constraint-definition.ebnf

constraints            ::= { constraint }
constraint             ::= "@", constraint-def
constraint-def         ::= constraint-name, param-def
constraint-name        ::= valid-starting-char { valid-char }
valid-starting-char    ::= [A-Za-z_]
valid-char             ::= [0-9A-Za-z_]
param-def              ::= [ "(", [ param | { ",", param } ], ")" ]
param                  ::= param-name, "=", param-value
param-name             ::= valid-starting-char { valid-char }
param-value            ::= number | quoted-string | regular-expression | boolean
number                 ::= positive | negative
negative               ::= "-", positive
positive               ::= digit { digit }
quoted-string          ::= "\"", { char }, "\""
char                   ::= .
regular-expression     ::= "/", { char }, "/"
boolean                ::= "true" | "false"