Tools to run antlr4 w/o needing to install java or antlr4! The only requirement is Python3, which is typically installed on all developer machines on all operating systems.
$ pip install antlr4-toolsThat creates antlr4 and antlr4-parse executables. On Windows, of course, this doesn't just work. You need to add the ...\local-packages\python38\scripts dir to your PATH, which itself might require a fun reboot or perhaps reinstall of the OS. haha.
On Windows, the pip command doesn't just work---you need to add the ...\local-packages\python38\scripts dir to your PATH, which itself might require a fun reboot. If you use WSL on Windows, then the pip install will also properly at the scripts directly (if you run from bash shell).
- Go to the Microsoft Store
- Search in Microsoft Store for Python
- Select the newest version of Python (3.10).
- Click the "Get" button. Store installs python and pip at "c:\Users...\AppData\Local\Microsoft\WindowsApps\python.exe" and "c:\Users...\AppData\Local\Microsoft\WindowsApps\pip.exe", respectively. And, it updates the search path immediately with the install.
- Open a "cmd" terminal.
- You can now type "python" and "pip", and "pip install antlr4-tools". 7. Unfortunately, it does not add that to the search path.
- Update the search path to contain
c:\Users...\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.10_qbz5n2kfra8p8\LocalCache\local-packages\Python310\Scripts. You may need to install MSYS2, then do afind /c/ -name antlr4.exe 2> /dev/nulland enter that path. - Or, you can set up an alias to antlr4.exe on that path.
The good news is that the ANTLR4 Python tool downloads the ANTLR jar in a standard location, and you don't need to do that manually. It's also possible to go in a browser, go to python.org, and download the python package. But, it's likely you will need to update the path for antlr4.exe as before.
If needed, antlr4 will download and install Java 11 and the latest ANTLR jar:
$ antlr4
Downloading antlr4-4.11.1-complete.jar
ANTLR tool needs Java to run; install Java JRE 11 yes/no (default yes)? y
Installed Java in /Users/parrt/.jre/jdk-11.0.15+10-jre; remove that dir to uninstall
ANTLR Parser Generator Version 4.11.1
-o ___ specify output directory where all output is generated
-lib ___ specify location of grammars, tokens files
...To override the version of ANTLR jar used, you can pass a -v <version> argument or set ANTLR4_TOOLS_ANTLR_VERSION environment variable:
$ antlr4 -v 4.9.3
ANTLR Parser Generator Version 4.9.3
-o ___ specify output directory where all output is generated
-lib ___ specify location of grammars, tokens files
...
$ ANTLR4_TOOLS_ANTLR_VERSION=4.10.1 antlr4
ANTLR Parser Generator Version 4.10.1
-o ___ specify output directory where all output is generated
-lib ___ specify location of grammars, tokens files
...The antlr4 command forwards all arguments (besides -v mentioned above) to the actual ANTLR tool command:
$ antlr4 JSON.g4
$ ls JSON*.java
JSONBaseListener.java JSONLexer.java JSONListener.java JSONParser.java
$ antlr4 -Dlanguage=Python3 -visitor JSON.g4
$ ls JSON*.py
JSONLexer.py JSONListener.py JSONParser.py JSONVisitor.pyThe antlr4-parse command requires ANTLR 4.11 and above (but any version of ANTLR works for the plain antlr4 command). It accepts the same -v argument or environment variable to override the ANTLR jar version used. (Note: ^D means control-D and indicates "end of input" on Unix but use ^Z on Windows.)
Let's play with a simple grammar:
grammar Expr;
prog: expr EOF ;
expr: expr ('*'|'/') expr
| expr ('+'|'-') expr
| INT
| '(' expr ')'
;
NEWLINE : [\r\n]+ -> skip;
INT : [0-9]+ ;
To parse and get the parse tree in text form, use:
$ antlr4-parse Expr.g4 prog -tree
10+20*30
^D
(prog:1 (expr:2 (expr:3 10) + (expr:1 (expr:3 20) * (expr:3 30))) <EOF>)Here's how to get the tokens and trace through the parse:
$ antlr4-parse Expr.g4 prog -tokens -trace
10+20*30
[@0,0:1='10',<INT>,1:0]
[@1,2:2='+',<'+'>,1:2]
[@2,3:4='20',<INT>,1:3]
[@3,5:5='*',<'*'>,1:5]
[@4,6:7='30',<INT>,1:6]
[@5,9:8='<EOF>',<EOF>,2:0]
enter prog, LT(1)=10
enter expr, LT(1)=10
consume [@0,0:1='10',<8>,1:0] rule expr
enter expr, LT(1)=+
consume [@1,2:2='+',<3>,1:2] rule expr
enter expr, LT(1)=20
consume [@2,3:4='20',<8>,1:3] rule expr
enter expr, LT(1)=*
consume [@3,5:5='*',<1>,1:5] rule expr
enter expr, LT(1)=30
consume [@4,6:7='30',<8>,1:6] rule expr
exit expr, LT(1)=<EOF>
exit expr, LT(1)=<EOF>
exit expr, LT(1)=<EOF>
consume [@5,9:8='<EOF>',<-1>,2:0] rule prog
exit prog, LT(1)=<EOF>Here's how to get a visual tree view:
$ antlr4-parse Expr.g4 prog -gui
10+20*30The following will pop up in a Java-based GUI window:
On real grammars, it can be useful to get decision-making profiling info:
$ antlr4-parse JavaLexer.g4 JavaParser.g4 compilationUnit -profile dump.csv T.java
$ open /tmp/dump.csv
$ head -5 /tmp/dump.csv
Rule,Invocations,Time (ms),Total k,Max k,Ambiguities,DFA cache miss
compilationUnit:0,1,0.164791,1,1,0,1
compilationUnit:1,42,1.106583,42,1,0,2
compilationUnit:2,2,1.73675,2,1,0,2
compilationUnit:3,1,3.969,1,1,0,1
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