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jbe@121
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1 #include <lua.h>
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2 #include <lauxlib.h>
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3 #include <string.h>
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4
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5 #define JSON_VALUE 0
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6 #define JSON_OBJECT_KEY 1
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7 #define JSON_OBJECT_KEY_TERMINATOR 2
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8 #define JSON_OBJECT_VALUE 3
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9 #define JSON_OBJECT_SEPARATOR 4
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10 #define JSON_ARRAY_VALUE 5
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11 #define JSON_ARRAY_SEPARATOR 6
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12 #define JSON_END 7
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13
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14 static int json_import(lua_State *L) {
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15 const char *str;
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16 size_t total;
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17 size_t pos = 0;
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18 size_t level = 0;
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19 int mode = JSON_VALUE;
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20 char c;
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21 luaL_Buffer luabuf;
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22 char *cbuf;
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23 size_t writepos;
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24 int aryidx;
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25 lua_settop(L, 1);
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26 str = lua_tostring(L, 1);
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27 total = strlen(str);
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28 json_import_loop:
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29 while (c = str[pos], c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == '\f') pos++;
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30 switch (c) {
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31 case 0:
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32 if (mode == JSON_END) return 1;
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33 json_import_unexpected_eof:
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34 lua_pushnil(L);
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35 if (level == 0) lua_pushliteral(L, "Empty string");
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36 else lua_pushliteral(L, "Unexpected end of JSON document");
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37 return 2;
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38 case '{':
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39 if (mode != JSON_VALUE && mode != JSON_OBJECT_VALUE && mode != JSON_ARRAY_VALUE)
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40 goto json_import_syntax_error;
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41 pos++;
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42 lua_newtable(L);
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43 mode = JSON_OBJECT_KEY;
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44 level++;
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45 goto json_import_loop;
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46 case '[':
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47 if (mode != JSON_VALUE && mode != JSON_OBJECT_VALUE && mode != JSON_ARRAY_VALUE)
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48 goto json_import_syntax_error;
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49 pos++;
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50 lua_newtable(L);
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51 lua_pushinteger(L, 0); // length of array (since it may contain nil's)
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52 mode = JSON_ARRAY_VALUE;
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53 level++;
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54 goto json_import_loop;
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55 case '}':
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56 if (mode != JSON_OBJECT_KEY && mode != JSON_OBJECT_SEPARATOR)
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57 goto json_import_syntax_error;
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58 goto json_import_close;
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59 case ']':
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60 if (mode != JSON_ARRAY_VALUE && mode != JSON_ARRAY_SEPARATOR)
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61 goto json_import_syntax_error;
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62 lua_pushvalue(L, -2); // use array table as key
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63 lua_insert(L, -2); // use length of array as value
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64 lua_rawset(L, lua_upvalueindex(1)); // store length in ephemeron table
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65 // leaves array table on top of stack
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66 json_import_close:
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67 pos++;
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68 if (--level) {
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69 if (lua_type(L, -2) == LUA_TNUMBER) {
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70 mode = JSON_ARRAY_VALUE;
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71 } else {
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72 mode = JSON_OBJECT_VALUE;
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73 }
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74 goto json_import_process_value;
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75 } else {
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76 mode = JSON_END;
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77 }
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78 goto json_import_loop;
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79 case ':':
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80 if (mode != JSON_OBJECT_KEY_TERMINATOR)
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81 goto json_import_syntax_error;
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82 pos++;
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83 mode = JSON_OBJECT_VALUE;
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84 goto json_import_loop;
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85 case ',':
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86 if (mode == JSON_OBJECT_SEPARATOR) {
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87 mode = JSON_OBJECT_KEY;
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88 } else if (mode == JSON_ARRAY_SEPARATOR) {
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89 mode = JSON_ARRAY_VALUE;
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90 } else {
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91 goto json_import_syntax_error;
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92 }
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93 pos++;
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94 goto json_import_loop;
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95 case '"':
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96 cbuf = luaL_buffinitsize(L, &luabuf, total-pos);
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97 writepos = 0;
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98 pos++;
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99 while ((c = str[pos++]) != '"') {
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100 if (c == 0) {
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101 goto json_import_unexpected_eof;
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102 } else if (c < 32 || c == 127) {
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103 lua_pushnil(L);
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104 lua_pushliteral(L, "Unexpected control character in JSON string");
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105 return 2;
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106 } else if (c == '\\') {
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107 c = str[pos++];
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108 switch (c) {
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109 case 0:
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110 goto json_import_unexpected_eof;
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111 case '"':
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112 case '/':
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113 case '\\':
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114 cbuf[writepos++] = c;
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115 break;
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116 case 'b':
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117 cbuf[writepos++] = '\b';
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118 break;
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119 case 'f':
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120 cbuf[writepos++] = '\f';
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121 break;
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122 case 'n':
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123 cbuf[writepos++] = '\n';
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124 break;
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125 case 'r':
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126 cbuf[writepos++] = '\r';
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127 break;
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128 case 't':
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129 cbuf[writepos++] = '\t';
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130 break;
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131 case 'u':
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132 lua_pushnil(L);
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133 lua_pushliteral(L, "JSON unicode escape sequences are not implemented yet"); // TODO
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134 return 2;
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135 default:
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136 lua_pushnil(L);
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137 lua_pushliteral(L, "Unexpected string escape sequence in JSON document");
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138 return 2;
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139 }
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140 } else {
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141 cbuf[writepos++] = c;
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142 }
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143 }
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144 if (!c) goto json_import_unexpected_eof;
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145 luaL_pushresultsize(&luabuf, writepos);
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146 goto json_import_process_value;
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147 }
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148 if (!strncmp(str+pos, "true", 4)) {
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149 lua_pushboolean(L, 1);
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150 pos += 4;
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151 } else if (!strncmp(str+pos, "false", 5)) {
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152 lua_pushboolean(L, 0);
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153 pos += 5;
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154 } else if (!strncmp(str+pos, "null", 4)) {
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155 lua_pushnil(L);
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156 pos += 4;
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157 } else {
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158 goto json_import_syntax_error;
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159 }
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160 json_import_process_value:
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161 switch (mode) {
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162 case JSON_OBJECT_KEY:
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163 if (lua_type(L, -1) != LUA_TSTRING) goto json_import_syntax_error;
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164 mode = JSON_OBJECT_KEY_TERMINATOR;
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165 goto json_import_loop;
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166 case JSON_OBJECT_VALUE:
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167 lua_rawset(L, -3);
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168 mode = JSON_OBJECT_SEPARATOR;
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169 goto json_import_loop;
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170 case JSON_ARRAY_VALUE:
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171 aryidx = lua_tointeger(L, -2) + 1;
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172 lua_rawseti(L, -3, aryidx);
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173 lua_pop(L, 1);
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174 lua_pushinteger(L, aryidx);
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175 mode = JSON_ARRAY_SEPARATOR;
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176 goto json_import_loop;
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177 case JSON_VALUE:
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178 mode = JSON_END;
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179 goto json_import_loop;
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180 }
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181 json_import_syntax_error:
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182 lua_pushnil(L);
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183 lua_pushliteral(L, "Syntax error in JSON document");
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184 return 2;
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185 }
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186
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187 static int json_arylen(lua_State *L) {
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188 lua_settop(L, 1);
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189 lua_rawget(L, lua_upvalueindex(1));
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190 return 1;
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191 }
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192
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193 static const struct luaL_Reg json_module_functions[] = {
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194 {"import", json_import},
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195 {"arylen", json_arylen},
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196 {NULL, NULL}
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197 };
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198
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199 int luaopen_json(lua_State *L) {
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200 lua_newtable(L); // library table
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201 lua_newtable(L); // ephemeron table to store the length of arrays (that may contain nil's)
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202 lua_newtable(L); // meta table for ephemeron table
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203 lua_pushliteral(L, "__mode");
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204 lua_pushliteral(L, "k");
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205 lua_rawset(L, -3);
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206 lua_setmetatable(L, -2);
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207 luaL_setfuncs(L, json_module_functions, 1);
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208 return 1;
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209 }
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