Quick Introduction to ANTLR
Once you know how to build lexers and parsers by hand, it’s a good idea to use a parser generator to make your life easier. This section gets you started using ANTLR[12] and its grammar DSL. (You can skip to the next chapter if you’re already familiar with it.) We’re going to build a simple grammar, run it through ANTLR, and write a test rig to exercise the generated lexer and parser.
Let’s build a grammar for a simple graphics DSL with a single command for drawing lines. Here’s how we’d draw a box 10 units on a side:
| parsing/antlr/box | |
| | line from 0,0 to 0,10 |
| | line from 0,10 to 10,10 |
| | line from 10,10 to 10,0 |
| | line from 10,0 to 0,0 |
The syntax of the DSL is a list of line commands:
| parsing/antlr/Graphics.g | |
| | grammar Graphics; ... |
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