jsmn.c

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/*
 * Copyright (c) 2010 Serge A. Zaitsev
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 * Slightly modified by AK to not assume 0 terminated input.
 */

#include <stdlib.h>
#include "jsmn.h"

/*
 * Allocates a fresh unused token from the token pool.
 */
static jsmntok_t *jsmn_alloc_token(jsmn_parser *parser,
                   jsmntok_t *tokens, size_t num_tokens)
{
    jsmntok_t *tok;

    if ((unsigned)parser->toknext >= num_tokens)
        return NULL;
    tok = &tokens[parser->toknext++];
    tok->start = tok->end = -1;
    tok->size = 0;
    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 jsmnerr_t 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; 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;
        default:
            break;
        }
        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:
    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);
    parser->pos--; /* parent sees closing brackets */
    return JSMN_SUCCESS;
}

/*
 * Fills next token with JSON string.
 */
static jsmnerr_t 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;

    /* Skip starting quote */
    parser->pos++;

    for (; parser->pos < len; parser->pos++) {
        char c = js[parser->pos];

        /* Quote: end of string */
        if (c == '\"') {
            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);
            return JSMN_SUCCESS;
        }

        /* Backslash: Quoted symbol expected */
        if (c == '\\') {
            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':
                /* TODO */
                break;
                /* Unexpected symbol */
            default:
                parser->pos = start;
                return JSMN_ERROR_INVAL;
            }
        }
    }
    parser->pos = start;
    return JSMN_ERROR_PART;
}

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

    for (; parser->pos < len; parser->pos++) {
        char c;
        jsmntype_t type;

        c = js[parser->pos];
        switch (c) {
        case '{':
        case '[':
            token = jsmn_alloc_token(parser, tokens, num_tokens);
            if (token == NULL)
                return JSMN_ERROR_NOMEM;
            if (parser->toksuper != -1)
                tokens[parser->toksuper].size++;
            token->type = (c == '{' ? JSMN_OBJECT : JSMN_ARRAY);
            token->start = parser->pos;
            parser->toksuper = parser->toknext - 1;
            break;
        case '}':
        case ']':
            type = (c == '}' ? JSMN_OBJECT : JSMN_ARRAY);
            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;
                }
            }
            break;
        case '\"':
            r = jsmn_parse_string(parser, js, len, tokens,
                          num_tokens);
            if (r < 0)
                return r;
            if (parser->toksuper != -1)
                tokens[parser->toksuper].size++;
            break;
        case '\t':
        case '\r':
        case '\n':
        case ':':
        case ',':
        case ' ':
            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':
#else
            /*
             * In non-strict mode every unquoted value
             * is a primitive.
             */
            /*FALL THROUGH */
        default:
#endif
            r = jsmn_parse_primitive(parser, js, len, tokens,
                         num_tokens);
            if (r < 0)
                return r;
            if (parser->toksuper != -1)
                tokens[parser->toksuper].size++;
            break;

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

    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 JSMN_SUCCESS;
}

/*
 * 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;
}

const char *jsmn_strerror(jsmnerr_t err)
{
    switch (err) {
    case JSMN_ERROR_NOMEM:
        return "No enough tokens";
    case JSMN_ERROR_INVAL:
        return "Invalid character inside JSON string";
    case JSMN_ERROR_PART:
        return "The string is not a full JSON packet, more bytes expected";
    case JSMN_SUCCESS:
        return "Success";
    default:
        return "Unknown json error";
    }
}