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-rw-r--r--src/__OLD_parcom/eof.cr23
1 files changed, 23 insertions, 0 deletions
diff --git a/src/__OLD_parcom/eof.cr b/src/__OLD_parcom/eof.cr
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+++ b/src/__OLD_parcom/eof.cr
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+require "./parser.cr"
+
+module Parcom
+ # `EOF` is a `Parser` succeeds if the input stream is empty.
+ #
+ # This parser retuns `nil` when successful because there is no
+ # other meaningful value to return.
+ #
+ # This parser is also one of the few cases where it is ideal to not
+ # modify or take from the input stream, as it should be empty anyway.
+ class EOF(T) < Parser(T, Nil)
+ # Succeeds is the input stream is empty and returns `nil`.
+ # Raises a `ParserFail` exception when the input is not empty.
+ def parse(tokens : Tokens(T)) : Result(T, Nil)
+ if tokens.empty?
+ Result.new(tokens, nil)
+ else
+ raise ParserFail.new("Eof: input was not empty")
+ end
+ end
+ end
+end
+