Burrito.Internal.Expand

Documentation

expand :: [(String, Value)] -> Template -> String

Expands a template using the given values. Unlike parsing, expansion always succeeds. If no value is given for a variable, it will simply not appear in the output.

>>> expand [] <$> parse "valid-template"
Just "valid-template"
>>> expand [] <$> parse "template:{example}"
Just "template:"
>>> expand [("example", stringValue "true")] <$> parse "template:{example}"
Just "template:true"

expandWith :: Monad m => (Text -> m (Maybe Value)) -> Template -> m Builder

This is like expand except that it gives you more control over how variables are expanded. If you can, use expand. It's simpler.

Instead of passing in a static mapping form names to values, you pass in a function that is used to look up values on the fly. This can be useful if computing values takes a while or requires some impure actions.

>>> expandWith (\ x -> [Nothing, Just . stringValue $ unpack x]) <$> parse "template:{example}"
Just ["template:","template:example"]
>>> let Just template = parse "user={USER}"
>>> expandWith (fmap (fmap stringValue) . lookupEnv . unpack) template
"user=taylor"

Note that as the RFC specifies, the given function will be called at most once for each variable in the template.

>>> let Just template = parse "{a}{a}"
>>> expandWith (\ x -> do { putStrLn $ "-- expanding " <> show x; pure . Just $ Burrito.stringValue "A" }) template
-- expanding "a"
"AA"

type CacheT = StateT (Map Text (Maybe Value))

cached :: Monad m => (Text -> m (Maybe Value)) -> Name -> CacheT m (Maybe Value)

template :: Monad m => (Name -> CacheT m (Maybe Value)) -> Template -> CacheT m Builder

token :: Monad m => (Name -> CacheT m (Maybe Value)) -> Token -> CacheT m Builder

expression :: Monad m => (Name -> CacheT m (Maybe Value)) -> Expression -> CacheT m Builder

separator :: Operator -> Builder

prefix :: Operator -> Builder

variable :: Monad m => (Name -> CacheT m (Maybe Value)) -> Operator -> Variable -> CacheT m (Maybe Builder)

value :: Operator -> Variable -> Value -> Maybe Builder

dictionaryValue :: Operator -> Variable -> [(Text, Text)] -> Maybe Builder

listValue :: Operator -> Variable -> [Text] -> Maybe Builder

items :: (Operator -> Variable -> a -> [Builder]) -> Operator -> Variable -> [a] -> Maybe Builder

label :: Bool -> Variable -> Builder

name :: Name -> Builder

field :: Field -> Builder

character :: (Char -> Bool) -> Character tag -> Builder

stringValue :: Operator -> Variable -> Text -> Builder

string :: Operator -> Modifier -> Text -> Builder

isAllowed :: Char -> Bool

isUnreserved :: Char -> Bool

isReserved :: Char -> Bool

unencodedCharacter :: (Char -> Bool) -> Char -> Builder

encodeCharacter :: Char -> [(Digit, Digit)]

literal :: Literal -> Builder