jsmn.c

/*
    Copyright (C) 2013 Phil Wieland

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.

    phil@philwieland.com

*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "jsmn.h"
#include "misc.h"

/* Derived from "jasmine", substantially modified. 


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.

*/


/**
 * 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 - 1)
   {
      tokens[num_tokens - 1].start = tokens[num_tokens - 1].end = -1;
      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,
		jsmntok_t *tokens, size_t num_tokens) 
{
   jsmntok_t *token;
   int start;
   
   start = parser->pos;
   
   for (; js[parser->pos] != '\0'; parser->pos++) 
   {
      switch (js[parser->pos]) 
      {
      case ':':
      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;
      }
   }

 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--;
   return JSMN_SUCCESS;
}

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

   int start = parser->pos;

   parser->pos++;

   /* Skip starting quote */
   for (; js[parser->pos] != '\0'; 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;
         }
         if(js[parser->pos + 1] == ':')
         {
            jsmn_fill_token(token, JSMN_NAME, start+1, parser->pos);
         }
         else
         {
            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, jsmntok_t *tokens, 
		unsigned int num_tokens) 
{
   jsmnerr_t r;
   int i;
   jsmntok_t *token;
   
   for (; js[parser->pos] != '\0'; 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, 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;

      default:
         r = jsmn_parse_primitive(parser, js, tokens, num_tokens);
         if (r < 0) return r;
         if (parser->toksuper != -1)
            tokens[parser->toksuper].size++;
         break;
         
      }
   }
   
   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;
      }
   }

   // Append an "END" token
   if(parser->toknext < num_tokens)
   {
      tokens[parser->toknext].start = tokens[parser->toknext].end = -1;
   }
   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;
}

word jsmn_find_name_token(const char * string, const jsmntok_t * tokens, const word object_index, const char * search)
{
   // Search the object at token number object_index for a name of value search, and return its token number or 0 for not found.
   char zs[2048];

   word i;
   for(i = object_index + 1; tokens[i].start >= 0 && tokens[i].start < tokens[object_index].end; i++)
   {
      if(tokens[i].type == JSMN_NAME)
      {
         jsmn_extract_token(string, tokens, i, zs, sizeof(zs));
         if(!strcasecmp(zs, search))
         {
            // Hit
            return i;
         }
      }
   }

   //sprintf(zs, "jsmn_find_name_token(\"%s\") Miss.", search);
   //_log(MAJOR, zs);

   return 0;
}

void jsmn_extract_token(const char * string, const jsmntok_t * tokens, const word index, char * result, const size_t max_length)
{
   // Note:  Doesn't check the token type.  Truncates to fit if necessary.
   size_t length = tokens[index].end-tokens[index].start;
   if (length > max_length - 1) length = max_length - 1;

   strncpy(result, string + tokens[index].start, length);
   result[length] = '\0';

   if(strcmp(result, "null") == 0) result[0] = '\0';
}

void jsmn_find_extract_token(const char * string, const jsmntok_t * tokens, const word object_index, const char * search, char * result, const size_t max_length)
{
   // Search the object at token number object_index for a name of value search, and return the value of the next token.
   size_t index = jsmn_find_name_token(string, tokens, object_index, search);
   if(index > 0 && tokens[index + 1].start >= 0)
   {
      jsmn_extract_token(string, tokens, index + 1, result, max_length);
   }
   else
   {
      result[0] = '\0';
   }
}
      