grammar.txt

Statement : Statements
		  | LetStatement // let a = 3;
		  | ReturnStatement // return a;
		  | ExpressionStatement // 5 + 5;
		  | AssignStatement // a = 4;
		  | BlockStatement // { let b = 4; a + b; }
		  | /* nothing */
		  ;

Statements : Statement Statements
		   |
		   ;

LetStatement : "let" Identifier "=" Expression
			 ;

ReturnStatement : "return" Expression ";"
				;

ExpressionStatement : Expression ";"
					;

AssignStatement : Identifier "=" Expression
				| Identifier "+=" Expression
				| Identifier "-=" Expression
				| Identifier "*=" Expression
				| Identifier "/=" Expression
				;

BlockStatement : "{" Statements "}"
			   ;

Expression : NULLLITERAL
		   | BOOLEAN
		   | INTEGERLITERAL
		   | FLOATLITERAL
		   | STRINGLITERAL
		   | Identifier
		   | HashLiteral
		   | ArrayLiteral
		   | IndexExpression
		   | FunctionLiteral
		   | CallExpression
		   | IfExpression
		   | WhileExpression
		   | PrefixExpression
		   | InfixExpression
		   ;

Expressions : Expression Expressions
			|
			;

Identifiers : Identifier Identifiers
			|
			;


HashLiteral : "{" Pairs "}"
			;

Pairs : Pair Pairs
	  |
	  ;

Pair : Expression ":" Expression
	 ;

ArrayLiteral : "[" Expressions "]"
			 ;

IndexExpression : "[" Expression "]"
				;

FunctionLiteral | "fn" "(" Identifiers ")" "{" BlockStatement "}"
				;

CallExpression : FunctionLiteral "(" Expressions ")"
			   ;

IfExpression : "if" "(" Expression ")" BlockStatement
			 | "if" "(" Expression ")" "{" BlockStatement "}" "else" "{" BlockStatement "}"

WhileExpression : "while" "(" Expression ")" "{" BlockStatement "}"
				;

PrefixExpression : PrefixLiteral Expression 
				 ;

PrefixLiteral : "!" | "-" ;

InfixExpression: Expression InfixLiteral Expression
			   ;

InfixLiteral : "+" | "-" | "*" | "/" ;