# pon

# pan object notation
#



# v 0.1 ; 2024-09-09



## tokens
paren_open     =| "(" ;
paren_close    =| ")" ;
bracket_open   =| "[" ;
bracket_close  =| "]" ;
dot            =| "." ;
quote          =| "\"" ;
backslash      =| "\\" ;
whitespace     =| " "
                | "\t"
                | "\v" # XXX
                | "\r"
                | "\n"
                | "\f" # XXX
                ;
any            =| . ;
semicolon      =| ";" ;
newline        =| "\n" ; # XXX ... comments may change



## grammar

start =| _ pon ;

pon =| paren_open _ identifier body paren_close _    # record
     | bracket_open _ pon* bracket_close _           # list
     ;

body =| ( dot identifier pon )*    # field, null
      | identifier                 # literal
      | string                     # string
      ;

identifier =| (
                !paren_open
                !paren_close
                !bracket_open
                !bracket_close
                !dot
                !quote
                !backslash
                !whitespace
                any
            )+ _ ;

string =| quote string_content* quote _ ;

string_content =| !quote !backslash any    # "hello"
                | backslash quote          # " \" "
                | backslash backslash      # " \\ "
                ;

_ =| whitespace
   | semicolon comment* newline    # maybe '/' instead ?
   ;

comment =| !newline any ;



# v 0.2 ; 2024-09-10

# ( null )
# ( u8 1 )
# ( rec field (x) )
# ( list (x) )
#
# XXX ( _ )
# ( _ _ )
# ( _ _ (_) )
# ( _ (_) )
#
# XXX worth considering that records & lists cannot be empty in this variation...
#
# records extend primitives
# XXX lists overlap strings



## tokens

PAREN_OPEN     =| "(" ;
PAREN_CLOSE    =| ")" ;
QUOTE          =| "\"" ;
BACKSLASH      =| "\\" ;
SPACE          =| " " ;
TAB            =| "\t" ;
RETURN         =| "\r" ;
NEWLINE        =| "\n" ;
SEMICOLON      =| ";" ;
ANY            =| . ;



## grammar

start =| _ pon ;

_ =
| SPACE
| TAB
| RETURN
| NEWLINE
| comment
;

comment =| SEMICOLON ( !NEWLINE ANY )* NEWLINE ;

pon =| PAREN_OPEN _ type value PAREN_CLOSE _ ;

type =| string ;

string =
| literal
| quoted
;

literal =| (
 !PAREN_OPEN !PAREN_CLOSE
 !SPACE !TAB !RETURN !NEWLINE !SEMICOLON
 ANY
)+ _ ;

quoted =| QUOTE char* QUOTE _ ;

char =
| !QUOTE !BACKSLASH ANY
| BACKSLASH QUOTE
| BACKSLASH BACKSLASH
;

value =
| string
| record
| list
;

record =| ( string pon )+ ;

list =| pon* ;