Uma abordagem para avaliar a expressividade de gramáticas de linguagens específicas de domínio: um estudo de caso com SQL.

Abstract

Domain-Specific Languages (DSLs) are defined as designed languages focused on a specific problem domain. Currently, there is a wide variety of DSLs, such as HTML for web pages, XML for data encoding, SQL for database queries, Latex, Mathematica, and Verilog, among others. DSLs can contribute to substantial gains related to the abstraction, understanding, and creation of simple notations in the development of software artifacts. Furthermore, in developers’ work, DSLs are widely used in problem-solving, because they have concepts and terms familiar to them. However, the DSLs evaluation under characteristics that affect the ability to write in a language, such as its expressiveness, is still an insufficiently investigated area, and few are presented in studies. On the other hand, when these evaluations are proposed, approaches specifically directed to the languages under study are used, that is, they do not show an analysis based on metrics that can validate any type of DSL. Considering this problem, the present study aimed to develop an approach through a case study with SQL for evaluations of DSLs based on their grammar, athwart the proposition, and application of quantitative metrics related to the characteristic of expressiveness. The results of the study indicate that the expressiveness gain was observed mainly by the significant increase of 160 new terminals in the SQL version of 1999. These new terminals are related to categories such as data types, commands, expressions, and exceptions that were added to the language. This work can help people interested in the area of DSLs and languages in general, to evaluate the expressiveness quality of their language under study, with a new vision based on the analysis of the grammar developed.