EECS4302 ANTLR4 Parser Generator Tutorial: Part 2

Step-by-Step Tutorial: Implementing ANTLR for Parsing Projects

1. Rationale for Using ANTLR:

   • Before starting with individual projects, it's important to understand the rationale behind using ANTLR for parsing tasks instead of implementing a parser from scratch.
   • ANTLR helps in generating parser and lexer components efficiently, making the parsing process more manageable.

2. Setting Up ANTLR Packages:

   • Create a new package named antlr under the source directory for both projects.
   • Within the package, create a new file with the extension .g4, which is the standard extension for ANTLR grammar files.
   • The grammar file should be named appropriately, such as expression.g4.

3. Defining Grammar Rules:

   • Inside the .g4 file, start by defining the grammar using the grammar keyword followed by the grammar name and a semicolon.
   • Ensure that the grammar name matches the file name for consistency.
   • Define production rules and tokens in the grammar file following the ANTLR syntax.

4. Generating Java Classes:

   • Use ANTLR to generate Java classes based on the grammar file by running the appropriate command in the terminal.
   • Refresh the project in Eclipse to see the newly generated Java classes in the package structure.

5. Testing the Grammar:

   • Create test cases in separate text files within a tests folder in the project directory.
   • Use the G run tool to test the grammar against the test files and visualize the parse tree for each input.

6. Compiling Java Classes:

   • Compile all Java classes generated by ANTLR using the javac command in the terminal to prepare for running the G run tool.

7. Running G Run Tool:

   • Run the G run tool with the appropriate arguments, including the grammar name, test file, and GUI flag to visualize the parse tree.
   • Verify that the parse tree generated by the G run tool aligns with the expected structure based on the grammar rules.

8. Analyzing Parse Tree:

   • Examine the parse tree generated by the G run tool to ensure that the grammar is correctly interpreting the input text.
   • Verify that the parse tree reflects the intended structure of the parsed expressions and tokens.

9. Extending Grammar for Visitor Classes:

   • Copy the grammar file to the ANTLR package within the Eclipse project to prepare for generating visitor classes.
   • Generate Java classes with the visitor mode to enable the implementation of visitor design pattern for parsing tasks.

10. Testing Visitor Classes:

    • Use the G run tool to test the grammar against the test files with the visitor classes generated by ANTLR.
    • Verify that the parse tree and output align with the grammar rules and expected behavior.

11. Final Steps:

    • Ensure that all Java classes, grammar files, and test cases are organized within the project structure for easy access and testing.
    • Continue to iterate on the grammar rules, test cases, and Java classes to refine the parsing process for the specific project requirements.

By following these steps, you can effectively implement ANTLR for parsing tasks and leverage its capabilities to streamline the development of parsers for various projects.