Parsing is the process of turning the text of a program into its Abstract Syntax Tree representation.
Truffle does not have a built-in way to perform parsing, and instead allows you to use any library you want for this task.
This article series uses ANTLR.
The way it's set up is that we have a
grammar file, EasyScript.g4,
that represents a language for adding integer and double literals from part 3.
That grammar file is read by the ANTLR Gradle plugin,
enabled in the build.gradle file of the module,
to generate classes that perform the parsing.
Those generated classes are then used by the
EasyScriptTruffleParser class
to turn the ANTLR parse tree into the Truffle AST.
There is a unit test confirming this works as expected.
TruffleLanguage is an abstract class that you can extend to make your language part of the GraalVM polyglot API.
Our implementation is in the
EasyScriptTruffleLanguage class.
Here is a unit test showing how can you invoke EasyScript using GraalVM's polyglot API.