docs(users/Profpatsch/jbovlaste-sqlite): add parser docs
Change-Id: I62b6b9ee1ce5231e1d486db9f7e1e7b66408fca6 Reviewed-on: https://cl.tvl.fyi/c/depot/+/9010 Reviewed-by: Profpatsch <mail@profpatsch.de> Autosubmit: Profpatsch <mail@profpatsch.de> Tested-by: BuildkiteCI
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@ -338,6 +338,8 @@ nodeElementMay = \case
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Xml.NodeElement el -> Just el
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_ -> Nothing
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-- | A generic applicative “vertical” parser.
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-- Similar to `FieldParser`, but made for parsing whole structures and collect all errors in an `ErrorTree`.
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newtype Parse from to = Parse ((Context, from) -> Validation (NonEmpty ErrorTree) (Context, to))
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deriving
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(Functor, Applicative, Selective)
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@ -349,6 +351,8 @@ newtype Parse from to = Parse ((Context, from) -> Validation (NonEmpty ErrorTree
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((,) Context)
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)
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-- | Every parser can add to the context, like e.g. an element parser will add the name of the element it should be parsing.
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-- This should be added to the error message of each parser, with `showContext`.
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newtype Context = Context (Maybe [Text])
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deriving stock (Show)
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deriving (Semigroup, Monoid) via (First [Text])
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@ -413,16 +417,18 @@ attributeMay name = Parse $ \(ctx, el) ->
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Just a -> Success (ctx & addContext [fmt|{{attr:{name}}}|], Just a)
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Nothing -> Success (ctx, Nothing)
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-- | 'oneOf' but only one value possible
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-- | Accept only exactly the given value
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exactly :: Eq from => (from -> Text) -> from -> Parse from from
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exactly errDisplay from = Parse $ \(ctx, from') ->
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if from == from'
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then Success (ctx, from')
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else Failure $ singleton [fmt|Field has to be exactly {errDisplay from}, was: {errDisplay from'} at {showContext ctx}|]
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-- | Make a parser to parse the whole list
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multiple :: Parse a1 a2 -> Parse [a1] [a2]
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multiple inner = dimap nonEmpty (Prelude.maybe [] toList) (maybe $ multipleNE inner)
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-- | Make a parser to parse the whole non-empty list
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multipleNE :: Parse from to -> Parse (NonEmpty from) (NonEmpty to)
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multipleNE inner = Parse $ \(ctx, from) ->
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from
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@ -431,28 +437,33 @@ multipleNE inner = Parse $ \(ctx, from) ->
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-- we assume that, since the same parser is used everywhere, the context will be the same as well (TODO: correct?)
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& second (\((ctx', y) :| ys) -> (ctx', y :| (snd <$> ys)))
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-- | Lift a parser into an optional value
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maybe :: Parse from to -> Parse (Maybe from) (Maybe to)
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maybe inner = Parse $ \(ctx, m) -> case m of
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Nothing -> Success (ctx, Nothing)
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Just a -> runParse' inner (ctx, a) & second (fmap Just)
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-- | Assert that there is exactly one element in the list
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exactlyOne :: Parse [from] from
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exactlyOne = Parse $ \(ctx, xs) -> case xs of
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[] -> Failure $ singleton [fmt|Expected exactly 1 element, but got 0, at {ctx & showContext}|]
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[one] -> Success (ctx, one)
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_more -> Failure $ singleton [fmt|Expected exactly 1 element, but got 2, at {ctx & showContext}|]
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-- | Assert that there is exactly zero or one element in the list
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zeroOrOne :: Parse [from] (Maybe from)
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zeroOrOne = Parse $ \(ctx, xs) -> case xs of
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[] -> Success (ctx, Nothing)
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[one] -> Success (ctx, Just one)
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_more -> Failure $ singleton [fmt|Expected exactly 1 element, but got 2, at {ctx & showContext}|]
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-- | Find the first element on which the sub-parser succeeds; if there was no match, return all error messages.
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find :: Parse from to -> Parse [from] to
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find inner = Parse $ \(ctx, xs) -> case xs of
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[] -> failure [fmt|Wanted to get the first sub-parser that succeeds, but there were no elements in the list, at {ctx & showContext}|]
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(y : ys) -> runParse' (findNE' inner) (ctx, y :| ys)
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-- | Find the first element on which the sub-parser succeeds; if there was no match, return all error messages.
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findNE' :: Parse from to -> Parse (NonEmpty from) to
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findNE' inner = Parse $ \(ctx, xs) ->
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xs
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@ -472,6 +483,7 @@ findNE' inner = Parse $ \(ctx, xs) ->
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& singleton
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& Failure
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-- | Find all elements on which the sub-parser succeeds; if there was no match, return an empty list
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findAll :: Parse from to -> Parse [from] [to]
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findAll inner = Parse $ \(ctx, xs) ->
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xs
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@ -483,6 +495,7 @@ findAll inner = Parse $ \(ctx, xs) ->
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Success (ctx, [])
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(_miss, (hitCtx, hit) : hits) -> Success (hitCtx, hit : (hits <&> snd))
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-- | convert a 'FieldParser' into a 'Parse'.
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fieldParser :: FieldParser from to -> Parse from to
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fieldParser fp = Parse $ \(ctx, from) -> case Field.runFieldParser fp from of
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Right a -> Success (ctx, a)
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