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) */

//// A bunch of common definitions separator : ' ' | unscoped_separator unscoped_separator : '\n'| ',' | ';' alt_scope_beg : '(' | '[' alt_scope_end : ')' | ']' id : alpha [alphanumeric] | '' [alphanumeric] alphanumeric : alpha [alphanumeric] | digit [alphanumeric] | '' [alphanumeric] 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' digit : '0'|'1'|'2'|'3'|'4'|'5'|'6'|'7'|'8'|'9' label : id | integer_literal | char_literal | string_literal | symbol_label 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 | ' ' symbol_no_backslash_no_quotes : symbol_no_backslash_no_quotes_1 | symbol_no_backslash_no_quotes_2 symbol_no_backslash_no_quotes_1 : '!'|'#'|'$'|'%'|'&'|'('|')'|'*'|'+'|','|'-'|'.'|'/'|':' symbol_no_backslash_no_quotes_2 : ';'|'<'|'='|'>'|'?'|'@'|'['|']'|'^'|'_'|'{'|'|'|'}'|'~' string_literal : @markup '"' [string_literal_items] @markup '"' | @markup '' [string_literal_items] @markup '`' string_literal_items : string_literal_item [string_literal_items] string_literal_item : ascii_no_backslash_no_quotes | ''' | '\' ascii symbol_label : '~'|'!'|'%'|'^'|'&'|'*'|'+'|'-'|'/'|'|'|'<'|'>'|'$'|'='|'.'|'?'|'$'

//// Arbitrarily deep tree, possibly empty // file : [@child set_list] // set_list : '{' [@child set_list] '}' [separator @sibling set_list]

//// Labeled leaves // file : [@child set_list] // set_list : set [separator @sibling set_list] // set : @fill 'A' | '{' [@child set_list] '}'

//// Labeled internal nodes // file : [@child set_list] // set_list : set [separator @sibling set_list] // set : @fill 'A' | [@fill 'A' ':'] '{' [@child set_list] '}'

//// Unscoped sets // file : [@child set_list] // set_list : scoped_set [separator @sibling set_list] | unscoped_set [unscoped_separator @sibling set_list] // scoped_set : '{' [@child set_list] '}' // unscoped_set : @fill 'A' [unscoped_set_tail] // unscoped_set_tail : ':' @child unscoped_set | ' ' @sibling unscoped_set | ':' scoped_set |' ' @sibling scoped_set

//// Tags // file : [@child set_list] // set_list : scoped_set [separator @sibling set_list] | unscoped_set [unscoped_separator @sibling set_list] // scoped_set : {[tag_list] '{' [@child set_list] '}'} // unscoped_set : {[tag_list] @fill 'A' [unscoped_set_tail]} // tag_list : '@' @tag tag ' ' [tag_list] // tag : @fill 'T'['(' [@child set_list] ')'] // // unscoped_set_tail : ':' @child unscoped_set | ' ' @sibling unscoped_set | ':' @child scoped_set | ' ' @sibling scoped_set // unscoped_set_tail : {':' @child unscoped_set | ' ' @sibling unscoped_set | set_tail_hack | ' ' @sibling scoped_set} // // NOTE(mal): Ideally the set_tail_hack should be captured by the simpler // // ':' @child scoped_set // // but there's a quirk in the grammar. // // In "A:{}", A has no children but in "A:@T{}", it has one tagged children, // // which means that the presence of tags introduces the child // set_tail_hack : ':' [@child tag_list] '{' '}' | ':' @child [tag_list] '{' @child set_list '}'

//// Alternative scope markers // file : [@child set_list] // set_list : scoped_set [separator @sibling set_list] | unscoped_set [unscoped_separator @sibling set_list] // scoped_set : {[tag_list] untagged_scoped_set} // untagged_scoped_set : '{' [@child set_list] '}' | alt_scope_beg [@child set_list] alt_scope_end // unscoped_set : {[tag_list] @fill 'A' [unscoped_set_tail]} // tag_list : '@' @tag tag ' ' [tag_list] // tag : @fill 'T'['(' [@child set_list] ')'] // unscoped_set_tail : {':' @child unscoped_set | ' ' @sibling unscoped_set | set_tail_hack | ' ' @sibling scoped_set} // set_tail_hack : {':' [@child tag_list] '{' '}' | // ':' @child [tag_list] '{' @child set_list '}' | // ':' [@child tag_list] alt_scope_beg alt_scope_end | // ':' @child [tag_list] alt_scope_beg @child set_list alt_scope_end // }

//// General tags and labels file : [@child set_list] set_list : scoped_set [separator @sibling set_list] | unscoped_set [unscoped_separator @sibling set_list] scoped_set : {[tag_list] untagged_scoped_set} untagged_scoped_set : '{' [@child set_list] '}' | alt_scope_beg [@child set_list] alt_scope_end unscoped_set : {[tag_list] @fill label [unscoped_set_tail]} tag_list : '@' @tag tag ' ' [tag_list] tag : @fill id['(' [@child set_list] ')'] unscoped_set_tail : {':' @child unscoped_set | ' ' @sibling unscoped_set | set_tail_hack | ' ' @sibling scoped_set} set_tail_hack : {':' [@child tag_list] '{' '}' | ':' @child [tag_list] '{' @child set_list '}' | ':' [@child tag_list] alt_scope_beg alt_scope_end | ':' @child [tag_list] alt_scope_beg @child set_list alt_scope_end }

//// Comments before //// TODO: This needs some work to make sure that "a /* comment_before_b / b" can't be generated //// but that "a / comment_after_a / b" can // file : [@child set_list] // set_list : scoped_set [separator @sibling set_list] | unscoped_set [unscoped_separator @sibling set_list] // scoped_set : {[tag_list] [@pre_comment pre_comment] untagged_scoped_set} // pre_comment : '/' '/' [' '] [@fill c_code_content] '\n' | '/' '' [@fill cpp_code_content] '' '/' // c_code_content : 'c''o''m''m''e''n''t' // TODO: Arbitrary strings, including C-style comments, as long as / */ pairs are balanced // cpp_code_content : 'c''o''m''m''e''n''t' // TODO: Arbitrary strings that don't start with space // untagged_scoped_set : '{' [@child set_list] '}' | alt_scope_beg [@child set_list] alt_scope_end // unscoped_set : {[tag_list] @fill label [unscoped_set_tail]} // tag_list : '@' @tag tag ' ' [tag_list] // tag : @fill id['(' [@child set_list] ')'] // unscoped_set_tail : {':' @child unscoped_set | ' ' @sibling unscoped_set | set_tail_hack | ' ' @sibling scoped_set} // set_tail_hack : {':' [@child tag_list] '{' '}' | // ':' @child [tag_list] '{' @child set_list '}' | // ':' [@child tag_list] alt_scope_beg alt_scope_end | // ':' @child [tag_list] alt_scope_beg @child set_list alt_scope_end // }