metadesk/tests/grammar.md

/* MetaDesk grammar with semantic annotations *

• Each line represents a BNF-esque production:

•  symbol : rule_1 | ... | rule_n
  

• • Pipe signs indicate mutually exclusive alternatives
• • Square quotes denote optional rules
• • Character literals are terminal productions
• • Tags indicate which way the productions attach to the generated tree (@child, @sibling, @tag)
• and miscellaneous semantics (@fill, @markup) */

file : [@child file_set_list] file_set_list : { [tag_list] set [file_set_separator @sibling file_set_list] } file_set_separator : ' ' | '\n'

// TODO(mal): Unify file_set_separator and set_separator by allowing ',' and ';' everywhere set_list : { [tag_list] set [set_separator @sibling file_set_list] } set_separator : ' ' | '\n' | ',' | ';' // TODO(mal): Accept other open/close tokens tag_list : '@' @tag tag ' ' [tag_list] tag : identifier [@markup '(' [@child set_list] @markup ')'] set : @fill leaf | @fill identifier ':' @child @fill leaf | [@fill identifier ':'] set_open [@child set_list] set_close set_open : '{' | '[' | '(' set_close : '}' | ']' | ')' leaf : identifier | integer_literal | char_literal | string_literal // TODO(mal): Also symbol_label identifier : alpha [alphanumeric] | '' [alphanumeric] alphanumeric : alpha [alphanumeric] | digit [alphanumeric] | '' [alphanumeric]

integer_literal : { ['-'] natural_literal } natural_literal : digit [natural_literal]

char_literal : @markup ''' [char_literal_items] @markup ''' char_literal_items : char_literal_item [char_literal_items] char_literal_item : ascii_no_backslash_no_quotes | '"' | '\' ascii ascii : ascii_no_backslash_no_quotes | ''' | '"' | '\' ascii_no_backslash_no_quotes : digit | alpha | symbol_no_backslash_no_quotes | space symbol_no_backslash_no_quotes : symbol_no_backslash_no_quotes_1 | symbol_no_backslash_no_quotes_2 symbol_no_backslash_no_quotes_1 : '!'|'#'|'$'|'%'|'&'|'('|')'|'*'|'+'|','|'-'|'.'|'/'|':'|';' symbol_no_backslash_no_quotes_2 : '<'|'='|'>'|'?'|'@'|'['|']'|'^'|'_'|'`'|'{'|'|'|'}'|'~'

string_literal : @markup '"' [string_literal_items] @markup '"' string_literal_items : string_literal_item [string_literal_items] string_literal_item : ascii_no_backslash_no_quotes | ''' | '\' ascii

digit : '0'|'1'|'2'|'3'|'4'|'5'|'6'|'7'|'8'|'9' alpha : lowercase | uppercase lowercase : 'a'|'b'|'c'|'d'|'e'|'f'|'g'|'h'|'i'|'j'|'k'|'l'|'m'|'n'|'o'|'p'|'q'|'r'|'s'|'t'|'u'|'v'|'w'|'z'|'y'|'z' uppercase : 'A'|'B'|'C'|'D'|'E'|'F'|'G'|'H'|'I'|'J'|'K'|'L'|'M'|'N'|'O'|'P'|'Q'|'R'|'S'|'T'|'U'|'V'|'W'|'Z'|'Y'|'Z' space : ' '

symbol_label : '~'|'!'|'%'|'^'|'&'|'*'|'+'|'-'|'/'|'|'|'<'|'>'|'$'|'='|'.'|'?'|'_'|'\'

/*

symbol_no_quote : symbol_label | symbol_colon | symbol_group

symbol : symbol_label | symbol_colon | symbol_group

symbol_group : symbol_open | symbol_close symbol_open : '(' | '[' | '{' symbol_close : ')' | ']' | '}'

escaped_char : '\' '\' | '\' ''' | '\' '"' symbol_colon : ':'

*/

/* // NOTE(mal): This is the simplest subset of the grammar that works file : [@child set_list] set_list : set ['\n' @sibling set_list] set : @fill element | '{' [@child set_list] '}' element : 'A' */