jsmn.c

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#include "jsmn.h"

/**
 * Allocates a fresh unused token from the token pull.
 */
static jsmntok_t *jsmn_alloc_token(jsmn_parser *parser,
                jsmntok_t *tokens, size_t num_tokens) {
        jsmntok_t *tok;
        if (parser->toknext >= num_tokens) {
                return NULL;
        }
        tok = &tokens[parser->toknext++];
        tok->start = tok->end = -1;
        tok->size = 0;
#ifdef JSMN_PARENT_LINKS
        tok->parent = -1;
#endif
        return tok;
}

/**
 * Fills token type and boundaries.
 */
static void jsmn_fill_token(jsmntok_t *token, jsmntype_t type,
                            int start, int end) {
        token->type = type;
        token->start = start;
        token->end = end;
        token->size = 0;
}

/**
 * Fills next available token with JSON primitive.
 */
static int jsmn_parse_primitive(jsmn_parser *parser, const char *js,
                size_t len, jsmntok_t *tokens, size_t num_tokens) {
        jsmntok_t *token;
        int start;

        start = parser->pos;

        for (; parser->pos < len && js[parser->pos] != '\0'; parser->pos++) {
                switch (js[parser->pos]) {
#ifndef JSMN_STRICT
                        /* In strict mode primitive must be followed by "," or "}" or "]" */
                        case ':':
#endif
                        case '\t' : case '\r' : case '\n' : case ' ' :
                        case ','  : case ']'  : case '}' :
                                goto found;
                }
                if (js[parser->pos] < 32 || js[parser->pos] >= 127) {
                        parser->pos = start;
                        return JSMN_ERROR_INVAL;
                }
        }
#ifdef JSMN_STRICT
        /* In strict mode primitive must be followed by a comma/object/array */
        parser->pos = start;
        return JSMN_ERROR_PART;
#endif

found:
        if (tokens == NULL) {
                parser->pos--;
                return 0;
        }
        token = jsmn_alloc_token(parser, tokens, num_tokens);
        if (token == NULL) {
                parser->pos = start;
                return JSMN_ERROR_NOMEM;
        }
        jsmn_fill_token(token, JSMN_PRIMITIVE, start, parser->pos);
#ifdef JSMN_PARENT_LINKS
        token->parent = parser->toksuper;
#endif
        parser->pos--;
        return 0;
}

/**
 * Fills next token with JSON string.
 */
static int jsmn_parse_string(jsmn_parser *parser, const char *js,
                size_t len, jsmntok_t *tokens, size_t num_tokens) {
        jsmntok_t *token;

        int start = parser->pos;

        parser->pos++;

        /* Skip starting quote */
        for (; parser->pos < len && js[parser->pos] != '\0'; parser->pos++) {
                char c = js[parser->pos];

                /* Quote: end of string */
                if (c == '\"') {
                        if (tokens == NULL) {
                                return 0;
                        }
                        token = jsmn_alloc_token(parser, tokens, num_tokens);
                        if (token == NULL) {
                                parser->pos = start;
                                return JSMN_ERROR_NOMEM;
                        }
                        jsmn_fill_token(token, JSMN_STRING, start+1, parser->pos);
#ifdef JSMN_PARENT_LINKS
                        token->parent = parser->toksuper;
#endif
                        return 0;
                }

                /* Backslash: Quoted symbol expected */
                if (c == '\\' && parser->pos + 1 < len) {
                        int i;
                        parser->pos++;
                        switch (js[parser->pos]) {
                                /* Allowed escaped symbols */
                                case '\"': case '/' : case '\\' : case 'b' :
                                case 'f' : case 'r' : case 'n'  : case 't' :
                                        break;
                                /* Allows escaped symbol \uXXXX */
                                case 'u':
                                        parser->pos++;
                                        for(i = 0; i < 4 && parser->pos < len && js[parser->pos] != '\0'; i++) {
                                                /* If it isn't a hex character we have an error */
                                                if(!((js[parser->pos] >= 48 && js[parser->pos] <= 57) || /* 0-9 */
                                                                        (js[parser->pos] >= 65 && js[parser->pos] <= 70) || /* A-F */
                                                                        (js[parser->pos] >= 97 && js[parser->pos] <= 102))) { /* a-f */
                                                        parser->pos = start;
                                                        return JSMN_ERROR_INVAL;
                                                }
                                                parser->pos++;
                                        }
                                        parser->pos--;
                                        break;
                                /* Unexpected symbol */
                                default:
                                        parser->pos = start;
                                        return JSMN_ERROR_INVAL;
                        }
                }
        }
        parser->pos = start;
        return JSMN_ERROR_PART;
}

/**
 * Parse JSON string and fill tokens.
 */
int jsmn_parse(jsmn_parser *parser, const char *js, size_t len,
                jsmntok_t *tokens, unsigned int num_tokens) {
        int r;
        int i;
        jsmntok_t *token;
        int count = parser->toknext;

        for (; parser->pos < len && js[parser->pos] != '\0'; parser->pos++) {
                char c;
                jsmntype_t type;

                c = js[parser->pos];
                switch (c) {
                        case '{': case '[':
                                count++;
                                if (tokens == NULL) {
                                        break;
                                }
                                token = jsmn_alloc_token(parser, tokens, num_tokens);
                                if (token == NULL)
                                        return JSMN_ERROR_NOMEM;
                                if (parser->toksuper != -1) {
                                        tokens[parser->toksuper].size++;
#ifdef JSMN_PARENT_LINKS
                                        token->parent = parser->toksuper;
#endif
                                }
                                token->type = (c == '{' ? JSMN_OBJECT : JSMN_ARRAY);
                                token->start = parser->pos;
                                parser->toksuper = parser->toknext - 1;
                                break;
                        case '}': case ']':
                                if (tokens == NULL)
                                        break;
                                type = (c == '}' ? JSMN_OBJECT : JSMN_ARRAY);
#ifdef JSMN_PARENT_LINKS
                                if (parser->toknext < 1) {
                                        return JSMN_ERROR_INVAL;
                                }
                                token = &tokens[parser->toknext - 1];
                                for (;;) {
                                        if (token->start != -1 && token->end == -1) {
                                                if (token->type != type) {
                                                        return JSMN_ERROR_INVAL;
                                                }
                                                token->end = parser->pos + 1;
                                                parser->toksuper = token->parent;
                                                break;
                                        }
                                        if (token->parent == -1) {
                                                break;
                                        }
                                        token = &tokens[token->parent];
                                }
#else
                                for (i = parser->toknext - 1; i >= 0; i--) {
                                        token = &tokens[i];
                                        if (token->start != -1 && token->end == -1) {
                                                if (token->type != type) {
                                                        return JSMN_ERROR_INVAL;
                                                }
                                                parser->toksuper = -1;
                                                token->end = parser->pos + 1;
                                                break;
                                        }
                                }
                                /* Error if unmatched closing bracket */
                                if (i == -1) return JSMN_ERROR_INVAL;
                                for (; i >= 0; i--) {
                                        token = &tokens[i];
                                        if (token->start != -1 && token->end == -1) {
                                                parser->toksuper = i;
                                                break;
                                        }
                                }
#endif
                                break;
                        case '\"':
                                r = jsmn_parse_string(parser, js, len, tokens, num_tokens);
                                if (r < 0) return r;
                                count++;
                                if (parser->toksuper != -1 && tokens != NULL)
                                        tokens[parser->toksuper].size++;
                                break;
                        case '\t' : case '\r' : case '\n' : case ' ':
                                break;
                        case ':':
                                parser->toksuper = parser->toknext - 1;
                                break;
                        case ',':
                                if (tokens != NULL && parser->toksuper != -1 &&
                                                tokens[parser->toksuper].type != JSMN_ARRAY &&
                                                tokens[parser->toksuper].type != JSMN_OBJECT) {
#ifdef JSMN_PARENT_LINKS
                                        parser->toksuper = tokens[parser->toksuper].parent;
#else
                                        for (i = parser->toknext - 1; i >= 0; i--) {
                                                if (tokens[i].type == JSMN_ARRAY || tokens[i].type == JSMN_OBJECT) {
                                                        if (tokens[i].start != -1 && tokens[i].end == -1) {
                                                                parser->toksuper = i;
                                                                break;
                                                        }
                                                }
                                        }
#endif
                                }
                                break;
#ifdef JSMN_STRICT
                        /* In strict mode primitives are: numbers and booleans */
                        case '-': case '0': case '1' : case '2': case '3' : case '4':
                        case '5': case '6': case '7' : case '8': case '9':
                        case 't': case 'f': case 'n' :
                                /* And they must not be keys of the object */
                                if (tokens != NULL && parser->toksuper != -1) {
                                        jsmntok_t *t = &tokens[parser->toksuper];
                                        if (t->type == JSMN_OBJECT ||
                                                        (t->type == JSMN_STRING && t->size != 0)) {
                                                return JSMN_ERROR_INVAL;
                                        }
                                }
#else
                        /* In non-strict mode every unquoted value is a primitive */
                        default:
#endif
                                r = jsmn_parse_primitive(parser, js, len, tokens, num_tokens);
                                if (r < 0) return r;
                                count++;
                                if (parser->toksuper != -1 && tokens != NULL)
                                        tokens[parser->toksuper].size++;
                                break;

#ifdef JSMN_STRICT
                        /* Unexpected char in strict mode */
                        default:
                                return JSMN_ERROR_INVAL;
#endif
                }
        }

        if (tokens != NULL) {
                for (i = parser->toknext - 1; i >= 0; i--) {
                        /* Unmatched opened object or array */
                        if (tokens[i].start != -1 && tokens[i].end == -1) {
                                return JSMN_ERROR_PART;
                        }
                }
        }

        return count;
}

/**
 * Creates a new parser based over a given  buffer with an array of tokens
 * available.
 */
void jsmn_init(jsmn_parser *parser) {
        parser->pos = 0;
        parser->toknext = 0;
        parser->toksuper = -1;
}