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/****************************************************************\
*  ebnf.ebnf: a self describing grammar for describing grammars  *
*   by codewitch honey crisis, july 2019                         *
\****************************************************************/

grammar<start>= productions;

//
// productions
//
// marking a non-terminal with collapse removes it from 
// the tree and propagates its children to its parent
// marking a terminal with it similarly hides it from
// the result but not from the grammar, unlike hidden
//
productions<collapsed> = production productions | production;
production= identifier [ "<" attributes ">" ] "=" expressions ";";

//
// expressions
//
expressions<collapsed>= expression { "|" expression }; 
expression= { symbol };
symbol= literal | regex | identifier | 
	"(" expressions ")" | 
	"[" expressions "]" |
	"{" expressions ("}"|"}+");

//
// attributes
//
// recognized attributes are hidden, collapsed, terminal, start, 
// followsConflict (which can be "error", "first" or "last")
// and blockEnd (string)
attributes<collapsed>= attribute { "," attribute};
attribute<color="red">= identifier [ "=" attrvalue ];
attrvalue<color="orange">= literal | integer | identifier;

//
// terminals
//
literal= '"([^"\\]|\\.)*"';
regex= '\'([^\'\\]|\\.)*\'';
identifier= '[A-Z_a-z][\-0-9A-Z_a-z]*';
integer= '\-?[0-9]+';

// hide comments and whitespace
//
// if you mark a production with the terminal attribute, you
// can use ebnf to define it. Anything that's text or regex 
// is automatically a terminal
whitespace<hidden,terminal>= {" "|"\v"|"\f"|"\t"|"\r"|"\n"}+; //'[ \v\f\t\r\n]+';
// single quotes denote regex. make sure to escape single
// quotes in the regex with \'
// attributes get passed through to the parser, and you can define your own
lineComment<hidden,color="green">= '//[^\n]*[\n]';
blockComment<hidden,blockEnd="*/",color="green">= "/*";

// defining these isn't required, but gives
// us better constant names
// double quotes denote a literal. the escapes are nearly the
// same as C#. \U and \x are not supported
or="|";
lt="<";
gt=">";
eq="=";
semi=";";
comma=",";
lparen="(";
rparen=")";
lbracket="[";
rbracket="]";
lbrace="{";
rbrace="}";
rbracePlus="}+";

License <- LicenseTerm (EOL LicenseTerm)* EOL*

LicenseTerm <- SecretTerm / TimeTerm / LocationTerm / IdentityTerm

SecretTerm <- SECRET EQUAL < REST_OF_LINE > 
REST_OF_LINE <- ( !EOL_C . )+

LocationTerm <- ANYWHERE / NodeTerm

NodeTerm <- NODE EQUAL NO_SPACE_STRING

IdentityTerm <- ANYONE / UserTerm / DomainTerm

UserTerm <- USER EQUAL NO_SPACE_STRING
DomainTerm <- DOMAIN EQUAL NO_SPACE_STRING

TimeTerm <- PerpetualTerm / ExpiryTerm

PerpetualTerm <- PERPETUAL

ExpiryTerm <- EXPIRY EQUAL ExpiryDate
ExpiryDate <- TermLength / EndDate

TermLength <- NATURAL TermUnit
TermUnit <- DAY_UNIT / WEEK_UNIT / MONTH_UNIT / YEAR_UNIT
WEEK_UNIT <- < [Ww][Ee][Ee][Kk] [Ss]? >
MONTH_UNIT <- < [Mm][Oo][Nn][Tt][Hh] [Ss]? >
DAY_UNIT <- < [Dd][Aa][Yy] [Ss]? >
YEAR_UNIT <- < [Yy][Ee][Aa][rR] [Ss]? >

EndDate <- ISO8601 / NamedDate

ISO8601 <- < ISOYEAR DASH ISOMONTH DASH ISODAY >
ISOYEAR <- DIGIT DIGIT DIGIT DIGIT
ISOMONTH <- DIGIT DIGIT
ISODAY <- DIGIT DIGIT

NamedDate <- DAY MonthName YEAR
MonthName <- JAN / FEB / MAR / APR / MAY / JUN / JUL / AUG / SEP / OCT / NOV / DEC
YEAR <- < DIGIT DIGIT DIGIT DIGIT >
JAN <- < [Jj][Aa][Nn] ( [Uu][Aa][Rr][Yy] )? >
FEB <- < [Ff][Ee][Bb] ( [Rr][Uu][Aa][Rr][Yy] )? >
MAR <- < [Mm][Aa][Rr] ( [Cc][Hh] )? >
APR <- < [Aa][Pp][Rr] ( [Ii][Ll] )? >
MAY <- < [Mm][Aa][Yy] >
JUN <- < [Jj][Uu][Nn] ( [Ee] )? >
JUL <- < [Jj][Uu][Ll] ( [Yy] )? >
AUG <- < [Aa][Uu][Gg] ( [Uu][Ss][Tt] )? >
SEP <- < [Ss][Ee][Pp] ( [Tt][Ee][Mm][Bb][Ee][Rr] )? >
OCT <- < [Oo][Cc][Tt] ( [Oo][Bb][Ee][Rr] )? >
NOV <- < [Nn][Oo][Vv] ( [Ee][Mm][Bb][Ee][Rr] )? >
DEC <- < [Dd][Ee][Cc] ( [Ee][Mm][Bb][Ee][Rr] )? >
DAY <- < DIGIT DIGIT? >

~DASH <- < '-' >
DIGIT <- [0-9]
~EQUAL <- < '=' >
NATURAL <- < DIGIT+ >
NO_SPACE_STRING <- < (![ \t\n\r] .)+ >

~ANYONE <- < [Aa][Nn][Yy][Oo][Nn][Ee] >
~ANYWHERE <- < [Aa][Nn][Yy][Ww][Hh][Ee][Rr][Ee] >
~NODE <- < [Nn][Oo][Dd][Ee] >
~DOMAIN <- < [Dd][Oo][Mm][Aa][Ii][Nn] >
~USER <- < [Uu][Ss][Ee][Rr] >
~EXPIRY <- < [Ee][Xx][Pp][Ii][Rr][Yy] >
~PERPETUAL <- < [Pp][Ee][Rr][Pp][Ee][Tt][Uu][Aa][Ll] > 
~SECRET <- < [Ss][Ee][Cc][Rr][Ee][Tt] >

%whitespace <- [ \t]*
~EOL <- < EOL_C+ >
~EOL_C <- [\n\r]

codewitch honey crisis wrote:

do you know the magic of FA to regular expression conversion?

Ron Anders wrote:

Windows laptops can be cad for 1/2 a song.