jsmn.c

#include <stdlib.h>

#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 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 && 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;
}

/**
 * Filsl 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;

  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++;
      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++;
          int i = 0;
          for(; i < 4 && 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.
 */
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;
  int count = 0;

  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 ':' : 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 */
      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
    }
  }

  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;
}