diff options
| -rw-r--r-- | src/parcom.cr | 12 | ||||
| -rw-r--r-- | src/parcom/recover.cr | 27 |
2 files changed, 27 insertions, 12 deletions
diff --git a/src/parcom.cr b/src/parcom.cr index fdf7e31..6715e07 100644 --- a/src/parcom.cr +++ b/src/parcom.cr @@ -81,18 +81,6 @@ module Parcom end end - class Recover(T, V) < Parser(T, V) - @p : Map(T, V?, V) - - def initialize(p : Parser(T, V), default : V) - @p = Optional.new(p).map { |x| x.nil? ? default : x } - end - - def parse(tokens : Tokens(T)) : Result(T, V) - @p.parse(tokens) - end - end - class Sequence(T, V) < Parser(T, Array(V)) def initialize(@ps : Iterable(Parser(T, V))) end diff --git a/src/parcom/recover.cr b/src/parcom/recover.cr new file mode 100644 index 0000000..378f8d6 --- /dev/null +++ b/src/parcom/recover.cr @@ -0,0 +1,27 @@ +require "./parser.cr" +require "./optional.cr" +require "./map.cr" + +module Parcom + # `Recover` is a `Parser` that tries to parse with another parser, + # but does not fail the parser chain if the wrapped parser fails. + # If the wrapped parser fails, a `Recover` will not modify the input + # stream, and return an arbitrary value of type `V` instead. + class Recover(T, V) < Parser(T, V) + @p : Map(T, V?, V) + + # Accepts the parser to use, and the default value + # to return if the parser fails. + def initialize(p : Parser(T, V), default : V) + @p = Optional.new(p).map { |x| x.nil? ? default : x } + end + + # Tries to parse with the given parser, succeeds with the + # default value instead of failing. This parser does not + # consume input if the wrapped parser fails. + def parse(tokens : Tokens(T)) : Result(T, V) + @p.parse(tokens) + end + end +end + |