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--[[
JSON Encoder and Parser for Lua 5.1
Copyright © 2007 Shaun Brown (http://www.chipmunkav.com).
All Rights Reserved.
Permission is hereby granted, free of charge, to any person
obtaining a copy of this software to deal in the Software without
restriction, including without limitation the rights to use,
copy, modify, merge, publish, distribute, sublicense, and/or
sell copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.
If you find this software useful please give www.chipmunkav.com a mention.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR
ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
Usage:
-- Lua script:
local t = {
["name1"] = "value1",
["name2"] = {1, false, true, 23.54, "a \021 string"},
name3 = Json.Null()
}
local json = Json.Encode (t)
print (json)
--> {"name1":"value1","name3":null,"name2":[1,false,true,23.54,"a \u0015 string"]}
local t = Json.Decode(json)
print(t.name2[4])
--> 23.54
Notes:
1) Encodable Lua types: string, number, boolean, table, nil
2) Use Json.Null() to insert a null value into a Json object
3) All control chars are encoded to \uXXXX format eg "\021" encodes to "\u0015"
4) All Json \uXXXX chars are decoded to chars (0-255 byte range only)
5) Json single line // and /* */ block comments are discarded during decoding
6) Numerically indexed Lua arrays are encoded to Json Lists eg [1,2,3]
7) Lua dictionary tables are converted to Json objects eg {"one":1,"two":2}
8) Json nulls are decoded to Lua nil and treated by Lua in the normal way
--]]
local string = string
local math = math
local table = table
local error = error
local tonumber = tonumber
local tostring = tostring
local type = type
local setmetatable = setmetatable
local pairs = pairs
local ipairs = ipairs
local assert = assert
local Chipmunk = Chipmunk
module("Json")
local StringBuilder = {
buffer = {}
}
function StringBuilder:New()
local o = {}
setmetatable(o, self)
self.__index = self
o.buffer = {}
return o
end
function StringBuilder:Append(s)
self.buffer[#self.buffer+1] = s
end
function StringBuilder:ToString()
return table.concat(self.buffer)
end
local JsonWriter = {
backslashes = {
['\b'] = "\\b",
['\t'] = "\\t",
['\n'] = "\\n",
['\f'] = "\\f",
['\r'] = "\\r",
['"'] = "\\\"",
['\\'] = "\\\\",
['/'] = "\\/"
}
}
function JsonWriter:New()
local o = {}
o.writer = StringBuilder:New()
setmetatable(o, self)
self.__index = self
return o
end
function JsonWriter:Append(s)
self.writer:Append(s)
end
function JsonWriter:ToString()
return self.writer:ToString()
end
function JsonWriter:Write(o)
local t = type(o)
if t == "nil" then
self:WriteNil()
elseif t == "boolean" then
self:WriteString(o)
elseif t == "number" then
self:WriteString(o)
elseif t == "string" then
self:ParseString(o)
elseif t == "table" then
self:WriteTable(o)
elseif t == "function" then
self:WriteFunction(o)
elseif t == "thread" then
self:WriteError(o)
elseif t == "userdata" then
self:WriteError(o)
end
end
function JsonWriter:WriteNil()
self:Append("null")
end
function JsonWriter:WriteString(o)
self:Append(tostring(o))
end
function JsonWriter:ParseString(s)
self:Append('"')
self:Append(string.gsub(s, "[%z%c\\\"/]", function(n)
local c = self.backslashes[n]
if c then return c end
return string.format("\\u%.4X", string.byte(n))
end))
self:Append('"')
end
function JsonWriter:IsArray(t)
local count = 0
local isindex = function(k)
if type(k) == "number" and k > 0 then
if math.floor(k) == k then
return true
end
end
return false
end
for k,v in pairs(t) do
if not isindex(k) then
return false, '{', '}'
else
count = math.max(count, k)
end
end
return true, '[', ']', count
end
function JsonWriter:WriteTable(t)
local ba, st, et, n = self:IsArray(t)
self:Append(st)
if ba then
for i = 1, n do
self:Write(t[i])
if i < n then
self:Append(',')
end
end
else
local first = true;
for k, v in pairs(t) do
if not first then
self:Append(',')
end
first = false;
self:ParseString(k)
self:Append(':')
self:Write(v)
end
end
self:Append(et)
end
function JsonWriter:WriteError(o)
error(string.format(
"Encoding of %s unsupported",
tostring(o)))
end
function JsonWriter:WriteFunction(o)
if o == Null then
self:WriteNil()
else
self:WriteError(o)
end
end
local StringReader = {
s = "",
i = 0
}
function StringReader:New(s)
local o = {}
setmetatable(o, self)
self.__index = self
o.s = s or o.s
return o
end
function StringReader:Peek()
local i = self.i + 1
if i <= #self.s then
return string.sub(self.s, i, i)
end
return nil
end
function StringReader:Next()
self.i = self.i+1
if self.i <= #self.s then
return string.sub(self.s, self.i, self.i)
end
return nil
end
function StringReader:All()
return self.s
end
local JsonReader = {
escapes = {
['t'] = '\t',
['n'] = '\n',
['f'] = '\f',
['r'] = '\r',
['b'] = '\b',
}
}
function JsonReader:New(s)
local o = {}
o.reader = StringReader:New(s)
setmetatable(o, self)
self.__index = self
return o;
end
function JsonReader:Read()
self:SkipWhiteSpace()
local peek = self:Peek()
if peek == nil then
error(string.format(
"Nil string: '%s'",
self:All()))
elseif peek == '{' then
return self:ReadObject()
elseif peek == '[' then
return self:ReadArray()
elseif peek == '"' then
return self:ReadString()
elseif string.find(peek, "[%+%-%d]") then
return self:ReadNumber()
elseif peek == 't' then
return self:ReadTrue()
elseif peek == 'f' then
return self:ReadFalse()
elseif peek == 'n' then
return self:ReadNull()
elseif peek == '/' then
self:ReadComment()
return self:Read()
else
error(string.format(
"Invalid input: '%s'",
self:All()))
end
end
function JsonReader:ReadTrue()
self:TestReservedWord{'t','r','u','e'}
return true
end
function JsonReader:ReadFalse()
self:TestReservedWord{'f','a','l','s','e'}
return false
end
function JsonReader:ReadNull()
self:TestReservedWord{'n','u','l','l'}
return nil
end
function JsonReader:TestReservedWord(t)
for i, v in ipairs(t) do
if self:Next() ~= v then
error(string.format(
"Error reading '%s': %s",
table.concat(t),
self:All()))
end
end
end
function JsonReader:ReadNumber()
local result = self:Next()
local peek = self:Peek()
while peek ~= nil and string.find(
peek,
"[%+%-%d%.eE]") do
result = result .. self:Next()
peek = self:Peek()
end
result = tonumber(result)
if result == nil then
error(string.format(
"Invalid number: '%s'",
result))
else
return result
end
end
function JsonReader:ReadString()
local result = ""
assert(self:Next() == '"')
while self:Peek() ~= '"' do
local ch = self:Next()
if ch == '\\' then
ch = self:Next()
if self.escapes[ch] then
ch = self.escapes[ch]
end
end
result = result .. ch
end
assert(self:Next() == '"')
local fromunicode = function(m)
return string.char(tonumber(m, 16))
end
return string.gsub(
result,
"u%x%x(%x%x)",
fromunicode)
end
function JsonReader:ReadComment()
assert(self:Next() == '/')
local second = self:Next()
if second == '/' then
self:ReadSingleLineComment()
elseif second == '*' then
self:ReadBlockComment()
else
error(string.format(
"Invalid comment: %s",
self:All()))
end
end
function JsonReader:ReadBlockComment()
local done = false
while not done do
local ch = self:Next()
if ch == '*' and self:Peek() == '/' then
done = true
end
if not done and
ch == '/' and
self:Peek() == "*" then
error(string.format(
"Invalid comment: %s, '/*' illegal.",
self:All()))
end
end
self:Next()
end
function JsonReader:ReadSingleLineComment()
local ch = self:Next()
while ch ~= '\r' and ch ~= '\n' do
ch = self:Next()
end
end
function JsonReader:ReadArray()
local result = {}
assert(self:Next() == '[')
local done = false
if self:Peek() == ']' then
done = true;
end
while not done do
local item = self:Read()
result[#result+1] = item
self:SkipWhiteSpace()
if self:Peek() == ']' then
done = true
end
if not done then
local ch = self:Next()
if ch ~= ',' then
error(string.format(
"Invalid array: '%s' due to: '%s'",
self:All(), ch))
end
end
end
assert(']' == self:Next())
return result
end
function JsonReader:ReadObject()
local result = {}
assert(self:Next() == '{')
local done = false
if self:Peek() == '}' then
done = true
end
while not done do
local key = self:Read()
if type(key) ~= "string" then
error(string.format(
"Invalid non-string object key: %s",
key))
end
self:SkipWhiteSpace()
local ch = self:Next()
if ch ~= ':' then
error(string.format(
"Invalid object: '%s' due to: '%s'",
self:All(),
ch))
end
self:SkipWhiteSpace()
local val = self:Read()
result[key] = val
self:SkipWhiteSpace()
if self:Peek() == '}' then
done = true
end
if not done then
ch = self:Next()
if ch ~= ',' then
error(string.format(
"Invalid array: '%s' near: '%s'",
self:All(),
ch))
end
end
end
assert(self:Next() == "}")
return result
end
function JsonReader:SkipWhiteSpace()
local p = self:Peek()
while p ~= nil and string.find(p, "[%s/]") do
if p == '/' then
self:ReadComment()
else
self:Next()
end
p = self:Peek()
end
end
function JsonReader:Peek()
return self.reader:Peek()
end
function JsonReader:Next()
return self.reader:Next()
end
function JsonReader:All()
return self.reader:All()
end
function Encode(o)
local writer = JsonWriter:New()
writer:Write(o)
return writer:ToString()
end
function Decode(s)
local reader = JsonReader:New(s)
return reader:Read()
end
function Null()
return Null
end
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