The Lexical and Syntactic Analyzers of the Translator for the EI Language

摘要

This paper contains the task of implementation of functionally-imperative programming language EI, the composition and structure of the its translator, a brief description of the lexical and syntactic rules of the language, the algorithms and the basic functions of the lexical and syntactic analyzers. It describes fragments of formal definitions of lexic and syntax of the El-Ianguage that was used for the automated construction of lexical and syntactic analyzers of the compiler in C++ using the client-server package Webtranslab. It describes also the basic algorithms of lexical analyzer (scanner), which in this version of the compiler performs macroprocessing, files including, deleting all the insignificant character sequences and transformation of correct words of language into an internal representation - tokens. We consider the structure and functions of a parser that performs a descending analysis. This parser constructed in the form of a stack automaton with multi-states controlled by the current input token and the current state fields. The composition of the state cell of the automaton and the algorithms of its operation are described, as well as the mechanisms for performing the operations that are embedded in the grammar and intended to implement the functionality of the semantic analyzer and code generator. The current state of realization of two constituent parts of the translator for EI-language - scanner and parser - is described.