Our goal is to use the vast repositories of available open source code to generate specific functions or classes that meet a user’s specifications. The key words here are specifications and generate. We let users specify what they are looking for as precisely as possible using keywords, class or method signatures, test cases, contracts, and security constraints. Our system then uses an open set of program transformations to map retrieved code into what the user asked for. This approach is implemented in a prototype system for Java with a web interface. 1.

Programming languages such as Java and C++ provide exception-handling constructs to handle exception conditions. Applications are expected to handle these exception conditions and take necessary recovery actions such as releasing opened database connections. However, exceptionhandling rules that describe these necessary recovery actions are often not available in practice. To address this issue, we develop a novel approach that mines exceptionhandling rules as sequence association rules of the form “(FC 1 c...FC n c) ∧ FCa ⇒ (FC 1 e...FC m e)”. This rule describes that function call FCa should be followed by a sequence of function calls (FC 1 e...FC m e) when FCa is preceded by a sequence of function calls (FC 1 c...FC n c). Such form of rules is required to characterize common exceptionhandling rules. We show the usefulness of these mined rules by applying them on five real-world applications (including 285 KLOC) to detect violations in our evaluation. Our empirical results show that our approach mines 294 real exception-handling rules in these five applications and also detects 160 defects, where 87 defects are new defects that are not found by a previous related approach. 1

An objective of unit testing is to achieve high structural coverage of the code under test. Achieving high structural coverage of object-oriented code requires desirable method-call sequences that create and mutate objects. These sequences help generate target object states such as argument or receiver object states (in short as target states) of a method under test. Automatic generation of sequences for achieving target states is often challenging due to a large search space of possible sequences. On the other hand, code bases using object types (such as receiver or argument object types) include sequences that can be used to assist automatic testgeneration approaches in achieving target states. In this paper, we propose a novel approach, called MSeqGen, that mines code bases and extracts sequences related to receiver

Abstract. To improve software productivity, when constructing new software systems, programmers often reuse existing libraries or frameworks by invoking methods provided in their APIs. Those API methods, however, are often complex and not well documented. To get familiar with how those API methods are used, programmers often exploit a source code search tool to search for code snippets that use the API methods of interest. However, the returned code snippets are often large in number, and the huge number of snippets places a barrier for programmers to locate useful ones. In order to help programmers overcome this barrier, we have developed an API usage mining framework and its supporting tool called MAPO (Mining API usage Pattern from Open source repositories) for mining API usage patterns automatically. A mined pattern describes that in a certain usage scenario, some API methods are frequently called together and their usages follow some sequential rules. MAPO further recommends the mined API usage patterns and their associated code snippets upon programmers ’ requests. Our experimental results show that with these patterns MAPO helps programmers locate useful code snippets more effectively than two state-of-the-art code search tools. To investigate whether MAPO can assist programmers in programming tasks, we further conducted an empirical study. The results show that using MAPO, programmers produce code with fewer bugs when facing relatively complex API usages, comparing with using the two state-of-the-art code search tools. 1

The ready availability of online source-code examples has fundamentally changed programming practices. However, current search tools are not designed to assist with programming tasks and are wholly separate from editing tools. This paper proposes that embedding a task-specific search engine in the development environment can significantly reduce the cost of finding information and thus enable programmers to write better code more easily. This paper describes the design, implementation, and evaluation of Blueprint, a Web search interface integrated into the Adobe Flex Builder development environment that helps users locate example code. Blueprint automatically augments queries with code context, presents a code-centric view of search results, embeds the search experience into the editor, and retains a link between copied code and its source. A comparative laboratory study found that Blueprint enables participants to write significantly better code and find example code significantly faster than with a standard Web browser. Analysis of three months of usage logs with 2,024 users suggests that task-specific search interfaces can significantly change how and when people search the Web.

Over the past 40 years, database management systems (DBMSs) have evolved to provide a sophisticated variety of data management capabilities. At the same time, tools for managing queries over the data have remained relatively primitive. One reason for this is that queries are typically issued through applications. They are thus debugged once and re-used repeatedly. This mode of interaction, however, is changing. As scientists (and others) store and share increasingly large volumes of data in data centers, they need the ability to analyze the data by issuing exploratory queries. In this paper, we argue that, in these new settings, data management systems must provide powerful query management capabilities, from query browsing to automatic query recommendations. We first discuss the requirements for a collaborative query management system. We outline an early system architecture and discuss the many research challenges associated with building such an engine. 1.

Software engineering tools often deal with the source code of programs retrieved from the web or source code repositories. Typically, these tools only have access to a subset of a program’s source code (one file or a subset of files) which makes it difficult to build a complete and typed intermediate representation (IR). Indeed, for incomplete objectoriented programs, it is not always possible to completely disambiguate the syntactic constructs and to recover the declared type of certain expressions because the declaration of many types and class members are not accessible. We present a framework that performs partial type inference and uses heuristics to recover the declared type of expressions and resolve ambiguities in partial Java programs. Our framework produces a complete and typed IR suitable for further static analysis. We have implemented this framework and used it in an empirical study on four large open source systems which shows that our system recovers most declared types with a low error rate, even when only one class is accessible.

Abstract—To improve software quality, static or dynamic verification tools accept programming rules as input and detect their violations in software as defects. As these programming rules are often not well documented in practice, previous work developed various approaches that mine programming rules as frequent patterns from program source code. Then these approaches use static defect-detection techniques to detect pattern violations in source code under analysis. These existing approaches often produce many false positives due to various factors. To reduce false positives produced by these mining approaches, we develop a novel approach, called Alattin, that includes a new mining algorithm and a technique for detecting neglected conditions based on our mining algorithm. Our new mining algorithm mines alternative patterns in example form “P1 or P2”, where P1 and P2 are alternative rules such as condition checks on method arguments or return values related to the same API method. We conduct two evaluations to show the effectiveness of our Alattin approach. Our evaluation results show that (1) alternative patterns reach more than 40% of all mined patterns for APIs provided by six open source libraries; (2) the mining of alternative patterns helps reduce nearly 28 % of false positives among detected violations. Keywords-code search; frequent itemset mining; alternative patterns; I.

Abstract—Software developers often face challenges in reusing open source frameworks due to several factors such as the framework complexity and lack of proper documentation. In this paper, we propose a code-search-engine-based approach that detects hotspots in a given framework by mining code examples gathered from open source repositories available on the web; these hotspots are API classes and methods that are frequently reused. Hotspots can serve as starting points for developers in understanding and reusing the given framework. Our approach also detects coldspots, which are API classes and methods that are rarely used. Coldspots serve as caveats for developers as there can be difficulties in finding relevant code examples and are generally less exercised compared to hotspots. We developed a tool, called SpotWeb, for frameworks or libraries written in Java and used our tool to detect hotspots and coldspots of eight widely used open source frameworks. We show the utility of our detected hotspots by comparing these hotspots with the API classes reused by a real application and compare our results with the results of a previous related approach. I.

Abstract. Application frameworks provide reusable concepts that are instantiated in application code through potentially complex implementation steps such as subclassing, implementing callbacks, and making calls. Existing applications contain valuable examples of such steps, except that locating them in the application code is often challenging. We propose the notion of concept implementation templates, which summarize the necessary implementation steps, and an approach to automatic extraction of such templates from traces of sample applications. We demonstrate the feasibility of the template extraction with high precision and recall through an empirical study with twelve realistic concepts from four widely-used frameworks. Finally, we report on a user experiment with twelve subjects in which the choice of templates vs. documentation had much less impact on development time than the concept complexity. 1