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| 1 | +#ifndef VM_JSON_H |
| 2 | +#define VM_JSON_H |
| 3 | + |
| 4 | +#ifdef __cplusplus |
| 5 | +extern "C" { |
| 6 | +#endif |
| 7 | + |
| 8 | +/* |
| 9 | + * Small header-only JSON tokenizer/parser for the VM. |
| 10 | + * |
| 11 | + * This is intentionally not a full DOM parser. It walks valid JSON tokens and |
| 12 | + * extracts string values by key without substring searching inside model text. |
| 13 | + */ |
| 14 | + |
| 15 | +char *vm_json_find_string_value(const char *json, const char *key); |
| 16 | + |
| 17 | +#ifdef __cplusplus |
| 18 | +} |
| 19 | +#endif |
| 20 | + |
| 21 | +#endif |
| 22 | + |
| 23 | +#if defined(VM_JSON_IMPLEMENTATION) && !defined(VM_JSON_IMPLEMENTED) |
| 24 | +#define VM_JSON_IMPLEMENTED |
| 25 | + |
| 26 | +#include <ctype.h> |
| 27 | +#include <stdlib.h> |
| 28 | +#include <string.h> |
| 29 | + |
| 30 | +typedef enum { |
| 31 | + VM_JSON_EOF = 0, |
| 32 | + VM_JSON_LBRACE, |
| 33 | + VM_JSON_RBRACE, |
| 34 | + VM_JSON_LBRACKET, |
| 35 | + VM_JSON_RBRACKET, |
| 36 | + VM_JSON_COLON, |
| 37 | + VM_JSON_COMMA, |
| 38 | + VM_JSON_STRING, |
| 39 | + VM_JSON_NUMBER, |
| 40 | + VM_JSON_TRUE, |
| 41 | + VM_JSON_FALSE, |
| 42 | + VM_JSON_NULL, |
| 43 | + VM_JSON_ERROR |
| 44 | +} VMJsonTokenKind; |
| 45 | + |
| 46 | +typedef struct { |
| 47 | + VMJsonTokenKind kind; |
| 48 | + char *text; |
| 49 | +} VMJsonToken; |
| 50 | + |
| 51 | +typedef struct { |
| 52 | + const char *src; |
| 53 | + size_t pos; |
| 54 | +} VMJsonParser; |
| 55 | + |
| 56 | +static char *vm_json_strdup_range(const char *start, size_t len) { |
| 57 | + char *out = (char *)malloc(len + 1); |
| 58 | + if (!out) return NULL; |
| 59 | + memcpy(out, start, len); |
| 60 | + out[len] = '\0'; |
| 61 | + return out; |
| 62 | +} |
| 63 | + |
| 64 | +static int vm_json_append_char(char **out, size_t *len, size_t *cap, char ch) { |
| 65 | + char *next; |
| 66 | + if (*len + 2 > *cap) { |
| 67 | + size_t next_cap = *cap ? *cap * 2 : 32; |
| 68 | + next = (char *)realloc(*out, next_cap); |
| 69 | + if (!next) return 0; |
| 70 | + *out = next; |
| 71 | + *cap = next_cap; |
| 72 | + } |
| 73 | + (*out)[(*len)++] = ch; |
| 74 | + (*out)[*len] = '\0'; |
| 75 | + return 1; |
| 76 | +} |
| 77 | + |
| 78 | +static void vm_json_skip_ws(VMJsonParser *parser) { |
| 79 | + while (parser->src[parser->pos] && isspace((unsigned char)parser->src[parser->pos])) { |
| 80 | + parser->pos++; |
| 81 | + } |
| 82 | +} |
| 83 | + |
| 84 | +static char *vm_json_read_string(VMJsonParser *parser) { |
| 85 | + char *out = NULL; |
| 86 | + size_t len = 0; |
| 87 | + size_t cap = 0; |
| 88 | + char ch; |
| 89 | + |
| 90 | + if (parser->src[parser->pos] != '"') return NULL; |
| 91 | + parser->pos++; |
| 92 | + while ((ch = parser->src[parser->pos++]) != '\0') { |
| 93 | + if (ch == '"') { |
| 94 | + return out ? out : vm_json_strdup_range("", 0); |
| 95 | + } |
| 96 | + if (ch == '\\') { |
| 97 | + ch = parser->src[parser->pos++]; |
| 98 | + switch (ch) { |
| 99 | + case '"': |
| 100 | + case '\\': |
| 101 | + case '/': |
| 102 | + if (!vm_json_append_char(&out, &len, &cap, ch)) goto oom; |
| 103 | + break; |
| 104 | + case 'b': |
| 105 | + if (!vm_json_append_char(&out, &len, &cap, '\b')) goto oom; |
| 106 | + break; |
| 107 | + case 'f': |
| 108 | + if (!vm_json_append_char(&out, &len, &cap, '\f')) goto oom; |
| 109 | + break; |
| 110 | + case 'n': |
| 111 | + if (!vm_json_append_char(&out, &len, &cap, '\n')) goto oom; |
| 112 | + break; |
| 113 | + case 'r': |
| 114 | + if (!vm_json_append_char(&out, &len, &cap, '\r')) goto oom; |
| 115 | + break; |
| 116 | + case 't': |
| 117 | + if (!vm_json_append_char(&out, &len, &cap, '\t')) goto oom; |
| 118 | + break; |
| 119 | + case 'u': |
| 120 | + /* Keep unicode escapes stable without pretending to decode UTF-16. */ |
| 121 | + if (!vm_json_append_char(&out, &len, &cap, '\\')) goto oom; |
| 122 | + if (!vm_json_append_char(&out, &len, &cap, 'u')) goto oom; |
| 123 | + for (int i = 0; i < 4; i++) { |
| 124 | + ch = parser->src[parser->pos++]; |
| 125 | + if (!isxdigit((unsigned char)ch)) goto oom; |
| 126 | + if (!vm_json_append_char(&out, &len, &cap, ch)) goto oom; |
| 127 | + } |
| 128 | + break; |
| 129 | + default: |
| 130 | + goto oom; |
| 131 | + } |
| 132 | + } else { |
| 133 | + if ((unsigned char)ch < 0x20) goto oom; |
| 134 | + if (!vm_json_append_char(&out, &len, &cap, ch)) goto oom; |
| 135 | + } |
| 136 | + } |
| 137 | + |
| 138 | +oom: |
| 139 | + free(out); |
| 140 | + return NULL; |
| 141 | +} |
| 142 | + |
| 143 | +static int vm_json_match_literal(VMJsonParser *parser, const char *literal) { |
| 144 | + size_t len = strlen(literal); |
| 145 | + if (strncmp(parser->src + parser->pos, literal, len) != 0) return 0; |
| 146 | + parser->pos += len; |
| 147 | + return 1; |
| 148 | +} |
| 149 | + |
| 150 | +static VMJsonToken vm_json_next(VMJsonParser *parser) { |
| 151 | + VMJsonToken token; |
| 152 | + const char *start; |
| 153 | + char ch; |
| 154 | + memset(&token, 0, sizeof(token)); |
| 155 | + vm_json_skip_ws(parser); |
| 156 | + ch = parser->src[parser->pos]; |
| 157 | + if (!ch) { |
| 158 | + token.kind = VM_JSON_EOF; |
| 159 | + return token; |
| 160 | + } |
| 161 | + parser->pos++; |
| 162 | + switch (ch) { |
| 163 | + case '{': token.kind = VM_JSON_LBRACE; return token; |
| 164 | + case '}': token.kind = VM_JSON_RBRACE; return token; |
| 165 | + case '[': token.kind = VM_JSON_LBRACKET; return token; |
| 166 | + case ']': token.kind = VM_JSON_RBRACKET; return token; |
| 167 | + case ':': token.kind = VM_JSON_COLON; return token; |
| 168 | + case ',': token.kind = VM_JSON_COMMA; return token; |
| 169 | + case '"': |
| 170 | + parser->pos--; |
| 171 | + token.kind = VM_JSON_STRING; |
| 172 | + token.text = vm_json_read_string(parser); |
| 173 | + if (!token.text) token.kind = VM_JSON_ERROR; |
| 174 | + return token; |
| 175 | + case 't': |
| 176 | + parser->pos--; |
| 177 | + token.kind = vm_json_match_literal(parser, "true") ? VM_JSON_TRUE : VM_JSON_ERROR; |
| 178 | + return token; |
| 179 | + case 'f': |
| 180 | + parser->pos--; |
| 181 | + token.kind = vm_json_match_literal(parser, "false") ? VM_JSON_FALSE : VM_JSON_ERROR; |
| 182 | + return token; |
| 183 | + case 'n': |
| 184 | + parser->pos--; |
| 185 | + token.kind = vm_json_match_literal(parser, "null") ? VM_JSON_NULL : VM_JSON_ERROR; |
| 186 | + return token; |
| 187 | + default: |
| 188 | + if (ch == '-' || isdigit((unsigned char)ch)) { |
| 189 | + parser->pos--; |
| 190 | + start = parser->src + parser->pos; |
| 191 | + if (parser->src[parser->pos] == '-') parser->pos++; |
| 192 | + while (isdigit((unsigned char)parser->src[parser->pos])) parser->pos++; |
| 193 | + if (parser->src[parser->pos] == '.') { |
| 194 | + parser->pos++; |
| 195 | + while (isdigit((unsigned char)parser->src[parser->pos])) parser->pos++; |
| 196 | + } |
| 197 | + if (parser->src[parser->pos] == 'e' || parser->src[parser->pos] == 'E') { |
| 198 | + parser->pos++; |
| 199 | + if (parser->src[parser->pos] == '+' || parser->src[parser->pos] == '-') parser->pos++; |
| 200 | + while (isdigit((unsigned char)parser->src[parser->pos])) parser->pos++; |
| 201 | + } |
| 202 | + token.kind = VM_JSON_NUMBER; |
| 203 | + token.text = vm_json_strdup_range(start, (size_t)(parser->src + parser->pos - start)); |
| 204 | + if (!token.text) token.kind = VM_JSON_ERROR; |
| 205 | + return token; |
| 206 | + } |
| 207 | + token.kind = VM_JSON_ERROR; |
| 208 | + return token; |
| 209 | + } |
| 210 | +} |
| 211 | + |
| 212 | +static void vm_json_free_token(VMJsonToken *token) { |
| 213 | + if (!token) return; |
| 214 | + free(token->text); |
| 215 | + token->text = NULL; |
| 216 | +} |
| 217 | + |
| 218 | +static int vm_json_search_from_token(VMJsonParser *parser, VMJsonToken token, const char *key, char **out); |
| 219 | + |
| 220 | +static int vm_json_search_object(VMJsonParser *parser, const char *key, char **out) { |
| 221 | + for (;;) { |
| 222 | + VMJsonToken name = vm_json_next(parser); |
| 223 | + VMJsonToken colon; |
| 224 | + VMJsonToken value; |
| 225 | + int matched; |
| 226 | + |
| 227 | + if (name.kind == VM_JSON_RBRACE) return 0; |
| 228 | + if (name.kind != VM_JSON_STRING) { |
| 229 | + vm_json_free_token(&name); |
| 230 | + return 0; |
| 231 | + } |
| 232 | + colon = vm_json_next(parser); |
| 233 | + if (colon.kind != VM_JSON_COLON) { |
| 234 | + vm_json_free_token(&name); |
| 235 | + return 0; |
| 236 | + } |
| 237 | + value = vm_json_next(parser); |
| 238 | + matched = strcmp(name.text, key) == 0; |
| 239 | + vm_json_free_token(&name); |
| 240 | + if (matched && value.kind == VM_JSON_STRING) { |
| 241 | + *out = value.text; |
| 242 | + value.text = NULL; |
| 243 | + return 1; |
| 244 | + } |
| 245 | + if (vm_json_search_from_token(parser, value, key, out)) return 1; |
| 246 | + value = vm_json_next(parser); |
| 247 | + if (value.kind == VM_JSON_RBRACE) return 0; |
| 248 | + if (value.kind != VM_JSON_COMMA) { |
| 249 | + vm_json_free_token(&value); |
| 250 | + return 0; |
| 251 | + } |
| 252 | + } |
| 253 | +} |
| 254 | + |
| 255 | +static int vm_json_search_array(VMJsonParser *parser, const char *key, char **out) { |
| 256 | + for (;;) { |
| 257 | + VMJsonToken value = vm_json_next(parser); |
| 258 | + if (value.kind == VM_JSON_RBRACKET) return 0; |
| 259 | + if (vm_json_search_from_token(parser, value, key, out)) return 1; |
| 260 | + value = vm_json_next(parser); |
| 261 | + if (value.kind == VM_JSON_RBRACKET) return 0; |
| 262 | + if (value.kind != VM_JSON_COMMA) { |
| 263 | + vm_json_free_token(&value); |
| 264 | + return 0; |
| 265 | + } |
| 266 | + } |
| 267 | +} |
| 268 | + |
| 269 | +static int vm_json_search_from_token(VMJsonParser *parser, VMJsonToken token, const char *key, char **out) { |
| 270 | + switch (token.kind) { |
| 271 | + case VM_JSON_LBRACE: |
| 272 | + return vm_json_search_object(parser, key, out); |
| 273 | + case VM_JSON_LBRACKET: |
| 274 | + return vm_json_search_array(parser, key, out); |
| 275 | + case VM_JSON_STRING: |
| 276 | + case VM_JSON_NUMBER: |
| 277 | + vm_json_free_token(&token); |
| 278 | + return 0; |
| 279 | + default: |
| 280 | + return 0; |
| 281 | + } |
| 282 | +} |
| 283 | + |
| 284 | +char *vm_json_find_string_value(const char *json, const char *key) { |
| 285 | + VMJsonParser parser; |
| 286 | + VMJsonToken token; |
| 287 | + char *out = NULL; |
| 288 | + |
| 289 | + if (!json || !key || !*key) return NULL; |
| 290 | + parser.src = json; |
| 291 | + parser.pos = 0; |
| 292 | + token = vm_json_next(&parser); |
| 293 | + if (vm_json_search_from_token(&parser, token, key, &out)) return out; |
| 294 | + return NULL; |
| 295 | +} |
| 296 | + |
| 297 | +#endif |
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