Module:Wt/json

local export = {}

-- This function makes an effort to convert an arbitrary Lua value to a string -- containing a JSON representation of it. It's not intended to be very robust, -- but may be useful for prototyping. function export.toJSON(val, opts) opts = opts or {} function converter(val) if type(val) == 'nil' then return 'null' elseif type(val) == 'boolean' then return val and 'true' or 'false' elseif type(val) == 'number' then return json_fromNumber(val) elseif type(val) == 'string' then return json_fromString(val) elseif type(val) == 'table' then -- If the table has a toJSON member function, call that. if val.toJSON then return val:toJSON else return json_fromTable(val, converter) end else error('Unsupported type: ' .. type(val)) end end return converter(val) end

-- Given a string, escapes any illegal characters and wraps it in double-quotes. -- Raises an error if the string is not valid UTF-8. function json_fromString(s) if type(s) ~= 'string' or not mw.ustring.isutf8(s) then error('Not a valid UTF-8 string: ' .. s)	end s = s:gsub('[\\"]', '\\%0')	s = s:gsub('%c', function (c)		return string.format('\\u00%02X', c:byte)	end)	-- Not needed for valid JSON, but needed for compatibility with JavaScript:	s = s:gsub('\226\128\168', '\\u2028')	s = s:gsub('\226\128\169', '\\u2029')	return '"' .. s .. '"' end

-- Given a finite real number x, returns a string containing its JSON -- representation, with enough precision that it *should* round-trip correctly -- (depending on the well-behavedness of the system on the other end). function json_fromNumber(x) if type(x) ~= 'number' then error('Not of type "number": ' .. x .. ' (' .. type(x) .. ')')	end if x ~= x or x == math.huge or x == -math.huge then error('Not a finite real number: ' .. x)	end return string.format("%.17g", x) end

-- Given a table, treats it as an array and assembles its values in the form -- '[ v1, v2, v3 ]'. Optionally takes a function to JSONify the values before -- assembly; if that function is omitted, then the values should already be -- strings containing valid JSON data. function json_arrayFromTable(t, f)	f = f or function (x) return x end local ret = {} for _, elem in ipairs(t) do		elem = f(elem) if elem ~= nil then table.insert(ret, ', ') table.insert(ret, elem) end end if # ret == 0 then return '[]' end ret[1] = '[ ' table.insert(ret, ' ]') return table.concat(ret) end

-- Given a table whose keys are all strings, assembles its keys and values in -- the form '{ "k1": v1, "k2": v2, "k3": v3 }'. Optionally takes a function to -- JSONify the values before assembly; if that function is omitted, then the -- values should already be strings containing valid JSON data. (The keys, by -- contrast, should just be regular Lua strings; they will be passed to this -- module's jsonStringFromString.) function json_fromTable(val, converter) converter = converter or function (x) return x end local as_array = {} local as_object = {} local string_key = false for key, value in pairs(val) do		value = converter(value) if type(key) ~= "number" then string_key = true end if value ~= nil then key = json_fromString(tostring(key)) table.insert(as_array, value) table.insert(as_object, key .. ' : ' .. value) end end if string_key then return '{' .. table.concat(as_object, ", ") .. '}'	else return '[' .. table.concat(as_array, ", ") .. ']'	end end

return export