grammar

AssemblyUnit:
    Instruction*

Instruction:
    Ident ':' Ident (Expr ',')* (Expr ','?)? '\n'

Expr:
    Ident | Literal | Bracket | '(' Expr ')'

Operation:
    Expr '+' Expr |
    Expr '-' Expr |
    Expr '*' Expr |
    Expr '/' Expr |
    Expr '%' Expr |
    Expr '&' Expr |
    Expr '|' Expr |
    Expr '^' Expr

Bracket:
    '[' Instruction ']'

Ident:
    Alphabetic (Alphabetic | DecDigit)*

Alphabetic:
    'a' .. 'z' | 'A' .. 'Z' | '_' | '<' | '>' | '$'

Literal:
    String | Char | Number

String:
    '"' <what you expect> '"'

Char:
    "'" <what you expect> "'"

Number:
    FloatNumber | DecNumber | BinNumber | OctNumber | HexNumber

FloatNumber:
    DecNumber '.' ( DecNumber (('E' | 'e') DecNumber)?)? |
    '.' DecNumber (('E' | 'e') DecNumber)?

DecNumber:
    DecDigit (DecDigit | '_')*

DecDigit:
    '0' .. '9'

BinNumber:
    ('0b' | '0B') BinDigit (BinDigit | '_')*

BinDigit:
    '0' | '1'

OctNumber:
    ('0x' | '0O') OctDigit (OctDigit | '_')*

OctDigit:
    '0' .. '7'

HexNumber:
    ('0x' | '0X') HexNumber (HexNumber | '_')*

HexNumber:
    '0' .. '9' | 'a' .. 'f' | 'A' .. 'F'