567 lines
12 KiB
Lua
567 lines
12 KiB
Lua
--[[
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LuCI - Lua Configuration Interface
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Copyright 2008 Steven Barth <steven@midlink.org>
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Copyright 2008 Jo-Philipp Wich <xm@leipzig.freifunk.net>
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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$Id$
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Decoder:
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Info:
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null will be decoded to luci.json.null if first parameter of Decoder() is true
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Example:
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decoder = luci.json.Decoder()
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luci.ltn12.pump.all(luci.ltn12.source.string("decodableJSON"), decoder:sink())
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luci.util.dumptable(decoder:get())
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Known issues:
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does not support unicode conversion \uXXYY with XX != 00 will be ignored
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Encoder:
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Info:
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Accepts numbers, strings, nil, booleans as they are
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Accepts luci.json.null as replacement for nil
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Accepts full associative and full numerically indexed tables
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Mixed tables will loose their associative values during conversion
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Iterator functions will be encoded as an array of their return values
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Non-iterator functions will probably corrupt the encoder
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Example:
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encoder = luci.json.Encoder(encodableData)
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luci.ltn12.pump.all(encoder:source(), luci.ltn12.sink.file(io.open("someFile", w)))
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]]--
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local util = require "luci.util"
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local table = require "table"
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local string = require "string"
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local coroutine = require "coroutine"
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local assert = assert
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local tonumber = tonumber
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local tostring = tostring
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local error = error
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local type = type
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local pairs = pairs
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local ipairs = ipairs
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local next = next
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local pcall = pcall
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local getmetatable = getmetatable
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--- LuCI JSON-Library
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-- @cstyle instance
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module "luci.json"
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--- Directly decode a JSON string
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-- @param json JSON-String
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-- @return Lua object
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function decode(json, ...)
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local a = ActiveDecoder(function() return nil end, ...)
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a.chunk = json
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local s, obj = pcall(a.get, a)
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return s and obj or nil
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end
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--- Direcly encode a Lua object into a JSON string.
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-- @param obj Lua Object
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-- @return JSON string
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function encode(obj, ...)
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local out = {}
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local e = Encoder(obj, 1, ...):source()
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local chnk, err
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repeat
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chnk, err = e()
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out[#out+1] = chnk
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until chnk
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return not err and table.concat(out) or nil
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end
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--- Null replacement function
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-- @return null
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function null()
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return null
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end
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--- Create a new JSON-Encoder.
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-- @class function
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-- @name Encoder
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-- @param data Lua-Object to be encoded.
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-- @param buffersize Blocksize of returned data source.
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-- @param fastescape Use non-standard escaping (don't escape control chars)
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-- @return JSON-Encoder
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Encoder = util.class()
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function Encoder.__init__(self, data, buffersize, fastescape)
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self.data = data
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self.buffersize = buffersize or 512
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self.buffer = ""
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self.fastescape = fastescape
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getmetatable(self).__call = Encoder.source
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end
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--- Create an LTN12 source providing the encoded JSON-Data.
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-- @return LTN12 source
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function Encoder.source(self)
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local source = coroutine.create(self.dispatch)
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return function()
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local res, data = coroutine.resume(source, self, self.data, true)
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if res then
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return data
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else
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return nil, data
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end
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end
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end
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function Encoder.dispatch(self, data, start)
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local parser = self.parsers[type(data)]
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parser(self, data)
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if start then
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if #self.buffer > 0 then
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coroutine.yield(self.buffer)
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end
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coroutine.yield()
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end
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end
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function Encoder.put(self, chunk)
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if self.buffersize < 2 then
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corountine.yield(chunk)
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else
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if #self.buffer + #chunk > self.buffersize then
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local written = 0
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local fbuffer = self.buffersize - #self.buffer
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coroutine.yield(self.buffer .. chunk:sub(written + 1, fbuffer))
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written = fbuffer
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while #chunk - written > self.buffersize do
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fbuffer = written + self.buffersize
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coroutine.yield(chunk:sub(written + 1, fbuffer))
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written = fbuffer
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end
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self.buffer = chunk:sub(written + 1)
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else
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self.buffer = self.buffer .. chunk
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end
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end
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end
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function Encoder.parse_nil(self)
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self:put("null")
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end
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function Encoder.parse_bool(self, obj)
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self:put(obj and "true" or "false")
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end
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function Encoder.parse_number(self, obj)
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self:put(tostring(obj))
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end
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function Encoder.parse_string(self, obj)
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if self.fastescape then
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self:put('"' .. obj:gsub('\\', '\\\\'):gsub('"', '\\"') .. '"')
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else
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self:put('"' ..
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obj:gsub('[%c\\"]',
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function(char)
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return '\\u00%02x' % char:byte()
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end
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)
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.. '"')
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end
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end
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function Encoder.parse_iter(self, obj)
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if obj == null then
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return self:put("null")
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end
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if type(obj) == "table" and (#obj == 0 and next(obj)) then
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self:put("{")
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local first = true
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for key, entry in pairs(obj) do
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first = first or self:put(",")
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first = first and false
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self:parse_string(tostring(key))
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self:put(":")
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self:dispatch(entry)
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end
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self:put("}")
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else
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self:put("[")
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local first = true
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if type(obj) == "table" then
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for i=1, #obj do
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first = first or self:put(",")
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first = first and nil
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self:dispatch(obj[i])
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end
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else
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for entry in obj do
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first = first or self:put(",")
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first = first and nil
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self:dispatch(entry)
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end
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end
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self:put("]")
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end
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end
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Encoder.parsers = {
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['nil'] = Encoder.parse_nil,
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['table'] = Encoder.parse_iter,
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['number'] = Encoder.parse_number,
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['string'] = Encoder.parse_string,
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['boolean'] = Encoder.parse_bool,
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['function'] = Encoder.parse_iter
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}
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--- Create a new JSON-Decoder.
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-- @class function
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-- @name Decoder
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-- @param customnull Use luci.json.null instead of nil for decoding null
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-- @return JSON-Decoder
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Decoder = util.class()
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function Decoder.__init__(self, customnull)
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self.cnull = customnull
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getmetatable(self).__call = Decoder.sink
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end
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--- Create an LTN12 sink from the decoder object which accepts the JSON-Data.
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-- @return LTN12 sink
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function Decoder.sink(self)
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local sink = coroutine.create(self.dispatch)
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return function(...)
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return coroutine.resume(sink, self, ...)
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end
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end
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--- Get the decoded data packets after the rawdata has been sent to the sink.
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-- @return Decoded data
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function Decoder.get(self)
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return self.data
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end
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function Decoder.dispatch(self, chunk, src_err, strict)
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local robject, object
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local oset = false
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while chunk do
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while chunk and #chunk < 1 do
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chunk = self:fetch()
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end
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assert(not strict or chunk, "Unexpected EOS")
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if not chunk then break end
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local char = chunk:sub(1, 1)
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local parser = self.parsers[char]
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or (char:match("%s") and self.parse_space)
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or (char:match("[0-9-]") and self.parse_number)
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or error("Unexpected char '%s'" % char)
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chunk, robject = parser(self, chunk)
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if parser ~= self.parse_space then
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assert(not oset, "Scope violation: Too many objects")
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object = robject
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oset = true
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if strict then
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return chunk, object
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end
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end
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end
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assert(not src_err, src_err)
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assert(oset, "Unexpected EOS")
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self.data = object
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end
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function Decoder.fetch(self)
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local tself, chunk, src_err = coroutine.yield()
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assert(chunk or not src_err, src_err)
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return chunk
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end
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function Decoder.fetch_atleast(self, chunk, bytes)
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while #chunk < bytes do
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local nchunk = self:fetch()
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assert(nchunk, "Unexpected EOS")
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chunk = chunk .. nchunk
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end
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return chunk
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end
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function Decoder.fetch_until(self, chunk, pattern)
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local start = chunk:find(pattern)
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while not start do
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local nchunk = self:fetch()
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assert(nchunk, "Unexpected EOS")
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chunk = chunk .. nchunk
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start = chunk:find(pattern)
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end
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return chunk, start
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end
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function Decoder.parse_space(self, chunk)
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local start = chunk:find("[^%s]")
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while not start do
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chunk = self:fetch()
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if not chunk then
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return nil
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end
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start = chunk:find("[^%s]")
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end
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return chunk:sub(start)
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end
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function Decoder.parse_literal(self, chunk, literal, value)
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chunk = self:fetch_atleast(chunk, #literal)
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assert(chunk:sub(1, #literal) == literal, "Invalid character sequence")
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return chunk:sub(#literal + 1), value
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end
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function Decoder.parse_null(self, chunk)
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return self:parse_literal(chunk, "null", self.cnull and null)
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end
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function Decoder.parse_true(self, chunk)
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return self:parse_literal(chunk, "true", true)
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end
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function Decoder.parse_false(self, chunk)
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return self:parse_literal(chunk, "false", false)
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end
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function Decoder.parse_number(self, chunk)
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local chunk, start = self:fetch_until(chunk, "[^0-9eE.+-]")
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local number = tonumber(chunk:sub(1, start - 1))
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assert(number, "Invalid number specification")
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return chunk:sub(start), number
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end
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function Decoder.parse_string(self, chunk)
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local str = ""
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local object = nil
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assert(chunk:sub(1, 1) == '"', 'Expected "')
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chunk = chunk:sub(2)
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while true do
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local spos = chunk:find('[\\"]')
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if spos then
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str = str .. chunk:sub(1, spos - 1)
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local char = chunk:sub(spos, spos)
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if char == '"' then -- String end
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chunk = chunk:sub(spos + 1)
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break
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elseif char == "\\" then -- Escape sequence
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chunk, object = self:parse_escape(chunk:sub(spos))
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str = str .. object
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end
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else
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str = str .. chunk
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chunk = self:fetch()
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assert(chunk, "Unexpected EOS while parsing a string")
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end
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end
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return chunk, str
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end
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function Decoder.parse_escape(self, chunk)
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local str = ""
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chunk = self:fetch_atleast(chunk:sub(2), 1)
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local char = chunk:sub(1, 1)
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chunk = chunk:sub(2)
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if char == '"' then
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return chunk, '"'
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elseif char == "\\" then
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return chunk, "\\"
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elseif char == "u" then
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chunk = self:fetch_atleast(chunk, 4)
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local s1, s2 = chunk:sub(1, 2), chunk:sub(3, 4)
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s1, s2 = tonumber(s1, 16), tonumber(s2, 16)
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assert(s1 and s2, "Invalid Unicode character")
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-- ToDo: Unicode support
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return chunk:sub(5), s1 == 0 and string.char(s2) or ""
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elseif char == "/" then
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return chunk, "/"
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elseif char == "b" then
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return chunk, "\b"
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elseif char == "f" then
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return chunk, "\f"
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elseif char == "n" then
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return chunk, "\n"
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elseif char == "r" then
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return chunk, "\r"
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elseif char == "t" then
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return chunk, "\t"
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else
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error("Unexpected escaping sequence '\\%s'" % char)
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end
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end
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function Decoder.parse_array(self, chunk)
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chunk = chunk:sub(2)
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local array = {}
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local nextp = 1
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local chunk, object = self:parse_delimiter(chunk, "%]")
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if object then
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return chunk, array
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end
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repeat
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chunk, object = self:dispatch(chunk, nil, true)
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table.insert(array, nextp, object)
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nextp = nextp + 1
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chunk, object = self:parse_delimiter(chunk, ",%]")
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assert(object, "Delimiter expected")
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until object == "]"
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return chunk, array
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end
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function Decoder.parse_object(self, chunk)
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chunk = chunk:sub(2)
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local array = {}
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local name
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local chunk, object = self:parse_delimiter(chunk, "}")
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if object then
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return chunk, array
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end
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repeat
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chunk = self:parse_space(chunk)
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assert(chunk, "Unexpected EOS")
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chunk, name = self:parse_string(chunk)
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chunk, object = self:parse_delimiter(chunk, ":")
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assert(object, "Separator expected")
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chunk, object = self:dispatch(chunk, nil, true)
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array[name] = object
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chunk, object = self:parse_delimiter(chunk, ",}")
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assert(object, "Delimiter expected")
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until object == "}"
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return chunk, array
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end
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function Decoder.parse_delimiter(self, chunk, delimiter)
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while true do
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chunk = self:fetch_atleast(chunk, 1)
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local char = chunk:sub(1, 1)
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if char:match("%s") then
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chunk = self:parse_space(chunk)
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assert(chunk, "Unexpected EOS")
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elseif char:match("[%s]" % delimiter) then
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return chunk:sub(2), char
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else
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return chunk, nil
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end
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end
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end
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Decoder.parsers = {
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['"'] = Decoder.parse_string,
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['t'] = Decoder.parse_true,
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['f'] = Decoder.parse_false,
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['n'] = Decoder.parse_null,
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['['] = Decoder.parse_array,
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['{'] = Decoder.parse_object
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}
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--- Create a new Active JSON-Decoder.
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-- @class function
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-- @name ActiveDecoder
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-- @param customnull Use luci.json.null instead of nil for decoding null
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-- @return Active JSON-Decoder
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ActiveDecoder = util.class(Decoder)
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function ActiveDecoder.__init__(self, source, customnull)
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Decoder.__init__(self, customnull)
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self.source = source
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self.chunk = nil
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getmetatable(self).__call = self.get
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end
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--- Fetches one JSON-object from given source
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-- @return Decoded object
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function ActiveDecoder.get(self)
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local chunk, src_err, object
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if not self.chunk then
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chunk, src_err = self.source()
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else
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chunk = self.chunk
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end
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self.chunk, object = self:dispatch(chunk, src_err, true)
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return object
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end
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function ActiveDecoder.fetch(self)
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local chunk, src_err = self.source()
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assert(chunk or not src_err, src_err)
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return chunk
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end
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