dot.peg

file          <- _ graph+
graph         <- ('strict' _)? ('graph' / 'digraph') _ ID? '{' _ stmt_list '}' _
stmt_list     <- (stmt (';' _)?)*
stmt          <- attr_stmt
               / edge_stmt
               / subgraph
               / ID '=' _ ID
               / node_stmt
attr_stmt     <- ('graph' / 'node' / 'edge') _ attr_list
attr_list     <- ('[' _ attr* ']' _)+
attr          <- ID '=' _ ID ([;,] _)?
edge_stmt     <- (subgraph / node_id) edgeRHS attr_list?
edgeRHS       <- (edgeop (subgraph / node_id))+
node_stmt     <- node_id attr_list?
node_id       <- ID port? port?
port          <- ':' _ ID
subgraph      <- ('subgraph' _ ID?)? '{' _ stmt_list '}' _
edgeop        <- ('--' / '->') _
ID            <- HTML
               / QUOTED
               / NUMERAL
               / STRING
HTML          <- '<' (![<>] . / HTML)* '>' _
QUOTED        <- '"' ESCAPED* '"' _ ('+' _ '"' ESCAPED* '"' _)*
ESCAPED       <- ESC_QUOTE
               / ESC_EOL
               / '\\' .
               / !'"' .
ESC_QUOTE     <- '\\"'
ESC_EOL       <- '\\' EOL
NUMERAL       <- '-'? ([0-9]+ ('.' [0-9]*)? / '.' [0-9]+) _
STRING        <- [A-Z_a-z\u0080-\uFFFF] [0-9A-Z_a-z\u0080-\uFFFF]* _
_             <- ([ \t] / EOL / COMMENT)*
COMMENT       <- COMMENT_HASH
               / COMMENT_SLASH
               / COMMENT_BLOCK
COMMENT_HASH  <- '#' (!EOL .)*
COMMENT_SLASH <- '//' (!EOL .)*
COMMENT_BLOCK <- '/*' (!'*/' .)* '*/'
EOL           <- '\r\n' / '\n' / '\r'