ANTLR is a powerful parser generator for multiple programming languages including Java.

ANTLR contains 2 major modules:

• Runtime - For building and executing parsers/lexers generated in Java.
• Tool (The Parser Generator) - For generating parsers/lexers Java class.

ANTLR Tool Source Code files are provided in the distribution packge (antlr4-4.10.1.zip). You can download them at ANTLR Website.

You can also browse the source code below:

⏎ org/antlr/v4/tool/ErrorSeverity.java

/*
 * Copyright (c) 2012-2017 The ANTLR Project. All rights reserved.
 * Use of this file is governed by the BSD 3-clause license that
 * can be found in the LICENSE.txt file in the project root.
 */
package org.antlr.v4.tool;

/**
 * Abstracts away the definition of Message severity and the text that should
 * display to represent that severity if there is no StringTemplate available
 * to do it.
 *
 * @author Jim Idle - Temporal Wave LLC (jimi@temporal-wave.com)
 */
public enum ErrorSeverity {
    INFO    ("info"),
	WARNING ("warning"),
	WARNING_ONE_OFF ("warning"),
	ERROR   ("error"),
	ERROR_ONE_OFF   ("error"),
    FATAL   ("fatal"),  // TODO: add fatal for which phase? sync with ErrorManager
    ;

    /**
     * The text version of the ENUM value, used for display purposes
     */
    private final String text;

    /**
     * Standard getter method for the text that should be displayed in order to
     * represent the severity to humans and product modelers.
     *
     * @return The human readable string representing the severity level
     */
    public String getText() { return text; }

    /**
     * Standard constructor to build an instance of the Enum entries
     *
     * @param text The human readable string representing the severity level
     */
    private ErrorSeverity(String text) { this.text = text; }
}

⏎ org/antlr/v4/tool/ErrorSeverity.java

Or download all of them as a single archive file:

File name: antlr-tool-4.10.1-sources.jar
File size: 347718 bytes
Release date: 2022-04-15
Download 

⇒ Donwload antlr4-4.10.1.zip

⇐ ANTLR Runtime Source Code

⇑ Download and Review ANTLR Parser Generator

⇑⇑ FAQ for ANTLR Parser Generator