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https://github.com/bjc/prosody.git
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util.json: New, faster, stricter, more compliant JSON decoder. Now returns nil,err instead of throwing errors on invalid input.
This commit is contained in:
Waqas Hussain
parent
11684a2d6c
commit
d960ec8fb7
1 changed files with 168 additions and 205 deletions
373
util/json.lua
373
util/json.lua
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@ -185,214 +185,177 @@ end
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-----------------------------------
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local function _skip_whitespace(json, index)
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return json:find("[^ \t\r\n]", index) or index; -- no need to check \r\n, we converted those to \t
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end
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local function _fixobject(obj)
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local __array = obj.__array;
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if __array then
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obj.__array = nil;
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for i,v in ipairs(__array) do
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t_insert(obj, v);
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end
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end
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local __hash = obj.__hash;
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if __hash then
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obj.__hash = nil;
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local k;
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for i,v in ipairs(__hash) do
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if k ~= nil then
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obj[k] = v; k = nil;
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else
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k = v;
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end
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end
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end
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return obj;
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end
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local _readvalue, _readstring;
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local function _readobject(json, index)
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local o = {};
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while true do
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local key, val;
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index = _skip_whitespace(json, index + 1);
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if json:byte(index) ~= 0x22 then -- "\""
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if json:byte(index) == 0x7d then return o, index + 1; end -- "}"
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return nil, "key expected";
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end
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key, index = _readstring(json, index);
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if key == nil then return nil, index; end
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index = _skip_whitespace(json, index);
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if json:byte(index) ~= 0x3a then return nil, "colon expected"; end -- ":"
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val, index = _readvalue(json, index + 1);
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if val == nil then return nil, index; end
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o[key] = val;
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index = _skip_whitespace(json, index);
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local b = json:byte(index);
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if b == 0x7d then return _fixobject(o), index + 1; end -- "}"
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if b ~= 0x2c then return nil, "object eof"; end -- ","
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end
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end
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local function _readarray(json, index)
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local a = {};
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local oindex = index;
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while true do
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local val;
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val, index = _readvalue(json, index + 1);
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if val == nil then
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if json:byte(oindex + 1) == 0x5d then return setmetatable(a, array_mt), oindex + 2; end -- "]"
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return val, index;
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end
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t_insert(a, val);
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index = _skip_whitespace(json, index);
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local b = json:byte(index);
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if b == 0x5d then return setmetatable(a, array_mt), index + 1; end -- "]"
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if b ~= 0x2c then return nil, "array eof"; end -- ","
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end
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end
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local _unescape_error;
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local function _unescape_surrogate_func(x)
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local lead, trail = tonumber(x:sub(3, 6), 16), tonumber(x:sub(9, 12), 16);
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local codepoint = lead * 0x400 + trail - 0x35FDC00;
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local a = codepoint % 64;
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codepoint = (codepoint - a) / 64;
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local b = codepoint % 64;
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codepoint = (codepoint - b) / 64;
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local c = codepoint % 64;
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codepoint = (codepoint - c) / 64;
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return s_char(0xF0 + codepoint, 0x80 + c, 0x80 + b, 0x80 + a);
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end
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local function _unescape_func(x)
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x = x:match("%x%x%x%x", 3);
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if x then
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--if x >= 0xD800 and x <= 0xDFFF then _unescape_error = true; end -- bad surrogate pair
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return codepoint_to_utf8(tonumber(x, 16));
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end
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_unescape_error = true;
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end
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function _readstring(json, index)
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index = index + 1;
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local endindex = json:find("\"", index, true);
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if endindex then
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local s = json:sub(index, endindex - 1);
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--if s:find("[%z-\31]") then return nil, "control char in string"; end
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-- FIXME handle control characters
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_unescape_error = nil;
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--s = s:gsub("\\u[dD][89abAB]%x%x\\u[dD][cdefCDEF]%x%x", _unescape_surrogate_func);
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-- FIXME handle escapes beyond BMP
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s = s:gsub("\\u.?.?.?.?", _unescape_func);
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if _unescape_error then return nil, "invalid escape"; end
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return s, endindex + 1;
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end
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return nil, "string eof";
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end
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local function _readnumber(json, index)
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local m = json:match("[0-9%.%-eE%+]+", index); -- FIXME do strict checking
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return tonumber(m), index + #m;
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end
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local function _readnull(json, index)
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local a, b, c = json:byte(index + 1, index + 3);
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if a == 0x75 and b == 0x6c and c == 0x6c then
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return null, index + 4;
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end
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return nil, "null parse failed";
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end
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local function _readtrue(json, index)
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local a, b, c = json:byte(index + 1, index + 3);
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if a == 0x72 and b == 0x75 and c == 0x65 then
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return true, index + 4;
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end
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return nil, "true parse failed";
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end
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local function _readfalse(json, index)
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local a, b, c, d = json:byte(index + 1, index + 4);
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if a == 0x61 and b == 0x6c and c == 0x73 and d == 0x65 then
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return false, index + 5;
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end
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return nil, "false parse failed";
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end
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function _readvalue(json, index)
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index = _skip_whitespace(json, index);
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local b = json:byte(index);
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-- TODO try table lookup instead of if-else?
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if b == 0x7B then -- "{"
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return _readobject(json, index);
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elseif b == 0x5B then -- "["
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return _readarray(json, index);
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elseif b == 0x22 then -- "\""
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return _readstring(json, index);
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elseif b ~= nil and b >= 0x30 and b <= 0x39 or b == 0x2d then -- "0"-"9" or "-"
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return _readnumber(json, index);
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elseif b == 0x6e then -- "n"
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return _readnull(json, index);
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elseif b == 0x74 then -- "t"
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return _readtrue(json, index);
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elseif b == 0x66 then -- "f"
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return _readfalse(json, index);
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else
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return nil, "value expected";
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end
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end
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local first_escape = {
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["\\\""] = "\\u0022";
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["\\\\"] = "\\u005c";
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["\\/" ] = "\\u002f";
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["\\b" ] = "\\u0008";
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["\\f" ] = "\\u000C";
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["\\n" ] = "\\u000A";
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["\\r" ] = "\\u000D";
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["\\t" ] = "\\u0009";
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["\\u" ] = "\\u";
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};
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function json.decode(json)
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json = json.." "; -- appending a space ensures valid json wouldn't touch EOF
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local pos = 1;
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local current = {};
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local stack = {};
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local ch, peek;
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local function next()
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ch = json:sub(pos, pos);
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if ch == "" then error("Unexpected EOF"); end
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pos = pos+1;
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peek = json:sub(pos, pos);
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return ch;
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end
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json = json:gsub("\\.", first_escape) -- get rid of all escapes except \uXXXX, making string parsing much simpler
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--:gsub("[\r\n]", "\t"); -- \r\n\t are equivalent, we care about none of them, and none of them can be in strings
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local function skipwhitespace()
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while ch and (ch == "\r" or ch == "\n" or ch == "\t" or ch == " ") do
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next();
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end
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end
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local function skiplinecomment()
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repeat next(); until not(ch) or ch == "\r" or ch == "\n";
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skipwhitespace();
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end
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local function skipstarcomment()
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next(); next(); -- skip '/', '*'
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while peek and ch ~= "*" and peek ~= "/" do next(); end
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if not peek then error("eof in star comment") end
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next(); next(); -- skip '*', '/'
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skipwhitespace();
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end
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local function skipstuff()
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while true do
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skipwhitespace();
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if ch == "/" and peek == "*" then
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skipstarcomment();
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elseif ch == "/" and peek == "/" then
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skiplinecomment();
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else
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return;
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end
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end
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end
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-- TODO do encoding verification
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local readvalue;
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local function readarray()
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local t = setmetatable({}, array_mt);
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next(); -- skip '['
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skipstuff();
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if ch == "]" then next(); return t; end
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t_insert(t, readvalue());
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while true do
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skipstuff();
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if ch == "]" then next(); return t; end
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if not ch then error("eof while reading array");
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elseif ch == "," then next();
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elseif ch then error("unexpected character in array, comma expected"); end
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if not ch then error("eof while reading array"); end
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t_insert(t, readvalue());
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end
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end
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local function checkandskip(c)
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local x = ch or "eof";
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if x ~= c then error("unexpected "..x..", '"..c.."' expected"); end
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next();
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end
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local function readliteral(lit, val)
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for c in lit:gmatch(".") do
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checkandskip(c);
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end
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return val;
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end
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local function readstring()
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local s = {};
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checkandskip("\"");
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while ch do
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while ch and ch ~= "\\" and ch ~= "\"" do
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t_insert(s, ch); next();
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end
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if ch == "\\" then
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next();
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if unescapes[ch] then
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t_insert(s, unescapes[ch]);
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next();
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elseif ch == "u" then
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local seq = "";
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for i=1,4 do
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next();
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if not ch then error("unexpected eof in string"); end
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if not ch:match("[0-9a-fA-F]") then error("invalid unicode escape sequence in string"); end
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seq = seq..ch;
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end
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t_insert(s, codepoint_to_utf8(tonumber(seq, 16)));
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next();
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else error("invalid escape sequence in string"); end
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end
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if ch == "\"" then
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next();
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return t_concat(s);
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end
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end
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error("eof while reading string");
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end
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local function readnumber()
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local s = "";
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if ch == "-" then
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s = s..ch; next();
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if not ch:match("[0-9]") then error("number format error"); end
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end
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if ch == "0" then
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s = s..ch; next();
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if ch:match("[0-9]") then error("number format error"); end
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else
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while ch and ch:match("[0-9]") do
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s = s..ch; next();
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end
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end
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if ch == "." then
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s = s..ch; next();
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if not ch:match("[0-9]") then error("number format error"); end
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while ch and ch:match("[0-9]") do
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s = s..ch; next();
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end
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if ch == "e" or ch == "E" then
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s = s..ch; next();
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if ch == "+" or ch == "-" then
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s = s..ch; next();
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if not ch:match("[0-9]") then error("number format error"); end
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while ch and ch:match("[0-9]") do
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s = s..ch; next();
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end
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end
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end
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end
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return tonumber(s);
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end
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local function readmember(t)
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skipstuff();
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local k = readstring();
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skipstuff();
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checkandskip(":");
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t[k] = readvalue();
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end
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local function fixobject(obj)
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local __array = obj.__array;
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if __array then
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obj.__array = nil;
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for i,v in ipairs(__array) do
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t_insert(obj, v);
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end
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end
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local __hash = obj.__hash;
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if __hash then
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obj.__hash = nil;
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local k;
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for i,v in ipairs(__hash) do
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if k ~= nil then
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obj[k] = v; k = nil;
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else
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k = v;
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end
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end
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end
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return obj;
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end
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local function readobject()
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local t = {};
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next(); -- skip '{'
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skipstuff();
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if ch == "}" then next(); return t; end
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if not ch then error("eof while reading object"); end
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readmember(t);
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while true do
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skipstuff();
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if ch == "}" then next(); return fixobject(t); end
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if not ch then error("eof while reading object");
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elseif ch == "," then next();
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elseif ch then error("unexpected character in object, comma expected"); end
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if not ch then error("eof while reading object"); end
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readmember(t);
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end
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end
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function readvalue()
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skipstuff();
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while ch do
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if ch == "{" then
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return readobject();
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elseif ch == "[" then
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return readarray();
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elseif ch == "\"" then
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return readstring();
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elseif ch:match("[%-0-9%.]") then
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return readnumber();
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elseif ch == "n" then
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return readliteral("null", null);
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elseif ch == "t" then
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return readliteral("true", true);
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elseif ch == "f" then
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return readliteral("false", false);
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else
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error("invalid character at value start: "..ch);
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end
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end
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error("eof while reading value");
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end
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next();
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return readvalue();
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local val, index = _readvalue(json, 1);
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if val == nil then return val, index; end
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if json:find("[^ \t\r\n]", index) then return nil, "garbage at eof"; end
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return val;
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end
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function json.test(object)
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