1 | #ifndef JSMN_H
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2 | #define JSMN_H
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3 |
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4 | /**
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5 | * JSON type identifier. Basic types are:
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6 | * o Object
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7 | * o Array
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8 | * o String
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9 | * o Other primitive: number, boolean (true/false) or null
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10 | */
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11 | typedef enum
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12 | {
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13 | JSMN_PRIMITIVE = 0,
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14 | JSMN_OBJECT = 1,
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15 | JSMN_ARRAY = 2,
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16 | JSMN_STRING = 3
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17 | } jsmntype_t;
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18 |
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19 | typedef enum
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20 | {
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21 | // Not enough tokens were provided
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22 | JSMN_ERROR_NOMEM = -1,
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23 | // Invalid character inside JSON string
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24 | JSMN_ERROR_INVAL = -2,
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25 | // The string is not a full JSON packet, more bytes expected
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26 | JSMN_ERROR_PART = -3,
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27 | // Everything was fine
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28 | JSMN_SUCCESS = 0
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29 | } jsmnerr_t;
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30 |
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31 | /**
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32 | * JSON token description.
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33 | * @param type type (object, array, string etc.)
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34 | * @param start start position in JSON data string
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35 | * @param end end position in JSON data string
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36 | */
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37 | typedef struct
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38 | {
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39 | jsmntype_t type;
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40 | int start;
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41 | int end;
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42 | int size;
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43 | } jsmntok_t;
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44 |
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45 | /**
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46 | * JSON parser. Contains an array of token blocks available. Also stores
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47 | * the string being parsed now and current position in that string
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48 | */
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49 | typedef struct
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50 | {
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51 | unsigned int pos; // offset in the JSON string
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52 | int toknext; // next token to allocate
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53 | int toksuper; // suporior token node, e.g parent object or array
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54 | } jsmn_parser;
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55 |
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56 | /**
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57 | * Allocates a fresh unused token from the token pull.
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58 | */
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59 | static jsmntok_t *jsmn_alloc_token(jsmn_parser *parser, jsmntok_t *tokens, size_t num_tokens)
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60 | {
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61 | unsigned int i;
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62 | for(i = parser->toknext; i < num_tokens; i++)
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63 | {
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64 | if(tokens[i].start == -1 && tokens[i].end == -1)
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65 | {
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66 | parser->toknext = i + 1;
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67 | return &tokens[i];
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68 | }
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69 | }
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70 | return NULL;
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71 | }
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72 |
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73 | /**
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74 | * Fills token type and boundaries.
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75 | */
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76 | static void jsmn_fill_token(jsmntok_t *token, jsmntype_t type, int start, int end)
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77 | {
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78 | token->type = type;
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79 | token->start = start;
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80 | token->end = end;
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81 | token->size = 0;
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82 | }
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83 |
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84 | /**
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85 | * Fills next available token with JSON primitive.
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86 | */
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87 | static int jsmn_parse_primitive(jsmn_parser *parser, const char *js, jsmntok_t *tokens, size_t num_tokens)
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88 | {
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89 | jsmntok_t *token;
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90 | int start;
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91 |
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92 | start = parser->pos;
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93 |
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94 | for(; js[parser->pos] != '\0'; parser->pos++)
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95 | {
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96 | switch(js[parser->pos])
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97 | {
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98 | #ifndef JSMN_STRICT
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99 | // In strict mode primitive must be followed by "," or "}" or "]"
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100 | case '\t' : case '\r' : case '\n' : case ' ' : case ':':
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101 | #endif
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102 | case ',' : case ']' : case '}' :
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103 | goto found;
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104 | }
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105 | if(js[parser->pos] < 32 || js[parser->pos] >= 127)
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106 | {
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107 | parser->pos = start;
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108 | return JSMN_ERROR_INVAL;
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109 | }
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110 | }
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111 | #ifdef JSMN_STRICT
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112 | // In strict mode primitive must be followed by a comma/object/array
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113 | parser->pos = start;
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114 | return JSMN_ERROR_PART;
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115 | #endif
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116 |
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117 | found:
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118 | token = jsmn_alloc_token(parser, tokens, num_tokens);
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119 | if(token == NULL)
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120 | {
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121 | parser->pos = start;
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122 | return JSMN_ERROR_NOMEM;
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123 | }
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124 | jsmn_fill_token(token, JSMN_PRIMITIVE, start, parser->pos);
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125 | parser->pos--;
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126 | return JSMN_SUCCESS;
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127 | }
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128 |
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129 | /**
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130 | * Filsl next token with JSON string.
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131 | */
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132 | static int jsmn_parse_string(jsmn_parser *parser, const char *js, jsmntok_t *tokens, size_t num_tokens)
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133 | {
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134 | jsmntok_t *token;
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135 |
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136 | int start = parser->pos;
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137 |
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138 | parser->pos++;
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139 |
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140 | // Skip starting quote
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141 | for(; js[parser->pos] != '\0'; parser->pos++)
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142 | {
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143 | char c = js[parser->pos];
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144 |
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145 | // Quote: end of string
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146 | if(c == '\"')
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147 | {
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148 | token = jsmn_alloc_token(parser, tokens, num_tokens);
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149 | if(token == NULL)
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150 | {
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151 | parser->pos = start;
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152 | return JSMN_ERROR_NOMEM;
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153 | }
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154 | jsmn_fill_token(token, JSMN_STRING, start+1, parser->pos);
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155 | return JSMN_SUCCESS;
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156 | }
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157 |
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158 | // Backslash: Quoted symbol expected
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159 | if(c == '\\')
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160 | {
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161 | parser->pos++;
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162 | switch (js[parser->pos])
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163 | {
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164 | // Allowed escaped symbols
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165 | case '\"': case '/': case '\\': case 'b':
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166 | case 'f': case 'r': case 'n': case 't':
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167 | break;
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168 | // Allows escaped symbol \uXXXX
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169 | case 'u':
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170 | // TODO
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171 | break;
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172 | // Unexpected symbol
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173 | default:
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174 | parser->pos = start;
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175 | return JSMN_ERROR_INVAL;
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176 | }
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177 | }
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178 | }
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179 | parser->pos = start;
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180 | return JSMN_ERROR_PART;
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181 | }
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182 |
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183 | /**
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184 | * Parse JSON string and fill tokens.
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185 | */
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186 | jsmnerr_t jsmn_parse(jsmn_parser *parser, const char *js, jsmntok_t *tokens, unsigned int num_tokens)
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187 | {
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188 | int r;
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189 | int i;
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190 | jsmntok_t *token;
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191 |
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192 | // initialize the rest of tokens (they could be reallocated)
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193 | for(i = parser->toknext; i < num_tokens; i++)
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194 | jsmn_fill_token(&tokens[i], JSMN_PRIMITIVE, -1, -1);
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195 |
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196 | for(; js[parser->pos] != '\0'; parser->pos++)
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197 | {
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198 | char c;
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199 | jsmntype_t type;
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200 |
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201 | c = js[parser->pos];
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202 | switch(c)
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203 | {
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204 | case '{': case '[':
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205 | token = jsmn_alloc_token(parser, tokens, num_tokens);
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206 | if(token == NULL)
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207 | return JSMN_ERROR_NOMEM;
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208 | if(parser->toksuper != -1)
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209 | tokens[parser->toksuper].size++;
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210 | token->type = (c == '{' ? JSMN_OBJECT : JSMN_ARRAY);
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211 | token->start = parser->pos;
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212 | parser->toksuper = parser->toknext - 1;
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213 | break;
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214 | case '}': case ']':
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215 | type = (c == '}' ? JSMN_OBJECT : JSMN_ARRAY);
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216 | for(i = parser->toknext - 1; i >= 0; i--)
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217 | {
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218 | token = &tokens[i];
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219 | if(token->start != -1 && token->end == -1)
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220 | {
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221 | if(token->type != type)
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222 | return JSMN_ERROR_INVAL;
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223 |
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224 | parser->toksuper = -1;
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225 | token->end = parser->pos + 1;
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226 | break;
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227 | }
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228 | }
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229 | // Error if unmatched closing bracket
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230 | if(i == -1) return JSMN_ERROR_INVAL;
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231 | for(; i >= 0; i--)
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232 | {
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233 | token = &tokens[i];
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234 | if(token->start != -1 && token->end == -1)
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235 | {
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236 | parser->toksuper = i;
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237 | break;
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238 | }
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239 | }
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240 | break;
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241 | case '\"':
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242 | r = jsmn_parse_string(parser, js, tokens, num_tokens);
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243 | if(r < 0) return r;
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244 | if(parser->toksuper != -1)
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245 | tokens[parser->toksuper].size++;
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246 | break;
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247 | case '\t': case '\r': case '\n': case ':': case ',': case ' ':
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248 | break;
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249 | #ifdef JSMN_STRICT
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250 | // In strict mode primitives are: numbers and booleans
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251 | case '-': case '0': case '1': case '2': case '3': case '4':
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252 | case '5': case '6': case '7': case '8': case '9':
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253 | case 't': case 'f': case 'n':
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254 | #else
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255 | // In non-strict mode every unquoted value is a primitive
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256 | default:
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257 | #endif
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258 | r = jsmn_parse_primitive(parser, js, tokens, num_tokens);
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259 | if(r < 0) return r;
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260 | if(parser->toksuper != -1)
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261 | tokens[parser->toksuper].size++;
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262 | break;
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263 |
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264 | #ifdef JSMN_STRICT
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265 | // Unexpected char in strict mode
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266 | default:
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267 | return JSMN_ERROR_INVAL;
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268 | #endif
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269 |
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270 | }
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271 | }
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272 |
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273 | for(i = parser->toknext - 1; i >= 0; i--)
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274 | {
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275 | // Unmatched opened object or array */
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276 | if(tokens[i].start != -1 && tokens[i].end == -1)
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277 | return JSMN_ERROR_PART;
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278 | }
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279 |
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280 | return JSMN_SUCCESS;
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281 | }
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282 |
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283 | /**
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284 | * Creates a new parser based over a given buffer with an array of tokens
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285 | * available.
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286 | */
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287 | void jsmn_init(jsmn_parser *parser)
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288 | {
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289 | parser->pos = 0;
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290 | parser->toknext = 0;
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291 | parser->toksuper = -1;
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292 | }
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293 |
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294 | #endif
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