chess.gbnf

# - bishop to c3
# - rook to d4
# - knight to e5
# - d4 d5 knight to c3
# - c3 queen to d4 king b1
# - pawn to a1 bishop to b2 knight to c3
#
# The prompt (--prompt) is the initial phrase that the user has to say.
# This is used to prime Whisper with how the user is expected to speak.
#
# Provide long context (--context) with sample moves to help Whisper decode the correct sequence.
# Longer context is better, but it slightly increases the processing time.
#
# example:
#
#   ./command -m ./models/ggml-tiny.en.bin -t 8 --grammar ./grammars/chess.gbnf --prompt "rook to b4, f3," --context "d4 d5 knight to c3, pawn to a1, bishop to b2 king e8," --grammar-penalty 100
#

root   ::= init move move? move? "."
prompt ::= init "."

# leading space is very important!
init ::= " rook to b4, f3"

move ::= ", " ((piece | pawn | king) " " "to "?)? [a-h] [1-8]

piece ::= "bishop" | "rook" | "knight" | "queen"
king  ::= "king"
pawn  ::= "pawn"