------------------------------------------------------------------------ -- David Kolf's JSON module for Lua 5.1 -- Version 1.0 -- -- This module writes no global values of itself, not even the module -- table. Import it using -- json = require ("dkjson") -- -- Exported functions and values: -- json.null -- You can use this value for setting explicit 'null' values. -- -- json.encode (object [, state]) -- Create a string representing the object. 'Object' can be a table, -- a string, a number, a boolean, nil, json.null or any object with -- a function __tojson in its metatable. A table can only use strings -- and numbers as keys and its values have to be valid objects as -- well. It will return an error message for any invalid data types or -- reference cycles. -- -- 'state' is an optional table with the following fields: -- - indent -- When 'indent' (a boolean) is set, the created string will contain -- newlines and indentations. Otherwise it will be one long line. -- - level -- This is the level of indentation used when 'indent' is set. For -- each level two spaces are added. When absent it is set to 0. -- - buffer -- 'buffer' is an array to store the strings for the result so they -- can be concatenated at once. When it isn't given, the encode -- function will create it temporary and will return the -- concatenated result. -- - bufferlen -- When 'bufferlen' is set, it has to be the index of the last -- element of 'buffer'. -- - tables -- 'tables' is a set to detect reference cycles. It is created -- temporary when absent. Every table that is currently processed -- is used as key, the value is 'true'. -- -- When state.buffer was set, the return value will be true on -- success. Without state.buffer the return value will be a string. -- In case of errors nil and an error message will be returned. -- -- json.decode (string [, position [, null]]) -- Decode 'string' starting at 'position' or at 1 if 'position' was -- omitted. -- -- 'null' is an optional value to be returned for null values. The -- default is 'nil', but you could set it to json.null or any other -- value. -- -- The return values are the object or nil, the position of the next -- character that doesn't belong to the object, and in case of errors -- an error message. -- -- .__tojson (self, state) -- You can provide your own __tojson function in a metatable. In this -- function you can either add directly to the buffer and return true, -- or you can return a string. On errors nil and a message should be -- returned. -- -- json.quotestring (string) -- Quote a UTF-8 string and escape critical characters using JSON -- escape sequences. This function is only necessary when you build -- your own __tojson functions. -- -- json.addnewline (state) -- When state.indent is set, add a newline to state.buffer and spaces -- according to state.level. When state.indent isn't set, only a -- single space is added. -- -- You can contact the author by sending an e-mail to 'kolf' at the -- e-mail provider 'gmx.de'. -- -- Copyright (C) 2010 David Heiko Kolf -- -- Permission is hereby granted, free of charge, to any person obtaining -- a copy of this software and associated documentation files (the -- "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. -- -- 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. -- global dependencies: local pairs, type, tostring, tonumber, getmetatable, setmetatable = pairs, type, tostring, tonumber, getmetatable, setmetatable local floor = math.floor local strrep, gsub, strsub, strbyte, strchar, strfind, strlen, strformat = string.rep, string.gsub, string.sub, string.byte, string.char, string.find, string.len, string.format local concat = table.concat if _VERSION == "Lua 5.2" then _ENV = nil end local json = {} json.null = setmetatable ({}, {__tojson = function () return "null" end}) local function isarray (tbl) local max, n = 0, 0 for k,v in pairs (tbl) do if k == "n" then if v ~= #tbl then return false end else if type(k) ~= "number" or k < 1 or floor(k) ~= k then return false end if k > max then max = k end n = n + 1 end end if max > 10 and max > n * 2 then return false -- don't create an array with too many holes end return true, max end local escapecodes = { ["\""] = "\\\"", ["\\"] = "\\\\", ["\b"] = "\\b", ["\f"] = "\\f", ["\n"] = "\\n", ["\r"] = "\\r", ["\t"] = "\\t" } local function escapeutf8 (uchar) local value = escapecodes[uchar] if value then return value end local a, b, c, d = strbyte (uchar, 1, 4) a, b, c, d = a or 0, b or 0, c or 0, d or 0 if a <= 0x7f then value = a elseif 0xc0 <= a and a <= 0xdf and b >= 0x80 then value = (a - 0xc0) * 0x40 + b - 0x80 elseif 0xe0 <= a and a <= 0xef and b >= 0x80 and c >= 0x80 then value = ((a - 0xe0) * 0x40 + b - 0x80) * 0x40 + c - 0x80 elseif 0xf0 <= a and a <= 0xf7 and b >= 0x80 and c >= 0x80 and d >= 0x80 then value = (((a - 0xf0) * 0x40 + b - 0x80) * 0x40 + c - 0x80) * 0x40 + d - 0x80 else return "" end if value <= 0xffff then return strformat ("\\u%.4x", value) elseif value <= 0x10ffff then -- encode as UTF-16 surrogate pair value = value - 0x10000 local highsur, lowsur = 0xD800 + floor (value/0x400), 0xDC00 + (value % 0x400) return strformat ("\\u%.4x\\u%.4x", highsur, lowsur) else return "" end end local function fsub (str, pattern, repl) -- gsub always builds a new string in a buffer, even when no match -- exists. First using find should be more efficient when most strings -- don't contain the pattern. if strfind (str, pattern) then return gsub (str, pattern, repl) else return str end end local function quotestring (value) -- based on the regexp "escapable" in http://www.json.org/json2.js value = fsub (value, "[%z\1-\31\"\\\127]", escapeutf8) if strfind (value, "[\194\216\220\225\226\239]") then value = fsub (value, "\194[\128-\159\173]", escapeutf8) value = fsub (value, "\216[\128-\132]", escapeutf8) value = fsub (value, "\220\143", escapeutf8) value = fsub (value, "\225\158[\180\181]", escapeutf8) value = fsub (value, "\226\128[\140-\143\168\175]", escapeutf8) value = fsub (value, "\226\129[\160-\175]", escapeutf8) value = fsub (value, "\239\187\191", escapeutf8) value = fsub (value, "\239\191[\190\191]", escapeutf8) end return "\"" .. value .. "\"" end json.quotestring = quotestring local function addnewline2 (indent, level, buffer, buflen) if indent then buffer[buflen+1] = "\n" buffer[buflen+2] = strrep (" ", level) buflen = buflen + 2 return buflen else buflen = buflen + 1 buffer[buflen] = " " return buflen end end function json.addnewline (state) state.bufferlen = addnewline2 (state.indent, state.level or 0, state.buffer, state.bufferlen or #(state.buffer)) end local function encode2 (value, indent, level, buffer, buflen, tables) local valtype = type (value) local valmeta = getmetatable (value) local valtojson = type (valmeta) == "table" and valmeta.__tojson if valtojson then if tables[value] then return nil, "reference cycle" end tables[value] = true local state = { indent = indent, level = level, buffer = buffer, bufferlen = buflen, tables = tables } local ret, msg = valtojson (value, state) if not ret then return nil, msg end tables[value] = nil buflen = state.bufferlen if type (ret) == "string" then buflen = buflen + 1 buffer[buflen] = ret end elseif value == nil then buflen = buflen + 1 buffer[buflen] = "null" elseif valtype == "number" or valtype == "boolean" then buflen = buflen + 1 buffer[buflen] = tostring (value) elseif valtype == "string" then buflen = buflen + 1 buffer[buflen] = quotestring (value) elseif valtype == "table" then if tables[value] then return nil, "reference cycle" end tables[value] = true level = level + 1 local isa, n = isarray (value) local msg if isa then -- JSON array buflen = buflen + 1 buffer[buflen] = "[ " for i = 1, n do buflen, msg = encode2 (value[i], indent, level, buffer, buflen, tables) if not buflen then return nil, msg end if i < n then buflen = buflen + 1 buffer[buflen] = ", " end end buflen = buflen + 1 buffer[buflen] = " ]" else -- JSON object local prev = false buflen = buflen + 1 buffer[buflen] = "{" for k,v in pairs (value) do local kt = type (k) if kt ~= "string" and kt ~= "number" then return nil, "type '" .. kt .. "' is not supported as a key by JSON." end if prev then buflen = buflen + 1 buffer[buflen] = "," end buflen = addnewline2 (indent, level, buffer, buflen) buffer[buflen+1] = quotestring (k) buffer[buflen+2] = ": " buflen = buflen + 2 buflen, msg = encode2 (v, indent, level, buffer, buflen, tables) if not buflen then return nil, msg end prev = true -- add a seperator before the next element end buflen = addnewline2 (indent, level - 1, buffer, buflen) buflen = buflen + 1 buffer[buflen] = "}" end tables[value] = nil else return nil, "type '" .. valtype .. "' is not supported by JSON." end return buflen end function json.encode (value, state) state = state or {} local oldbuffer = state.buffer local buffer = oldbuffer or {} local ret, msg = encode2 (value, state.indent, state.level or 0, buffer, state.bufferlen or 0, state.tables or {}) if not ret then return nil, msg elseif oldbuffer then state.bufferlen = ret return true else return concat (buffer) end end local function loc (str, where) local line, pos, linepos = 1, 1, 1 while true do pos = strfind (str, "\n", pos, true) if pos and pos < where then line = line + 1 linepos = pos pos = pos + 1 else break end end return "line " .. line .. ", column " .. (where - linepos) end local function unterminated (str, what, where) return nil, strlen (str) + 1, "unterminated " .. what .. " at " .. loc (str, where) end local function scanwhite (str, pos) while true do pos = strfind (str, "%S", pos) if not pos then return nil end if strsub (str, pos, pos + 2) == "\239\187\191" then -- UTF-8 Byte Order Mark pos = pos + 3 else return pos end end end local escapechars = { ["b"] = "\b", ["f"] = "\f", ["n"] = "\n", ["r"] = "\r", ["t"] = "\t" } local function unichar (value) if value < 0 then return nil elseif value <= 0x007f then return strchar (value) elseif value <= 0x07ff then return strchar (0xc0 + floor(value/0x40), 0x80 + (floor(value) % 0x40)) elseif value <= 0xffff then return strchar (0xe0 + floor(value/0x1000), 0x80 + (floor(value/0x40) % 0x40), 0x80 + (floor(value) % 0x40)) elseif value <= 0x10ffff then return strchar (0xf0 + floor(value/0x40000), 0x80 + (floor(value/0x1000) % 0x40), 0x80 + (floor(value/0x40) % 0x40), 0x80 + (floor(value) % 0x40)) else return nil end end local function scanstring (str, pos) local lastpos = pos + 1 local buffer, n = {}, 0 while true do local nextpos = strfind (str, "[\"\\]", lastpos) if not nextpos then return unterminated (str, "string", pos) end if nextpos > lastpos then n = n + 1 buffer[n] = strsub (str, lastpos, nextpos - 1) end if strsub (str, nextpos, nextpos) == "\"" then lastpos = nextpos + 1 break else local escchar = strsub (str, nextpos + 1, nextpos + 1) local value if escchar == "u" then value = tonumber (strsub (str, nextpos + 2, nextpos + 5), 16) if value then local value2 if 0xD800 <= value and value <= 0xDBff then -- we have the high surrogate of UTF-16. Check if there is a -- low surrogate escaped nearby to combine them. if strsub (str, nextpos + 6, nextpos + 7) == "\\u" then value2 = tonumber (strsub (str, nextpos + 8, nextpos + 11), 16) if value2 and 0xDC00 <= value2 and value2 <= 0xDFFF then value = (value - 0xD800) * 0x400 + (value2 - 0xDC00) + 0x10000 else value2 = nil -- in case it was out of range for a low surogate end end end value = value and unichar (value) if value then if value2 then lastpos = nextpos + 12 else lastpos = nextpos + 6 end end end end if not value then value = escapechars[escchar] or escchar lastpos = nextpos + 2 end n = n + 1 buffer[n] = value end end if n == 1 then return buffer[1], lastpos elseif n > 1 then return concat (buffer), lastpos else return "", lastpos end end local scanvalue -- forward declaration local function scantable (what, closechar, str, startpos, nullval) local len = strlen (str) local tbl, n = {}, 0 local pos = startpos + 1 while true do pos = scanwhite (str, pos) if not pos then return unterminated (str, what, startpos) end local char = strsub (str, pos, pos) if char == closechar then return tbl, pos + 1 end local val1, err val1, pos, err = scanvalue (str, pos, nullval) if err then return nil, pos, err end pos = scanwhite (str, pos) if not pos then return unterminated (str, what, startpos) end char = strsub (str, pos, pos) if char == ":" then if val1 == nil then return nil, pos, "cannot use nil as table index (at " .. loc (str, pos) .. ")" end pos = scanwhite (str, pos + 1) if not pos then return unterminated (str, what, startpos) end local val2 val2, pos, err = scanvalue (str, pos, nullval) if err then return nil, pos, err end tbl[val1] = val2 pos = scanwhite (str, pos) if not pos then return unterminated (str, what, startpos) end char = strsub (str, pos, pos) else n = n + 1 tbl[n] = val1 end if char == "," then pos = pos + 1 end end end scanvalue = function (str, pos, nullval) pos = pos or 1 pos = scanwhite (str, pos) if not pos then return nil, strlen (str) + 1, "no valid JSON value (reached the end)" end local char = strsub (str, pos, pos) if char == "{" then return scantable ("object", "}", str, pos, nullval) elseif char == "[" then return scantable ("array", "]", str, pos, nullval) elseif char == "\"" then return scanstring (str, pos) else local pstart, pend = strfind (str, "^%-?[%d%.]+[eE]?[%+%-]?%d*%W", pos) if pstart then local number = tonumber (strsub (str, pstart, pend - 1)) if number then return number, pend end end pstart, pend = strfind (str, "^%a%w*", pos) if pstart then local name = strsub (str, pstart, pend) if name == "true" then return true, pend + 1 elseif name == "false" then return false, pend + 1 elseif name == "null" then return nullval, pend + 1 end end return nil, pos, "no valid JSON value at " .. loc (str, pos) end end json.decode = scanvalue return json