in CSCC can even outweigh graph-based statistical language models. Existing method call completion techniques leave the task of completing method parameters to developers. To address this issue, this thesis has investigated how developers complete method parameters. Based on the analysis, a method parameter completion technique, called PARC, has been developed. To date, the technique supports the largest number of expressions to complete method parameters. The technique has been implemented as an Eclipse plug-in that demonstrates the proof of the concept. To meet application-specific requirements, software frameworks need to be customized via extension points. It was observed that developers often pass a framework related object as an argument to an API call to customize default aspects of application frameworks. To enable such customizations, the object can be created by extending a framework class, implementing an interface, or changing the properties of the object via API calls. However, it is both a common and non-trivial task to find all the details related to the customizations. To address this issue, a technique has been developed, called FEMIR. The technique utilizes partial program analysis and graph mining technique to detect, group, and rank framework extension examples. The tool extends existing code completion infrastructure to inform developers about customization choices, enabling them to browse through extension points of a framework, and frequent usages of each point in terms of code examples. Findings from this research and proposed techniques have the potential to help developers to learn different aspects of APIs, thus ease software development, and improve the productivity of developers

Quantum Ising model on two dimensional anti-de Sitter space

This paper investigates the transverse Ising model on a discretization of two-dimensional anti-de Sitter space. We use classical and quantum algorithms to simulate real-time evolution and measure out-of-time-ordered correlators (OTOC). The latter can probe thermalization and scrambling of quantum information under time evolution. We compared tensor network-based methods both with simulation on gated-based superconducting quantum devices and analog quantum simulation using Rydberg arrays. While studying this system's thermalization properties, we observed different regimes depending on the radius of curvature of the space. In particular, we find a region of parameter space where the thermalization time depends only logarithmically on the number of degrees of freedom.Comment: 16 pages, 29 figure