dtonhofer

dtonhofer

The Definitive ANTLR 4 Reference - "Java.g4" grammer (used on page 40) no longer passes ANTLR

@parrt

In the context of Chapter 4.3, the grammar Java.g4, meant to parse Java 6 compilation units, no longer passes ANTLR (currently 4.10.1)

That file is included in the Zip file of examples & source code that comes with the book (as code/tour/Java.g4)

Two problems:

The definition of “expression” uses “<assoc=right>” on each operator from line 546 onwards. However, “<assoc=right>” now needs to be placed in front:

    |   <assoc=right> expression
        ('^='
        |'+='
        |'-='
        |'*='
        |'/='
        |'&='
        |'|='
        |'='
        |'>' '>' '='
        |'>' '>' '>' '='
        |'<' '<' '='
        |'%='
        ) 

The definitin for “Escape Sequence” contains the string ‘"’ which is considered an illegal escape. The backslash has to be removed.

In fact, the current ANTLR distro comes with its own Java.g4, or rather two of them (very confusing!)

A grammer for Java 7 from 2013:

antlr4-4.10.1/runtime-testsuite/test/org/antlr/v4/test/runtime/java/api/Java.g4

A grammar for Java 5 from 2008;

antlr4-4.10.1/tool-testsuite/test/org/antlr/v4/test/tool/Java.g4

The example code should probably be upgrade to

antlr4-4.10.1/runtime-testsuite/test/org/antlr/v4/test/runtime/java/api/Java.g4

which seems to work.

Marked As Solved

ariel.lenis

ariel.lenis

Thank you @dtonhofer and @parrt I was able to make it work using the grammars from

https://github.com/antlr/grammars-v4/tree/master/java/java

You need to generate the Java files in order: Lexer first and Parser last

antlr4 JavaLexer.g4
antlr4 JavaParser.g4

And finally this is the code that I have used for the ExtractInterfaceListener.java file:

import org.antlr.v4.runtime.TokenStream;

public class ExtractInterfaceListener extends JavaParserBaseListener {
    JavaParser parser;
    public ExtractInterfaceListener(JavaParser parser) {this.parser = parser;}

    @Override
    public void enterClassDeclaration(JavaParser.ClassDeclarationContext ctx) {
        // Errata Suggestion: previous implementation
        // System.out.println("interface I" + ctx.Identifier() + " {");
        // Errata Suggestion: fix
        System.out.println("interface I" + ctx.identifier().getText() + " {");
    }

    @Override
    public void exitClassDeclaration(JavaParser.ClassDeclarationContext classDeclarationContext) {
        System.out.println("}");
    }

    @Override
    public void enterMethodDeclaration(JavaParser.MethodDeclarationContext ctx) {
        // need parser to get tokens
        TokenStream tokens = parser.getTokenStream();
        
        /*
        // Errata Suggestion: previous implementation
        String type = "void";

        if ( ctx.type()!=null ) {
            type = tokens.getText(ctx.type());
        }
        */
        // Errata Suggestion: fix
        String type = ctx.typeTypeOrVoid().getText();

        String args = tokens.getText(ctx.formalParameters());

        // Errata Suggestion: previous implementation
        // System.out.println("\t" + type + " " + ctx.Identifier() + args + ";");
        // Errata Suggestion: fix
        System.out.println("\t" + type + " " + ctx.identifier().getText() + args + ";");
    }
}

I hope it will help someone.

Where Next?

Popular Pragmatic Bookshelf topics Top

Alexandr
Hi everyone! There is an error on the page 71 in the book “Programming machine learning from coding to depp learning” P. Perrotta. You c...
New
mikecargal
Title: Hands-On Rust (Chap 8 (Adding a Heads Up Display) It looks like ​.with_simple_console_no_bg​(SCREEN_WIDTH*2, SCREEN_HEIGHT*2...
New
Mmm
Hi, build fails on: bracket-lib = “~0.8.1” when running on Mac Mini M1 Rust version 1.5.0: Compiling winit v0.22.2 error[E0308]: mi...
New
rmurray10127
Title: Intuitive Python: docker run… denied error (page 2) Attempted to run the docker command in both CLI and Powershell PS C:\Users\r...
New
jeremyhuiskamp
Title: Web Development with Clojure, Third Edition, vB17.0 (p9) The create table guestbook syntax suggested doesn’t seem to be accepted ...
New
adamwoolhether
When trying to generate the protobuf .go file, I receive this error: Unknown flag: --go_opt libprotoc 3.12.3 MacOS 11.3.1 Googling ...
New
brunogirin
When trying to run tox in parallel as explained on page 151, I got the following error: tox: error: argument -p/–parallel: expected one...
New
New
hazardco
On page 78 the following code appears: &lt;%= link_to ‘Destroy’, product, class: ‘hover:underline’, method: :delete, data: { confirm...
New
roadbike
From page 13: On Python 3.7, you can install the libraries with pip by running these commands inside a Python venv using Visual Studio ...
New

Other popular topics Top

PragmaticBookshelf
Stop developing web apps with yesterday’s tools. Today, developers are increasingly adopting Clojure as a web-development platform. See f...
New
PragmaticBookshelf
Brace yourself for a fun challenge: build a photorealistic 3D renderer from scratch! In just a couple of weeks, build a ray tracer that r...
New
AstonJ
I’ve been hearing quite a lot of comments relating to the sound of a keyboard, with one of the most desirable of these called ‘thock’, he...
New
AstonJ
This looks like a stunning keycap set :orange_heart: A LEGENDARY KEYBOARD LIVES ON When you bought an Apple Macintosh computer in the e...
New
Margaret
Hello everyone! This thread is to tell you about what authors from The Pragmatic Bookshelf are writing on Medium.
1147 29994 760
New
DevotionGeo
I have always used antique keyboards like Cherry MX 1800 or Cherry MX 8100 and almost always have modified the switches in some way, like...
New
New
NewsBot
Node.js v22.14.0 has been released. Link: Release 2025-02-11, Version 22.14.0 'Jod' (LTS), @aduh95 · nodejs/node · GitHub
New
RobertRichards
Hair Salon Games for Girls Fun Girls Hair Saloon game is mainly developed for kids. This game allows users to select virtual avatars to ...
New
PragmaticBookshelf
Fight complexity and reclaim the original spirit of agility by learning to simplify how you develop software. The result: a more humane a...
New

Sub Categories: