Module:JSON

-- -- Copyright 2010-2012 Jeffrey Friedl -- http://regex.info/blog/ -- local VERSION = 20111207.5 --

-- -- Simple JSON encoding and decoding in pure Lua. -- http://www.json.org/ -- -- --  JSON = (loadfile "JSON.lua") -- one-time load of the routines -- --  local lua_value = JSON:decode(raw_json_text) -- --

-- --  local lua_value = JSON:decode(raw_json_text) -- --  If the JSON text is for an object or an --     [ "Larry", "Curly", "Moe" ] -- --  the result is a Lua table, e.g. --     = 3 } --  or --     { -- -- --  The encode and decode routines accept an optional second argument, "etc", which is not used --  during encoding or decoding, but upon error is passed along to error handlers. It can be of any --  type (including nil). -- --  With most errors during decoding, this code calls -- --     JSON:onDecodeError(message, text, location, etc) -- --  with a message about the error, and if known, the JSON text being parsed and the byte count --  where the problem was discovered. You can rep --  The default onDecodeError merely augments the message with data about the text and the --  location if known (and if a second 'etc' argument had been provided to decode, its value is --   tacked onto the message as well), and then calls JSON.assert, which itself defaults to Lua's --   built-in assert, and can also be overridden. -- --  For example, in an Adobe Lightroom plugin, you might use something like -- --        --            -- --   or even just -- --         function JSON.assert(message) --            LrErrors.throwUserError("Internal Error: " .. message) --         end --     JSON:onD nil, etc) -- --   and if JSON:decode is passed HTML instead of JSON, this lled: -- --      -- --   The use of the fourth 'etc' argument allows stronger coordination between decoding and error --   reporting, especially when you prov error-handling routines. Continuing with the --   the -- --          function JSON:onDecodeError(message, text, location, etc) --             local note = "Internal Error: invalid JSON data" --             if type(etc) = 'table' and etc.photo then --                note = nophoto:getFormattedMetadata('fileName') --             end --             LrErrors.throwUserError(note) --          end -- --            : --            : -- --   --               :             --               :             --   --               :             --               :     -- -- --

-- DECODING AND STRICT TYPES -- --  Because both JSON objects and JSON arrays are converted to Lua tables, it's not normally --  possible to tell which a Lua table came from, or guarantee decode-encode round-trip --  equivalency. -- --  However, if you enable strictTypes, e.g. -- --     JSON = (loadfile "JSON.lua") --load the routines --     JSON.strictTypes = true -- --  then the Lua table resulting from the decoding of a JSON object or JSON array is marked via Lua --  metatable, so that when re-encoded with JSON:encode it ends up as the appropriate JSON type. -- --  (This is not the default because other routines may not work well with tables that have a --   metatable set, for example, Lightroom API calls.) -- -- -- ENCODING -- --  JSON = (loadfile "JSON.lua") -- one-time load of the routines -- --  local raw_json_text    = JSON:encode(lua_table_or_value) --  local pretty_json_text = JSON:encode_pretty(lua_table_or_value) -- "pretty printed" version for human readability

--  On error during encoding, this code calls: -- --   JSON:onEncodeError(message, etc) -- --  which you can override in your local JSON object. -- -- -- SUMMARY OF METHODS YOU CAN OVERRIDE IN YOUR LOCAL LUA JSON OBJECT -- --   assert --   onDecodeError --   onDecodeOfNilError --   onDecodeOfHTMLError --   onEncodeError -- -- If you want to create a separate Lua JSON object with its own error handlers, -- you can reload JSON.lua or use the :new method. -- ---

local author = "-[ JSON.lua package by Jeffrey Friedl (http://regex.info/blog/lua/json), version " .. tostring(VERSION) .. " ]-" local isArray = { __tostring = function return "JSON array"  end }    isArray.__index  = isArray local isObject = { __tostring = function return "JSON object" end }   isObject.__index = isObject

function OBJDEF:newArray(tbl) return setmetatable(tbl or {}, isArray) end

function OBJDEF:newObject(tbl) return setmetatable(tbl or {}, isObject) end

local function unicode_codepoint_as_utf8(codepoint) --  -- codepoint is a number --  if codepoint <= 127 then return string.char(codepoint)

elseif codepoint <= 2047 then --     -- 110yyyxx 10xxxxxx         <-- useful notation from http://en.wikipedia.org/wiki/Utf8 --     local highpart = math.floor(codepoint / 0x40) local lowpart = codepoint - (0x40 * highpart) return string.char(0xC0 + highpart,                        0x80 + lowpart)

elseif codepoint <= 65535 then --     -- 1110yyyy 10yyyyxx 10xxxxxx --     local highpart  = math.floor(codepoint / 0x1000) local remainder = codepoint - 0x1000 * highpart local midpart  = math.floor(remainder / 0x40) local lowpart  = remainder - 0x40 * midpart

highpart = 0xE0 + highpart midpart = 0x80 + midpart lowpart = 0x80 + lowpart

--     -- Check for an invalid character (thanks Andy R. at Adobe). -- See table 3.7, page 93, in http://www.unicode.org/versions/Unicode5.2.0/ch03.pdf#G28070 --     if ( highpart == 0xE0 and midpart < 0xA0 ) or         ( highpart == 0xED and midpart > 0x9F ) or         ( highpart == 0xF0 and midpart < 0x90 ) or         ( highpart == 0xF4 and midpart > 0x8F ) then return "?" else return string.char(highpart,                           midpart,                            lowpart) end

else --     -- 11110zzz 10zzyyyy 10yyyyxx 10xxxxxx --     local highpart  = math.floor(codepoint / 0x40000) local remainder = codepoint - 0x40000 * highpart local midA     = math.floor(remainder / 0x1000) remainder      = remainder - 0x1000 * midA local midB     = math.floor(remainder / 0x40) local lowpart  = remainder - 0x40 * midB

return string.char(0xF0 + highpart,                        0x80 + midA,                         0x80 + midB,                         0x80 + lowpart) end end

function OBJDEF:onDecodeError(message, text, location, etc) if text then if location then message = string.format("%s at char %d of: %s", message, location, text) else message = string.format("%s: %s", message, text) end end if etc ~= nil then message = message .. " (" .. OBJDEF:encode(etc) .. ")" end

if self.assert then self.assert(false, message) else assert(false, message) end end

OBJDEF.onDecodeOfNilError = OBJDEF.onDecodeError OBJDEF.onDecodeOfHTMLError = OBJDEF.onDecodeError

function OBJDEF:onEncodeError(message, etc) if etc ~= nil then message = message .. " (" .. OBJDEF:encode(etc) .. ")" end

if self.assert then self.assert(false, message) else assert(false, message) end end

local function grok_number(self, text, start, etc) --  -- Grab the integer part --  local integer_part = text:match('^-?[1-9]%d*', start) or text:match("^-?0",       start)

if not integer_part then self:onDecodeError("expected number", text, start, etc) end

local i = start + integer_part:len

--  -- Grab an optional decimal part --  local decimal_part = text:match('^%.%d+', i) or ""

i = i + decimal_part:len

--  -- Grab an optional exponential part --  local exponent_part = text:match('^[eE][-+]?%d+', i) or ""

i = i + exponent_part:len

local full_number_text = integer_part .. decimal_part .. exponent_part local as_number = tonumber(full_number_text)

if not as_number then self:onDecodeError("bad number", text, start, etc) end

return as_number, i end

local function grok_string(self, text, start, etc)

if text:sub(start,start) ~= '"' then     self:onDecodeError("expected string's opening quote", text, start, etc)   end

local i = start + 1 -- +1 to bypass the initial quote local text_len = text:len local VALUE = "" while i <= text_len do     local c = text:sub(i,i) if c == '"' then        return VALUE, i + 1      end      if c ~= '\\' then         VALUE = VALUE .. c         i = i + 1      elseif text:match('^\\b', i) then         VALUE = VALUE .. "\b"         i = i + 2      elseif text:match('^\\f', i) then         VALUE = VALUE .. "\f"         i = i + 2      elseif text:match('^\\n', i) then         VALUE = VALUE .. "\n"         i = i + 2      elseif text:match('^\\r', i) then         VALUE = VALUE .. "\r"         i = i + 2      elseif text:match('^\\t', i) then         VALUE = VALUE .. "\t"         i = i + 2      else         local hex = text:match('^\\u([0123456789aAbBcCdDeEfF][0123456789aAbBcCdDeEfF][0123456789aAbBcCdDeEfF][0123456789aAbBcCdDeEfF])', i)         if hex then            i = i + 6 -- bypass what we just read

-- We have a Unicode codepoint. It could be standalone, or if in the proper range and -- followed by another in a specific range, it'll be a two-code surrogate pair. local codepoint = tonumber(hex, 16) if codepoint >= 0xD800 and codepoint <= 0xDBFF then -- it's a hi surrogate... see whether we have a following low local lo_surrogate = text:match('^\\u([dD][cdefCDEF][0123456789aAbBcCdDeEfF][0123456789aAbBcCdDeEfF])', i)              if lo_surrogate then i = i + 6 -- bypass the low surrogate we just read codepoint = 0x2400 + (codepoint - 0xD800) * 0x400 + tonumber(lo_surrogate, 16) else -- not a proper low, so we'll just leave the first codepoint as is and spit it out. end end VALUE = VALUE .. unicode_codepoint_as_utf8(codepoint)

else

-- just pass through what's escaped VALUE = VALUE .. text:match('^\\(.)', i)           i = i + 2 end end end

self:onDecodeError("unclosed string", text, start, etc) end

local function skip_whitespace(text, start)

local match_start, match_end = text:find("^[ \n\r\t]+", start) -- Section 2 if match_end then return match_end + 1 else return start end end

local grok_one -- assigned later

local function grok_object(self, text, start, etc) if not text:sub(start,start) == '{' then self:onDecodeError("expected '{'", text, start, etc) end

local i = skip_whitespace(text, start + 1) -- +1 to skip the '{'

local VALUE = self.strictTypes and self:newObject { } or { }

if text:sub(i,i) == '}' then return VALUE, i + 1 end local text_len = text:len while i <= text_len do     local key, new_i = grok_string(self, text, i, etc)

i = skip_whitespace(text, new_i)

if text:sub(i, i) ~= ':' then self:onDecodeError("expected colon", text, i, etc) end

i = skip_whitespace(text, i + 1)

local val, new_i = grok_one(self, text, i)

VALUE[key] = val

--     -- Expect now either '}' to end things, or a ',' to allow us to continue. --     i = skip_whitespace(text, new_i)

local c = text:sub(i,i)

if c == '}' then return VALUE, i + 1 end

if text:sub(i, i) ~= ',' then self:onDecodeError("expected comma or '}'", text, i, etc) end

i = skip_whitespace(text, i + 1) end

self:onDecodeError("unclosed '{'", text, start, etc) end

local function grok_array(self, text, start, etc) if not text:sub(start,start) == '[' then self:onDecodeError("expected '['", text, start, etc) end

local i = skip_whitespace(text, start + 1) -- +1 to skip the '[' local VALUE = self.strictTypes and self:newArray { } or { } if text:sub(i,i) == ']' then return VALUE, i + 1 end

local text_len = text:len while i <= text_len do     local val, new_i = grok_one(self, text, i)

table.insert(VALUE, val)

i = skip_whitespace(text, new_i)

--     -- Expect now either ']' to end things, or a ',' to allow us to continue. --     local c = text:sub(i,i) if c == ']' then return VALUE, i + 1 end if text:sub(i, i) ~= ',' then self:onDecodeError("expected comma or '['", text, i, etc) end i = skip_whitespace(text, i + 1) end self:onDecodeError("unclosed '['", text, start, etc) end

grok_one = function(self, text, start, etc) -- Skip any whitespace start = skip_whitespace(text, start)

if start > text:len then self:onDecodeError("unexpected end of string", text, nil, etc) end

if text:find('^"', start) then     return grok_string(self, text, start, etc)

elseif text:find('^[-0123456789 ]', start) then return grok_number(self, text, start, etc)

elseif text:find('^%{', start) then return grok_object(self, text, start, etc)

elseif text:find('^%[', start) then return grok_array(self, text, start, etc)

elseif text:find('^true', start) then return true, start + 4

elseif text:find('^false', start) then return false, start + 5

elseif text:find('^null', start) then return nil, start + 4

else self:onDecodeError("can't parse JSON", text, start, etc) end end

function OBJDEF:decode(text, etc) if type(self) ~= 'table' or self.__index ~= OBJDEF then OBJDEF:onDecodeError("JSON:decode must be called in method format", nil, nil, etc) end

if text == nil then self:onDecodeOfNilError(string.format("nil passed to JSON:decode"), nil, nil, etc) elseif type(text) ~= 'string' then self:onDecodeError(string.format("expected string argument to JSON:decode, got %s", type(text)), nil, nil, etc) end

if text:match('^%s*$') then return nil end

if text:match('^%s*<') then -- Can't be JSON... we'll assume it's HTML self:onDecodeOfHTMLError(string.format("html passed to JSON:decode"), text, nil, etc) end

--  -- Ensure that it's not UTF-32 or UTF-16. -- Those are perfectly valid encodings for JSON (as per RFC 4627 section 3), -- but this package can't handle them. --  if text:sub(1,1):byte == 0 or (text:len >= 2 and text:sub(2,2):byte == 0) then self:onDecodeError("JSON package groks only UTF-8, sorry", text, nil, etc) end

local success, value = pcall(grok_one, self, text, 1, etc) if success then return value else -- should never get here... JSON parse errors should have been caught earlier assert(false, value) return nil end end

local function backslash_replacement_function(c) if c == "\n" then return "\\n" elseif c == "\r" then return "\\r" elseif c == "\t" then return "\\t" elseif c == "\b" then return "\\b" elseif c == "\f" then return "\\f" elseif c == '"' then     return '\\"' elseif c == '\\' then return '\\\\' else return string.format("\\u%04x", c:byte) end end

local chars_to_be_escaped_in_JSON_string = '['  ..    '"'    -- class sub-pattern to match a double quote   ..    '%\\'  -- class sub-pattern to match a backslash   ..    '%z'   -- class sub-pattern to match a null   ..    '\001' .. '-' .. '\031' -- class sub-pattern to match control characters   .. ']'

local function json_string_literal(value) local newval = value:gsub(chars_to_be_escaped_in_JSON_string, backslash_replacement_function) return '"' .. newval .. '"' end

local function object_or_array(self, T, etc) --  -- We need to inspect all the keys... if there are any strings, we'll convert to a JSON -- object. If there are only numbers, it's a JSON array. --  -- If we'll be converting to a JSON object, we'll want to sort the keys so that the -- end result is deterministic. --  local string_keys = { } local seen_number_key = false local maximum_number_key

for key in pairs(T) do     if type(key) == 'number' then seen_number_key = true if not maximum_number_key or maximum_number_key < key then maximum_number_key = key end elseif type(key) == 'string' then table.insert(string_keys, key) else self:onEncodeError("can't encode table with a key of type " .. type(key), etc) end end

if seen_number_key and #string_keys > 0 then --     -- Mixed key types... don't know what to do, so bail --     self:onEncodeError("a table with both numeric and string keys could be an object or array; aborting", etc)

elseif #string_keys == 0 then --     -- An array --     if seen_number_key then return nil, maximum_number_key -- an array else --        -- An empty table... --        if tostring(T) == "JSON array" then return nil elseif tostring(T) == "JSON object" then return { } else -- have to guess, so we'll pick array, since empty arrays are likely more common than empty objects return nil end end else --     -- An object, so return a list of keys --     table.sort(string_keys) return string_keys end end

-- -- Encode -- local encode_value -- must predeclare because it calls itself function encode_value(self, value, parents, etc)

if value == nil then return 'null' end

if type(value) == 'string' then return json_string_literal(value) elseif type(value) == 'number' then if value ~= value then --        -- NaN (Not a Number). -- JSON has no NaN, so we have to fudge the best we can. This should really be a package option. --        return "null" elseif value >= math.huge then --        -- Positive infinity. JSON has no INF, so we have to fudge the best we can. This should -- really be a package option. Note: at least with some implementations, positive infinity -- is both ">= math.huge" and "<= -math.huge", which makes no sense but that's how it is. -- Negative infinity is properly "<= -math.huge". So, we must be sure to check the ">=" -- case first. --        return "1e+9999" elseif value <= -math.huge then --        -- Negative infinity. -- JSON has no INF, so we have to fudge the best we can. This should really be a package option. --        return "-1e+9999" else return tostring(value) end elseif type(value) == 'boolean' then return tostring(value)

elseif type(value) ~= 'table' then self:onEncodeError("can't convert " .. type(value) .. " to JSON", etc)

else --     -- A table to be converted to either a JSON object or array. --     local T = value

if parents[T] then self:onEncodeError("table " .. tostring(T) .. " is a child of itself", etc) else parents[T] = true end

local result_value

local object_keys, maximum_number_key = object_or_array(self, T, etc) if maximum_number_key then --        -- An array... --        local ITEMS = { } for i = 1, maximum_number_key do           table.insert(ITEMS, encode_value(self, T[i], parents, etc)) end

result_value = "[" .. table.concat(ITEMS, ",") .. "]"     elseif object_keys then --        -- An object --

--        -- We'll always sort the keys, so that comparisons can be made on         -- the results, etc. The actual order is not particularly -- important (e.g. it doesn't matter what character set we sort        -- as); it's only important that it be deterministic... the same -- every time. --        local PARTS = { } for _, key in ipairs(object_keys) do           local encoded_key = encode_value(self, tostring(key), parents, etc) local encoded_val = encode_value(self, T[key],       parents, etc) table.insert(PARTS, string.format("%s:%s", encoded_key, encoded_val)) end result_value = "{" .. table.concat(PARTS, ",") .. "}"     else --        -- An empty array/object... we'll treat it as an array, though it should really be an option --        result_value = "[]" end

parents[T] = false return result_value end end

local encode_pretty_value -- must predeclare because it calls itself function encode_pretty_value(self, value, parents, indent, etc)

if type(value) == 'string' then return json_string_literal(value)

elseif type(value) == 'number' then return tostring(value)

elseif type(value) == 'boolean' then return tostring(value)

elseif type(value) == 'nil' then return 'null'

elseif type(value) ~= 'table' then self:onEncodeError("can't convert " .. type(value) .. " to JSON", etc)

else --     -- A table to be converted to either a JSON object or array. --     local T = value

if parents[T] then self:onEncodeError("table " .. tostring(T) .. " is a child of itself", etc) end parents[T] = true

local result_value

local object_keys = object_or_array(self, T, etc) if not object_keys then --        -- An array... --        local ITEMS = { } for i = 1, #T do           table.insert(ITEMS, encode_pretty_value(self, T[i], parents, indent, etc)) end

result_value = "[ " .. table.concat(ITEMS, ", ") .. " ]"

else

--        -- An object -- can keys be numbers? --

local KEYS = { } local max_key_length = 0 for _, key in ipairs(object_keys) do           local encoded = encode_pretty_value(self, tostring(key), parents, "", etc) max_key_length = math.max(max_key_length, #encoded) table.insert(KEYS, encoded) end local key_indent = indent .. "   "         local subtable_indent = indent .. string.rep(" ", max_key_length + 2 + 4) local FORMAT = "%s%" .. tostring(max_key_length) .. "s: %s"

local COMBINED_PARTS = { } for i, key in ipairs(object_keys) do           local encoded_val = encode_pretty_value(self, T[key], parents, subtable_indent, etc) table.insert(COMBINED_PARTS, string.format(FORMAT, key_indent, KEYS[i], encoded_val)) end result_value = "{\n" .. table.concat(COMBINED_PARTS, ",\n") .. "\n" .. indent .. "}"     end

parents[T] = false return result_value end end

function OBJDEF:encode(value, etc) if type(self) ~= 'table' or self.__index ~= OBJDEF then OBJDEF:onEncodeError("JSON:encode must be called in method format", etc) end

local parents = {} return encode_value(self, value, parents, etc) end

function OBJDEF:encode_pretty(value, etc) local parents = {} local subtable_indent = "" return encode_pretty_value(self, value, parents, subtable_indent, etc) end

function OBJDEF.__tostring return "JSON encode/decode package" end

OBJDEF.__index = OBJDEF

function OBJDEF:new(args) local new = { }

if args then for key, val in pairs(args) do        new[key] = val end end

return setmetatable(new, OBJDEF) end

return OBJDEF:new

-- -- Version history: -- --  20111207.5    Added support for the 'etc' arguments, for better error reporting. -- --  20110731.4    More feedback from David Kolf on how to make the tests for Nan/Infinity system independent. -- --  20110730.3    Incorporated feedback from David Kolf at http://lua-users.org/wiki/JsonModules: -- --                  * When encoding lua for JSON, Sparse numeric arrays are now handled by --                     spitting out full arrays, such that --                       JSON:encode({"one", "two", [10] = "ten"}) --                    returns --                       ["one","two",null,null,null,null,null,null,null,"ten"] -- --                    In 20100810.2 and earlier, only up to the first non-null value would have been retained. -- --                  * When encoding lua for JSON, numeric value NaN gets spit out as null, and infinity as "1+e9999". --                    Version 20100810.2 and earlier created invalid JSON in both cases. -- --                  * Unicode surrogate pairs are now detected when decoding JSON. -- --  20100810.2    added some checking to ensure that an invalid Unicode character couldn't leak in to the UTF-8 encoding -- --  20100731.1    initial public release --