模組:JSON
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local export = {}
-- 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).
local 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
-- 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 export.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 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 export.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 export.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