Measuring code maintainability with deep neural networks

The maintainability of source code is a key quality characteristic for software quality. Many approaches have been proposed to quantitatively measure code maintainability. Such approaches rely heavily on code metrics, e.g., the number of Lines of Code and McCabe’s Cyclomatic Complexity. The employed code metrics are essentially statistics regarding code elements, e.g., the numbers of tokens, lines, references, and branch statements. However, natural language in source code, especially identifiers, is rarely exploited by such approaches. As a result, replacing meaningful identifiers with nonsense tokens would not significantly influence their outputs, although the replacement should have significantly reduced code maintainability. To this end, in this paper, we propose a novel approach (called DeepM) to measure code maintainability by exploiting the lexical semantics of text in source code. DeepM leverages deep learning techniques (e.g., LSTM and attention mechanism) to exploit these lexical semantics in measuring code maintainability. Another key rationale of DeepM is that measuring code maintainability is complex and often far beyond the capabilities of statistics or simple heuristics. Consequently, DeepM leverages deep learning techniques to automatically select useful features from complex and lengthy inputs and to construct a complex mapping (rather than simple heuristics) from the input to the output (code maintainability index). DeepM is evaluated on a manually-assessed dataset. The evaluation results suggest that DeepM is accurate, and it generates the same rankings of code maintainability as those of experienced programmers on 87.5% of manually ranked pairs of Java classes.     

Undivided and Indistinguishable Histories in Branching-Time Logics

In the tree-like representation of Time, two histories are undivided at a moment t whenever they share a common moment in the future of t. In the present paper, it will first be proved that Ockhamist and Peircean branching-time logics are unable to express some important sentences in which the notion of undividedness is involved. Then, a new semantics for branching-time logic will be presented. The new semantics is based on trees endowed with an indistinguishability function, a generalization of the notion of undividedness. It will be shown that Ockhamist and Peircean semantics can be viewed as limit cases of the semantics developed in this paper.     

型构兼容的继承及其语义

本文揭示了在面向对象程序设计语言中,若劲旅子类重定义其继承的分类方法以发迹这些方法的规约,并且采用类似于Ｓｍａｌｔａｌｋ－８０中的继承机制的语义,将导致封将与继承之间的一个新总是为此,本文提出了一种新的继承机制－型构兼容的继承,以代替传统的增量继承。型构兼容的继承是一种灵活的代码复用机制,并且能够充分支持封装。     

A semantics of introspection in a reflective prototype-based language

In Malenfant et al. [19], we have described a reflective model for a prototype-based language based on thelookup o apply reflective introspection protocol. In this paper, we augment our previous protocol by converting it to handle continuations reified as first-class objects. First-class continuations provide much more control over the current computation; during the introspection phase fired by message sending, they make it possible not only to change the behavior of the program for that message but also for the entire future computation. In this paper, we provide this introspection protocol with a formal semantics. This result is obtained by exhibiting a mapping from program configurations to priority rewrite systems (PRS) as well as a mapping from message expressions to ground first-order terms used to query the PRS. Other advantages of this approach are: to ensure the termination of the introspection using the smallest set of formally justified conditions and to provide a clear declarative account of this reflective protocol. The PRS also appears as a meta-level to the base language, independent of the implementation, but from which we derive fundamental clues to obtain an efficient language processor. By our new model, we finally highlight the link between reflection in object-oriented languages and the one originally proposed by 3-Lisp [24], although object-orientation provides reusability to reflection, making it easier to use.     

Numerical solution of Riccati equation using the cubic B-spline scaling functions and Chebyshev cardinal functions

Two numerical techniques are presented for solving the solution of Riccati differential equation. These methods use the cubic B-spline scaling functions and Chebyshev cardinal functions. The methods consist of expanding the required approximate solution as the elements of cubic B-spline scaling function or Chebyshev cardinal functions. Using the operational matrix of derivative, we reduce the problem to a set of algebraic equations. Some numerical examples are included to demonstrate the validity and applicability of the new techniques. The methods are easy to implement and produce very accurate results.     

UML状态图的测试用例自动生成

现有的研究在对UML状态图生成测试用例时,为简化问题而忽略了对伪状态的支持。针对这一问题,首先对UML状态图的伪状态概念进行分析,并讨论了其对相关测试用例生成算法的影响;改进了UMLstatechart语义对伪状态的定义,对伪状态进行适当的转换,同时扩充现有算法对伪状态的支持;提出了一套可以处理伪状态的UML状态图平坦化算法以及相应的测试用例生成方法,并对实际应用效果进行了验证。     

应用ANTLR实现过程式语言操作语义的动态演示

介绍了一个面向过程语言的文法特点,应用ANTLR实现了该语言操作语义的动态演示,系统可辅助教师进行课堂教学,为学生自主学习提供良好的支撑环境,从而用形象的图形界面为学生搭起通向掌握抽象思维方法的桥梁。     

基于语义的单文档自动摘要算法

单文档自动摘要的目的是在原始的文本中通过摘取、提炼主要信息,提供一篇简洁全面的摘要。自动摘要的主流方法是通过统计和机器学习的技术从文本中直接提取出句子,而单文档由于篇章有限,统计的方法无效。针对此问题,提出了基于语义的单文本自动摘要方法。该方法首先将文档划分为句子,然后计算每一对句子的语义相似度,通过运用改进型K-Medoids聚类算法将相似的句子归类,在每一类中选出最具代表性的句子,最后将句子组成文档摘要。实验结果表明,通过融合语义信息,该方法提高了摘要的质量。     

Defining the meaning of tabular mathematical expressions

Mathematical expressions in tabular form (also called “tabular expressions” or “tables”) have been shown to be useful for documenting and analysing software systems. They are usually easier to read than conventional mathematical expressions but are no less precise. They can be used wherever mathematical expressions are used. To avoid misunderstandings, and to support users with trustworthy tools, the meaning of these expressions must be fully defined.This paper presents a new method for defining the meaning of tabular expressions. Each definition of an expression type names the expression’s constituents, and provides a restriction schema and one or more evaluation schemas. The restriction schema defines the class of well-formed expressions of the type. An evaluation schema maps a well-formed tabular expression of the type to a mathematical expression of a previously defined type. Since the meaning of conventional mathematical expressions is well known, describing an equivalent expression fully defines the meaning of a tabular expression.In this approach, indexation is used to decouple the appearance of a tabular expression from its semantics. A tabular expression is an indexed set of grids; a grid is an indexed set of expressions. The expressions in a grid can be either conventional expressions or tabular expressions of a previously defined type.Defining the meaning of a tabular expression in this way facilitates the building of tools that faithfully implement the semantics. The decoupling of syntax and semantics by means of indices overcomes some limitations of older approaches.The method presented in the paper is illustrated by defining several previously known types of tabular expressions and some new ones. The use of the new model to build a suite of tools for the input, presentation, validation, evaluation, simplification, conversion and composition of tabular expressions is discussed.