Antlr4_Grammars

Antlr4 is used for lexical, syntax, and semantic analysis of structured text.

From the website:

Download https://www.antlr.org/download/antlr-4.8-complete.jar.
Add antlr4-complete.jar to CLASSPATH, either:
  Permanently: Using System Properties dialog > Environment variables > Create or append to CLASSPATH variable
  Temporarily, at command line:
    SET CLASSPATH=.;C:\Javalib\antlr4-complete.jar;%CLASSPATH%
Create batch commands for ANTLR Tool, TestRig in dir in PATH
   antlr4.bat: java org.antlr.v4.Tool %*
   grun.bat:   java org.antlr.v4.gui.TestRig %*

For myself I had to make sure the classpath in environment variables pointed to the antlr4-complete.jar. If you have Java like me installed append it as such:

.;
antlr4-complete.jar;

If using VSCode, the referenced libraries need to be set to the antlr jar also.

Folders and their difficulty

1. hello.g4 is an introductory program to show the tokens.
2. slp.g4 is good for viewing the gui.
3. draw.g4 uses a java file and reads from a file.
4. cal.g4 overwrites the ErrorListener.java file.
5. bp.g4 extends the BaseVisitor.java file and gives results back.