kitty.grammar

statements  : (NLINE | INLINE_COMMENT)* statement ((NLINE | INLINE_COMMENT)* statement)* (NLINE | INLINE_COMMENT)*

statement   : func-def
            : var-def
            : expr

expr        : comp-expr ((KEYWORD:and|KEYWORD:or) comp-expr)*
            : KEYWORD:ret expr?
            : KEYWORD:continue
            : KEYWORD:break

var-def     : KEYWORD:var IDENTIFIER
              ((COLON IDENTIFIER) (ASSIGN expr)?) | ASSIGN expr

comp-expr   : KEYWORD:not comp-expr
            : arith-expr ((EQ|LT|GT|LTE|GTE) arith-expr)*

arith-expr  : term ((ADD|SUB) term)*

term        : factor ((MUL|DIV) factor)*

factor      : (ADD|SUB) factor 
            : call

call        : atom (L_BRC (expr (COMMA expr)*)? R_BRC)?

atom        : INT|FLOAT|STR|CHAR|BOOL|COMMENT|E_BLOCK
            : L_BRC expr R_BRC
            : if-expr
            : for-expr
            : while-expr
            : list-expr
            : var-access

var-access  : IDENTIFIER

var-assign  : var-access ASSIGN expr

list-expr   : L_SQUARE (expr (COMMA expr)*)? R_SQUARE

if-expr-a   : KEYWORD:if expr R_ARROW expr (if-expr-d|if-expr-e)?
            | (S_BLOCK statements E_BLOCK (if-expr-b|if-expr-c)?)

if-expr-b   : KEYWORD:elif expr
              S_BLOCK statements E_BLOCK (if-expr-b|if-expr-c)?

if-expr-c   : KEYWORD:else S_BLOCK statements E_BLOCK

if-expr-d   : KEYWORD:elif R_ARROW expr (if-expr-d|if-expr-e)?

if-expr-e   : KEYWORD:else R_ARROW expr

for-expr    : KEYWORD:for
              (L_BRC var-access KEYWORD:in expr R_BRC)
            | (var-access KEYWORD:in expr)
              R_ARROW expr
            | (S_BLOCK statements E_BLOCK)

while-expr  : KEYWORD:while expr
              S_BLOCK statements E_BLOCK

func-def    : KEYWORD:func IDENTIFIER
              L_BRC (IDENTIFIER COLON IDENTIFIER (COMMA IDENTIFIER COLON IDENTIFIER)*)? R_BRC R_ARROW IDENTIFIER
              (R_ARROW expr)
            | (S_BLOCK statements E_BLOCK)