Document    <- Spacing Element
Element     <- Standalone / OpenTag (Element / TextNode)* CloseTag

Standalone  <- '<' Identifier Attribute* '/>' Spacing

OpenTag     <- '<' Identifier Attribute* '>' Spacing
CloseTag    <- '</' Identifier '>' Spacing

Identifier  <- ([a-zA-Z_] [a-zA-Z0-9-_]*) Spacing
Attribute   <- Identifier EQUALS Literal Spacing
Literal     <- '"' LiteralSegment* '"'

TextNode    <- TextSegment+ Spacing

LiteralSegment <- LiteralText / Entity / CDATA
LiteralText    <- < (!["&<] .)+ >

TextSegment    <- TextNodeText / Entity / CDATA
TextNodeText   <- < (![&<] .)+ >

Entity      <- '&' <(!';' .)+> ';'
CDATA       <- '<![CDATA[' <(!']]>' .)*> ']]>'

EQUALS      <- '=' Spacing

Spacing     <- Space* 
Space       <- ' ' / '\t' / '\r\n' / '\n' / '\r'