qgymib / cjson.lua

cjson.lua

A Lua wrapper for cJSON.

API

cjson.serialize

string cjson.serialize(object)

Serialize a Lua value into JSON string, which can be deserialized by cjson.deserialize() later.

Convert rule in order:

1. A Lua value will always have a key v as it's top level key.

   { "v": "example" }
   

2. If a value have metatable field __name, and metamethod __tostring, the value of __name and return value of __tostring will be the json value.

   { "v": { "t": "typename", "p": "payload" } }
   

3. If it is a Lua native type (nil, boolean, number, string), the value is the equal JSON value:

   { "v": null }
   { "v": true }
   { "v": 1.2 }
   { "v": "hello world" }
   

4. If it is a userdata (at this stage, it does not have metatable), and it is equal to C value NULL, treat it as JSON null.

   { "v": null }
   

5. If it is a table, expand it as JSON array. The content in array is a series of JSON object that have k as table key and v as table value. The value of k and v follows the same convert rule.

   { "v": [ { "k": 0, "v": 3 }, { "k": "b", "v": { "t": "typename", "p": "payload"} } ] }
   

6. For other conditions raise an error.

cjson.deserialize

object cjson.deserialize(string)

Deserialize a JSON string into Lua value.

Convert rule in order:

1. A Lua value will always have a key v as it's top level key.
2. If the JSON value is null, boolean, number or string, convert it into equal Lua value.
3. If the JSON value is array, treat it as Lua table.
4. If the JSON value is object, treat it as userdata. The t specify the type name of userdata. A metamethod __fromstring will be called with payload as it's argument. The return value will be treat it as Lua value.