Vladimir Oliveira Di Iorio

An on-the-fly grammar modification mechanism for composing and defining extensible languages

Adaptable Parsing Expression Grammar (APEG) is a formal method for defining the syntax of programming languages. It provides an on-the-fly mechanism to perform modifications of the syntax of the language during parsing time. The primary goal of this dynamic mechanism is the formal specification and the automatic parser generation for extensible languages. In this paper, we show how APEG can be used for the definition of the extensible languages SugarJ and Fortress, clarifying many aspects of the syntax of these languages. We also show that the mechanism for on-the-fly modification of syntax rules can be useful for defining grammars in a modular way, implementing almost all types of language composition in the context of specification of extensible languages. HighlightsWe evaluate an adaptable model based on Parsing Expressions Grammars, called APEG.we define the syntax of SugarJ and Fortress using APEG.We analyze the flexible mechanism of APEG to change the grammar on-the-fly.The flexibility to modify grammars allows APEG to reuse other grammars definitions.The mechanism of on-the-fly modification of grammars allows composing languages.

Defining the syntax of extensible languages

The interest in Domain-Specific Languages (DSLs) has been increasing as a way of improving the productivity and read-ability of software. Some modern extensible languages offer facilities for building modular specifications for extensions, so they may be considered an interesting option for implementing domain specific languages. But there are at least two disadvantages that currently affect most extensible languages. First, their syntax is usually defined informally, because there is a lack of formal tools for the definition of extensible languages. Second, extensible languages are usually implemented in an ad-hoc and inefficient way. In this paper, we show how the syntax of extensible languages like Fortress and SugarJ can be formally defined using a novel model designated Adaptable Parsing Expression Grammars (APEG). The formal definitions of the languages help clarifying many aspects of their syntax. We also use an interpreter of the APEG model to parse programs of the languages, showing that the model can be used in practice to implement parsers for extensible languages.

A proposal for extensible AspectJ

This article presents the preliminary results achieved while working with a language to define extensions to the concrete syntax of AspectJ. The language uses the concept of syntax classes, units that extend classes with syntax definitions, building modular specifications for extensions. A syntax class can define a new construct with cross-cutting features either by translating it into pure AspectJ code or by modifying the behaviour of elements in different parts of the program, acting like an aspect weaver. The definition of new pointcut designators is also possible, with clear separation between run-time and weave-time processing. The language can be used as a tool to create domain-specific extensions to AspectJ, and domain-specific aspect languages embedded into AspectJ.

A Mixed Approach for Building Extensible Parsers

For languages whose syntax is fixed, parsers are usually built with a static structure. The implementation of features like macro mechanisms or extensible languages requires the use of parsers that may be dynamically extended. In this work, we discuss a mixed approach for building efficient top-down dynamically extensible parsers. Our view is based on the fact that a large part of the parser code can be statically compiled and only the parts that are dynamic should be interpreted for a more efficient processing. We propose the generation of code for the base parser, in which hooks are included to allow efficient extension of the underlying grammar and activation of a grammar interpreter whenever it is necessary to use an extended syntax. As a proof of concept, we present a prototype implementation of a parser generator using Adaptable Parsing Expression Grammars (APEG) as the underlying method for syntax definition. We show that APEG has features which allow an efficient implementation using the proposed mixed approach.

Weave time macros

This ongoing work presents a methodology to extend the pointcut language of AspectJ based on macro definitions. The main features of the proposed approach are: syntax extension in a very exible way; arguments for new pointcuts are defined by other pointcuts; the semantics of new point-cuts is given by a translation to pure AspectJ, defining precisely the code to be executed at weave time and at runtime. One of the main goals of this methodology is to provide an efficient implementation of the extension mechanism

What's the Name of the Game? Formal Specification of Artificial Intelligence Games

Artificial intelligence games are a very interesting tool for teaching Artificial Intelligence techniques. Competitors write programs for agents, which are supposed to complete a given task or fight against other agents. In order to achieve the best performance, programs may have to use advanced Artificial Intelligence methods. In this paper, we present a framework to build artificial intelligence games, using Abstract State Machines (ASM) for the specification of the rules of the games. Choosing ASM, we expect that the competitors will be able to understand clearly the semantics of the rules. The framework includes a compiler for an ASM-based language, allows complete control of the order of execution of agents and easy integration with graphical libraries.