1. Introduction to ANTLR
Jin Tianxing

2. What ANTLR do
All ANTLR need is a grammar file where the syntactic rule is defined.
The output of ANTLR is a Lexer and a Parser written with Java.

3. About Versions ANTLR 3.5 ANTLR 4 Tree-rewrite enabled(AST)
No GUI Interface to display trees
ANTLR 4
Tree-rewrite disabled(Parsing tree)
GUI Interface

4. Grammar grammar example; prog: (expr NEWLINE)* ; expr: INT (OP expr)?
NEWLINE: ('\r' | '\n')+;
INT: ('0'..'9')+;
OP: '+' | '-' | '*' | '/';
However, using this grammar still produce a Parsing Tree.

5. Tree-Rewrite(ANTLR 3.x)
Option: output=AST
Different ways of Rewrite:
expr: INT (OP^ expr);
expr: INT (OP expr) -> ^(OP INT expr);
expr: ‘(‘! expr^ ‘)’!;
ANTLR 4.x does not support rewrite