From b274828831fec26cd8b3089ffef14cb96ce2de2f Mon Sep 17 00:00:00 2001 From: Matthew Hall Date: Thu, 16 Mar 2023 20:36:03 +1300 Subject: Second rewrite attempt, this one should work, monkaS --- src/__OLD_parcom/peek.cr | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) create mode 100644 src/__OLD_parcom/peek.cr (limited to 'src/__OLD_parcom/peek.cr') diff --git a/src/__OLD_parcom/peek.cr b/src/__OLD_parcom/peek.cr new file mode 100644 index 0000000..2b6f657 --- /dev/null +++ b/src/__OLD_parcom/peek.cr @@ -0,0 +1,23 @@ +require "./parser.cr" + +module Parcom + # `Peek` is a `Parser` that runs another `Parser` while + # leaving the input stream unmodified. + class Peek(T, V) < Parser(T, V) + # Accepts the parser to run. + def initialize(@p : Parser(T, V)) + end + + # Runs the parser it was initialized with, and returns + # that parser's result along with the original input. + # + # Re-raises a `ParserFail` exception if the other parser fails. + def parse(tokens : Tokens(T)) : Result(T, V) + result = @p.parse(tokens) + Result.new(tokens, result.value) + rescue ex : ParserFail + raise ParserFail.new("Peek: #{ex.message}") + end + end +end + -- cgit v1.2.1