From f5e87b41ffcb036c705c32b55161ae91a04c72e1 Mon Sep 17 00:00:00 2001 From: Matthew Hall Date: Thu, 9 Mar 2023 01:44:06 +1300 Subject: Implement Token sequence parser --- src/parcom.cr | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-) (limited to 'src/parcom.cr') diff --git a/src/parcom.cr b/src/parcom.cr index 14d2e44..760a450 100644 --- a/src/parcom.cr +++ b/src/parcom.cr @@ -133,7 +133,7 @@ module Parcom result = @p.parse(tokens) unless @f.call(result.value) - raise ParserException.new("Assert: predicate failed") + raise ParserException.new("Assert: predicate failed for <#{result.value}>") end result @@ -153,6 +153,8 @@ module Parcom def parse(tokens : TokenStream(T)) : Result(T, T) @p.parse(tokens) + rescue ex : ParserException + raise ParserException.new("Token <#{@expected}>: #{ex.message}") end end @@ -226,7 +228,22 @@ module Parcom end end - class Tokens + class Tokens(T) < Parser(T, Array(T)) + def initialize(@expected : Iterable(T)) + end + + # TODO: this can probably be optimised more for Arrays + # TODO: might be better to use #zip? + def parse(tokens : TokenStream(T)) : Result(T, Array(T)) + parsed_tokens = [] of T + + @expected.each_with_index do |t, i| + r = Token.new(t).parse(tokens[i..]) + parsed_tokens << r.value + end + + Result.new(tokens[parsed_tokens.size..], parsed_tokens) + end end class Many -- cgit v1.2.1