/* 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 : '!'|'#'|'$'|'%'|'&'|'('|')'|'*'|'+'|','|'-'|'.'|'/'|':' symbol_no_backslash_no_quotes_2 : ';'|'<'|'='|'>'|'?'|'@'|'['|']'|'^'|'_'|'{'|'|'|'}'|'~' string_literal : @markup '"' [string_literal_items] @markup '"' | @markup '`' [string_literal_items] @markup '`' string_literal_items : string_literal_item [string_literal_items] string_literal_item : ascii_no_backslash_no_quotes | '\'' | '\\' ascii symbol_label : '~'|'!'|'%'|'^'|'&'|'*'|'+'|'-'|'/'|'|'|'<'|'>'|'$'|'='|'.'|'?'|'_' /* What follows is a range of annotated grammars that can be used to generate * tests of increasing complexity and completeness to check against MetaDesk. * To run them, uncomment them one by one and run the build/grammar test. */ //// 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] untagged_scoped_set} // untagged_scoped_set : '{' [@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 | ':' untagged_scoped_set | ' ' @sibling scoped_set} //// 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 | ':' untagged_scoped_set | ' ' @sibling scoped_set} //// 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 | ':' untagged_scoped_set | ' ' @sibling scoped_set} /* Comments * Comments around nodes are accessible to the user. Here's how they behave: * - The text inside a comment immediatly following a node is stored as the * comment_after member of that node. No newlines can happen between a * node and its after_comment. * - The text inside a comment preceding a node is stored as the * comment_before of that node _unless_ it is already the comment_after * of another node. One newline between the comment and the node is * obviously necessary in the case of C++-style comments and it's also * allowed for C-style comments. * - If the first character inside a C++-style comment is a space, it's * omitted from the stored string * * The semantically annotated Backus-Naur form that we're using is not a * good fit to describe the grammar of comments. * To prevent the comment in "a /* comment */ b" from being interpreted as * a comment_before of "b", instead of what it is (a comment_after of "a"), * we would have to complicate the grammar by introducing several extra * productions with this specific purpose in mind. * The sensitivity of whitespace in the attachment of comments to nodes is * also cumbersome to express in BNF. */