root / src / Ganeti / JSON.hs @ 67ebc173
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1 | edc1acde | Iustin Pop | {-# LANGUAGE TypeSynonymInstances, FlexibleInstances #-} |
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2 | daa79414 | Iustin Pop | {-# OPTIONS_GHC -fno-warn-orphans #-} |
3 | daa79414 | Iustin Pop | |
4 | f047f90f | Iustin Pop | {-| JSON utility functions. -} |
5 | f047f90f | Iustin Pop | |
6 | f047f90f | Iustin Pop | {- |
7 | f047f90f | Iustin Pop | |
8 | 3ad57194 | Iustin Pop | Copyright (C) 2009, 2010, 2011, 2012 Google Inc. |
9 | f047f90f | Iustin Pop | |
10 | f047f90f | Iustin Pop | This program is free software; you can redistribute it and/or modify |
11 | f047f90f | Iustin Pop | it under the terms of the GNU General Public License as published by |
12 | f047f90f | Iustin Pop | the Free Software Foundation; either version 2 of the License, or |
13 | f047f90f | Iustin Pop | (at your option) any later version. |
14 | f047f90f | Iustin Pop | |
15 | f047f90f | Iustin Pop | This program is distributed in the hope that it will be useful, but |
16 | f047f90f | Iustin Pop | WITHOUT ANY WARRANTY; without even the implied warranty of |
17 | f047f90f | Iustin Pop | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
18 | f047f90f | Iustin Pop | General Public License for more details. |
19 | f047f90f | Iustin Pop | |
20 | f047f90f | Iustin Pop | You should have received a copy of the GNU General Public License |
21 | f047f90f | Iustin Pop | along with this program; if not, write to the Free Software |
22 | f047f90f | Iustin Pop | Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
23 | f047f90f | Iustin Pop | 02110-1301, USA. |
24 | f047f90f | Iustin Pop | |
25 | f047f90f | Iustin Pop | -} |
26 | f047f90f | Iustin Pop | |
27 | f3baf5ef | Iustin Pop | module Ganeti.JSON |
28 | ebf38064 | Iustin Pop | ( fromJResult |
29 | ebf38064 | Iustin Pop | , readEitherString |
30 | ebf38064 | Iustin Pop | , JSRecord |
31 | ebf38064 | Iustin Pop | , loadJSArray |
32 | ebf38064 | Iustin Pop | , fromObj |
33 | ebf38064 | Iustin Pop | , maybeFromObj |
34 | ebf38064 | Iustin Pop | , fromObjWithDefault |
35 | 706f7f51 | Iustin Pop | , fromKeyValue |
36 | ebf38064 | Iustin Pop | , fromJVal |
37 | 77cab679 | Agata Murawska | , jsonHead |
38 | 318853ab | Iustin Pop | , getMaybeJsonHead |
39 | ebf38064 | Iustin Pop | , asJSObject |
40 | ebf38064 | Iustin Pop | , asObjectList |
41 | f3f76ccc | Iustin Pop | , tryFromObj |
42 | a4f35477 | Bernardo Dal Seno | , tryArrayMaybeFromObj |
43 | 3ad57194 | Iustin Pop | , toArray |
44 | 3c8e6d09 | Michele Tartara | , optionalJSField |
45 | 3c8e6d09 | Michele Tartara | , optFieldsToObj |
46 | edc1acde | Iustin Pop | , HasStringRepr(..) |
47 | edc1acde | Iustin Pop | , GenericContainer(..) |
48 | edc1acde | Iustin Pop | , Container |
49 | ebf38064 | Iustin Pop | ) |
50 | ebf38064 | Iustin Pop | where |
51 | f047f90f | Iustin Pop | |
52 | daa79414 | Iustin Pop | import Control.DeepSeq |
53 | f047f90f | Iustin Pop | import Control.Monad (liftM) |
54 | 3c8e6d09 | Michele Tartara | import Data.Maybe (fromMaybe, catMaybes) |
55 | 84835174 | Iustin Pop | import qualified Data.Map as Map |
56 | f047f90f | Iustin Pop | import Text.Printf (printf) |
57 | f047f90f | Iustin Pop | |
58 | f047f90f | Iustin Pop | import qualified Text.JSON as J |
59 | c12a68e2 | Iustin Pop | import Text.JSON.Pretty (pp_value) |
60 | f047f90f | Iustin Pop | |
61 | 32a569fe | Iustin Pop | -- Note: this module should not import any Ganeti-specific modules |
62 | 32a569fe | Iustin Pop | -- beside BasicTypes, since it's used in THH which is used itself to |
63 | 32a569fe | Iustin Pop | -- build many other modules. |
64 | 32a569fe | Iustin Pop | |
65 | f3f76ccc | Iustin Pop | import Ganeti.BasicTypes |
66 | f3f76ccc | Iustin Pop | |
67 | f047f90f | Iustin Pop | -- * JSON-related functions |
68 | f047f90f | Iustin Pop | |
69 | daa79414 | Iustin Pop | instance NFData J.JSValue where |
70 | daa79414 | Iustin Pop | rnf J.JSNull = () |
71 | daa79414 | Iustin Pop | rnf (J.JSBool b) = rnf b |
72 | daa79414 | Iustin Pop | rnf (J.JSRational b r) = rnf b `seq` rnf r |
73 | daa79414 | Iustin Pop | rnf (J.JSString s) = rnf $ J.fromJSString s |
74 | daa79414 | Iustin Pop | rnf (J.JSArray a) = rnf a |
75 | daa79414 | Iustin Pop | rnf (J.JSObject o) = rnf o |
76 | daa79414 | Iustin Pop | |
77 | daa79414 | Iustin Pop | instance (NFData a) => NFData (J.JSObject a) where |
78 | daa79414 | Iustin Pop | rnf = rnf . J.fromJSObject |
79 | daa79414 | Iustin Pop | |
80 | 3c8e6d09 | Michele Tartara | -- | A type alias for a field of a JSRecord. |
81 | 3c8e6d09 | Michele Tartara | type JSField = (String, J.JSValue) |
82 | 3c8e6d09 | Michele Tartara | |
83 | f047f90f | Iustin Pop | -- | A type alias for the list-based representation of J.JSObject. |
84 | 3c8e6d09 | Michele Tartara | type JSRecord = [JSField] |
85 | f047f90f | Iustin Pop | |
86 | f047f90f | Iustin Pop | -- | Converts a JSON Result into a monadic value. |
87 | f047f90f | Iustin Pop | fromJResult :: Monad m => String -> J.Result a -> m a |
88 | f047f90f | Iustin Pop | fromJResult s (J.Error x) = fail (s ++ ": " ++ x) |
89 | f047f90f | Iustin Pop | fromJResult _ (J.Ok x) = return x |
90 | f047f90f | Iustin Pop | |
91 | f047f90f | Iustin Pop | -- | Tries to read a string from a JSON value. |
92 | f047f90f | Iustin Pop | -- |
93 | f047f90f | Iustin Pop | -- In case the value was not a string, we fail the read (in the |
94 | f047f90f | Iustin Pop | -- context of the current monad. |
95 | f047f90f | Iustin Pop | readEitherString :: (Monad m) => J.JSValue -> m String |
96 | f047f90f | Iustin Pop | readEitherString v = |
97 | ebf38064 | Iustin Pop | case v of |
98 | ebf38064 | Iustin Pop | J.JSString s -> return $ J.fromJSString s |
99 | ebf38064 | Iustin Pop | _ -> fail "Wrong JSON type" |
100 | f047f90f | Iustin Pop | |
101 | f047f90f | Iustin Pop | -- | Converts a JSON message into an array of JSON objects. |
102 | f047f90f | Iustin Pop | loadJSArray :: (Monad m) |
103 | f047f90f | Iustin Pop | => String -- ^ Operation description (for error reporting) |
104 | f047f90f | Iustin Pop | -> String -- ^ Input message |
105 | f047f90f | Iustin Pop | -> m [J.JSObject J.JSValue] |
106 | f047f90f | Iustin Pop | loadJSArray s = fromJResult s . J.decodeStrict |
107 | f047f90f | Iustin Pop | |
108 | a4f35477 | Bernardo Dal Seno | -- | Helper function for missing-key errors |
109 | a4f35477 | Bernardo Dal Seno | buildNoKeyError :: JSRecord -> String -> String |
110 | a4f35477 | Bernardo Dal Seno | buildNoKeyError o k = |
111 | a4f35477 | Bernardo Dal Seno | printf "key '%s' not found, object contains only %s" k (show (map fst o)) |
112 | a4f35477 | Bernardo Dal Seno | |
113 | f047f90f | Iustin Pop | -- | Reads the value of a key in a JSON object. |
114 | f047f90f | Iustin Pop | fromObj :: (J.JSON a, Monad m) => JSRecord -> String -> m a |
115 | f047f90f | Iustin Pop | fromObj o k = |
116 | ebf38064 | Iustin Pop | case lookup k o of |
117 | a4f35477 | Bernardo Dal Seno | Nothing -> fail $ buildNoKeyError o k |
118 | ebf38064 | Iustin Pop | Just val -> fromKeyValue k val |
119 | f047f90f | Iustin Pop | |
120 | f2f06e2e | Iustin Pop | -- | Reads the value of an optional key in a JSON object. Missing |
121 | f2f06e2e | Iustin Pop | -- keys, or keys that have a \'null\' value, will be returned as |
122 | f2f06e2e | Iustin Pop | -- 'Nothing', otherwise we attempt deserialisation and return a 'Just' |
123 | f2f06e2e | Iustin Pop | -- value. |
124 | f047f90f | Iustin Pop | maybeFromObj :: (J.JSON a, Monad m) => |
125 | f047f90f | Iustin Pop | JSRecord -> String -> m (Maybe a) |
126 | f047f90f | Iustin Pop | maybeFromObj o k = |
127 | ebf38064 | Iustin Pop | case lookup k o of |
128 | ebf38064 | Iustin Pop | Nothing -> return Nothing |
129 | f2f06e2e | Iustin Pop | -- a optional key with value JSNull is the same as missing, since |
130 | f2f06e2e | Iustin Pop | -- we can't convert it meaningfully anyway to a Haskell type, and |
131 | f2f06e2e | Iustin Pop | -- the Python code can emit 'null' for optional values (depending |
132 | f2f06e2e | Iustin Pop | -- on usage), and finally our encoding rules treat 'null' values |
133 | f2f06e2e | Iustin Pop | -- as 'missing' |
134 | f2f06e2e | Iustin Pop | Just J.JSNull -> return Nothing |
135 | ebf38064 | Iustin Pop | Just val -> liftM Just (fromKeyValue k val) |
136 | f047f90f | Iustin Pop | |
137 | f2f06e2e | Iustin Pop | -- | Reads the value of a key in a JSON object with a default if |
138 | f2f06e2e | Iustin Pop | -- missing. Note that both missing keys and keys with value \'null\' |
139 | f2f06e2e | Iustin Pop | -- will case the default value to be returned. |
140 | f047f90f | Iustin Pop | fromObjWithDefault :: (J.JSON a, Monad m) => |
141 | f047f90f | Iustin Pop | JSRecord -> String -> a -> m a |
142 | f047f90f | Iustin Pop | fromObjWithDefault o k d = liftM (fromMaybe d) $ maybeFromObj o k |
143 | f047f90f | Iustin Pop | |
144 | a4f35477 | Bernardo Dal Seno | -- | Reads an array of optional items |
145 | a4f35477 | Bernardo Dal Seno | arrayMaybeFromObj :: (J.JSON a, Monad m) => |
146 | a4f35477 | Bernardo Dal Seno | JSRecord -> String -> m [Maybe a] |
147 | a4f35477 | Bernardo Dal Seno | arrayMaybeFromObj o k = |
148 | a4f35477 | Bernardo Dal Seno | case lookup k o of |
149 | a4f35477 | Bernardo Dal Seno | Just (J.JSArray xs) -> mapM parse xs |
150 | a4f35477 | Bernardo Dal Seno | where |
151 | a4f35477 | Bernardo Dal Seno | parse J.JSNull = return Nothing |
152 | a4f35477 | Bernardo Dal Seno | parse x = liftM Just $ fromJVal x |
153 | a4f35477 | Bernardo Dal Seno | _ -> fail $ buildNoKeyError o k |
154 | a4f35477 | Bernardo Dal Seno | |
155 | a4f35477 | Bernardo Dal Seno | -- | Wrapper for arrayMaybeFromObj with better diagnostic |
156 | a4f35477 | Bernardo Dal Seno | tryArrayMaybeFromObj :: (J.JSON a) |
157 | a4f35477 | Bernardo Dal Seno | => String -- ^ Textual "owner" in error messages |
158 | a4f35477 | Bernardo Dal Seno | -> JSRecord -- ^ The object array |
159 | a4f35477 | Bernardo Dal Seno | -> String -- ^ The desired key from the object |
160 | a4f35477 | Bernardo Dal Seno | -> Result [Maybe a] |
161 | a4f35477 | Bernardo Dal Seno | tryArrayMaybeFromObj t o = annotateResult t . arrayMaybeFromObj o |
162 | a4f35477 | Bernardo Dal Seno | |
163 | f047f90f | Iustin Pop | -- | Reads a JValue, that originated from an object key. |
164 | f047f90f | Iustin Pop | fromKeyValue :: (J.JSON a, Monad m) |
165 | f047f90f | Iustin Pop | => String -- ^ The key name |
166 | f047f90f | Iustin Pop | -> J.JSValue -- ^ The value to read |
167 | f047f90f | Iustin Pop | -> m a |
168 | f047f90f | Iustin Pop | fromKeyValue k val = |
169 | 706f7f51 | Iustin Pop | fromJResult (printf "key '%s'" k) (J.readJSON val) |
170 | f047f90f | Iustin Pop | |
171 | f047f90f | Iustin Pop | -- | Small wrapper over readJSON. |
172 | f047f90f | Iustin Pop | fromJVal :: (Monad m, J.JSON a) => J.JSValue -> m a |
173 | f047f90f | Iustin Pop | fromJVal v = |
174 | ebf38064 | Iustin Pop | case J.readJSON v of |
175 | c12a68e2 | Iustin Pop | J.Error s -> fail ("Cannot convert value '" ++ show (pp_value v) ++ |
176 | ebf38064 | Iustin Pop | "', error: " ++ s) |
177 | ebf38064 | Iustin Pop | J.Ok x -> return x |
178 | f047f90f | Iustin Pop | |
179 | 77cab679 | Agata Murawska | -- | Helper function that returns Null or first element of the list. |
180 | 77cab679 | Agata Murawska | jsonHead :: (J.JSON b) => [a] -> (a -> b) -> J.JSValue |
181 | 77cab679 | Agata Murawska | jsonHead [] _ = J.JSNull |
182 | 77cab679 | Agata Murawska | jsonHead (x:_) f = J.showJSON $ f x |
183 | 77cab679 | Agata Murawska | |
184 | 318853ab | Iustin Pop | -- | Helper for extracting Maybe values from a possibly empty list. |
185 | 318853ab | Iustin Pop | getMaybeJsonHead :: (J.JSON b) => [a] -> (a -> Maybe b) -> J.JSValue |
186 | 318853ab | Iustin Pop | getMaybeJsonHead [] _ = J.JSNull |
187 | 318853ab | Iustin Pop | getMaybeJsonHead (x:_) f = maybe J.JSNull J.showJSON (f x) |
188 | 318853ab | Iustin Pop | |
189 | f047f90f | Iustin Pop | -- | Converts a JSON value into a JSON object. |
190 | f047f90f | Iustin Pop | asJSObject :: (Monad m) => J.JSValue -> m (J.JSObject J.JSValue) |
191 | f047f90f | Iustin Pop | asJSObject (J.JSObject a) = return a |
192 | f047f90f | Iustin Pop | asJSObject _ = fail "not an object" |
193 | f047f90f | Iustin Pop | |
194 | f047f90f | Iustin Pop | -- | Coneverts a list of JSON values into a list of JSON objects. |
195 | f047f90f | Iustin Pop | asObjectList :: (Monad m) => [J.JSValue] -> m [J.JSObject J.JSValue] |
196 | f047f90f | Iustin Pop | asObjectList = mapM asJSObject |
197 | f3f76ccc | Iustin Pop | |
198 | 7209d304 | Klaus Aehlig | -- | Try to extract a key from an object with better error reporting |
199 | f3f76ccc | Iustin Pop | -- than fromObj. |
200 | f3f76ccc | Iustin Pop | tryFromObj :: (J.JSON a) => |
201 | f3f76ccc | Iustin Pop | String -- ^ Textual "owner" in error messages |
202 | f3f76ccc | Iustin Pop | -> JSRecord -- ^ The object array |
203 | f3f76ccc | Iustin Pop | -> String -- ^ The desired key from the object |
204 | f3f76ccc | Iustin Pop | -> Result a |
205 | f3f76ccc | Iustin Pop | tryFromObj t o = annotateResult t . fromObj o |
206 | 3ad57194 | Iustin Pop | |
207 | 3ad57194 | Iustin Pop | -- | Ensure a given JSValue is actually a JSArray. |
208 | 3ad57194 | Iustin Pop | toArray :: (Monad m) => J.JSValue -> m [J.JSValue] |
209 | 3ad57194 | Iustin Pop | toArray (J.JSArray arr) = return arr |
210 | c12a68e2 | Iustin Pop | toArray o = |
211 | c12a68e2 | Iustin Pop | fail $ "Invalid input, expected array but got " ++ show (pp_value o) |
212 | 84835174 | Iustin Pop | |
213 | 3c8e6d09 | Michele Tartara | -- | Creates a Maybe JSField. If the value string is Nothing, the JSField |
214 | 3c8e6d09 | Michele Tartara | -- will be Nothing as well. |
215 | 3c8e6d09 | Michele Tartara | optionalJSField :: (J.JSON a) => String -> Maybe a -> Maybe JSField |
216 | 3c8e6d09 | Michele Tartara | optionalJSField name (Just value) = Just (name, J.showJSON value) |
217 | 3c8e6d09 | Michele Tartara | optionalJSField _ Nothing = Nothing |
218 | 3c8e6d09 | Michele Tartara | |
219 | 3c8e6d09 | Michele Tartara | -- | Creates an object with all the non-Nothing fields of the given list. |
220 | 3c8e6d09 | Michele Tartara | optFieldsToObj :: [Maybe JSField] -> J.JSValue |
221 | 3c8e6d09 | Michele Tartara | optFieldsToObj = J.makeObj . catMaybes |
222 | 3c8e6d09 | Michele Tartara | |
223 | 84835174 | Iustin Pop | -- * Container type (special type for JSON serialisation) |
224 | 84835174 | Iustin Pop | |
225 | edc1acde | Iustin Pop | -- | Class of types that can be converted from Strings. This is |
226 | edc1acde | Iustin Pop | -- similar to the 'Read' class, but it's using a different |
227 | edc1acde | Iustin Pop | -- serialisation format, so we have to define a separate class. Mostly |
228 | edc1acde | Iustin Pop | -- useful for custom key types in JSON dictionaries, which have to be |
229 | edc1acde | Iustin Pop | -- backed by strings. |
230 | edc1acde | Iustin Pop | class HasStringRepr a where |
231 | edc1acde | Iustin Pop | fromStringRepr :: (Monad m) => String -> m a |
232 | edc1acde | Iustin Pop | toStringRepr :: a -> String |
233 | edc1acde | Iustin Pop | |
234 | edc1acde | Iustin Pop | -- | Trivial instance 'HasStringRepr' for 'String'. |
235 | edc1acde | Iustin Pop | instance HasStringRepr String where |
236 | edc1acde | Iustin Pop | fromStringRepr = return |
237 | edc1acde | Iustin Pop | toStringRepr = id |
238 | edc1acde | Iustin Pop | |
239 | 84835174 | Iustin Pop | -- | The container type, a wrapper over Data.Map |
240 | edc1acde | Iustin Pop | newtype GenericContainer a b = |
241 | edc1acde | Iustin Pop | GenericContainer { fromContainer :: Map.Map a b } |
242 | 139c0683 | Iustin Pop | deriving (Show, Eq) |
243 | 84835174 | Iustin Pop | |
244 | daa79414 | Iustin Pop | instance (NFData a, NFData b) => NFData (GenericContainer a b) where |
245 | daa79414 | Iustin Pop | rnf = rnf . Map.toList . fromContainer |
246 | daa79414 | Iustin Pop | |
247 | edc1acde | Iustin Pop | -- | Type alias for string keys. |
248 | edc1acde | Iustin Pop | type Container = GenericContainer String |
249 | edc1acde | Iustin Pop | |
250 | 84835174 | Iustin Pop | -- | Container loader. |
251 | edc1acde | Iustin Pop | readContainer :: (Monad m, HasStringRepr a, Ord a, J.JSON b) => |
252 | edc1acde | Iustin Pop | J.JSObject J.JSValue -> m (GenericContainer a b) |
253 | 84835174 | Iustin Pop | readContainer obj = do |
254 | 84835174 | Iustin Pop | let kjvlist = J.fromJSObject obj |
255 | edc1acde | Iustin Pop | kalist <- mapM (\(k, v) -> do |
256 | edc1acde | Iustin Pop | k' <- fromStringRepr k |
257 | edc1acde | Iustin Pop | v' <- fromKeyValue k v |
258 | edc1acde | Iustin Pop | return (k', v')) kjvlist |
259 | edc1acde | Iustin Pop | return $ GenericContainer (Map.fromList kalist) |
260 | 84835174 | Iustin Pop | |
261 | 417ab39c | Iustin Pop | {-# ANN showContainer "HLint: ignore Use ***" #-} |
262 | 84835174 | Iustin Pop | -- | Container dumper. |
263 | edc1acde | Iustin Pop | showContainer :: (HasStringRepr a, J.JSON b) => |
264 | edc1acde | Iustin Pop | GenericContainer a b -> J.JSValue |
265 | 84835174 | Iustin Pop | showContainer = |
266 | edc1acde | Iustin Pop | J.makeObj . map (\(k, v) -> (toStringRepr k, J.showJSON v)) . |
267 | edc1acde | Iustin Pop | Map.toList . fromContainer |
268 | 84835174 | Iustin Pop | |
269 | edc1acde | Iustin Pop | instance (HasStringRepr a, Ord a, J.JSON b) => |
270 | edc1acde | Iustin Pop | J.JSON (GenericContainer a b) where |
271 | 84835174 | Iustin Pop | showJSON = showContainer |
272 | 84835174 | Iustin Pop | readJSON (J.JSObject o) = readContainer o |
273 | 84835174 | Iustin Pop | readJSON v = fail $ "Failed to load container, expected object but got " |
274 | c12a68e2 | Iustin Pop | ++ show (pp_value v) |