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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 <stdlib.h>
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4 #include <string.h>
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5
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6 #define JSON_UPVAL_METATABLE lua_upvalueindex(1)
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7 #define JSON_UPVAL_NULLS lua_upvalueindex(2)
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8 #define JSON_UPVAL_ARYLEN lua_upvalueindex(3)
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9
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10 #define JSON_STATE_VALUE 0
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11 #define JSON_STATE_OBJECT_KEY 1
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12 #define JSON_STATE_OBJECT_KEY_TERMINATOR 2
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13 #define JSON_STATE_OBJECT_VALUE 3
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14 #define JSON_STATE_OBJECT_SEPARATOR 4
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15 #define JSON_STATE_ARRAY_VALUE 5
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16 #define JSON_STATE_ARRAY_SEPARATOR 6
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17 #define JSON_STATE_END 7
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18
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19 static int json_import(lua_State *L) {
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20 const char *str;
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21 size_t total;
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22 size_t pos = 0;
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23 size_t level = 0;
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24 int mode = JSON_STATE_VALUE;
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25 char c;
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26 luaL_Buffer luabuf;
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27 char *cbuf;
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28 size_t writepos;
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29 int aryidx;
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30 lua_settop(L, 1);
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31 str = lua_tostring(L, 1);
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32 total = strlen(str);
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33 json_import_loop:
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34 while (c = str[pos], c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == '\f') pos++;
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35 switch (c) {
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36 case 0:
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37 if (mode == JSON_STATE_END) return 1;
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38 json_import_unexpected_eof:
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39 lua_pushnil(L);
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40 if (level == 0) lua_pushliteral(L, "Empty string");
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41 else lua_pushliteral(L, "Unexpected end of JSON document");
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42 return 2;
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43 case '{':
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44 if (mode != JSON_STATE_VALUE && mode != JSON_STATE_OBJECT_VALUE && mode != JSON_STATE_ARRAY_VALUE)
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45 goto json_import_syntax_error;
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46 pos++;
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47 lua_newtable(L); // the actual JSON object
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48 lua_pushvalue(L, JSON_UPVAL_METATABLE);
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49 lua_setmetatable(L, -2);
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50 lua_newtable(L); // stores set of NULL values
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51 lua_pushvalue(L, -2);
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52 lua_pushvalue(L, -2);
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53 lua_rawset(L, JSON_UPVAL_NULLS);
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54 mode = JSON_STATE_OBJECT_KEY;
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55 level++;
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56 goto json_import_loop;
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57 case '[':
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58 if (mode != JSON_STATE_VALUE && mode != JSON_STATE_OBJECT_VALUE && mode != JSON_STATE_ARRAY_VALUE)
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59 goto json_import_syntax_error;
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60 pos++;
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61 lua_newtable(L); // the actual JSON array
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62 lua_pushvalue(L, JSON_UPVAL_METATABLE);
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63 lua_setmetatable(L, -2);
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64 lua_newtable(L); // stores set of NULL values
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65 lua_pushvalue(L, -2);
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66 lua_pushvalue(L, -2);
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67 lua_rawset(L, JSON_UPVAL_NULLS);
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68 lua_pushinteger(L, 0); // length of array (since it may contain nil's)
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69 mode = JSON_STATE_ARRAY_VALUE;
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70 level++;
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71 goto json_import_loop;
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72 case '}':
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73 if (mode != JSON_STATE_OBJECT_KEY && mode != JSON_STATE_OBJECT_SEPARATOR)
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74 goto json_import_syntax_error;
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75 goto json_import_close;
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76 case ']':
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77 if (mode != JSON_STATE_ARRAY_VALUE && mode != JSON_STATE_ARRAY_SEPARATOR)
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78 goto json_import_syntax_error;
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79 lua_pushvalue(L, -2); // use array table as key
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80 lua_insert(L, -2); // use length of array as value
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81 lua_rawset(L, JSON_UPVAL_ARYLEN); // store length in ephemeron table
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82 // leaves array table on top of stack
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83 json_import_close:
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84 pos++;
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85 lua_pop(L, 1); // pop table that stores set of NULL values
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86 if (--level) {
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87 if (lua_type(L, -2) == LUA_TNUMBER) {
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88 mode = JSON_STATE_ARRAY_VALUE;
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89 } else {
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90 mode = JSON_STATE_OBJECT_VALUE;
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91 }
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92 goto json_import_process_value;
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93 } else {
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94 mode = JSON_STATE_END;
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95 }
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96 goto json_import_loop;
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97 case ':':
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98 if (mode != JSON_STATE_OBJECT_KEY_TERMINATOR)
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99 goto json_import_syntax_error;
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100 pos++;
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101 mode = JSON_STATE_OBJECT_VALUE;
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102 goto json_import_loop;
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103 case ',':
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104 if (mode == JSON_STATE_OBJECT_SEPARATOR) {
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105 mode = JSON_STATE_OBJECT_KEY;
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106 } else if (mode == JSON_STATE_ARRAY_SEPARATOR) {
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107 mode = JSON_STATE_ARRAY_VALUE;
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108 } else {
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109 goto json_import_syntax_error;
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110 }
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111 pos++;
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112 goto json_import_loop;
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113 case '"':
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114 cbuf = luaL_buffinitsize(L, &luabuf, total-pos);
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115 writepos = 0;
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116 pos++;
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117 while ((c = str[pos++]) != '"') {
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118 if (c == 0) {
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119 goto json_import_unexpected_eof;
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120 } else if (c < 32 || c == 127) {
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121 lua_pushnil(L);
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122 lua_pushliteral(L, "Unexpected control character in JSON string");
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123 return 2;
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124 } else if (c == '\\') {
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125 c = str[pos++];
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126 switch (c) {
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127 case 0:
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128 goto json_import_unexpected_eof;
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129 case '"':
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130 case '/':
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131 case '\\':
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132 cbuf[writepos++] = c;
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133 break;
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134 case 'b':
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135 cbuf[writepos++] = '\b';
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136 break;
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137 case 'f':
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138 cbuf[writepos++] = '\f';
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139 break;
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140 case 'n':
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141 cbuf[writepos++] = '\n';
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142 break;
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143 case 'r':
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144 cbuf[writepos++] = '\r';
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145 break;
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146 case 't':
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147 cbuf[writepos++] = '\t';
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148 break;
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149 case 'u':
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150 lua_pushnil(L);
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151 lua_pushliteral(L, "JSON unicode escape sequences are not implemented yet"); // TODO
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152 return 2;
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153 default:
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154 lua_pushnil(L);
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155 lua_pushliteral(L, "Unexpected string escape sequence in JSON document");
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156 return 2;
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157 }
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158 } else {
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159 cbuf[writepos++] = c;
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160 }
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161 }
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162 if (!c) goto json_import_unexpected_eof;
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163 luaL_pushresultsize(&luabuf, writepos);
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164 goto json_import_process_value;
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165 }
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166 if (c == '-' || (c >= '0' && c <= '9')) {
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167 char *endptr;
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168 double numval;
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169 numval = strtod(str+pos, &endptr);
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170 if (endptr == str+pos) goto json_import_syntax_error;
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171 pos += endptr - (str+pos);
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172 lua_pushnumber(L, numval);
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173 } else if (!strncmp(str+pos, "true", 4)) {
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174 lua_pushboolean(L, 1);
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175 pos += 4;
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176 } else if (!strncmp(str+pos, "false", 5)) {
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177 lua_pushboolean(L, 0);
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178 pos += 5;
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179 } else if (!strncmp(str+pos, "null", 4)) {
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180 lua_pushnil(L);
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181 pos += 4;
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182 } else {
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183 goto json_import_syntax_error;
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184 }
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185 json_import_process_value:
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186 switch (mode) {
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187 case JSON_STATE_OBJECT_KEY:
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188 if (lua_type(L, -1) != LUA_TSTRING) goto json_import_syntax_error;
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189 mode = JSON_STATE_OBJECT_KEY_TERMINATOR;
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190 goto json_import_loop;
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191 case JSON_STATE_OBJECT_VALUE:
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192 if (lua_isnil(L, -1)) {
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193 lua_pushvalue(L, -2);
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194 lua_pushboolean(L, 1);
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195 lua_rawset(L, -5);
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196 }
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197 lua_rawset(L, -4);
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198 mode = JSON_STATE_OBJECT_SEPARATOR;
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199 goto json_import_loop;
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200 case JSON_STATE_ARRAY_VALUE:
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201 aryidx = lua_tointeger(L, -2) + 1;
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202 if (lua_isnil(L, -1)) {
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203 lua_pushinteger(L, aryidx);
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204 lua_pushboolean(L, 1);
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205 lua_rawset(L, -5);
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206 }
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207 lua_rawseti(L, -4, aryidx);
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208 lua_pop(L, 1);
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209 lua_pushinteger(L, aryidx);
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210 mode = JSON_STATE_ARRAY_SEPARATOR;
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211 goto json_import_loop;
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212 case JSON_STATE_VALUE:
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213 mode = JSON_STATE_END;
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214 goto json_import_loop;
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215 }
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216 json_import_syntax_error:
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217 lua_pushnil(L);
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218 lua_pushliteral(L, "Syntax error in JSON document");
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219 return 2;
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220 }
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221
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222 static int json_arylen(lua_State *L) {
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223 lua_settop(L, 1);
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224 lua_rawget(L, JSON_UPVAL_ARYLEN);
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225 return 1;
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226 }
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227
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228 static int json_isnull(lua_State *L) {
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229 lua_pushvalue(L, 1);
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230 lua_rawget(L, JSON_UPVAL_NULLS);
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231 if (lua_isnil(L, -1)) goto json_isnull_false;
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232 lua_pushvalue(L, 2);
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233 lua_rawget(L, -2);
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234 if (!lua_isnil(L, -1)) return 1;
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235 json_isnull_false:
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236 lua_pushboolean(L, 0);
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237 return 1;
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238 }
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239
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240 static const struct luaL_Reg json_module_functions[] = {
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241 {"import", json_import},
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242 {"arylen", json_arylen},
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243 {"isnull", json_isnull},
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244 {NULL, NULL}
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245 };
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246
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247 int luaopen_json(lua_State *L) {
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248 lua_newtable(L); // library table
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249 lua_newtable(L); // metatable for JSON objects and JSON arrays
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250 lua_pushvalue(L, -1);
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251 lua_setfield(L, -3, "metatable");
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252 lua_newtable(L); // ephemeron table to store a set of keys associated with JSON-null values
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253 lua_newtable(L); // ephemeron table to store the length of arrays (that may contain nil's)
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254 lua_newtable(L); // meta table for ephemeron table
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255 lua_pushliteral(L, "__mode");
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256 lua_pushliteral(L, "k");
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257 lua_rawset(L, -3);
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258 lua_pushvalue(L, -1);
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259 lua_setmetatable(L, -3);
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260 lua_setmetatable(L, -2);
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261 luaL_setfuncs(L, json_module_functions, 3);
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262 return 1;
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263 }
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