An extension of CodeMirror for VisualQuery language.
expresion ::= literal | literal separator expresion
literal ::= key operator value
key ::= An element from the keys list.
operator ::= An element from the key's operators list.
value ::= [^.;\\s]+ | ' [^']* ' | " [^"]* " | ( values ) | [ values ] | { values }
values ::= values-list |
values-list ::= values-list separator value | value
separator ::= separator single-separator | single-separator
single-separator ::= , | ; | <space>