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| -rw-r--r-- | README.md | 42 |
1 files changed, 37 insertions, 5 deletions
@@ -99,20 +99,52 @@ Another way to do this is to use `Parser#recover`, which allows a default value ``` # `#map_const` is like `#map`, but it takes a single value to replace # the parser value with unconditionally. -sign = Parser.token('-').map_const(-1_i32).recover(1_i32) +sign = Parser.token('-') + .map_const(-1_i32) + .recover(1_i32) ``` Final code: +TODO: add to practical tests + ``` -d = Parser(Char, Char).satisfy(&.number?) -abs_num = d.some.map { |ds| ds.join.to_i32 } +d = Parser(Char, Char).satisfy(&.number?).named("digit") +abs_num = d.some.map { |ds| ds.join.to_i32 }.named("abs_num") -sign = Parser.token('-').map_const(-1_i32).recover(1_i32) +sign = Parser.token('-').map_const(-1_i32).recover(1_i32).named("sign") int32 = parser_chain Char, Int32, "int32", {s, sign}, {n, abs_num}, - finally: Parser.pure(n * s) + pure: n * s + +ws = Parser(Char, Char).satisfy(&.whitespace?) + .many + .named("whitespace") + +arrow = (ws >> Parser.token_sequence("=>".chars) >> ws).named("arrow") + +pair = parser_chain Char, {Int32, Int32}, "pair", + {x, int32}, + {_, sep}, + {y, int32}, + pure: {x, y} + +delim = (ws >> Parser.token(',') >> ws).named("delim") + +elements = parser_chain Char, Array({Int32, Int32}), "elements", + {pairs, pair.sep_by(delim)}, + {_, delim.optional}, # trailing comma + pure: pairs + +hash_start = (Parser.token('{') >> ws).named("start") +hash_end = (ws >> Parser.token('}')).named("end") + +hash = parser_chain Char, Hash(Int32, Int32), "hash", + {_, hash_start}, + {es, elements.recover([] of {Int32, Int32})} + {_, hash_end}, + pure: es.to_h ``` |