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# Grammar for the pgen parser specification language
#
# This was used to bootstrap the parser for the emu-grammar parser
# specification language, and it's not clear why we should have two things.
# Ignore this for now.
var token IDENT;
var token STR;
var token MATCH;
var token COMMENT;
token Eq = "=";
token Arrow = "=>";
token Semi = ";";
token Token = "token";
token Var = "var";
token Nt = "nt";
token Goal = "goal";
token Some = "Some";
token None = "None";
token OpenBrace = "{";
token CloseBrace = "}";
token OpenParen = "(";
token CloseParen = ")";
token Comma = ",";
token QuestionMark = "?";
goal nt grammar {
token_defs? nt_defs => grammar($0, $1);
}
nt token_defs {
token_def => single($0);
token_defs token_def => append($0, $1);
}
nt token_def {
"token" IDENT "=" STR ";" => const_token($1, $3);
"var" "token" IDENT ";" => var_token($2);
}
nt nt_defs {
nt_def => nt_defs_single($0);
nt_defs nt_def => nt_defs_append($0, $1);
}
nt nt_def {
COMMENT? "goal"? "nt" IDENT "{" prods? "}" => nt_def($0, $1, $3, $5);
}
nt prods {
prod => single($0);
prods prod => append($0, $1);
COMMENT => empty($0);
}
nt prod {
terms reducer? ";" => prod($0, $1);
}
nt terms {
term => single($0);
terms term => append($0, $1);
}
nt term {
symbol;
symbol "?" => optional($0);
}
nt symbol {
IDENT => ident($0);
STR => str($0);
}
nt reducer {
"=>" expr => $1;
}
nt expr {
MATCH => expr_match($0);
IDENT "(" expr_args? ")" => expr_call($0, $2);
"Some" "(" expr ")" => expr_some($2);
"None" => expr_none();
}
nt expr_args {
expr => args_single($0);
expr_args "," expr => args_append($0, $2);
}