peg_parser/parser.peg at main · emezac/peg_parser · GitHub

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grammar PGN

# PGN Spec: http://www.saremba.de/chessgml/standards/pgn/pgn-complete.htm
# Representation of a full game in pgn format, tag_pairs, movetext and score
game <- tag_pairs:tag_pairs [\n]? gcomment:comment? movetext:movetext score:score? [\s]* %make_game

# A tag pair is a key, value store in the form [Key "Value"]
tag_pairs <- tag_pair* %make_tag_pairs
tag_pair <- "[" dlm key dlm "\"" value "\"" dlm "]" dlm %make_tag_pair
key <- [A-Za-z0-9_]+
value <- [^\"]*


# Movetext is one or more moves, terminated by a score, like 1. "e4 e5 0-1"
movetext <- move* %make_movetext
move <- move_number dlm dlm white:san dlm dlm wnags:nags? dlm wcomment:comment? dlm wvars:variations? dlm black:san? dlm bnags:nags? dlm bcomment:comment? dlm bvars:variations? dlm mcomment:comment?
move_number <- [0-9]+ "."

# A SAN is a standard algebraic notation representation of a single players move, like e4
san <- (file rank dlm file rank / file rank file rank dlm file rank file rank / file rank dlm file rank file rank / piece file rank file rank dlm  piece file rank file rank  / piece file rank file rank dlm file rank file rank / file rank file rank dlm piece file rank file rank / square / san_psq / file takes square / castle / blacks_move) promotes? check?
san_psq <- piece square takes? square / piece takes? square / piece file takes? square / piece rank takes? square
piece <- [KQRNBP]
disam <- square / file / rank
odisam <- square / disam
takes <- "x"
square <- file rank
file <- [a-h]
rank <- [1-8]
promotes <- "=" [KQRNB]
check <- [+#]
castle <- "O-O-O" / "O-O" / "e1g1" / "e8g8" / "e1c1" / "e8c8"
comment <- "{" [^\}]* "}"

# for when it is 1...
blacks_move <- ".."
cblacks_move <- "..."

# A NAG is a numeric annotation glyph, representing anontations on a move such as !! ($3)
nags <- nag+
nag <- "$" [0-9]+ dlm

# A var or variation is a list of one or more moves surrounded by ()
variations <- variation+ %make_variations
variation <- "(" dlm movetext ")" dlm %make_variation

# The score is one of the following, * being unknown
score <- "1-0" / "0-1" / "1/2-1/2" / "*"

# A possible whitespace delimeter
dlm <- [\s+]?