treerack/syntax.treerack

/*
  foo
*/
// bar
// bar
// baz
/* foo
  bar baz */ // foo bar baz
wschar:alias               = // foo
                             /* bar */
                             " " | "\t" | "\n" | "\b" | "\f" | "\r" | "\v";
wsc:ws                     = wschar | comment;
block-comment:alias:nows   = /* foo */ // bar
                             "/*" ("*" [^/] | [^*])* "*/";
line-comment:alias:nows    = /*
                             foo
                             */
                             "//" [^\n]*;
comment-segment:alias:nows = // bar
                             line-comment | block-comment;
ws-no-nl:alias:nows        = " "
                           | "\t"
                           | "\b"
                           /* this one */ /* is a */
                           | "\f"
                           /* form feed */ /* for sure */
                           | "\r"
                           | "\v";
comment:nows               = comment-segment
                             /* segment is not the best name */ /* but */
                             ( ws-no-nl*
                               "\n"?
                               ws-no-nl*
                               /* fine */
                               comment-segment
                             )*;
any-char                   = "."; // equivalent to [^]

// caution: newline is accepted
/* class not */
class-not       = "^";
class-char:nows = [^\\\[\]\^\-] | "\\" .; /* foo
                  bar */
char-range:nows = class-char "-" class-char; // foo
char-class:nows = "[" class-not? (class-char | char-range)* "]";

// newline is accepted
sequence-char:nows = [^\\"] | "\\" .;
char-sequence:nows = "\"" sequence-char* "\"";
terminal:alias     = any-char | char-class | char-sequence;
symbol:nows        = [^\\ \n\t\b\f\r\v/.\[\]\"{}\^+*?|():=;]+;
group:alias        = "(" expression ")";
number:alias:nows  = [0-9]+;
count              = number;
count-quantifier   = "{" count "}";
range-from         = number;
range-to           = number;
range-quantifier   = "{" range-from? "," range-to? "}";
one-or-more        = "+";
zero-or-more       = "*";
zero-or-one        = "?";
quantity:alias     = count-quantifier | range-quantifier | one-or-more | zero-or-more | zero-or-one;
item:nows          = (terminal | symbol | group) quantity?;
sequence           = item+;
option:alias       = terminal | symbol | group | sequence;

// DOC: how the order matters
choice = option ("|" option)+;

// DOC: not having 'not' needs some tricks sometimes

expression:alias           = terminal | symbol | group | sequence | choice;
alias                      = "alias";
ws                         = "ws";
nows                       = "nows";
kw                         = "kw";
nokw                       = "nokw";
failpass                   = "failpass";
root                       = "root";
flag:alias                 = alias | ws | nows | kw | nokw | failpass | root;
definition-name:alias:nows = symbol (":" flag)*;
definition                 = definition-name "=" expression;
definitions:alias          = definition (";"+ definition)*;
syntax:root                = ";"* definitions? ";"*;