1

2 --[[--

3 json.null

4

5 A special marker to be used to write a value of null to a JSON object or JSON array. The marker is only used for setting a value to null: when reading null values from a JSON object or JSON array via the index operator, via json.get(...), or via pairs(...) or ipairs(...), then the null values will always read as nil.

6

7 --]]--

8 -- implemented as lightuserdata in json.c

9 -- pointing to field "nullmark" of json_lightuserdata struct

10 --//--

11

12

13 --[[--

14 obj = -- a new JSON object

15 json.object{

16 key1 = value1, -- key value pair to be set in JSON object

17 key2 = value2, -- another key value pair to be set in JSON object

18 ...

19 }

20

21 Converts a Lua table (or any other value with a __pairs metamethod) to a JSON object. The argument is never modified. May also be called without arguments to create an empty JSON object. All JSON objects support iteration using pairs(...).

22

23 --]]--

24 -- implemented as in json.c as

25 -- static int json_object(lua_State *L)

26 --//--

27

28

29 --[[--

30 ary = -- a new JSON array

31 json.array{

32 value1, -- first value to be set in JSON array

33 value2, -- second value to be set in JSON array

34 ...

35 }

36

37 Converts a Lua table (or any other value with an __ipairs metamethod) to a JSON array. The argument is never modified. May also be called without arguments to create an empty JSON array. All JSON arrays support iteration using ipairs(...).

38

39 --]]--

40 -- implemented in json.c as

41 -- static int json_object(lua_State *L)

42 --//--

43

44

45 --[[--

46 parsed_document, -- parsed value, json.null for null values, or nil in case of error

47 errmsg = -- error message if document could not be parsed

48 json.import(

49 json_document_as_string -- string to be parsed

50 )

51

52 Parses a JSON document. Returns a string, a number, a boolean, json.null, or a JSON object or JSON array as returned by json.object{...} or json.array{...} respectively. The special value json.null is only returned if the top level value is null; null values within the document always read as nil! (see json.null)

53

54 --]]--

55 -- implemented in json.c as

56 -- static int json_import(lua_State *L)

57 --//--

58

59

60 --[[--

61 value = -- value that has been read, or nil if path does not exist

62 json.get(

63 document, -- JSON value (usually object or array)

64 key1, -- first path element (e.g. a string key to descent into an object)

65 key2, -- second path element (e.g. an integer key to descent into an array)

66 ...,

67 last_key -- last path element

68 )

69

70 Reads a value from a JSON document by following a given path that may contain string keys (to descent into an object) or integer keys (to descent into an array). A JSON value of null is returned as nil. This function also works on plain Lua tables instead of JSON documents.

71

72 Examples:

73 json.get(json.import('{"a":{"b":3}}'), "a", "b") == 3

74 json.get(json.import('{"a":{"b":3}}'), "c", "d") == nil

75 json.get(json.import('{"n":null}'), "n") == nil

76

77 --]]--

78 -- implemented in json.c as

79 -- static int json_get(lua_State *L)

80 --//--

81

82

83 --[[--

84 type_string_or_nil -- "object", "array", "string", "number", "boolean", "null", string "nil", or nil

85 json.get(

86 document, -- a JSON value (usually object or array)

87 key1, -- first path element (e.g. a string key to descent into an object)

88 key2, -- second path element (e.g. an integer key to descent into an array)

89 ...,

90 last_key -- last path element

91 )

92

93 Determines the type of a value in a JSON document by following a given path that may contain string keys (to descent into an object) or integer keys (to descent into an array). If the path but its last path element could be followed, then the string "nil" is returned. If the previous path elements could not be followed, then nil itself is returned. Otherwise the type of the value is returned, whereas the string "null" indicates a JSON null value. This function also works on plain Lua tables instead of JSON documents.

94

95 Examples:

96 json.type(json.import('{"a":{"b":3}}'), "a", "b") == 3

97 json.type(json.import('{"a":{"b":null}}'), "a", "b") == "null"

98 json.type(json.import('{"a":{"b":null}}'), "a", "c") == "nil"

99 json.type(json.import('{"a":{"b":null}}'), "d", "c") == nil

100

101 --]]--

102 -- implemented in json.c as

103 -- static int json_type(lua_State *L)

104 --//--

105

106

107 --[[--

108 document =

109 json.set(

110 document,

111 value,

112 key1, -- first path element (e.g. a string key to descent into an object)

113 key2, -- second path element (e.g. an integer key to descent into an array)

114 ...

115 last_key -- last path element

116 )

117

118 Sets a value in a JSON document by following a given path that may contain string keys (to descent into an object) or integer keys (to descent into an array). If the path does not exist (or contains objects where arrays are expected or vice versa), then the necessary intermediate JSON objects or JSON arrays are created. This function also works on plain Lua tables but will create JSON objects or arrays where necessary.

119

120 --]]--

121 -- implemented in json.c as

122 -- static int json_set(lua_State *L)

123 --//--

124

125

126 --[[--

127 encoded_document = -- encoded JSON document as string

128 json.export(

129 document, -- a JSON value (usually object or array)

130 indentation -- indentation string to use for pretty printing, or true for two spaces

131 )

132

133 Encodes a JSON document. Since the order of object keys is deterministic, this function may also be used to compare two JSON documents for (deep) equality: json.export(a) == json.export(b). If the indentation argument is nil or false, then pretty printing is disabled.

134

135 --]]--

136 -- implemented in json.c as

137 -- static int json_export(lua_State *L)

138 --//--

139