/* json-scanner.c: Tokenizer for JSON

 *

 * SPDX-FileCopyrightText: 1997 Tim Janik

 * SPDX-FileCopyrightText: 1997-2000 The GLib Team and others

 * SPDX-FileCopyrightText: 2008 OpenedHand Ltd.

 * SPDX-FileCopyrightText: 2024 Emmanuele Bassi

 * SPDX-License-Identifier: LGPL-2.1-or-later

 *

 * Based on JsonScanner: Flexible lexical scanner for general purpose.

 *

 * Modified by Emmanuele Bassi <ebassi@openedhand.com>

 *

 * This library is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2 of the License, or (at your option) any later version.

 *

 * This library 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

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with this library; if not, see <http://www.gnu.org/licenses/>.

 */

#include "config.h"

#include "json-scanner.h"

#include <errno.h>

#include <stdint.h>

#include <stdbool.h>

#include <stdlib.h>

#include <stdarg.h>

#include <string.h>

#include <stdio.h>

#ifdef HAVE_UNISTD_H

#include <unistd.h>

#endif

#include <glib.h>

#include <glib/gprintf.h>

typedef enum

{

  JSON_ERROR_TYPE_UNKNOWN,

  JSON_ERROR_TYPE_UNEXP_EOF,

  JSON_ERROR_TYPE_UNEXP_EOF_IN_STRING,

  JSON_ERROR_TYPE_UNEXP_EOF_IN_COMMENT,

  JSON_ERROR_TYPE_NON_DIGIT_IN_CONST,

  JSON_ERROR_TYPE_DIGIT_RADIX,

  JSON_ERROR_TYPE_FLOAT_RADIX,

  JSON_ERROR_TYPE_FLOAT_MALFORMED,

  JSON_ERROR_TYPE_MALFORMED_SURROGATE_PAIR,

  JSON_ERROR_TYPE_LEADING_ZERO,

  JSON_ERROR_TYPE_UNESCAPED_CTRL,

  JSON_ERROR_TYPE_UNKNOWN_ESCAPE,

  JSON_ERROR_TYPE_MALFORMED_UNICODE

} JsonErrorType;

typedef struct

{

  const char *cset_skip_characters;

  const char *cset_identifier_first;

  const char *cset_identifier_nth;

  const char *cpair_comment_single;

  bool strict;

} JsonScannerConfig;

typedef union

{

  gpointer v_symbol;

  char *v_identifier;

  gint64 v_int64;

  double v_float;

  char *v_string;

  unsigned int v_error;

} JsonTokenValue;

/*< private >

 * JsonScanner:

 *

 * Tokenizer scanner for JSON. See #GScanner

 *

 * Since: 0.6

 */

struct _JsonScanner

{

  /* name of input stream, featured by the default message handler */

  const char *input_name;

  /* link into the scanner configuration */

  JsonScannerConfig config;

  /* fields filled in after json_scanner_get_next_token() */

  unsigned int token;

  JsonTokenValue value;

  unsigned int line;

  unsigned int position;

  /* fields filled in after json_scanner_peek_next_token() */

  unsigned int next_token;

  JsonTokenValue next_value;

  unsigned int next_line;

  unsigned int next_position;

  /* to be considered private */

  const char *text;

  const char *text_end;

  char *buffer;

  /* handler function for _warn and _error */

  JsonScannerMsgFunc msg_handler;

  gpointer user_data;

};

static const gchar json_symbol_names[] =

  "true\0"

  "false\0"

  "null\0"

  "var\0";

static const struct

{

  unsigned int name_offset;

  unsigned int token;

} json_symbols[] = {

  {  0, JSON_TOKEN_TRUE  },

  {  5, JSON_TOKEN_FALSE },

  { 11, JSON_TOKEN_NULL  },

  { 16, JSON_TOKEN_VAR   }

};

static void          json_scanner_get_token_ll   (JsonScanner    *scanner,

                                                   unsigned int   *token_p,

                                                  JsonTokenValue *value_p,

                                                  unsigned int   *line_p,

                                                  unsigned int   *position_p);

static void      json_scanner_get_token_i    (JsonScanner    *scanner,

                                                  unsigned int   *token_p,

                                                  JsonTokenValue *value_p,

                                                  unsigned int   *line_p,

                                                  unsigned int   *position_p);

static unsigned char json_scanner_peek_next_char (JsonScanner    *scanner);

static unsigned char json_scanner_get_char       (JsonScanner    *scanner,

                                                  unsigned int   *line_p,

                                                  unsigned int   *position_p);

static bool          json_scanner_get_unichar    (JsonScanner    *scanner,

                                                  gunichar       *ucs,

                                                  unsigned int   *line_p,

                                                  unsigned int   *position_p);

static void          json_scanner_error          (JsonScanner    *scanner,

                                                  const char     *format,

                                                  ...) G_GNUC_PRINTF (2,3);

JsonScanner *

json_scanner_new (bool strict)

{

  JsonScanner *scanner;

  scanner = g_new0 (JsonScanner, 1);

  scanner->config = (JsonScannerConfig) {

    // Skip whitespace

    .cset_skip_characters = ( " \t\r\n" ),

    // Identifiers can only be lower case

    .cset_identifier_first = (

      G_CSET_a_2_z

    ),

    .cset_identifier_nth = (

      G_CSET_a_2_z

    ),

    // Only used if strict = false

    .cpair_comment_single = ( "//\n" ),

    .strict = strict,

  };

  scanner->token = JSON_TOKEN_NONE;

  scanner->value.v_int64 = 0;

  scanner->line = 1;

  scanner->position = 0;

  scanner->next_token = JSON_TOKEN_NONE;

  scanner->next_value.v_int64 = 0;

  scanner->next_line = 1;

  scanner->next_position = 0;

  return scanner;

}

static inline void

json_scanner_free_value (JsonTokenType  *token_p,

                         JsonTokenValue *value_p)

{

  switch (*token_p)

    {

    case JSON_TOKEN_STRING:

    case JSON_TOKEN_IDENTIFIER:

    case JSON_TOKEN_COMMENT_SINGLE:

    case JSON_TOKEN_COMMENT_MULTI:

      g_free (value_p->v_string);

      break;

    default:

      break;

    }

  *token_p = JSON_TOKEN_NONE;

}

void

json_scanner_destroy (JsonScanner *scanner)

{

  g_return_if_fail (scanner != NULL);

  json_scanner_free_value (&scanner->token, &scanner->value);

  json_scanner_free_value (&scanner->next_token, &scanner->next_value);

  g_free (scanner->buffer);

  g_free (scanner);

}

void

json_scanner_set_msg_handler (JsonScanner        *scanner,

                              JsonScannerMsgFunc  msg_handler,

                              gpointer            user_data)

{

  g_return_if_fail (scanner != NULL);

  scanner->msg_handler = msg_handler;

  scanner->user_data = user_data;

}

static void

json_scanner_error (JsonScanner *scanner,

                    const char  *format,

                    ...)

{

  g_return_if_fail (scanner != NULL);

  g_return_if_fail (format != NULL);

  if (scanner->msg_handler)

    {

      va_list args;

      char *string;

      va_start (args, format);

      string = g_strdup_vprintf (format, args);

      va_end (args);

      scanner->msg_handler (scanner, string, scanner->user_data);

      g_free (string);

    }

}

unsigned int

json_scanner_peek_next_token (JsonScanner *scanner)

{

  g_return_val_if_fail (scanner != NULL, JSON_TOKEN_EOF);

  if (scanner->next_token == JSON_TOKEN_NONE)

    {

      scanner->next_line = scanner->line;

      scanner->next_position = scanner->position;

      json_scanner_get_token_i (scanner,

                                &scanner->next_token,

                                &scanner->next_value,

                                &scanner->next_line,

                                &scanner->next_position);

    }

  return scanner->next_token;

}

unsigned int

json_scanner_get_next_token (JsonScanner *scanner)

{

  g_return_val_if_fail (scanner != NULL, JSON_TOKEN_EOF);

  if (scanner->next_token != JSON_TOKEN_NONE)

    {

      json_scanner_free_value (&scanner->token, &scanner->value);

      scanner->token = scanner->next_token;

      scanner->value = scanner->next_value;

      scanner->line = scanner->next_line;

      scanner->position = scanner->next_position;

      scanner->next_token = JSON_TOKEN_NONE;

    }

  else

    json_scanner_get_token_i (scanner,

                              &scanner->token,

                              &scanner->value,

                              &scanner->line,

                              &scanner->position);

  return scanner->token;

}

void

json_scanner_input_text (JsonScanner *scanner,

                         const char  *text,

                         guint        text_len)

{

  g_return_if_fail (scanner != NULL);

  if (text_len)

    g_return_if_fail (text != NULL);

  else

    text = NULL;

  scanner->token = JSON_TOKEN_NONE;

  scanner->value.v_int64 = 0;

  scanner->line = 1;

  scanner->position = 0;

  scanner->next_token = JSON_TOKEN_NONE;

  scanner->text = text;

  scanner->text_end = text != NULL ? text + text_len : 0;

  g_clear_pointer (&scanner->buffer, g_free);

}

static guchar

json_scanner_peek_next_char (JsonScanner *scanner)

{

  if (scanner->text < scanner->text_end)

    return *scanner->text;

  else

    return 0;

}

static guchar

json_scanner_get_char (JsonScanner *scanner,

                       guint       *line_p,

                       guint       *position_p)

{

  guchar fchar;

  if (scanner->text < scanner->text_end)

    fchar = *(scanner->text++);

  else

    fchar = 0;

  if (fchar == '\n')

    {

      (*position_p) = 0;

      (*line_p)++;

    }

  else if (fchar)

    {

      (*position_p)++;

    }

  return fchar;

}

#define is_oct_digit(c)         ((c) >= '0' && (c) <= '7')

#define is_hex_digit(c)         (((c) >= '0' && (c) <= '9') || \

                                 ((c) >= 'a' && (c) <= 'f') || \

                                 ((c) >= 'A' && (c) <= 'F'))

#define to_hex_digit(c)         (((c) <= '9') ? (c) - '0' : ((c) & 7) + 9)

static bool

json_scanner_get_unichar (JsonScanner *scanner,

                          gunichar    *ucs,

                          guint       *line_p,

                          guint       *position_p)

{

  gunichar uchar;

  uchar = 0;

  for (int i = 0; i < 4; i++)

    {

      char ch = json_scanner_get_char (scanner, line_p, position_p);

      if (is_hex_digit (ch))

        uchar += ((gunichar) to_hex_digit (ch) << ((3 - i) * 4));

      else

        return false;

    }

  *ucs = uchar;

  return true;

}

/*

 * decode_utf16_surrogate_pair:

 * @units: (array length=2): a pair of UTF-16 code points

 *

 * Decodes a surrogate pair of UTF-16 code points into the equivalent

 * Unicode code point.

 *

 * Returns: the Unicode code point equivalent to the surrogate pair

 */

static inline gunichar

decode_utf16_surrogate_pair (const gunichar units[2])

{

  gunichar ucs;

  /* Already checked by caller */

  g_assert (0xd800 <= units[0] && units[0] <= 0xdbff);

  g_assert (0xdc00 <= units[1] && units[1] <= 0xdfff);

  ucs = 0x10000;

  ucs += (units[0] & 0x3ff) << 10;

  ucs += (units[1] & 0x3ff);

  return ucs;

}

static void

json_scanner_unexp_token (JsonScanner  *scanner,

                          unsigned int  expected_token,

                          const char   *identifier_spec,

                          const char   *symbol_spec,

                          const char   *symbol_name,

                          const char   *message)

{

  char *token_string;

  gsize token_string_len;

  char *expected_string;

  gsize expected_string_len;

  const char *message_prefix;

  bool print_unexp;

  g_return_if_fail (scanner != NULL);

  if (identifier_spec == NULL)

    identifier_spec = "identifier";

  if (symbol_spec == NULL)

    symbol_spec = "symbol";

  token_string_len = 56;

  token_string = g_new (char, token_string_len + 1);

  expected_string_len = 64;

  expected_string = g_new (char, expected_string_len + 1);

  print_unexp = true;

  switch (scanner->token)

    {

    case JSON_TOKEN_EOF:

      g_snprintf (token_string, token_string_len, "end of file");

      break;

    default:

      if (scanner->token >= 1 && scanner->token <= 255)

  {

    if ((scanner->token >= ' ' && scanner->token <= '~') ||

        strchr (scanner->config.cset_identifier_first, scanner->token) ||

        strchr (scanner->config.cset_identifier_nth, scanner->token))

      g_snprintf (token_string, token_string_len, "character `%c'", scanner->token);

    else

      g_snprintf (token_string, token_string_len, "character `\\%o'", scanner->token);

    break;

  }

      G_GNUC_FALLTHROUGH;

    case JSON_TOKEN_SYMBOL:

      if (expected_token == JSON_TOKEN_SYMBOL || expected_token > JSON_TOKEN_LAST)

  print_unexp = false;

      if (symbol_name)

  g_snprintf (token_string, token_string_len,

                    "%s%s `%s'",

                    print_unexp ? "" : "invalid ",

                    symbol_spec,

                    symbol_name);

      else

  g_snprintf (token_string, token_string_len,

                    "%s%s",

                    print_unexp ? "" : "invalid ",

                    symbol_spec);

      break;

    case JSON_TOKEN_ERROR:

      print_unexp = false;

      expected_token = JSON_TOKEN_NONE;

      switch (scanner->value.v_error)

  {

  case JSON_ERROR_TYPE_UNEXP_EOF:

    g_snprintf (token_string, token_string_len, "scanner: unexpected end of file");

    break;

  case JSON_ERROR_TYPE_UNEXP_EOF_IN_STRING:

    g_snprintf (token_string, token_string_len, "scanner: unterminated string constant");

    break;

  case JSON_ERROR_TYPE_UNEXP_EOF_IN_COMMENT:

    g_snprintf (token_string, token_string_len, "scanner: unterminated comment");

    break;

  case JSON_ERROR_TYPE_NON_DIGIT_IN_CONST:

    g_snprintf (token_string, token_string_len, "scanner: non digit in constant");

    break;

  case JSON_ERROR_TYPE_FLOAT_RADIX:

    g_snprintf (token_string, token_string_len, "scanner: invalid radix for floating constant");

    break;

  case JSON_ERROR_TYPE_FLOAT_MALFORMED:

    g_snprintf (token_string, token_string_len, "scanner: malformed floating constant");

    break;

  case JSON_ERROR_TYPE_DIGIT_RADIX:

    g_snprintf (token_string, token_string_len, "scanner: digit is beyond radix");

    break;

  case JSON_ERROR_TYPE_MALFORMED_SURROGATE_PAIR:

    g_snprintf (token_string, token_string_len, "scanner: malformed surrogate pair");

    break;

        case JSON_ERROR_TYPE_LEADING_ZERO:

          g_snprintf (token_string, token_string_len, "scanner: leading zero in number");

          break;

        case JSON_ERROR_TYPE_UNESCAPED_CTRL:

          g_snprintf (token_string, token_string_len, "scanner: unescaped control character");

          break;

        case JSON_ERROR_TYPE_UNKNOWN_ESCAPE:

          g_snprintf (token_string, token_string_len, "scanner: unknown backslash escape sequence");

          break;

        case JSON_ERROR_TYPE_MALFORMED_UNICODE:

          g_snprintf (token_string, token_string_len, "scanner: malformed Unicode escape");

          break;

  case JSON_ERROR_TYPE_UNKNOWN:

  default:

    g_snprintf (token_string, token_string_len, "scanner: unknown error");

    break;

  }

      break;

    case JSON_TOKEN_IDENTIFIER:

      if (expected_token == JSON_TOKEN_IDENTIFIER)

  print_unexp = false;

      g_snprintf (token_string, token_string_len,

                  "%s%s `%s'",

                  print_unexp ? "" : "invalid ",

                  identifier_spec,

                  scanner->value.v_string);

      break;

    case JSON_TOKEN_INT:

      g_snprintf (token_string, token_string_len, "number `%" G_GINT64_FORMAT "'", scanner->value.v_int64);

      break;

    case JSON_TOKEN_FLOAT:

      g_snprintf (token_string, token_string_len, "number `%.3f'", scanner->value.v_float);

      break;

    case JSON_TOKEN_STRING:

      if (expected_token == JSON_TOKEN_STRING)

  print_unexp = false;

      g_snprintf (token_string, token_string_len,

                  "%s%sstring constant \"%s\"",

                  print_unexp ? "" : "invalid ",

                  scanner->value.v_string[0] == 0 ? "empty " : "",

                  scanner->value.v_string);

      token_string[token_string_len - 2] = '"';

      token_string[token_string_len - 1] = 0;

      break;

    case JSON_TOKEN_COMMENT_SINGLE:

    case JSON_TOKEN_COMMENT_MULTI:

      g_snprintf (token_string, token_string_len, "comment");

      break;

    case JSON_TOKEN_NONE:

      /* somehow the user's parsing code is screwed, there isn't much

       * we can do about it.

       * Note, a common case to trigger this is

       * json_scanner_peek_next_token(); json_scanner_unexp_token();

       * without an intermediate json_scanner_get_next_token().

       */

      g_assert_not_reached ();

      break;

    }

  switch (expected_token)

    {

    case JSON_TOKEN_EOF:

      g_snprintf (expected_string, expected_string_len, "end of file");

      break;

    default:

      if (expected_token >= 1 && expected_token <= 255)

  {

    if ((expected_token >= ' ' && expected_token <= '~') ||

        strchr (scanner->config.cset_identifier_first, expected_token) ||

        strchr (scanner->config.cset_identifier_nth, expected_token))

      g_snprintf (expected_string, expected_string_len, "character `%c'", expected_token);

    else

      g_snprintf (expected_string, expected_string_len, "character `\\%o'", expected_token);

    break;

  }

      G_GNUC_FALLTHROUGH;

    case JSON_TOKEN_SYMBOL:

      {

        bool need_valid = (scanner->token == JSON_TOKEN_SYMBOL || scanner->token > JSON_TOKEN_LAST);

        g_snprintf (expected_string, expected_string_len,

                    "%s%s",

                    need_valid ? "valid " : "",

                    symbol_spec);

      }

      break;

    case JSON_TOKEN_INT:

      g_snprintf (expected_string,

                  expected_string_len,

                  "%snumber (integer)",

      scanner->token == expected_token ? "valid " : "");

      break;

    case JSON_TOKEN_FLOAT:

      g_snprintf (expected_string,

                  expected_string_len,

                  "%snumber (float)",

      scanner->token == expected_token ? "valid " : "");

      break;

    case JSON_TOKEN_STRING:

      g_snprintf (expected_string,

      expected_string_len,

      "%sstring constant",

      scanner->token == JSON_TOKEN_STRING ? "valid " : "");

      break;

    case JSON_TOKEN_IDENTIFIER:

      g_snprintf (expected_string,

      expected_string_len,

      "%s%s",

      scanner->token == JSON_TOKEN_IDENTIFIER ? "valid " : "",

      identifier_spec);

      break;

    case JSON_TOKEN_COMMENT_SINGLE:

      g_snprintf (expected_string,

                  expected_string_len,

                  "%scomment (single-line)",

      scanner->token == expected_token ? "valid " : "");

      break;

    case JSON_TOKEN_COMMENT_MULTI:

      g_snprintf (expected_string,

                  expected_string_len,

                  "%scomment (multi-line)",

      scanner->token == expected_token ? "valid " : "");

      break;

    case JSON_TOKEN_NONE:

    case JSON_TOKEN_ERROR:

      /* this is handled upon printout */

      break;

    }

  if (message && message[0] != 0)

    message_prefix = " - ";

  else

    {

      message_prefix = "";

      message = "";

    }

  if (expected_token == JSON_TOKEN_ERROR)

    {

      json_scanner_error (scanner,

                          "failure around %s%s%s",

                          token_string,

                          message_prefix,

                          message);

    }

  else if (expected_token == JSON_TOKEN_NONE)

    {

      if (print_unexp)

  json_scanner_error (scanner,

                            "unexpected %s%s%s",

                            token_string,

                            message_prefix,

                            message);

      else

  json_scanner_error (scanner,

                            "%s%s%s",

                            token_string,

                            message_prefix,

                            message);

    }

  else

    {

      if (print_unexp)

  json_scanner_error (scanner,

                            "unexpected %s, expected %s%s%s",

                            token_string,

                            expected_string,

                            message_prefix,

                            message);

      else

  json_scanner_error (scanner,

                            "%s, expected %s%s%s",

                            token_string,

                            expected_string,

                            message_prefix,

                            message);

    }

  g_free (token_string);

  g_free (expected_string);

}

void

json_scanner_unknown_token (JsonScanner  *scanner,

                            unsigned int  token)

{

  const char *symbol_name;

  char *msg;

  unsigned int cur_token;

  cur_token = json_scanner_get_current_token (scanner);

  msg = NULL;

  symbol_name = NULL;

  for (unsigned i = 0; i < G_N_ELEMENTS (json_symbols); i++)

    if (json_symbols[i].token == token)

      symbol_name = json_symbol_names + json_symbols[i].name_offset;

  if (symbol_name != NULL)

    msg = g_strconcat ("e.g. '", symbol_name, "'", NULL);

  symbol_name = "???";

  for (unsigned i = 0; i < G_N_ELEMENTS (json_symbols); i++)

    if (json_symbols[i].token == cur_token)

      symbol_name = json_symbol_names + json_symbols[i].name_offset;

  json_scanner_unexp_token (scanner, token,

                            NULL, "value",

                            symbol_name,

                            msg);

  g_free (msg);

}

static void

json_scanner_get_token_i (JsonScanner    *scanner,

              unsigned int   *token_p,

              JsonTokenValue *value_p,

              guint          *line_p,

              guint          *position_p)

{

  do

    {

      json_scanner_free_value (token_p, value_p);

      json_scanner_get_token_ll (scanner, token_p, value_p, line_p, position_p);

    }

  while (((*token_p > 0 && *token_p < 256) &&

    strchr (scanner->config.cset_skip_characters, *token_p)) ||

   *token_p == JSON_TOKEN_COMMENT_MULTI ||

   *token_p == JSON_TOKEN_COMMENT_SINGLE);

  switch (*token_p)

    {

    case JSON_TOKEN_IDENTIFIER:

      break;

    case JSON_TOKEN_SYMBOL:

      *token_p = GPOINTER_TO_UINT (value_p->v_symbol);

      break;

    default:

      break;

    }

  errno = 0;

}

static void

json_scanner_get_token_ll (JsonScanner    *scanner,

                           unsigned int   *token_p,

                           JsonTokenValue *value_p,

                           guint          *line_p,

                           guint          *position_p)

{

  const JsonScannerConfig *config;

  unsigned int token;

  bool in_comment_multi = false;

  bool in_comment_single = false;

  bool in_string_sq = false;

  bool in_string_dq = false;

  GString *gstring = NULL;

  JsonTokenValue value;

  guchar ch;

  config = &scanner->config;

  (*value_p).v_int64 = 0;

  if (scanner->text >= scanner->text_end ||

      scanner->token == JSON_TOKEN_EOF)

    {

      *token_p = JSON_TOKEN_EOF;

      return;

    }

  gstring = NULL;

  do /* while (ch != 0) */

    {

      ch = json_scanner_get_char (scanner, line_p, position_p);

      value.v_int64 = 0;

      token = JSON_TOKEN_NONE;

      /* this is *evil*, but needed ;(

       * we first check for identifier first character, because  it

       * might interfere with other key chars like slashes or numbers

       */

      if (ch != 0 && strchr (config->cset_identifier_first, ch))

  goto identifier_precedence;

      switch (ch)

  {

  case 0:

    token = JSON_TOKEN_EOF;

    (*position_p)++;

    /* ch = 0; */

    break;

  case '/':

    if (config->strict || json_scanner_peek_next_char (scanner) != '*')

      goto default_case;

    json_scanner_get_char (scanner, line_p, position_p);

    token = JSON_TOKEN_COMMENT_MULTI;

    in_comment_multi = true;

    gstring = g_string_new (NULL);

    while ((ch = json_scanner_get_char (scanner, line_p, position_p)) != 0)

      {

        if (ch == '*' && json_scanner_peek_next_char (scanner) == '/')

    {

      json_scanner_get_char (scanner, line_p, position_p);

      in_comment_multi = false;

      break;

    }

        else

    gstring = g_string_append_c (gstring, ch);

      }

    ch = 0;

    break;

        case '\'':

          if (config->strict)

            goto default_case;

          token = JSON_TOKEN_STRING;

          in_string_sq = true;

          gstring = g_string_new (NULL);

          while ((ch = json_scanner_get_char (scanner, line_p, position_p)) != 0)

            {

              if (ch == '\'' || token == JSON_TOKEN_ERROR)

                {

                  in_string_sq = false;

                  break;

                }

              else

                {

                  g_string_append_c (gstring, ch);

                }

            }

          ch = 0;

          break;

  case '"':

    token = JSON_TOKEN_STRING;

    in_string_dq = true;

    gstring = g_string_new (NULL);

    while ((ch = json_scanner_get_char (scanner, line_p, position_p)) != 0)

      {

        if (ch == '"' || token == JSON_TOKEN_ERROR)

    {

      in_string_dq = false;

      break;

    }

        else

    {

      if (ch == '\\')

        {

          ch = json_scanner_get_char (scanner, line_p, position_p);

          switch (ch)

      {

      case 0:

        break;

                        case '"':

                          gstring = g_string_append_c (gstring, '"');

                          break;

      case '\\':

        gstring = g_string_append_c (gstring, '\\');

        break;

                        case '/':

                          gstring = g_string_append_c (gstring, '/');

                          break;

      case 'n':

        gstring = g_string_append_c (gstring, '\n');

        break;

      case 't':

        gstring = g_string_append_c (gstring, '\t');

        break;

      case 'r':

        gstring = g_string_append_c (gstring, '\r');

        break;

      case 'b':

        gstring = g_string_append_c (gstring, '\b');

        break;

      case 'f':

        gstring = g_string_append_c (gstring, '\f');

        break;

                        case 'u':

                        {

                          guint fchar = json_scanner_peek_next_char (scanner);

                          if (is_hex_digit (fchar))

                            {

                              gunichar ucs;

                              if (!json_scanner_get_unichar (scanner, &ucs, line_p, position_p))

                                {

                                  token = JSON_TOKEN_ERROR;

                                  value.v_error = JSON_ERROR_TYPE_MALFORMED_UNICODE;

                                  g_string_free (gstring, TRUE);

                                  gstring = NULL;

                                  break;

                                }

                              /* resolve UTF-16 surrogates for Unicode characters not in the BMP,

                               * as per ECMA 404, § 9, "String"

                               */

                              if (g_unichar_type (ucs) == G_UNICODE_SURROGATE)

                                {

                                  unsigned int next_ch;

                                  next_ch = json_scanner_peek_next_char (scanner);

                                  if (next_ch != '\\')

                                    {

                                      token = JSON_TOKEN_ERROR;

                                      value.v_error = JSON_ERROR_TYPE_MALFORMED_SURROGATE_PAIR;

                                      g_string_free (gstring, TRUE);

                                      gstring = NULL;

                                      break;

                                    }

                                  else

                                    json_scanner_get_char (scanner, line_p, position_p);

                                  next_ch = json_scanner_peek_next_char (scanner);

                                  if (next_ch != 'u')

                                    {

                                      token = JSON_TOKEN_ERROR;

                                      value.v_error = JSON_ERROR_TYPE_MALFORMED_SURROGATE_PAIR;

                                      g_string_free (gstring, TRUE);

                                      gstring = NULL;

                                      break;

                                    }

                                  else

                                    json_scanner_get_char (scanner, line_p, position_p);

                                  /* read next surrogate */

                                  gunichar units[2];

                                  units[0] = ucs;

                                  if (!json_scanner_get_unichar (scanner, &ucs, line_p, position_p))

                                    {

                                      token = JSON_TOKEN_ERROR;

                                      value.v_error = JSON_ERROR_TYPE_MALFORMED_UNICODE;

                                      g_string_free (gstring, TRUE);

                                      gstring = NULL;

                                      break;

                                    }

                                  units[1] = ucs;

                                  if (0xdc00 <= units[1] && units[1] <= 0xdfff &&

                                      0xd800 <= units[0] && units[0] <= 0xdbff)

                                    {

                                      ucs = decode_utf16_surrogate_pair (units);

                                      if (!g_unichar_validate (ucs))

                                        {

                                          token = JSON_TOKEN_ERROR;

                                          value.v_error = JSON_ERROR_TYPE_MALFORMED_UNICODE;

                                          g_string_free (gstring, TRUE);

                                          gstring = NULL;

                                          break;

                                        }

                                    }

                                  else

                                    {

                                      token = JSON_TOKEN_ERROR;

                                      value.v_error = JSON_ERROR_TYPE_MALFORMED_SURROGATE_PAIR;

                                      g_string_free (gstring, TRUE);

                                      gstring = NULL;

                                      break;

                                    }

                                }

                              else

                                {

                                  if (!g_unichar_validate (ucs))

                                    {

                                      token = JSON_TOKEN_ERROR;

                                      value.v_error = JSON_ERROR_TYPE_MALFORMED_UNICODE;

                                      g_string_free (gstring, TRUE);

                                      gstring = NULL;

                                      break;

                                    }

                                }

                              gstring = g_string_append_unichar (gstring, ucs);

                            }

                          else

                            {

                              token = JSON_TOKEN_ERROR;

                              value.v_error = JSON_ERROR_TYPE_MALFORMED_UNICODE;

                              g_string_free (gstring, TRUE);

                              gstring = NULL;