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Diffstat (limited to 'src/__OLD_parcom/token_seq.cr')
| -rw-r--r-- | src/__OLD_parcom/token_seq.cr | 38 |
1 files changed, 38 insertions, 0 deletions
diff --git a/src/__OLD_parcom/token_seq.cr b/src/__OLD_parcom/token_seq.cr new file mode 100644 index 0000000..45900f9 --- /dev/null +++ b/src/__OLD_parcom/token_seq.cr @@ -0,0 +1,38 @@ +require "./parser.cr" +require "./sequence.cr" + +module Parcom + # `TokenSeq` is a `Parser` that attempts to parse a specific + # string of tokens. If the expected tokens are not at the start + # of the input stream, the parser fails. + # + # Example: + # ``` + # parse_test = TokenSeq(Char).new("test".chars) + # tokens = Tokens.from_string("testing") + # + # result = parse_test.parse(tokens) + # + # puts result.value # => ['t', 'e', 's', 't'] + # puts result.tokens # => ['i', 'n', 'g'] + # ``` + class TokenSeq(T) < Parser(T, Array(T)) + @p : Sequence(T, T) + + # Accepts the tokens to try and parse, in order. + def initialize(expected : Iterable(T)) + ps = [] of Parser(T, T) + expected.each { |t| ps << Token.new(t) } + + @p = Sequence.new(ps) + end + + # Tries to parse the list of tokens. + def parse(tokens : Tokens(T)) : Result(T, Array(T)) + @p.parse(tokens) + rescue ex : ParserFail + raise ParserFail.new("TokenSeq: #{ex.message}") + end + end +end + |
