44 lines
906 B
Haskell
44 lines
906 B
Haskell
{- Streaming JSON output.
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-
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- Copyright 2011 Joey Hess <joey@kitenet.net>
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-
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- Licensed under the GNU GPL version 3 or higher.
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-}
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module Utility.JSONStream (
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start,
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add,
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end
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) where
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import Text.JSON
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{- Text.JSON does not support building up a larger JSON document piece by
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- piece as a stream. To support streaming, a hack. The JSObject is converted
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- to a string with its final "}" is left off, allowing it to be added to
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- later. -}
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start :: JSON a => [(String, a)] -> String
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start l
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| last s == endchar = init s
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| otherwise = bad s
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where
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s = encodeStrict $ toJSObject l
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add :: JSON a => [(String, a)] -> String
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add l
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| head s == startchar = ',' : drop 1 s
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| otherwise = bad s
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where
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s = start l
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end :: String
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end = [endchar, '\n']
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startchar :: Char
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startchar = '{'
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endchar :: Char
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endchar = '}'
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bad :: String -> a
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bad s = error $ "Text.JSON returned unexpected string: " ++ s
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