Grammar.txt

// Tokens
KEYWORD: 'if' | 'while' | 'for' | 'print' | 'println' | 'fn'
IDENTIFIER: [a-zA-Z_][a-zA-Z0-9_]*
INTEGER: [0-9]+
STRING: '"' .*? '"'
OPERATOR: '+' | '-' | '*' | '/' | '>' | '<' | '==' | '!=' | '>=' | '<=' | '='
LPAREN: '('
RPAREN: ')'
LBRACKET: '['
RBRACKET: ']'
LBRACE: '{'
RBRACE: '}'
SEMICOLON: ';'
COMMA: ','
WHITESPACE: [ \t\n\r]+ -> skip

// Grammar Rules
program: statement* EOF;

statement: ifStatement
         | whileStatement
         | forStatement
         | printStatement
         | functionStatement
         | functionCallStatement
         | arrayStatement
         ;

ifStatement: 'if' LPAREN expression RPAREN LBRACE statement* RBRACE ( 'else' LBRACE statement* RBRACE )?;

whileStatement: 'while' LPAREN expression RPAREN LBRACE statement* RBRACE;

forStatement: 'for' LPAREN assignmentStatement expression SEMICOLON assignmentStatement RPAREN LBRACE statement* RBRACE;

printStatement: ('print' | 'println') LPAREN expression RPAREN SEMICOLON;

functionStatement: 'fn' IDENTIFIER LPAREN ( IDENTIFIER ( COMMA IDENTIFIER )* )? RPAREN LBRACE statement* RBRACE;

functionCallStatement: IDENTIFIER LPAREN ( expression ( COMMA expression )* )? RPAREN SEMICOLON;

assignmentStatement: IDENTIFIER '=' expression SEMICOLON;

expression: binaryExpression
          | unaryExpression
          | primaryExpression
          | arrayExpression
          ;

binaryExpression: expression OPERATOR expression;

unaryExpression: OPERATOR expression;

primaryExpression: INTEGER
                 | STRING
                 | IDENTIFIER
                 | LPAREN expression RPAREN
                 ;

arrayExpression: LBRACKET expression ( COMMA expression )* RBRACKET;