134 lines
4.2 KiB
Lua
134 lines
4.2 KiB
Lua
local json = {}
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local function kind_of(obj)
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if type(obj) ~= 'table' then return type(obj) end
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local i = 1
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for _ in pairs(obj) do
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if obj[i] ~= nil then i = i + 1 else return 'table' end
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end
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if i == 1 then return 'table' else return 'array' end
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end
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local function escape_str(s)
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local in_char = {'\\', '"', '/', '\b', '\f', '\n', '\r', '\t'}
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local out_char = {'\\', '"', '/', 'b', 'f', 'n', 'r', 't'}
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for i, c in ipairs(in_char) do
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s = s:gsub(c, '\\' .. out_char[i])
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end
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return s
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end
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local function skip_delim(str, pos, delim, err_if_missing)
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pos = pos + #str:match('^%s*', pos)
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if str:sub(pos, pos) ~= delim then
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if err_if_missing then
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error('Expected ' .. delim .. ' near position ' .. pos)
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end
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return pos, false
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end
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return pos + 1, true
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end
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local function parse_str_val(str, pos, val)
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val = val or ''
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local early_end_error = 'End of input found while parsing string.'
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if pos > #str then error(early_end_error) end
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local c = str:sub(pos, pos)
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if c == '"' then return val, pos + 1 end
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if c ~= '\\' then return parse_str_val(str, pos + 1, val .. c) end
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local esc_map = {b = '\b', f = '\f', n = '\n', r = '\r', t = '\t'}
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local nextc = str:sub(pos + 1, pos + 1)
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if not nextc then error(early_end_error) end
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return parse_str_val(str, pos + 2, val .. (esc_map[nextc] or nextc))
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end
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local function parse_num_val(str, pos)
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local num_str = str:match('^-?%d+%.?%d*[eE]?[+-]?%d*', pos)
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local val = tonumber(num_str)
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if not val then error('Error parsing number at position ' .. pos .. '.') end
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return val, pos + #num_str
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end
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function json.stringify(obj, as_key)
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local s = {}
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local kind = kind_of(obj)
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if kind == 'array' then
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if as_key then error('Can\'t encode array as key.') end
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s[#s + 1] = '['
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for i, val in ipairs(obj) do
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if i > 1 then s[#s + 1] = ', ' end
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s[#s + 1] = json.stringify(val)
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end
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s[#s + 1] = ']'
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elseif kind == 'table' then
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if as_key then error('Can\'t encode table as key.') end
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s[#s + 1] = '{'
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for k, v in pairs(obj) do
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if #s > 1 then s[#s + 1] = ', ' end
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s[#s + 1] = json.stringify(k, true)
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s[#s + 1] = ':'
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s[#s + 1] = json.stringify(v)
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end
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s[#s + 1] = '}'
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elseif kind == 'string' then
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return '"' .. escape_str(obj) .. '"'
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elseif kind == 'number' then
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if as_key then return '"' .. tostring(obj) .. '"' end
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return tostring(obj)
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elseif kind == 'boolean' then
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return tostring(obj)
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elseif kind == 'nil' then
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return 'null'
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else
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error('Unjsonifiable type: ' .. kind .. '.')
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end
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return table.concat(s)
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end
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json.null = {}
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function json.parse(str, pos, end_delim)
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pos = pos or 1
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if pos > #str then error('Reached unexpected end of input.') end
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local pos = pos + #str:match('^%s*', pos)
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local first = str:sub(pos, pos)
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if first == '{' then
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local obj, key, delim_found = {}, true, true
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pos = pos + 1
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while true do
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key, pos = json.parse(str, pos, '}')
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if key == nil then return obj, pos end
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if not delim_found then error('Comma missing between object items.') end
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pos = skip_delim(str, pos, ':', true)
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obj[key], pos = json.parse(str, pos)
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pos, delim_found = skip_delim(str, pos, ',')
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end
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elseif first == '[' then
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local arr, val, delim_found = {}, true, true
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pos = pos + 1
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while true do
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val, pos = json.parse(str, pos, ']')
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if val == nil then return arr, pos end
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if not delim_found then error('Comma missing between array items.') end
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arr[#arr + 1] = val
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pos, delim_found = skip_delim(str, pos, ',')
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end
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elseif first == '"' then
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return parse_str_val(str, pos + 1)
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elseif first == '-' or first:match('%d') then
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return parse_num_val(str, pos)
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elseif first == end_delim then
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return nil, pos + 1
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else
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local literals = {['true'] = true, ['false'] = false, ['null'] = json.null}
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for lit_str, lit_val in pairs(literals) do
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local lit_end = pos + #lit_str - 1
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if str:sub(pos, lit_end) == lit_str then return lit_val, lit_end + 1 end
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end
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local pos_info_str = 'position ' .. pos .. ': ' .. str:sub(pos, pos + 10)
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error('Invalid json syntax starting at ' .. pos_info_str)
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end
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end
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return json
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