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Diffstat (limited to 'src/__OLD_parcom/at_most.cr')
| -rw-r--r-- | src/__OLD_parcom/at_most.cr | 29 |
1 files changed, 29 insertions, 0 deletions
diff --git a/src/__OLD_parcom/at_most.cr b/src/__OLD_parcom/at_most.cr new file mode 100644 index 0000000..b70164f --- /dev/null +++ b/src/__OLD_parcom/at_most.cr @@ -0,0 +1,29 @@ +require "./parser.cr" +require "./map.cr" +require "./exactly.cr" +require "./optional.cr" + +module Parcom + # `AtMost` is a `Parser` that tries to parse with another parser a specific + # number of times. The results of each successful parse are returned in an + # array. If the specific number of parses succeed, the parsing stops, even + # if it is possible to keep parsing. If the parser is never successful, it + # succeeds with an empty array. + class AtMost(T, V) < Parser(T, Array(V)) + @p : Map(T, Array(V?), Array(V)) + + # Accepts the number of parsing attempts, and the parser to use. + def initialize(i : Int, p : Parser(T, V)) + @p = Exactly.new(i, Optional.new(p)).map(&.compact) + end + + # Tries to parse up to the given number of times. + # If the parser never succeeds, returns an empty array. + def parse(tokens : Tokens(T)) : Result(T, Array(V)) + @p.parse(tokens) + rescue ex : ParserFail + raise ParserFail.new("AtMost: #{ex.message}") + end + end +end + |
