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annotate libraries/json/json.c @ 121:9ad1165cf3a1

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Started work on a JSON library
author jbe
date Fri Jul 25 22:25:53 2014 +0200 (2014-07-25)
parents
children ff39d4a310b9
rev   line source
jbe@121 1 #include <lua.h>
jbe@121 2 #include <lauxlib.h>
jbe@121 3 #include <string.h>
jbe@121 4
jbe@121 5 #define JSON_VALUE 0
jbe@121 6 #define JSON_OBJECT_KEY 1
jbe@121 7 #define JSON_OBJECT_KEY_TERMINATOR 2
jbe@121 8 #define JSON_OBJECT_VALUE 3
jbe@121 9 #define JSON_OBJECT_SEPARATOR 4
jbe@121 10 #define JSON_ARRAY_VALUE 5
jbe@121 11 #define JSON_ARRAY_SEPARATOR 6
jbe@121 12 #define JSON_END 7
jbe@121 13
jbe@121 14 static int json_import(lua_State *L) {
jbe@121 15 const char *str;
jbe@121 16 size_t total;
jbe@121 17 size_t pos = 0;
jbe@121 18 size_t level = 0;
jbe@121 19 int mode = JSON_VALUE;
jbe@121 20 char c;
jbe@121 21 luaL_Buffer luabuf;
jbe@121 22 char *cbuf;
jbe@121 23 size_t writepos;
jbe@121 24 int aryidx;
jbe@121 25 lua_settop(L, 1);
jbe@121 26 str = lua_tostring(L, 1);
jbe@121 27 total = strlen(str);
jbe@121 28 json_import_loop:
jbe@121 29 while (c = str[pos], c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == '\f') pos++;
jbe@121 30 switch (c) {
jbe@121 31 case 0:
jbe@121 32 if (mode == JSON_END) return 1;
jbe@121 33 json_import_unexpected_eof:
jbe@121 34 lua_pushnil(L);
jbe@121 35 if (level == 0) lua_pushliteral(L, "Empty string");
jbe@121 36 else lua_pushliteral(L, "Unexpected end of JSON document");
jbe@121 37 return 2;
jbe@121 38 case '{':
jbe@121 39 if (mode != JSON_VALUE && mode != JSON_OBJECT_VALUE && mode != JSON_ARRAY_VALUE)
jbe@121 40 goto json_import_syntax_error;
jbe@121 41 pos++;
jbe@121 42 lua_newtable(L);
jbe@121 43 mode = JSON_OBJECT_KEY;
jbe@121 44 level++;
jbe@121 45 goto json_import_loop;
jbe@121 46 case '[':
jbe@121 47 if (mode != JSON_VALUE && mode != JSON_OBJECT_VALUE && mode != JSON_ARRAY_VALUE)
jbe@121 48 goto json_import_syntax_error;
jbe@121 49 pos++;
jbe@121 50 lua_newtable(L);
jbe@121 51 lua_pushinteger(L, 0); // length of array (since it may contain nil's)
jbe@121 52 mode = JSON_ARRAY_VALUE;
jbe@121 53 level++;
jbe@121 54 goto json_import_loop;
jbe@121 55 case '}':
jbe@121 56 if (mode != JSON_OBJECT_KEY && mode != JSON_OBJECT_SEPARATOR)
jbe@121 57 goto json_import_syntax_error;
jbe@121 58 goto json_import_close;
jbe@121 59 case ']':
jbe@121 60 if (mode != JSON_ARRAY_VALUE && mode != JSON_ARRAY_SEPARATOR)
jbe@121 61 goto json_import_syntax_error;
jbe@121 62 lua_pushvalue(L, -2); // use array table as key
jbe@121 63 lua_insert(L, -2); // use length of array as value
jbe@121 64 lua_rawset(L, lua_upvalueindex(1)); // store length in ephemeron table
jbe@121 65 // leaves array table on top of stack
jbe@121 66 json_import_close:
jbe@121 67 pos++;
jbe@121 68 if (--level) {
jbe@121 69 if (lua_type(L, -2) == LUA_TNUMBER) {
jbe@121 70 mode = JSON_ARRAY_VALUE;
jbe@121 71 } else {
jbe@121 72 mode = JSON_OBJECT_VALUE;
jbe@121 73 }
jbe@121 74 goto json_import_process_value;
jbe@121 75 } else {
jbe@121 76 mode = JSON_END;
jbe@121 77 }
jbe@121 78 goto json_import_loop;
jbe@121 79 case ':':
jbe@121 80 if (mode != JSON_OBJECT_KEY_TERMINATOR)
jbe@121 81 goto json_import_syntax_error;
jbe@121 82 pos++;
jbe@121 83 mode = JSON_OBJECT_VALUE;
jbe@121 84 goto json_import_loop;
jbe@121 85 case ',':
jbe@121 86 if (mode == JSON_OBJECT_SEPARATOR) {
jbe@121 87 mode = JSON_OBJECT_KEY;
jbe@121 88 } else if (mode == JSON_ARRAY_SEPARATOR) {
jbe@121 89 mode = JSON_ARRAY_VALUE;
jbe@121 90 } else {
jbe@121 91 goto json_import_syntax_error;
jbe@121 92 }
jbe@121 93 pos++;
jbe@121 94 goto json_import_loop;
jbe@121 95 case '"':
jbe@121 96 cbuf = luaL_buffinitsize(L, &luabuf, total-pos);
jbe@121 97 writepos = 0;
jbe@121 98 pos++;
jbe@121 99 while ((c = str[pos++]) != '"') {
jbe@121 100 if (c == 0) {
jbe@121 101 goto json_import_unexpected_eof;
jbe@121 102 } else if (c < 32 || c == 127) {
jbe@121 103 lua_pushnil(L);
jbe@121 104 lua_pushliteral(L, "Unexpected control character in JSON string");
jbe@121 105 return 2;
jbe@121 106 } else if (c == '\\') {
jbe@121 107 c = str[pos++];
jbe@121 108 switch (c) {
jbe@121 109 case 0:
jbe@121 110 goto json_import_unexpected_eof;
jbe@121 111 case '"':
jbe@121 112 case '/':
jbe@121 113 case '\\':
jbe@121 114 cbuf[writepos++] = c;
jbe@121 115 break;
jbe@121 116 case 'b':
jbe@121 117 cbuf[writepos++] = '\b';
jbe@121 118 break;
jbe@121 119 case 'f':
jbe@121 120 cbuf[writepos++] = '\f';
jbe@121 121 break;
jbe@121 122 case 'n':
jbe@121 123 cbuf[writepos++] = '\n';
jbe@121 124 break;
jbe@121 125 case 'r':
jbe@121 126 cbuf[writepos++] = '\r';
jbe@121 127 break;
jbe@121 128 case 't':
jbe@121 129 cbuf[writepos++] = '\t';
jbe@121 130 break;
jbe@121 131 case 'u':
jbe@121 132 lua_pushnil(L);
jbe@121 133 lua_pushliteral(L, "JSON unicode escape sequences are not implemented yet"); // TODO
jbe@121 134 return 2;
jbe@121 135 default:
jbe@121 136 lua_pushnil(L);
jbe@121 137 lua_pushliteral(L, "Unexpected string escape sequence in JSON document");
jbe@121 138 return 2;
jbe@121 139 }
jbe@121 140 } else {
jbe@121 141 cbuf[writepos++] = c;
jbe@121 142 }
jbe@121 143 }
jbe@121 144 if (!c) goto json_import_unexpected_eof;
jbe@121 145 luaL_pushresultsize(&luabuf, writepos);
jbe@121 146 goto json_import_process_value;
jbe@121 147 }
jbe@121 148 if (!strncmp(str+pos, "true", 4)) {
jbe@121 149 lua_pushboolean(L, 1);
jbe@121 150 pos += 4;
jbe@121 151 } else if (!strncmp(str+pos, "false", 5)) {
jbe@121 152 lua_pushboolean(L, 0);
jbe@121 153 pos += 5;
jbe@121 154 } else if (!strncmp(str+pos, "null", 4)) {
jbe@121 155 lua_pushnil(L);
jbe@121 156 pos += 4;
jbe@121 157 } else {
jbe@121 158 goto json_import_syntax_error;
jbe@121 159 }
jbe@121 160 json_import_process_value:
jbe@121 161 switch (mode) {
jbe@121 162 case JSON_OBJECT_KEY:
jbe@121 163 if (lua_type(L, -1) != LUA_TSTRING) goto json_import_syntax_error;
jbe@121 164 mode = JSON_OBJECT_KEY_TERMINATOR;
jbe@121 165 goto json_import_loop;
jbe@121 166 case JSON_OBJECT_VALUE:
jbe@121 167 lua_rawset(L, -3);
jbe@121 168 mode = JSON_OBJECT_SEPARATOR;
jbe@121 169 goto json_import_loop;
jbe@121 170 case JSON_ARRAY_VALUE:
jbe@121 171 aryidx = lua_tointeger(L, -2) + 1;
jbe@121 172 lua_rawseti(L, -3, aryidx);
jbe@121 173 lua_pop(L, 1);
jbe@121 174 lua_pushinteger(L, aryidx);
jbe@121 175 mode = JSON_ARRAY_SEPARATOR;
jbe@121 176 goto json_import_loop;
jbe@121 177 case JSON_VALUE:
jbe@121 178 mode = JSON_END;
jbe@121 179 goto json_import_loop;
jbe@121 180 }
jbe@121 181 json_import_syntax_error:
jbe@121 182 lua_pushnil(L);
jbe@121 183 lua_pushliteral(L, "Syntax error in JSON document");
jbe@121 184 return 2;
jbe@121 185 }
jbe@121 186
jbe@121 187 static int json_arylen(lua_State *L) {
jbe@121 188 lua_settop(L, 1);
jbe@121 189 lua_rawget(L, lua_upvalueindex(1));
jbe@121 190 return 1;
jbe@121 191 }
jbe@121 192
jbe@121 193 static const struct luaL_Reg json_module_functions[] = {
jbe@121 194 {"import", json_import},
jbe@121 195 {"arylen", json_arylen},
jbe@121 196 {NULL, NULL}
jbe@121 197 };
jbe@121 198
jbe@121 199 int luaopen_json(lua_State *L) {
jbe@121 200 lua_newtable(L); // library table
jbe@121 201 lua_newtable(L); // ephemeron table to store the length of arrays (that may contain nil's)
jbe@121 202 lua_newtable(L); // meta table for ephemeron table
jbe@121 203 lua_pushliteral(L, "__mode");
jbe@121 204 lua_pushliteral(L, "k");
jbe@121 205 lua_rawset(L, -3);
jbe@121 206 lua_setmetatable(L, -2);
jbe@121 207 luaL_setfuncs(L, json_module_functions, 1);
jbe@121 208 return 1;
jbe@121 209 }

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