Antlr4 Can't load as lexer or parser

Question

I know this probably looks like a duplicate. It's not. I've searched for an hour, trying everything I've seen and nothing has worked.

I have an antlr4 grammar file called MathLang.g4. I have put it into its own folder called Grammartest. antlr-4.7.1-complete.jar is in C:\Program Files\Java\libs, along with antlr4.bat and grun.bat. The folder is in the PATH and the jar is in the CLASSPATH. The bat files read as such:

// antlr4.bat
java org.antlr.v4.Tool %*

// grun.bat
java org.antlr.v4.gui.TestRig %*

I then run the following commands in the Grammartest folder:

antlr4 MathLang.g4
javac MathLang*.java
grun MathLang def

antlr4 and javac run silently, generating the .java and then .class files. grun responds with Can't load MathLang as lexer or parser.

How can I fix this?

Unlocked Unlocked · Accepted Answer · 2018-01-20T21:59:27

4

votes

Apparently I had to add the folder that I was testing in (Grammartest) to the CLASSPATH.

Antlr4 Can't load as lexer or parser

1 Answers