A starter project for the RichRail command line DSL. This project is part of an assignment for Patterns and Frameworks at the Hogeschool Utrecht.
- The project uses Java 11, but you can change this in
pom.xmlif need be - Install packages using Maven (see
pom.xml) - This automatically generates the required classes through ANTLR4
- For manually updating/regenerating the required classes based on the grammar, you can let Maven execute the antlr4:antlr4 command
Main.java is the entry point. This sets up
all the required components.
It requests input, tokenizes it, parses it
and walks over the ParseTree using our custom
RichRailCli, which is a Listener that extends
the RichRailBaseListener generated by ANTLR4. The
Listener listens to enter and exit events.
To configure our own actions, we need to override the relevant methods.
ANTLR4 generates Parser, Visitor and Listener
classes based on the RichRail.g4 grammar
found in src/main/antlr4/parser.
These classes contain context and methods needed
for visiting the nodes in the parse tree or
for listening to events when entering or exiting
the nodes in a parse tree.
In this example, a Visitor approach has been used.
The RichRailCli is a custom class that extends
the base listener generated by ANTLR4. In this custom class,
we can overwrite the steps taken when traversing each node
in a certain expression.
ANTLR4 generates these class files
in the target directory. You can use the
maven commands defined in the pom.xml.
The generated classes are output to
the target/generated-sources/antlr4 directory
and reside in the project's parser package.
This is due to the standard configuration of ANTLR4,
matching the location of the grammar file (src/antlr4/parser).
No further configuration required.
Alex Rothuis: @arothuis