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|
header {
}
options {
language="CSharp";
}
class LangParser extends Parser;
options {
buildAST=true;
}
tokens {
BLOCK; // imaginary token
}
block
: LCURLY! ( statement )* RCURLY!
// add imaginary BLOCK node on top of statement list
{#block = #([BLOCK, "BLOCK"], #block);}
;
statement
: ID ASSIGN^ expr SEMI!
| "if"^ LPAREN! expr RPAREN! statement
( "else"! statement )?
| "while"^ LPAREN! expr RPAREN! statement
|! b:block { statement_AST = #b; }
// do some manual tree returning
;
// add an EXPR node on top of an expression
// note that the two alternatives behave exactly
// the same way.
expr:! id:ID {#expr = #([EXPR,"EXPR"],#id);}
| INT {#expr = #([EXPR,"EXPR"],#expr);}
;
class LangWalker extends TreeParser;
block : #( BLOCK ( stat )+ )
;
stat: #("if" expr stat (stat)?)
| #("while" expr stat)
| expr
| block
| #( ASSIGN ID expr )
;
expr: #( EXPR
( a:ID {Console.Out.WriteLine("found ID "+a.getText());}
| b:INT {Console.Out.WriteLine("found INT "+b.getText());}
)
)
;
class LangLexer extends Lexer;
WS : (' '
| '\t'
| '\n'
| '\r')
{ _ttype = Token.SKIP; }
;
LPAREN: '('
;
RPAREN: ')'
;
LCURLY: '{'
;
RCURLY: '}'
;
ASSIGN
: '='
;
SEMI: ';'
;
protected
DIGIT
: '0'..'9'
;
INT : (DIGIT)+
;
ID
options {
testLiterals = true;
}
: ('a'..'z'|'A'..'Z'|'_') ('a'..'z'|'A'..'Z'|'_'|DIGIT)*
;
|
