Introduction to ANTLR4

Hannes Kinks

Tallinn 2014

Resources

• Homepage - http://www.antlr.org
• Book - https://pragprog.com/book/tpantlr2/the-definitive-antlr-4-reference
• Presentation about ANTLR4 by Terence Parr - 
  http://www.youtube.com/watch?v=q8p1voEiu8Q

• Homework from last year made in ANTLR4
  https://bitbucket.org/hkinks/estcompiler

ANTLR4 vs Flex+Bison

• Ease of use over performance
• Simplicity over complexity
• Automatic generation of parse trees
• Decoupled grammar and application-specific code
  • Listeners
  • Visitors
• Parsing algorithms
  • LL(*)
  • LALR 

Parsing algorithm comparison

Bison - LALR

Bottom-up parsing

ANTLR - LL(*)

Top-down parsing

Parsing with ANTLR4

• Grammar divided to
  • Lexer
  • Parser
• Described in *.g4 file

Example

1. Define grammar in  

Assign.g4

2. ANTLR tool generates code

4. Walking the parse tree

3. Input text: 
"sp = 100;"

Listener

• Parse tree walked depth-first
• Events fired at every node

Visitor pattern

• Option -visitor

Setting up the environment

• http://ati.ttu.ee/~hkinks/antlr/
• antlr.sh
  • ​downloads ANTLR4 library
  • adds lib to classpath
  • sets aliases for antlr4 and grun
• ​plugin.zip
  • ​Plugin for Intellij IDEA

• Plugins existing also for eclipse and netbeans