The Definitive ANTLR 4 Reference, 2nd Edition

The ANTLR Tool, Runtime, and Generated Code

To get started, let’s peek inside ANTLR’s jar. There are two key ANTLR components: the ANTLR tool itself and the ANTLR runtime (parse-time) API. When we say “run ANTLR on a grammar,” we’re talking about running the ANTLR tool, class org.antlr.v4.Tool. Running ANTLR generates code (a parser and a lexer) that recognizes sentences in the language described by the grammar. A lexer breaks up an input stream of characters into tokens and passes them to a parser that checks the syntax. The runtime is a library of classes and methods needed by that generated code such as Parser, Lexer, and Token. First we run ANTLR on a grammar and then compile the generated code against the runtime classes in the jar. Ultimately, ...