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(.module:
[lux (#- nat int rev)
[abstract
["." monad (#+ do)]]
[control
["." try (#+ Try)]]
[data
["." bit]
["." text ("#@." monoid)]
["." name]
[number
["." nat]
["." int]
["." rev]
["." frac]]
[collection
["." list ("#@." functor)]]]
[macro
["." code ("#@." equivalence)]]]
["." //])
(def: (join-pairs pairs)
(All [a] (-> (List [a a]) (List a)))
(case pairs
#.Nil #.Nil
(#.Cons [[x y] pairs']) (list& x y (join-pairs pairs'))))
(type: #export Parser
{#.doc "A Lux syntax parser."}
(//.Parser (List Code)))
(def: (remaining-inputs asts)
(-> (List Code) Text)
($_ text@compose text.new-line "Remaining input: "
(|> asts (list@map code.to-text) (list.interpose " ") (text.join-with ""))))
(def: #export any
{#.doc "Just returns the next input without applying any logic."}
(Parser Code)
(function (_ tokens)
(case tokens
#.Nil (#try.Failure "There are no tokens to parse!")
(#.Cons [t tokens']) (#try.Success [tokens' t]))))
(template [<query> <assertion> <type> <tag> <eq> <desc>]
[(with-expansions [<error> (as-is (#try.Failure ($_ text@compose "Cannot parse " <desc> (remaining-inputs tokens))))]
(def: #export <query>
{#.doc (code.text ($_ text@compose "Parses the next " <desc> " input."))}
(Parser <type>)
(function (_ tokens)
(case tokens
(#.Cons [[_ (<tag> x)] tokens'])
(#try.Success [tokens' x])
_
<error>)))
(def: #export (<assertion> expected)
(-> <type> (Parser Any))
(function (_ tokens)
(case tokens
(#.Cons [[_ (<tag> actual)] tokens'])
(if (:: <eq> = expected actual)
(#try.Success [tokens' []])
<error>)
_
<error>))))]
[bit bit! Bit #.Bit bit.equivalence "bit"]
[nat nat! Nat #.Nat nat.equivalence "nat"]
[int int! Int #.Int int.equivalence "int"]
[rev rev! Rev #.Rev rev.equivalence "rev"]
[frac frac! Frac #.Frac frac.equivalence "frac"]
[text text! Text #.Text text.equivalence "text"]
[identifier identifier! Name #.Identifier name.equivalence "identifier"]
[tag tag! Name #.Tag name.equivalence "tag"]
)
(def: #export (this! ast)
{#.doc "Ensures the given Code is the next input."}
(-> Code (Parser Any))
(function (_ tokens)
(case tokens
(#.Cons [token tokens'])
(if (code@= ast token)
(#try.Success [tokens' []])
(#try.Failure ($_ text@compose "Expected a " (code.to-text ast) " but instead got " (code.to-text token)
(remaining-inputs tokens))))
_
(#try.Failure "There are no tokens to parse!"))))
(template [<name> <tag> <desc>]
[(def: #export <name>
{#.doc (code.text ($_ text@compose "Parse a local " <desc> " (a " <desc> " that has no module prefix)."))}
(Parser Text)
(function (_ tokens)
(case tokens
(#.Cons [[_ (<tag> ["" x])] tokens'])
(#try.Success [tokens' x])
_
(#try.Failure ($_ text@compose "Cannot parse local " <desc> (remaining-inputs tokens))))))]
[local-identifier #.Identifier "identifier"]
[ local-tag #.Tag "tag"]
)
(template [<name> <tag> <desc>]
[(def: #export (<name> p)
{#.doc (code.text ($_ text@compose "Parse inside the contents of a " <desc> " as if they were the input Codes."))}
(All [a]
(-> (Parser a) (Parser a)))
(function (_ tokens)
(case tokens
(#.Cons [[_ (<tag> members)] tokens'])
(case (p members)
(#try.Success [#.Nil x]) (#try.Success [tokens' x])
_ (#try.Failure ($_ text@compose "Parser was expected to fully consume " <desc> (remaining-inputs tokens))))
_
(#try.Failure ($_ text@compose "Cannot parse " <desc> (remaining-inputs tokens))))))]
[ form #.Form "form"]
[tuple #.Tuple "tuple"]
)
(def: #export (record p)
{#.doc (code.text ($_ text@compose "Parse inside the contents of a record as if they were the input Codes."))}
(All [a]
(-> (Parser a) (Parser a)))
(function (_ tokens)
(case tokens
(#.Cons [[_ (#.Record pairs)] tokens'])
(case (p (join-pairs pairs))
(#try.Success [#.Nil x]) (#try.Success [tokens' x])
_ (#try.Failure ($_ text@compose "Parser was expected to fully consume record" (remaining-inputs tokens))))
_
(#try.Failure ($_ text@compose "Cannot parse record" (remaining-inputs tokens))))))
(def: #export end!
{#.doc "Ensures there are no more inputs."}
(Parser Any)
(function (_ tokens)
(case tokens
#.Nil (#try.Success [tokens []])
_ (#try.Failure ($_ text@compose "Expected list of tokens to be empty!" (remaining-inputs tokens))))))
(def: #export end?
{#.doc "Checks whether there are no more inputs."}
(Parser Bit)
(function (_ tokens)
(case tokens
#.Nil (#try.Success [tokens #1])
_ (#try.Success [tokens #0]))))
(def: #export (run syntax inputs)
(All [a] (-> (Parser a) (List Code) (Try a)))
(case (syntax inputs)
(#try.Failure error)
(#try.Failure error)
(#try.Success [unconsumed value])
(case unconsumed
#.Nil
(#try.Success value)
_
(#try.Failure (text@compose "Unconsumed inputs: "
(|> (list@map code.to-text unconsumed)
(text.join-with ", ")))))))
(def: #export (local inputs syntax)
{#.doc "Run a syntax parser with the given list of inputs, instead of the real ones."}
(All [a] (-> (List Code) (Parser a) (Parser a)))
(function (_ real)
(do try.monad
[value (run syntax inputs)]
(wrap [real value]))))
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