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authorMatthew Hall <hallmatthew314@gmail.com>2023-03-19 23:02:29 +1300
committerMatthew Hall <hallmatthew314@gmail.com>2023-03-19 23:02:29 +1300
commit9734fa2d530b9496b70a388a117ea57fe5730772 (patch)
tree78a42db1e64e5148edfa96cb2a451a17ef362485 /src/__OLD_parcom/plus.cr
parent2ef8841e9c7a48eea0f66cfe09d8fe996f43c2b2 (diff)
Remove old files
Diffstat (limited to 'src/__OLD_parcom/plus.cr')
-rw-r--r--src/__OLD_parcom/plus.cr54
1 files changed, 0 insertions, 54 deletions
diff --git a/src/__OLD_parcom/plus.cr b/src/__OLD_parcom/plus.cr
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--- a/src/__OLD_parcom/plus.cr
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-require "./parser.cr"
-
-module Parcom
- # `Plus` is a parser that tries to parse with two different
- # parsers in succession and fails if either of the two parsers fails.
- # The return type of this parser is `{V, U}`, where `V` is the return
- # type of the first parser and `U` is the return type of the second.
- #
- # Example:
- # ```
- # parse1 = Token.new('1')
- # parse2 = Token.new('2')
- # tokens = Tokens.from_string("12")
- # result = (parse1 + parse2).parse(tokens) # succeeds
- # result = (parse2 + parse1).parse(tokens) # fails, wrong order
- # ```
- #
- # `Plus` parsers can be chained together, but the resulting return type
- # can become unweildly with too many combined parsers:
- # ```
- # letter_a = Token.new('a')
- # a5 = letter_a + letter_a + letter_a + letter_a + letter_a
- # tokens = Tokens.from_string("aaaaa")
- # a5.parse(tokens) # succeeds
- # # `a5` has a return type of { { { {Char, Char}, Char}, Char}, Char}
- # ```
- #
- # If you need to parse more than two things in this manner,
- # consider using `Many`, `Some`, `Sequence`, or `TokenSeq` instead.
- class Plus(T, V, U) < Parser(T, {V, U})
- # Accepts the two parsers to use, in order.
- def initialize(@p1 : Parser(T, V), @p2 : Parser(T, U))
- end
-
- # Tries to parse with the two given parsers, and returns
- # their results in a tuple if the both succeed.
- def parse(tokens : Tokens(T)) : Result(T, {V, U})
- begin
- r1 = @p1.parse(tokens)
- rescue ex : ParserFail
- raise ParserFail.new("Plus (left): #{ex.message}")
- end
-
- begin
- r2 = @p2.parse(r1.tokens)
- rescue ex : ParserFail
- raise ParserFail.new("Plus (right): #{ex.message}")
- end
-
- Result.new(r2.tokens, {r1.value, r2.value})
- end
- end
-end
-