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204
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1
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2 local type = type;
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3 local t_insert, t_concat, t_remove = table.insert, table.concat, table.remove;
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4 local s_char = string.char;
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5 local tostring, tonumber = tostring, tonumber;
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6 local pairs, ipairs = pairs, ipairs;
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7 local next = next;
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8 local error = error;
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9 local newproxy, getmetatable = newproxy, getmetatable;
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10 local print = print;
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11
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12 --module("json")
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13 local _M = {};
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14
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15 local null = newproxy and newproxy(true) or {};
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16 if getmetatable and getmetatable(null) then
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17 getmetatable(null).__tostring = function() return "null"; end;
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18 end
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19 _M.null = null;
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20
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21 local escapes = {
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22 ["\""] = "\\\"", ["\\"] = "\\\\", ["\b"] = "\\b",
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23 ["\f"] = "\\f", ["\n"] = "\\n", ["\r"] = "\\r", ["\t"] = "\\t"};
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24 local unescapes = {
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25 ["\""] = "\"", ["\\"] = "\\", ["/"] = "/",
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26 b = "\b", f = "\f", n = "\n", r = "\r", t = "\t"};
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27 for i=0,31 do
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28 local ch = s_char(i);
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29 if not escapes[ch] then escapes[ch] = ("\\u%.4X"):format(i); end
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30 end
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31
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32 local valid_types = {
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33 number = true,
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34 string = true,
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35 table = true,
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36 boolean = true
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37 };
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38 local special_keys = {
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39 __array = true;
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40 __hash = true;
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41 };
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42
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43 local simplesave, tablesave, arraysave, stringsave;
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44
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45 function stringsave(o, buffer)
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46 -- FIXME do proper utf-8 and binary data detection
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47 t_insert(buffer, "\""..(o:gsub(".", escapes)).."\"");
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48 end
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49
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50 function arraysave(o, buffer)
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51 t_insert(buffer, "[");
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52 if next(o) then
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53 for i,v in ipairs(o) do
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54 simplesave(v, buffer);
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55 t_insert(buffer, ",");
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56 end
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57 t_remove(buffer);
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58 end
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59 t_insert(buffer, "]");
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60 end
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61
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62 function tablesave(o, buffer)
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63 local __array = {};
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64 local __hash = {};
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65 local hash = {};
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66 for i,v in ipairs(o) do
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67 __array[i] = v;
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68 end
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69 for k,v in pairs(o) do
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70 local ktype, vtype = type(k), type(v);
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71 if valid_types[vtype] or v == null then
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72 if ktype == "string" and not special_keys[k] then
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73 hash[k] = v;
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74 elseif (valid_types[ktype] or k == null) and __array[k] == nil then
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75 __hash[k] = v;
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76 end
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77 end
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78 end
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79 if next(__hash) ~= nil or next(hash) ~= nil or next(__array) == nil then
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80 t_insert(buffer, "{");
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81 local mark = #buffer;
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82 for k,v in pairs(hash) do
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83 stringsave(k, buffer);
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84 t_insert(buffer, ":");
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85 simplesave(v, buffer);
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86 t_insert(buffer, ",");
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87 end
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88 if next(__hash) ~= nil then
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89 t_insert(buffer, "\"__hash\":[");
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90 for k,v in pairs(__hash) do
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91 simplesave(k, buffer);
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92 t_insert(buffer, ",");
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93 simplesave(v, buffer);
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94 t_insert(buffer, ",");
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95 end
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96 t_remove(buffer);
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97 t_insert(buffer, "]");
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98 t_insert(buffer, ",");
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99 end
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100 if next(__array) then
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101 t_insert(buffer, "\"__array\":");
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102 arraysave(__array, buffer);
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103 t_insert(buffer, ",");
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104 end
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105 if mark ~= #buffer then t_remove(buffer); end
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106 t_insert(buffer, "}");
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107 else
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108 arraysave(__array, buffer);
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109 end
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110 end
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111
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112 function simplesave(o, buffer)
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113 local t = type(o);
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114 if t == "number" then
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115 t_insert(buffer, tostring(o));
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116 elseif t == "string" then
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117 stringsave(o, buffer);
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118 elseif t == "table" then
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119 tablesave(o, buffer);
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120 elseif t == "boolean" then
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121 t_insert(buffer, (o and "true" or "false"));
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122 else
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123 t_insert(buffer, "null");
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124 end
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125 end
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126
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127 function _M.encode(obj)
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128 local t = {};
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129 simplesave(obj, t);
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130 return t_concat(t);
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131 end
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132
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133 -----------------------------------
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134
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135
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136 function _M.decode(json)
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137 local pos = 1;
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138 local current = {};
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139 local stack = {};
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140 local ch, peek;
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141 local function next()
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142 ch = json:sub(pos, pos);
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143 pos = pos+1;
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144 peek = json:sub(pos, pos);
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145 return ch;
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146 end
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147
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148 local function skipwhitespace()
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149 while ch and (ch == "\r" or ch == "\n" or ch == "\t" or ch == " ") do
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150 next();
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151 end
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152 end
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153 local function skiplinecomment()
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154 repeat next(); until not(ch) or ch == "\r" or ch == "\n";
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155 skipwhitespace();
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156 end
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157 local function skipstarcomment()
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158 next(); next(); -- skip '/', '*'
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159 while peek and ch ~= "*" and peek ~= "/" do next(); end
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160 if not peek then error("eof in star comment") end
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161 next(); next(); -- skip '*', '/'
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162 skipwhitespace();
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163 end
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164 local function skipstuff()
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165 while true do
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166 skipwhitespace();
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167 if ch == "/" and peek == "*" then
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168 skipstarcomment();
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169 elseif ch == "/" and peek == "*" then
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170 skiplinecomment();
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171 else
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172 return;
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173 end
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174 end
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175 end
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176
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177 local readvalue;
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178 local function readarray()
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179 local t = {};
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180 next(); -- skip '['
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181 skipstuff();
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182 if ch == "]" then next(); return t; end
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183 t_insert(t, readvalue());
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184 while true do
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185 skipstuff();
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186 if ch == "]" then next(); return t; end
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187 if not ch then error("eof while reading array");
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188 elseif ch == "," then next();
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189 elseif ch then error("unexpected character in array, comma expected"); end
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190 if not ch then error("eof while reading array"); end
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191 t_insert(t, readvalue());
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192 end
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193 end
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194
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195 local function checkandskip(c)
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196 local x = ch or "eof";
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197 if x ~= c then error("unexpected "..x..", '"..c.."' expected"); end
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198 next();
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199 end
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200 local function readliteral(lit, val)
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201 for c in lit:gmatch(".") do
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202 checkandskip(c);
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203 end
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204 return val;
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205 end
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206 local function readstring()
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207 local s = "";
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208 checkandskip("\"");
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209 while ch do
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210 while ch and ch ~= "\\" and ch ~= "\"" do
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211 s = s..ch; next();
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212 end
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213 if ch == "\\" then
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214 next();
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215 if unescapes[ch] then
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216 s = s..unescapes[ch];
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217 next();
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218 elseif ch == "u" then
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219 local seq = "";
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220 for i=1,4 do
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221 next();
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222 if not ch then error("unexpected eof in string"); end
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223 if not ch:match("[0-9a-fA-F]") then error("invalid unicode escape sequence in string"); end
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224 seq = seq..ch;
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225 end
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226 s = s..s.char(tonumber(seq, 16)); -- FIXME do proper utf-8
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227 next();
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228 else error("invalid escape sequence in string"); end
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229 end
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230 if ch == "\"" then
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231 next();
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232 return s;
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233 end
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234 end
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235 error("eof while reading string");
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236 end
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237 local function readnumber()
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238 local s = "";
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239 if ch == "-" then
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240 s = s..ch; next();
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241 if not ch:match("[0-9]") then error("number format error"); end
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242 end
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243 if ch == "0" then
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244 s = s..ch; next();
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245 if ch:match("[0-9]") then error("number format error"); end
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246 else
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247 while ch and ch:match("[0-9]") do
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248 s = s..ch; next();
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249 end
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250 end
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251 if ch == "." then
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252 s = s..ch; next();
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253 if not ch:match("[0-9]") then error("number format error"); end
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254 while ch and ch:match("[0-9]") do
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255 s = s..ch; next();
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256 end
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257 if ch == "e" or ch == "E" then
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258 s = s..ch; next();
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259 if ch == "+" or ch == "-" then
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260 s = s..ch; next();
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261 if not ch:match("[0-9]") then error("number format error"); end
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262 while ch and ch:match("[0-9]") do
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263 s = s..ch; next();
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264 end
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265 end
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266 end
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267 end
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268 return tonumber(s);
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269 end
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270 local function readmember(t)
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271 local k = readstring();
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272 checkandskip(":");
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273 t[k] = readvalue();
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274 end
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275 local function fixobject(obj)
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276 local __array = obj.__array;
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277 if __array then
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278 obj.__array = nil;
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279 for i,v in ipairs(__array) do
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280 t_insert(obj, v);
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281 end
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282 end
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283 local __hash = obj.__hash;
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284 if __hash then
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285 obj.__hash = nil;
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286 local k;
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287 for i,v in ipairs(__hash) do
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288 if k ~= nil then
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289 obj[k] = v; k = nil;
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290 else
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291 k = v;
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292 end
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293 end
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294 end
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295 return obj;
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296 end
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297 local function readobject()
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298 local t = {};
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299 next(); -- skip '{'
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300 skipstuff();
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301 if ch == "}" then next(); return t; end
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302 if not ch then error("eof while reading object"); end
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303 readmember(t);
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304 while true do
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305 skipstuff();
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306 if ch == "}" then next(); return fixobject(t); end
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307 if not ch then error("eof while reading object");
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308 elseif ch == "," then next();
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309 elseif ch then error("unexpected character in object, comma expected"); end
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310 if not ch then error("eof while reading object"); end
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311 readmember(t);
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312 end
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313 end
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314
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315 function readvalue()
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316 skipstuff();
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317 while ch do
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318 if ch == "{" then
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319 return readobject();
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320 elseif ch == "[" then
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321 return readarray();
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322 elseif ch == "\"" then
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323 return readstring();
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324 elseif ch:match("[%-0-9%.]") then
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325 return readnumber();
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326 elseif ch == "n" then
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327 return readliteral("null", null);
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328 elseif ch == "t" then
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329 return readliteral("true", true);
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330 elseif ch == "f" then
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331 return readliteral("false", false);
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332 end
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333 end
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334 error("eof while reading value");
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335 end
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336 next();
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337 return readvalue();
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338 end
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339
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340 function _M.test(object)
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341 local encoded = encode(object);
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342 local decoded = decode(encoded);
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343 local recoded = encode(decoded);
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344 if encoded ~= recoded then
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345 print("FAILED");
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346 print("encoded:", encoded);
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347 print("recoded:", recoded);
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348 else
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349 print(encoded);
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350 end
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351 return encoded ~= recoded;
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352 end
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353
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354 return _M;
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