rutile/docs/grammar.abnf
tocariimaa 3836492ba2 use ABNF for the grammar specification instead
ABNF has a more accepted standard than EBNF.
2025-01-14 19:18:42 -03:00

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ABNF

; Rutile's grammar formal definition in ABNF
; NOTE: terminal strings are case sensitive here
function_kind = "proc" / "iter"
proc_decl = function_kind "(" [proc_decl_args] ")" [ident] *stmt 'end'
proc_decl_args = symbol_type_pair *("," symbol_type_pair)
symbol_type_pair = ident ":" ident
symbol_decl = ("var" / "let" / "const") ident_type_expr ; "Variable" declaration
ident_type_expr = ident [":" ident] ["=" expr]
function_call = ident_qualified "(" [funcargs] ")"
funcargs = expr_list
array_literal = "[" expr_list "]"
expr_list = expr *("," expr) [","] ; Allows a trailling comma
expr = number
expr =/ array_literal
expr =/ function_call
pragma = "#" "[" "]" ; TODO
decorated_decl = pragma (proc_decl / symbol_decl)
; Statements
while_stmt = "while" expr *stmt "end"
if_expr = "if" expr *stmt "end"
break_expr = "break" *expr
return_stmt = "return" *expr
yield_stmt = "yield" *expr
loop_control = "next" / break_expr
stmt = proc_decl
stmt =/ expr
stmt =/ loop_control
stmt =/ if_expr
stmt =/ while_stmt
stmt =/ return_stmt
stmt =/ yield_stmt
ident = (ALPHA / "_") *(ALPHA / DIGIT / "_" / "?" / "!")
; Identifier accounting for namespacing: std:io.print, aaa:bbb:ccc
ident_qualified = (ALPHA / "_") *(ALPHA / DIGIT / "_" / "?" / "!" / ":" / ".")
number = 1*DIGIT ; Decimal
/ "0b" 1*("0" / "1") ; Binary
/ "0o" 1*(0-8) ; Octal
/ "0x" 1*HEXDIGIT ; Hexadecimal
byte = %x00-FF
escape = "\" ("\" / DQUOTE / "0" / "a" / "b" / "n" / "r" / "t" / ("x" 1*2HEXDIGIT))
character = byte / escape
string_literal = DQUOTE *character DQUOTE