rev |
line source |
jbe@121
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1 #include <lua.h>
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jbe@121
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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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jbe@144
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6 // maximum number of nested JSON values (objects and arrays):
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jbe@142
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7 #define JSON_MAXDEPTH 100
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8
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jbe@144
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9 // macros for usage of Lua registry:
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10 #define JSON_REGENT char
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11 #define JSON_REGPOINTER void *
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12 #define json_pushlightref(L, x) (lua_pushlightuserdata((L), &json_reference.x))
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13 #define json_regpointer(x) (&json_registry.x)
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14 #define json_regfetchpointer(L, x) (lua_pushlightuserdata((L), (x)), lua_rawget((L), LUA_REGISTRYINDEX))
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15 #define json_regfetch(L, x) (json_regfetchpointer(L, json_regpointer(x)))
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16 #define json_regstore(L, x) (lua_pushlightuserdata(L, json_regpointer(x)), lua_pushvalue(L, -2), lua_rawset(L, LUA_REGISTRYINDEX));
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17
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18 // generate dummy memory addresses that represent non-modifiable lightuserdata (dummy) objects:
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19 static struct {
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20 JSON_REGENT nullmark; // magic value to indicate JSON null value in shadow table
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21 } json_reference;
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22
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23
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24 // generate dummy memory addresses that represent Lua objects
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25 // via lightuserdata keys and LUA_REGISTRYINDEX:
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26 static struct {
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27 JSON_REGENT shadowtbl; // ephemeron table that maps tables to their corresponding shadow table
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28 JSON_REGENT unknownmt; // metatable for tables that may be either JSON objects or JSON arrays
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29 JSON_REGENT objectmt; // metatable for JSON objects
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30 JSON_REGENT arraymt; // metatable for JSON arrays
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31 } json_registry;
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32
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33 // marks a Lua table as JSON object or JSON array:
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34 // (returns its modified argument or a new table if argument is nil)
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35 static int json_mark(lua_State *L, JSON_REGPOINTER mt) {
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36 // check if argument is nil
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37 if (lua_isnoneornil(L, 1)) {
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38 // create new table at stack position 1:
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39 lua_settop(L, 0);
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40 lua_newtable(L);
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jbe@145
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41 // create shadow table (leaving previously created table on stack position 1):
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42 json_regfetch(L, shadowtbl);
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43 lua_pushvalue(L, 1);
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44 lua_newtable(L);
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jbe@143
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45 lua_rawset(L, -3);
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46 } else {
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jbe@145
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47 // push shadow table on top of stack:
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48 json_regfetch(L, shadowtbl);
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49 lua_pushvalue(L, 1);
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50 lua_rawget(L, -2);
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51 // if shadow table does not exist:
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52 if (lua_isnil(L, -1)) {
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53 // create shadow table and leave it on top of stack:
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54 lua_newtable(L);
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55 lua_pushvalue(L, 1);
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56 lua_pushvalue(L, -2);
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57 lua_rawset(L, -5);
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58 }
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59 // move elements from original table to shadow table (that's expected on top of stack):
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60 for(lua_pushnil(L); lua_next(L, 1); lua_pop(L, 1)) {
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61 lua_pushvalue(L, -2);
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62 lua_pushnil(L);
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63 lua_rawset(L, 1);
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64 lua_pushvalue(L, -2);
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65 lua_pushvalue(L, -2);
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66 lua_rawset(L, -5);
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67 }
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68 }
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jbe@138
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69 // discard everything but table to return:
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70 lua_settop(L, 1);
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71 // set metatable:
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72 json_regfetchpointer(L, mt);
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73 lua_setmetatable(L, 1);
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74 // return table:
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75 return 1;
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76 }
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77
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78 // marks a table as JSON object:
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79 // (returns its modified argument or a new table if argument is nil)
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80 static int json_object(lua_State *L) {
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81 return json_mark(L, json_regpointer(objectmt));
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82 }
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83
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84 // marks a table as JSON array:
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85 // (returns its modified argument or a new table if argument is nil)
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86 static int json_array(lua_State *L) {
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87 return json_mark(L, json_regpointer(arraymt));
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88 }
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89
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jbe@145
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90 // internal states of JSON parser:
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91 #define JSON_STATE_VALUE 0
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92 #define JSON_STATE_OBJECT_KEY 1
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93 #define JSON_STATE_OBJECT_KEY_TERMINATOR 2
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94 #define JSON_STATE_OBJECT_VALUE 3
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95 #define JSON_STATE_OBJECT_SEPARATOR 4
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96 #define JSON_STATE_ARRAY_VALUE 5
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97 #define JSON_STATE_ARRAY_SEPARATOR 6
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98 #define JSON_STATE_END 7
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99
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100 // special Lua stack indicies for json_import function:
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101 #define json_import_objectmt_idx 2
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102 #define json_import_arraymt_idx 3
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103 #define json_import_shadowtbl_idx 4
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104 #define json_import_nullmark_idx 5
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105
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106 // decodes a JSON document:
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107 static int json_import(lua_State *L) {
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108 const char *str; // string to parse
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109 size_t total; // total length of string to parse
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110 size_t pos = 0; // current position in string to parse
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111 size_t level = 0; // nested levels of objects/arrays currently being processed
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112 int mode = JSON_STATE_VALUE; // state of parser (i.e. "what's expected next?")
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113 char c; // variable to store a single character to be processed
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114 luaL_Buffer luabuf; // Lua buffer to decode JSON string values
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115 char *cbuf; // C buffer to decode JSON string values
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116 size_t writepos; // write position of decoded strings in C buffer
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117 // stack shall only contain one function argument:
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118 lua_settop(L, 1);
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119 // push objectmt on stack position 2:
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120 json_regfetch(L, objectmt);
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121 // push arraymt on stack position 3:
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122 json_regfetch(L, arraymt);
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123 // push shadowtbl on stack position 4:
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124 json_regfetch(L, shadowtbl);
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jbe@145
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125 // push nullmark on stack position 5:
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126 json_pushlightref(L, nullmark);
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jbe@136
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127 // require string as first argument:
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128 str = luaL_checklstring(L, 1, &total);
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129 // if string contains a NULL byte, this is a syntax error
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130 if (strlen(str) != total) goto json_import_syntax_error;
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131 // main loop of parser:
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132 json_import_loop:
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133 // skip whitespace and store next character in variable 'c':
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134 while (c = str[pos],
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135 c == ' ' ||
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136 c == '\f' ||
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137 c == '\n' ||
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138 c == '\r' ||
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139 c == '\t' ||
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140 c == '\v'
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141 ) pos++;
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jbe@136
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142 // switch statement to handle certain (single) characters:
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jbe@121
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143 switch (c) {
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144 // handle end of JSON document:
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jbe@121
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145 case 0:
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jbe@136
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146 // if end of JSON document was expected, then return top element of stack as result:
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jbe@124
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147 if (mode == JSON_STATE_END) return 1;
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jbe@136
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148 // otherwise, the JSON document was malformed:
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149 json_import_unexpected_eof:
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150 lua_pushnil(L);
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151 if (level == 0) lua_pushliteral(L, "Empty string");
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152 else lua_pushliteral(L, "Unexpected end of JSON document");
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153 return 2;
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154 // new JSON object:
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jbe@121
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155 case '{':
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156 // if a JSON object is not expected here, then return an error:
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jbe@146
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157 if (
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158 mode != JSON_STATE_VALUE &&
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159 mode != JSON_STATE_OBJECT_VALUE &&
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160 mode != JSON_STATE_ARRAY_VALUE
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jbe@146
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161 ) goto json_import_syntax_error;
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jbe@136
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162 // create JSON object on stack:
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jbe@136
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163 lua_newtable(L);
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jbe@136
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164 // set metatable of JSON object:
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jbe@138
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165 lua_pushvalue(L, json_import_objectmt_idx);
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jbe@125
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166 lua_setmetatable(L, -2);
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jbe@136
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167 // create internal shadow table on stack:
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jbe@136
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168 lua_newtable(L);
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jbe@146
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169 // register internal shadow table:
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jbe@123
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170 lua_pushvalue(L, -2);
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jbe@123
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171 lua_pushvalue(L, -2);
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jbe@138
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172 lua_rawset(L, json_import_shadowtbl_idx);
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jbe@146
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173 // expect object key (or end of object) to follow:
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jbe@136
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174 mode = JSON_STATE_OBJECT_KEY;
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jbe@146
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175 // jump to common code for opening JSON object and JSON array:
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jbe@142
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176 goto json_import_open;
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jbe@136
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177 // new JSON array:
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jbe@121
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178 case '[':
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jbe@136
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179 // if a JSON array is not expected here, then return an error:
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jbe@146
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180 if (
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jbe@146
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181 mode != JSON_STATE_VALUE &&
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jbe@146
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182 mode != JSON_STATE_OBJECT_VALUE &&
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jbe@146
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183 mode != JSON_STATE_ARRAY_VALUE
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jbe@146
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184 ) goto json_import_syntax_error;
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jbe@136
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185 // create JSON array on stack:
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jbe@136
|
186 lua_newtable(L);
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jbe@136
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187 // set metatable of JSON array:
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jbe@138
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188 lua_pushvalue(L, json_import_arraymt_idx);
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jbe@125
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189 lua_setmetatable(L, -2);
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jbe@136
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190 // create internal shadow table on stack:
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jbe@136
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191 lua_newtable(L);
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jbe@146
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192 // register internal shadow table:
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jbe@123
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193 lua_pushvalue(L, -2);
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jbe@123
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194 lua_pushvalue(L, -2);
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jbe@138
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195 lua_rawset(L, json_import_shadowtbl_idx);
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jbe@140
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196 // add nil as key (needed to keep stack balance) and as magic to detect arrays:
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jbe@140
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197 lua_pushnil(L);
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jbe@146
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198 // expect array value (or end of array) to follow:
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jbe@142
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199 mode = JSON_STATE_ARRAY_VALUE;
|
jbe@142
|
200 // continue with common code for opening JSON object and JSON array:
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jbe@146
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201 // common code for opening JSON object or JSON array:
|
jbe@142
|
202 json_import_open:
|
jbe@142
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203 // limit nested levels:
|
jbe@142
|
204 if (level >= JSON_MAXDEPTH) {
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jbe@142
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205 lua_pushnil(L);
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jbe@142
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206 lua_pushliteral(L, "Too many nested JSON levels");
|
jbe@142
|
207 return 2;
|
jbe@142
|
208 }
|
jbe@142
|
209 // additional buffer overflow protection:
|
jbe@142
|
210 if (!lua_checkstack(L, LUA_MINSTACK))
|
jbe@142
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211 return luaL_error(L, "Caught stack overflow in JSON import function (too many nested levels and stack size too small)");
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jbe@136
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212 // increment level:
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jbe@121
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213 level++;
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jbe@142
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214 // consume input character:
|
jbe@142
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215 pos++;
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jbe@121
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216 goto json_import_loop;
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jbe@136
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217 // end of JSON object:
|
jbe@121
|
218 case '}':
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jbe@136
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219 // if end of JSON object is not expected here, then return an error:
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jbe@146
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220 if (
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jbe@146
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221 mode != JSON_STATE_OBJECT_KEY &&
|
jbe@146
|
222 mode != JSON_STATE_OBJECT_SEPARATOR
|
jbe@146
|
223 ) goto json_import_syntax_error;
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jbe@136
|
224 // jump to common code for end of JSON object and JSON array:
|
jbe@121
|
225 goto json_import_close;
|
jbe@136
|
226 // end of JSON array:
|
jbe@121
|
227 case ']':
|
jbe@136
|
228 // if end of JSON array is not expected here, then return an error:
|
jbe@146
|
229 if (
|
jbe@146
|
230 mode != JSON_STATE_ARRAY_VALUE &&
|
jbe@146
|
231 mode != JSON_STATE_ARRAY_SEPARATOR
|
jbe@146
|
232 ) goto json_import_syntax_error;
|
jbe@146
|
233 // pop nil key/magic (that was needed to keep stack balance):
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jbe@140
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234 lua_pop(L, 1);
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jbe@136
|
235 // continue with common code for end of JSON object and JSON array:
|
jbe@136
|
236 // common code for end of JSON object or JSON array:
|
jbe@121
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237 json_import_close:
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jbe@136
|
238 // consume input character:
|
jbe@121
|
239 pos++;
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jbe@136
|
240 // pop shadow table:
|
jbe@136
|
241 lua_pop(L, 1);
|
jbe@136
|
242 // check if nested:
|
jbe@121
|
243 if (--level) {
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jbe@146
|
244 // if nested,
|
jbe@146
|
245 // check if outer(!) structure is an array or object:
|
jbe@140
|
246 if (lua_isnil(L, -2)) {
|
jbe@136
|
247 // select array value processing:
|
jbe@124
|
248 mode = JSON_STATE_ARRAY_VALUE;
|
jbe@121
|
249 } else {
|
jbe@136
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250 // select object value processing:
|
jbe@124
|
251 mode = JSON_STATE_OBJECT_VALUE;
|
jbe@121
|
252 }
|
jbe@136
|
253 // store value in outer structure:
|
jbe@121
|
254 goto json_import_process_value;
|
jbe@121
|
255 }
|
jbe@136
|
256 // if not nested, then expect end of JSON document and continue with loop:
|
jbe@136
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257 mode = JSON_STATE_END;
|
jbe@121
|
258 goto json_import_loop;
|
jbe@136
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259 // key terminator:
|
jbe@121
|
260 case ':':
|
jbe@136
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261 // if key terminator is not expected here, then return an error:
|
jbe@124
|
262 if (mode != JSON_STATE_OBJECT_KEY_TERMINATOR)
|
jbe@121
|
263 goto json_import_syntax_error;
|
jbe@136
|
264 // consume input character:
|
jbe@121
|
265 pos++;
|
jbe@146
|
266 // expect object value to follow:
|
jbe@124
|
267 mode = JSON_STATE_OBJECT_VALUE;
|
jbe@146
|
268 // continue with loop:
|
jbe@121
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269 goto json_import_loop;
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jbe@136
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270 // value terminator (NOTE: trailing comma at end of value or key-value list is tolerated by this parser)
|
jbe@121
|
271 case ',':
|
jbe@146
|
272 // branch according to parser state:
|
jbe@124
|
273 if (mode == JSON_STATE_OBJECT_SEPARATOR) {
|
jbe@146
|
274 // expect an object key to follow:
|
jbe@124
|
275 mode = JSON_STATE_OBJECT_KEY;
|
jbe@124
|
276 } else if (mode == JSON_STATE_ARRAY_SEPARATOR) {
|
jbe@146
|
277 // expect an array value to follow:
|
jbe@124
|
278 mode = JSON_STATE_ARRAY_VALUE;
|
jbe@121
|
279 } else {
|
jbe@136
|
280 // if value terminator is not expected here, then return an error:
|
jbe@136
|
281 goto json_import_syntax_error;
|
jbe@121
|
282 }
|
jbe@136
|
283 // consume input character:
|
jbe@121
|
284 pos++;
|
jbe@136
|
285 // continue with loop:
|
jbe@121
|
286 goto json_import_loop;
|
jbe@136
|
287 // string literal:
|
jbe@121
|
288 case '"':
|
jbe@146
|
289 // consume quote character:
|
jbe@146
|
290 pos++;
|
jbe@136
|
291 // prepare buffer to decode string (with maximum possible length) and set write position to zero:
|
jbe@121
|
292 cbuf = luaL_buffinitsize(L, &luabuf, total-pos);
|
jbe@121
|
293 writepos = 0;
|
jbe@146
|
294 // loop through the characters until encountering end quote:
|
jbe@121
|
295 while ((c = str[pos++]) != '"') {
|
jbe@121
|
296 if (c == 0) {
|
jbe@146
|
297 // handle unexpected end of JSON document:
|
jbe@121
|
298 goto json_import_unexpected_eof;
|
jbe@121
|
299 } else if (c < 32 || c == 127) {
|
jbe@136
|
300 // do not allow ASCII control characters:
|
jbe@136
|
301 // NOTE: illegal UTF-8 sequences and extended control characters are not sanitized
|
jbe@136
|
302 // by this parser to allow different encodings than Unicode
|
jbe@121
|
303 lua_pushnil(L);
|
jbe@121
|
304 lua_pushliteral(L, "Unexpected control character in JSON string");
|
jbe@121
|
305 return 2;
|
jbe@121
|
306 } else if (c == '\\') {
|
jbe@136
|
307 // read next char after backslash escape:
|
jbe@121
|
308 c = str[pos++];
|
jbe@121
|
309 switch (c) {
|
jbe@136
|
310 // unexpected end-of-string:
|
jbe@121
|
311 case 0:
|
jbe@121
|
312 goto json_import_unexpected_eof;
|
jbe@136
|
313 // unescaping of quotation mark, slash, and backslash:
|
jbe@121
|
314 case '"':
|
jbe@121
|
315 case '/':
|
jbe@121
|
316 case '\\':
|
jbe@121
|
317 cbuf[writepos++] = c;
|
jbe@121
|
318 break;
|
jbe@136
|
319 // unescaping of backspace:
|
jbe@146
|
320 case 'b': cbuf[writepos++] = '\b'; break;
|
jbe@136
|
321 // unescaping of form-feed:
|
jbe@146
|
322 case 'f': cbuf[writepos++] = '\f'; break;
|
jbe@136
|
323 // unescaping of new-line:
|
jbe@146
|
324 case 'n': cbuf[writepos++] = '\n'; break;
|
jbe@136
|
325 // unescaping of carriage-return:
|
jbe@146
|
326 case 'r': cbuf[writepos++] = '\r'; break;
|
jbe@136
|
327 // unescaping of tabulator:
|
jbe@146
|
328 case 't': cbuf[writepos++] = '\t'; break;
|
jbe@136
|
329 // unescaping of UTF-16 characters
|
jbe@121
|
330 case 'u':
|
jbe@121
|
331 lua_pushnil(L);
|
jbe@121
|
332 lua_pushliteral(L, "JSON unicode escape sequences are not implemented yet"); // TODO
|
jbe@121
|
333 return 2;
|
jbe@136
|
334 // unexpected escape sequence:
|
jbe@121
|
335 default:
|
jbe@121
|
336 lua_pushnil(L);
|
jbe@121
|
337 lua_pushliteral(L, "Unexpected string escape sequence in JSON document");
|
jbe@121
|
338 return 2;
|
jbe@121
|
339 }
|
jbe@121
|
340 } else {
|
jbe@136
|
341 // normal character:
|
jbe@121
|
342 cbuf[writepos++] = c;
|
jbe@121
|
343 }
|
jbe@121
|
344 }
|
jbe@136
|
345 // process buffer to Lua string:
|
jbe@121
|
346 luaL_pushresultsize(&luabuf, writepos);
|
jbe@136
|
347 // continue with processing of decoded string:
|
jbe@121
|
348 goto json_import_process_value;
|
jbe@121
|
349 }
|
jbe@136
|
350 // process values whose type is is not deducible from a single character:
|
jbe@136
|
351 if ((c >= '0' && c <= '9') || c == '-' || c == '+') {
|
jbe@146
|
352 // for numbers,
|
jbe@146
|
353 // use strtod() call to parse a (double precision) floating point number:
|
jbe@122
|
354 char *endptr;
|
jbe@122
|
355 double numval;
|
jbe@122
|
356 numval = strtod(str+pos, &endptr);
|
jbe@146
|
357 // catch parsing errors:
|
jbe@122
|
358 if (endptr == str+pos) goto json_import_syntax_error;
|
jbe@146
|
359 // consume characters that were parsed:
|
jbe@122
|
360 pos += endptr - (str+pos);
|
jbe@146
|
361 // push parsed (double precision) floating point number on Lua stack:
|
jbe@122
|
362 lua_pushnumber(L, numval);
|
jbe@122
|
363 } else if (!strncmp(str+pos, "true", 4)) {
|
jbe@136
|
364 // consume 4 input characters for "true":
|
jbe@121
|
365 pos += 4;
|
jbe@136
|
366 // put Lua true value on stack:
|
jbe@136
|
367 lua_pushboolean(L, 1);
|
jbe@121
|
368 } else if (!strncmp(str+pos, "false", 5)) {
|
jbe@136
|
369 // consume 5 input characters for "false":
|
jbe@121
|
370 pos += 5;
|
jbe@136
|
371 // put Lua false value on stack:
|
jbe@136
|
372 lua_pushboolean(L, 0);
|
jbe@121
|
373 } else if (!strncmp(str+pos, "null", 4)) {
|
jbe@136
|
374 // consume 4 input characters for "null":
|
jbe@136
|
375 pos += 4;
|
jbe@136
|
376 // put special null-marker on stack:
|
jbe@138
|
377 lua_pushvalue(L, json_import_nullmark_idx);
|
jbe@121
|
378 } else {
|
jbe@136
|
379 // all other cases are a syntax error:
|
jbe@121
|
380 goto json_import_syntax_error;
|
jbe@121
|
381 }
|
jbe@136
|
382 // process a decoded value or key value pair (expected on top of Lua stack):
|
jbe@136
|
383 json_import_process_value:
|
jbe@121
|
384 switch (mode) {
|
jbe@136
|
385 // an object key has been read:
|
jbe@124
|
386 case JSON_STATE_OBJECT_KEY:
|
jbe@136
|
387 // if an object key is not a string, then this is a syntax error:
|
jbe@121
|
388 if (lua_type(L, -1) != LUA_TSTRING) goto json_import_syntax_error;
|
jbe@146
|
389 // expect key terminator to follow:
|
jbe@124
|
390 mode = JSON_STATE_OBJECT_KEY_TERMINATOR;
|
jbe@146
|
391 // continue with loop:
|
jbe@121
|
392 goto json_import_loop;
|
jbe@136
|
393 // a key value pair has been read:
|
jbe@124
|
394 case JSON_STATE_OBJECT_VALUE:
|
jbe@136
|
395 // store key value pair in outer shadow table:
|
jbe@130
|
396 lua_rawset(L, -3);
|
jbe@146
|
397 // expect value terminator (or end of object) to follow:
|
jbe@124
|
398 mode = JSON_STATE_OBJECT_SEPARATOR;
|
jbe@146
|
399 // continue with loop:
|
jbe@121
|
400 goto json_import_loop;
|
jbe@136
|
401 // an array value has been read:
|
jbe@124
|
402 case JSON_STATE_ARRAY_VALUE:
|
jbe@136
|
403 // store value in outer shadow table:
|
jbe@140
|
404 lua_rawseti(L, -3, lua_rawlen(L, -3) + 1);
|
jbe@146
|
405 // expect value terminator (or end of object) to follow:
|
jbe@124
|
406 mode = JSON_STATE_ARRAY_SEPARATOR;
|
jbe@146
|
407 // continue with loop
|
jbe@121
|
408 goto json_import_loop;
|
jbe@136
|
409 // a single value has been read:
|
jbe@124
|
410 case JSON_STATE_VALUE:
|
jbe@136
|
411 // leave value on top of stack, expect end of JSON document, and continue with loop:
|
jbe@124
|
412 mode = JSON_STATE_END;
|
jbe@121
|
413 goto json_import_loop;
|
jbe@121
|
414 }
|
jbe@146
|
415 // syntax error handling (reachable by goto statement):
|
jbe@136
|
416 json_import_syntax_error:
|
jbe@121
|
417 lua_pushnil(L);
|
jbe@121
|
418 lua_pushliteral(L, "Syntax error in JSON document");
|
jbe@121
|
419 return 2;
|
jbe@121
|
420 }
|
jbe@121
|
421
|
jbe@146
|
422 // special Lua stack indicies for json_path function:
|
jbe@138
|
423 #define json_path_shadowtbl_idx 1
|
jbe@138
|
424 #define json_path_nullmark_idx 2
|
jbe@146
|
425
|
jbe@146
|
426 // stack offset of arguments to json_path function:
|
jbe@138
|
427 #define json_path_idxshift 2
|
jbe@138
|
428
|
jbe@146
|
429 // gets a value or its type from a JSON document (passed as first argument)
|
jbe@146
|
430 // optionally using a path (passed as variable number of keys after first argument):
|
jbe@137
|
431 static int json_path(lua_State *L, int type_mode) {
|
jbe@146
|
432 int stacktop; // stack index of top of stack (after shifting)
|
jbe@146
|
433 int idx = 2 + json_path_idxshift; // stack index of current argument to process
|
jbe@146
|
434 // insert json_shadowtbl on stack at position 1 (shifting the arguments):
|
jbe@144
|
435 json_regfetch(L, shadowtbl);
|
jbe@138
|
436 lua_insert(L, 1);
|
jbe@146
|
437 // insert json_nullmark on stack at position 2 (shifting the arguments):
|
jbe@145
|
438 json_pushlightref(L, nullmark);
|
jbe@138
|
439 lua_insert(L, 2);
|
jbe@146
|
440 // store stack index of top of stack:
|
jbe@138
|
441 stacktop = lua_gettop(L);
|
jbe@146
|
442 // use first argument as "current value" (stored on top of stack):
|
jbe@138
|
443 lua_pushvalue(L, 1 + json_path_idxshift);
|
jbe@146
|
444 // process each "path key" (2nd argument and following arguments):
|
jbe@138
|
445 while (idx <= stacktop) {
|
jbe@146
|
446 // if "current value" (on top of stack) is nil, then the path cannot be walked and nil is returned:
|
jbe@137
|
447 if (lua_isnil(L, -1)) return 1;
|
jbe@137
|
448 // try to get shadow table of "current value":
|
jbe@130
|
449 lua_pushvalue(L, -1);
|
jbe@138
|
450 lua_rawget(L, json_path_shadowtbl_idx);
|
jbe@126
|
451 if (lua_isnil(L, -1)) {
|
jbe@137
|
452 // if no shadow table is found,
|
jbe@130
|
453 if (lua_type(L, -1) == LUA_TTABLE) {
|
jbe@146
|
454 // and if "current value" is a table,
|
jbe@146
|
455 // drop nil from stack:
|
jbe@146
|
456 lua_pop(L, 1);
|
jbe@137
|
457 // get "next value" using the "path key":
|
jbe@130
|
458 lua_pushvalue(L, idx++);
|
jbe@130
|
459 lua_gettable(L, -2);
|
jbe@130
|
460 } else {
|
jbe@137
|
461 // if "current value" is not a table,
|
jbe@146
|
462 // then the path cannot be walked and nil (already on top of stack) is returned:
|
jbe@137
|
463 return 1;
|
jbe@130
|
464 }
|
jbe@130
|
465 } else {
|
jbe@137
|
466 // if a shadow table is found,
|
jbe@137
|
467 // set "current value" to its shadow table:
|
jbe@130
|
468 lua_replace(L, -2);
|
jbe@137
|
469 // get "next value" using the "path key":
|
jbe@130
|
470 lua_pushvalue(L, idx++);
|
jbe@130
|
471 lua_rawget(L, -2);
|
jbe@126
|
472 }
|
jbe@137
|
473 // the "next value" replaces the "current value":
|
jbe@130
|
474 lua_replace(L, -2);
|
jbe@126
|
475 }
|
jbe@137
|
476 if (!type_mode) {
|
jbe@137
|
477 // if a value (and not its type) was requested,
|
jbe@137
|
478 // check if value is the null-marker, and store nil on top of Lua stack in that case:
|
jbe@138
|
479 if (lua_rawequal(L, -1, json_path_nullmark_idx)) lua_pushnil(L);
|
jbe@137
|
480 } else {
|
jbe@137
|
481 // if the type was requested,
|
jbe@137
|
482 // check if value is the null-marker:
|
jbe@138
|
483 if (lua_rawequal(L, -1, json_path_nullmark_idx)) {
|
jbe@137
|
484 // if yes, store string "null" on top of Lua stack:
|
jbe@130
|
485 lua_pushliteral(L, "null");
|
jbe@137
|
486 } else {
|
jbe@137
|
487 // otherwise,
|
jbe@138
|
488 // check if metatable indicates "object" or "array":
|
jbe@138
|
489 if (lua_getmetatable(L, -1)) {
|
jbe@144
|
490 json_regfetch(L, objectmt);
|
jbe@138
|
491 if (lua_rawequal(L, -2, -1)) {
|
jbe@146
|
492 // if value has metatable for JSON objects,
|
jbe@138
|
493 // return string "object":
|
jbe@138
|
494 lua_pushliteral(L, "object");
|
jbe@138
|
495 return 1;
|
jbe@138
|
496 }
|
jbe@144
|
497 json_regfetch(L, arraymt);
|
jbe@138
|
498 if (lua_rawequal(L, -3, -1)) {
|
jbe@146
|
499 // if value has metatable for JSON arrays,
|
jbe@146
|
500 // return string "object":
|
jbe@138
|
501 lua_pushliteral(L, "array");
|
jbe@138
|
502 return 1;
|
jbe@138
|
503 }
|
jbe@146
|
504 // remove 3 metatables (one of the value, two for comparison) from stack:
|
jbe@138
|
505 lua_pop(L, 3);
|
jbe@138
|
506 }
|
jbe@138
|
507 // otherwise, get the Lua type:
|
jbe@138
|
508 lua_pushstring(L, lua_typename(L, lua_type(L, -1)));
|
jbe@126
|
509 }
|
jbe@126
|
510 }
|
jbe@137
|
511 // return the top most value on the Lua stack:
|
jbe@137
|
512 return 1;
|
jbe@130
|
513 }
|
jbe@130
|
514
|
jbe@137
|
515 // gets a value from a JSON document (first argument)
|
jbe@137
|
516 // optionally using a path (variable number of keys after first argument):
|
jbe@130
|
517 static int json_get(lua_State *L) {
|
jbe@137
|
518 return json_path(L, 0);
|
jbe@130
|
519 }
|
jbe@130
|
520
|
jbe@137
|
521 // gets a value's type from a JSON document (first argument)
|
jbe@137
|
522 // optionally using a path (variable number of keys after first argument):
|
jbe@130
|
523 static int json_type(lua_State *L) {
|
jbe@137
|
524 return json_path(L, 1);
|
jbe@130
|
525 }
|
jbe@130
|
526
|
jbe@137
|
527 // checks if a value in a JSON document (first argument) is null:
|
jbe@130
|
528 static int json_isnull(lua_State *L) {
|
jbe@137
|
529 const char *jsontype;
|
jbe@138
|
530 lua_pushcfunction(L, json_type);
|
jbe@137
|
531 lua_insert(L, 1);
|
jbe@137
|
532 lua_call(L, lua_gettop(L) - 1, 1);
|
jbe@137
|
533 jsontype = lua_tostring(L, -1);
|
jbe@137
|
534 if (jsontype && !strcmp(jsontype, "null")) lua_pushboolean(L, 1);
|
jbe@137
|
535 else lua_pushboolean(L, 0);
|
jbe@137
|
536 return 1;
|
jbe@130
|
537 }
|
jbe@130
|
538
|
jbe@146
|
539 // special Lua stack indicies for json_setnull function:
|
jbe@138
|
540 #define json_setnull_unknownmt_idx 3
|
jbe@138
|
541 #define json_setnull_objectmt_idx 4
|
jbe@138
|
542 #define json_setnull_arraymt_idx 5
|
jbe@138
|
543 #define json_setnull_shadowtbl_idx 6
|
jbe@138
|
544
|
jbe@131
|
545 static int json_setnull(lua_State *L) {
|
jbe@138
|
546 // truncate stack to two elements:
|
jbe@131
|
547 lua_settop(L, 2);
|
jbe@138
|
548 // push json_unknownmt to stack position 3:
|
jbe@144
|
549 json_regfetch(L, unknownmt);
|
jbe@138
|
550 // push json_objectmt to stack position 4:
|
jbe@144
|
551 json_regfetch(L, objectmt);
|
jbe@138
|
552 // push json_arraymt to stack position 5:
|
jbe@144
|
553 json_regfetch(L, arraymt);
|
jbe@138
|
554 // push json_shadowtbl to stack position 6:
|
jbe@144
|
555 json_regfetch(L, shadowtbl);
|
jbe@138
|
556 //
|
jbe@138
|
557 lua_getmetatable(L, 1);
|
jbe@138
|
558 if (
|
jbe@138
|
559 !lua_rawequal(L, -1, json_setnull_unknownmt_idx) &&
|
jbe@138
|
560 !lua_rawequal(L, -1, json_setnull_objectmt_idx) &&
|
jbe@138
|
561 !lua_rawequal(L, -1, json_setnull_arraymt_idx)
|
jbe@138
|
562 ) {
|
jbe@138
|
563 lua_pushvalue(L, json_setnull_unknownmt_idx);
|
jbe@138
|
564 lua_setmetatable(L, 1);
|
jbe@138
|
565 }
|
jbe@131
|
566 lua_pushvalue(L, 1);
|
jbe@138
|
567 lua_rawget(L, json_setnull_shadowtbl_idx);
|
jbe@131
|
568 if (lua_isnil(L, -1)) {
|
jbe@131
|
569 lua_newtable(L);
|
jbe@131
|
570 lua_pushvalue(L, 1);
|
jbe@131
|
571 lua_pushvalue(L, -2);
|
jbe@138
|
572 lua_rawset(L, json_setnull_shadowtbl_idx);
|
jbe@131
|
573 }
|
jbe@131
|
574 lua_pushvalue(L, 2);
|
jbe@145
|
575 json_pushlightref(L, nullmark);
|
jbe@131
|
576 lua_rawset(L, -3);
|
jbe@131
|
577 return 0;
|
jbe@131
|
578 }
|
jbe@131
|
579
|
jbe@130
|
580 static int json_len(lua_State *L) {
|
jbe@130
|
581 lua_settop(L, 1);
|
jbe@144
|
582 json_regfetch(L, shadowtbl);
|
jbe@130
|
583 lua_pushvalue(L, 1);
|
jbe@138
|
584 lua_rawget(L, -2);
|
jbe@138
|
585 lua_pushinteger(L, lua_rawlen(L, lua_isnil(L, -1) ? 1 : -1));
|
jbe@123
|
586 return 1;
|
jbe@123
|
587 }
|
jbe@123
|
588
|
jbe@146
|
589 // special Lua stack indicies for json_index function:
|
jbe@141
|
590 #define json_index_nullmark_idx 3
|
jbe@141
|
591 #define json_index_shadowtbl_idx 4
|
jbe@141
|
592
|
jbe@130
|
593 static int json_index(lua_State *L) {
|
jbe@130
|
594 lua_settop(L, 2);
|
jbe@145
|
595 json_pushlightref(L, nullmark); // on stack position 3
|
jbe@144
|
596 json_regfetch(L, shadowtbl);
|
jbe@130
|
597 lua_pushvalue(L, 1);
|
jbe@141
|
598 lua_rawget(L, json_index_shadowtbl_idx);
|
jbe@139
|
599 if (lua_isnil(L, -1)) return luaL_error(L, "Shadow table not found");
|
jbe@130
|
600 lua_pushvalue(L, 2);
|
jbe@130
|
601 lua_rawget(L, -2);
|
jbe@141
|
602 if (lua_rawequal(L, -1, json_index_nullmark_idx)) lua_pushnil(L);
|
jbe@127
|
603 return 1;
|
jbe@127
|
604 }
|
jbe@127
|
605
|
jbe@130
|
606 static int json_newindex(lua_State *L) {
|
jbe@130
|
607 lua_settop(L, 3);
|
jbe@144
|
608 json_regfetch(L, shadowtbl);
|
jbe@123
|
609 lua_pushvalue(L, 1);
|
jbe@143
|
610 lua_rawget(L, -2);
|
jbe@130
|
611 if (lua_isnil(L, -1)) return luaL_error(L, "Shadow table not found");
|
jbe@130
|
612 lua_replace(L, 1);
|
jbe@139
|
613 lua_settop(L, 3);
|
jbe@130
|
614 lua_rawset(L, 1);
|
jbe@121
|
615 return 1;
|
jbe@121
|
616 }
|
jbe@121
|
617
|
jbe@146
|
618 // special Lua stack indicies for json_pairs_iterfunc function:
|
jbe@139
|
619 #define json_pairs_iterfunc_nullmark_idx 3
|
jbe@139
|
620 #define json_pairs_iterfunc_shadowtbl_idx 4
|
jbe@139
|
621
|
jbe@135
|
622 static int json_pairs_iterfunc(lua_State *L) {
|
jbe@135
|
623 lua_settop(L, 2);
|
jbe@145
|
624 json_pushlightref(L, nullmark); // on stack position 3
|
jbe@144
|
625 json_regfetch(L, shadowtbl);
|
jbe@135
|
626 lua_pushvalue(L, 1);
|
jbe@139
|
627 lua_rawget(L, json_pairs_iterfunc_shadowtbl_idx);
|
jbe@135
|
628 if (lua_isnil(L, -1)) return luaL_error(L, "Shadow table not found");
|
jbe@135
|
629 lua_pushvalue(L, 2);
|
jbe@135
|
630 if (!lua_next(L, -2)) return 0;
|
jbe@139
|
631 if (lua_rawequal(L, -1, json_pairs_iterfunc_nullmark_idx)) {
|
jbe@135
|
632 lua_pop(L, 1);
|
jbe@135
|
633 lua_pushnil(L);
|
jbe@135
|
634 }
|
jbe@135
|
635 return 2;
|
jbe@135
|
636 }
|
jbe@135
|
637
|
jbe@135
|
638 static int json_pairs(lua_State *L) {
|
jbe@139
|
639 lua_pushcfunction(L, json_pairs_iterfunc);
|
jbe@135
|
640 lua_pushvalue(L, 1);
|
jbe@135
|
641 lua_pushnil(L);
|
jbe@135
|
642 return 3;
|
jbe@135
|
643 }
|
jbe@135
|
644
|
jbe@146
|
645 // special Lua stack indicies for json_ipairs_iterfunc function:
|
jbe@139
|
646 #define json_ipairs_iterfunc_nullmark_idx 3
|
jbe@139
|
647 #define json_ipairs_iterfunc_shadowtbl_idx 4
|
jbe@139
|
648
|
jbe@134
|
649 static int json_ipairs_iterfunc(lua_State *L) {
|
jbe@134
|
650 int idx;
|
jbe@134
|
651 lua_settop(L, 2);
|
jbe@145
|
652 json_pushlightref(L, nullmark); // on stack position 3
|
jbe@144
|
653 json_regfetch(L, shadowtbl);
|
jbe@134
|
654 idx = lua_tointeger(L, 2) + 1;
|
jbe@134
|
655 lua_pushvalue(L, 1);
|
jbe@139
|
656 lua_rawget(L, json_ipairs_iterfunc_shadowtbl_idx);
|
jbe@134
|
657 if (lua_isnil(L, -1)) return luaL_error(L, "Shadow table not found");
|
jbe@134
|
658 lua_rawgeti(L, -1, idx);
|
jbe@134
|
659 if (lua_isnil(L, -1)) return 0;
|
jbe@134
|
660 lua_pushinteger(L, idx);
|
jbe@139
|
661 if (lua_rawequal(L, -2, json_ipairs_iterfunc_nullmark_idx)) lua_pushnil(L);
|
jbe@134
|
662 else lua_pushvalue(L, -2);
|
jbe@134
|
663 return 2;
|
jbe@134
|
664 }
|
jbe@134
|
665
|
jbe@134
|
666 static int json_ipairs(lua_State *L) {
|
jbe@139
|
667 lua_pushcfunction(L, json_ipairs_iterfunc);
|
jbe@134
|
668 lua_pushvalue(L, 1);
|
jbe@134
|
669 lua_pushinteger(L, 0);
|
jbe@134
|
670 return 3;
|
jbe@134
|
671 }
|
jbe@134
|
672
|
jbe@121
|
673 static const struct luaL_Reg json_module_functions[] = {
|
jbe@133
|
674 {"object", json_object},
|
jbe@133
|
675 {"array", json_array},
|
jbe@121
|
676 {"import", json_import},
|
jbe@130
|
677 {"get", json_get},
|
jbe@127
|
678 {"type", json_type},
|
jbe@123
|
679 {"isnull", json_isnull},
|
jbe@131
|
680 {"setnull", json_setnull},
|
jbe@121
|
681 {NULL, NULL}
|
jbe@121
|
682 };
|
jbe@121
|
683
|
jbe@126
|
684 static const struct luaL_Reg json_metatable_functions[] = {
|
jbe@130
|
685 {"__len", json_len},
|
jbe@130
|
686 {"__index", json_index},
|
jbe@130
|
687 {"__newindex", json_newindex},
|
jbe@135
|
688 {"__pairs", json_pairs},
|
jbe@134
|
689 {"__ipairs", json_ipairs},
|
jbe@126
|
690 {NULL, NULL}
|
jbe@126
|
691 };
|
jbe@126
|
692
|
jbe@121
|
693 int luaopen_json(lua_State *L) {
|
jbe@126
|
694 lua_settop(L, 0);
|
jbe@138
|
695 lua_newtable(L); // library
|
jbe@138
|
696 lua_newtable(L);
|
jbe@138
|
697 luaL_setfuncs(L, json_metatable_functions, 0);
|
jbe@144
|
698 json_regstore(L, unknownmt);
|
jbe@138
|
699 lua_setfield(L, 1, "ambiguous_mt");
|
jbe@138
|
700 lua_newtable(L);
|
jbe@138
|
701 luaL_setfuncs(L, json_metatable_functions, 0);
|
jbe@144
|
702 json_regstore(L, objectmt);
|
jbe@138
|
703 lua_setfield(L, 1, "object_mt");
|
jbe@138
|
704 lua_newtable(L);
|
jbe@138
|
705 luaL_setfuncs(L, json_metatable_functions, 0);
|
jbe@144
|
706 json_regstore(L, arraymt);
|
jbe@138
|
707 lua_setfield(L, 1, "array_mt");
|
jbe@138
|
708 lua_newtable(L); // ephemeron table to store shadow tables for each JSON object/array to allow NULL values returned as nil
|
jbe@138
|
709 lua_newtable(L); // metatable for ephemeron table
|
jbe@121
|
710 lua_pushliteral(L, "__mode");
|
jbe@121
|
711 lua_pushliteral(L, "k");
|
jbe@138
|
712 lua_rawset(L, -3);
|
jbe@138
|
713 lua_setmetatable(L, -2);
|
jbe@144
|
714 json_regstore(L, shadowtbl);
|
jbe@138
|
715 lua_settop(L, 1);
|
jbe@138
|
716 luaL_setfuncs(L, json_module_functions, 0);
|
jbe@121
|
717 return 1;
|
jbe@121
|
718 }
|