Difference between revisions of "Module:JSON"

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Latest revision as of 15:29, 15 January 2017

-- -*- coding: utf-8 -*- -- -- Copyright 2010-2012 Jeffrey Friedl -- http://regex.info/blog/ -- local VERSION = 20111207.5 -- version history at end of file local OBJDEF = { VERSION = VERSION }

-- -- 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 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 -- -- -- DECODING -- -- JSON = (loadfile "JSON.lua")() -- one-time load of the routines -- -- local lua_value = JSON:decode(raw_json_text) -- -- If the JSON text is for an object or an array, e.g. -- { "what": "books", "count": 3 } -- or -- [ "Larry", "Curly", "Moe" ] -- -- the result is a Lua table, e.g. -- { what = "books", count = 3 } -- or -- { "Larry", "Curly", "Moe" } -- -- -- 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 replace the default JSON:onDecodeError() with your -- own function. -- -- 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 -- -- function JSON:onDecodeError(message, text, location, etc) -- LrErrors.throwUserError("Internal Error: invalid JSON data") -- end -- -- or even just -- -- function JSON.assert(message) -- LrErrors.throwUserError("Internal Error: " .. message) -- end -- -- If JSON:decode() is passed a nil, this is called instead: -- -- JSON:onDecodeOfNilError(message, nil, nil, etc) -- -- and if JSON:decode() is passed HTML instead of JSON, this is called: -- -- JSON:onDecodeOfHTMLError(message, text, nil, etc) -- -- The use of the fourth 'etc' argument allows stronger coordination between decoding and error -- reporting, especially when you provide your own error-handling routines. Continuing with the -- the Adobe Lightroom plugin example: -- -- function JSON:onDecodeError(message, text, location, etc) -- local note = "Internal Error: invalid JSON data" -- if type(etc) = 'table' and etc.photo then -- note = note .. " while processing for " .. etc.photo:getFormattedMetadata('fileName') -- end -- LrErrors.throwUserError(note) -- end -- -- : -- : -- -- for i, photo in ipairs(photosToProcess) do -- : -- : -- local data = JSON:decode(someJsonText, { photo = photo }) -- : -- : -- 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) -- [1] 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 --