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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; |
