text: 
  /*
   * Introduction
   * ************
   *
   * The following notes assume that you are familiar with the YAML specification
   * (http://yaml.org/spec/cvs/current.html).  We mostly follow it, although in
   * some cases we are less restrictive that it requires.
   *
   * The process of transforming a YAML stream into a sequence of events is
   * divided on two steps: Scanning and Parsing.
   *
   * The Scanner transforms the input stream into a sequence of tokens, while the
   * parser transform the sequence of tokens produced by the Scanner into a
   * sequence of parsing events.
   *
   * The Scanner is rather clever and complicated. The Parser, on the contrary,
   * is a straightforward implementation of a recursive-descendant parser (or,
   * LL(1) parser, as it is usually called).
   *
   * Actually there are two issues of Scanning that might be called "clever", the
   * rest is quite straightforward.  The issues are "block collection start" and
   * "simple keys".  Both issues are explained below in details.
   *
   * Here the Scanning step is explained and implemented.  We start with the list
   * of all the tokens produced by the Scanner together with short descriptions.
   *
   * Now, tokens:
   *
   *      STREAM-START(encoding)          # The stream start.
   *      STREAM-END                      # The stream end.
   *      VERSION-DIRECTIVE(major,minor)  # The '%YAML' directive.
   *      TAG-DIRECTIVE(handle,prefix)    # The '%TAG' directive.
   *      DOCUMENT-START                  # '---'
   *      DOCUMENT-END                    # '...'
   *      BLOCK-SEQUENCE-START            # Indentation increase denoting a block
   *      BLOCK-MAPPING-START             # sequence or a block mapping.
   *      BLOCK-END                       # Indentation decrease.
   *      FLOW-SEQUENCE-START             # '['
   *      FLOW-SEQUENCE-END               # ']'
   *      BLOCK-SEQUENCE-START            # '{'
   *      BLOCK-SEQUENCE-END              # '}'
   *      BLOCK-ENTRY                     # '-'
   *      FLOW-ENTRY                      # ','
   *      KEY                             # '?' or nothing (simple keys).
   *      VALUE                           # ':'
   *      ALIAS(anchor)                   # '*anchor'
   *      ANCHOR(anchor)                  # '&anchor'
   *      TAG(handle,suffix)              # '!handle!suffix'
   *      SCALAR(value,style)             # A scalar.
   *
   * The following two tokens are "virtual" tokens denoting the beginning and the
   * end of the stream:
   *
   *      STREAM-START(encoding)
   *      STREAM-END
   *
   * We pass the information about the input stream encoding with the
   * STREAM-START token.
   *
   * The next two tokens are responsible for tags:
   *
   *      VERSION-DIRECTIVE(major,minor)
   *      TAG-DIRECTIVE(handle,prefix)
   *
   * Example:
   *
   *      %YAML   1.1
   *      %TAG    !   !foo
   *      %TAG    !yaml!  tag:yaml.org,2002:
   *      ---
   *
   * The corresponding sequence of tokens:
   *
   *      STREAM-START(utf-8)
   *      VERSION-DIRECTIVE(1,1)
   *      TAG-DIRECTIVE("!","!foo")
   *      TAG-DIRECTIVE("!yaml","tag:yaml.org,2002:")
   *      DOCUMENT-START
   *      STREAM-END
   *
   * Note that the VERSION-DIRECTIVE and TAG-DIRECTIVE tokens occupy a whole
   * line.
   *
   * The document start and end indicators are represented by:
   *
   *      DOCUMENT-START
   *      DOCUMENT-END
   *
   * Note that if a YAML stream contains an implicit document (without '---'
   * and '...' indicators), no DOCUMENT-START and DOCUMENT-END tokens will be
   * produced.
   *
   * In the following examples, we present whole documents together with the
   * produced tokens.
   *
   *      1. An implicit document:
   *
   *          'a scalar'
   *
   *      Tokens:
   *
   *          STREAM-START(utf-8)
   *          SCALAR("a scalar",single-quoted)
   *          STREAM-END
   *
   *      2. An explicit document:
   *
   *          ---
   *          'a scalar'
   *          ...
   *
   *      Tokens:
   *
   *          STREAM-START(utf-8)
   *          DOCUMENT-START
   *          SCALAR("a scalar",single-quoted)
   *          DOCUMENT-END
   *          STREAM-END
   *
   *      3. Several documents in a stream:
   *
   *          'a scalar'
   *          ---
   *          'another scalar'
   *          ---
   *          'yet another scalar'
   *
   *      Tokens:
   *
   *          STREAM-START(utf-8)
   *          SCALAR("a scalar",single-quoted)
   *          DOCUMENT-START
   *          SCALAR("another scalar",single-quoted)
   *          DOCUMENT-START
   *          SCALAR("yet another scalar",single-quoted)
   *          STREAM-END
   *
   * We have already introduced the SCALAR token above.  The following tokens are
   * used to describe aliases, anchors, tag, and scalars:
   *
   *      ALIAS(anchor)
   *      ANCHOR(anchor)
   *      TAG(handle,suffix)
   *      SCALAR(value,style)
   *
   * The following series of examples illustrate the usage of these tokens:
   *
   *      1. A recursive sequence:
   *
   *          &A [ *A ]
   *
   *      Tokens:
   *
   *          STREAM-START(utf-8)
   *          ANCHOR("A")
   *          FLOW-SEQUENCE-START
   *          ALIAS("A")
   *          FLOW-SEQUENCE-END
   *          STREAM-END
   *
   *      2. A tagged scalar:
   *
   *          !!float "3.14"  # A good approximation.
   *
   *      Tokens:
   *
   *          STREAM-START(utf-8)
   *          TAG("!!","float")
   *          SCALAR("3.14",double-quoted)
   *          STREAM-END
   *
   *      3. Various scalar styles:
   *
   *          --- # Implicit empty plain scalars do not produce tokens.
   *          --- a plain scalar
   *          --- 'a single-quoted scalar'
   *          --- "a double-quoted scalar"
   *          --- |-
   *            a literal scalar
   *          --- >-
   *            a folded
   *            scalar
   *
   *      Tokens:
   *
   *          STREAM-START(utf-8)
   *          DOCUMENT-START
   *          DOCUMENT-START
   *          SCALAR("a plain scalar",plain)
   *          DOCUMENT-START
   *          SCALAR("a single-quoted scalar",single-quoted)
   *          DOCUMENT-START
   *          SCALAR("a double-quoted scalar",double-quoted)
   *          DOCUMENT-START
   *          SCALAR("a literal scalar",literal)
   *          DOCUMENT-START
   *          SCALAR("a folded scalar",folded)
   *          STREAM-END
   *
   * Now it's time to review collection-related tokens. We will start with
   * flow collections:
   *
   *      FLOW-SEQUENCE-START
   *      FLOW-SEQUENCE-END
   *      FLOW-MAPPING-START
   *      FLOW-MAPPING-END
   *      FLOW-ENTRY
   *      KEY
   *      VALUE
   *
   * The tokens FLOW-SEQUENCE-START, FLOW-SEQUENCE-END, FLOW-MAPPING-START, and
   * FLOW-MAPPING-END represent the indicators '[', ']', '{', and '}'
   * correspondingly.  FLOW-ENTRY represent the ',' indicator.  Finally the
   * indicators '?' and ':', which are used for denoting mapping keys and values,
   * are represented by the KEY and VALUE tokens.
   *
   * The following examples show flow collections:
   *
   *      1. A flow sequence:
   *
   *          [item 1, item 2, item 3]
   *
   *      Tokens:
   *
   *          STREAM-START(utf-8)
   *          FLOW-SEQUENCE-START
   *          SCALAR("item 1",plain)
   *          FLOW-ENTRY
   *          SCALAR("item 2",plain)
   *          FLOW-ENTRY
   *          SCALAR("item 3",plain)
   *          FLOW-SEQUENCE-END
   *          STREAM-END
   *
   *      2. A flow mapping:
   *
   *          {
   *              a simple key: a value,  # Note that the KEY token is produced.
   *              ? a complex key: another value,
   *          }
   *
   *      Tokens:
   *
   *          STREAM-START(utf-8)
   *          FLOW-MAPPING-START
   *          KEY
   *          SCALAR("a simple key",plain)
   *          VALUE
   *          SCALAR("a value",plain)
   *          FLOW-ENTRY
   *          KEY
   *          SCALAR("a complex key",plain)
   *          VALUE
   *          SCALAR("another value",plain)
   *          FLOW-ENTRY
   *          FLOW-MAPPING-END
   *          STREAM-END
   *
   * A simple key is a key which is not denoted by the '?' indicator.  Note that
   * the Scanner still produce the KEY token whenever it encounters a simple key.
   *
   * For scanning block collections, the following tokens are used (note that we
   * repeat KEY and VALUE here):
   *
   *      BLOCK-SEQUENCE-START
   *      BLOCK-MAPPING-START
   *      BLOCK-END
   *      BLOCK-ENTRY
   *      KEY
   *      VALUE
   *
   * The tokens BLOCK-SEQUENCE-START and BLOCK-MAPPING-START denote indentation
   * increase that precedes a block collection (cf. the INDENT token in Python).
   * The token BLOCK-END denote indentation decrease that ends a block collection
   * (cf. the DEDENT token in Python).  However YAML has some syntax pecularities
   * that makes detections of these tokens more complex.
   *
   * The tokens BLOCK-ENTRY, KEY, and VALUE are used to represent the indicators
   * '-', '?', and ':' correspondingly.
   *
   * The following examples show how the tokens BLOCK-SEQUENCE-START,
   * BLOCK-MAPPING-START, and BLOCK-END are emitted by the Scanner:
   *
   *      1. Block sequences:
   *
   *          - item 1
   *          - item 2
   *          -
   *            - item 3.1
   *            - item 3.2
   *          -
   *            key 1: value 1
   *            key 2: value 2
   *
   *      Tokens:
   *
   *          STREAM-START(utf-8)
   *          BLOCK-SEQUENCE-START
   *          BLOCK-ENTRY
   *          SCALAR("item 1",plain)
   *          BLOCK-ENTRY
   *          SCALAR("item 2",plain)
   *          BLOCK-ENTRY
   *          BLOCK-SEQUENCE-START
   *          BLOCK-ENTRY
   *          SCALAR("item 3.1",plain)
   *          BLOCK-ENTRY
   *          SCALAR("item 3.2",plain)
   *          BLOCK-END
   *          BLOCK-ENTRY
   *          BLOCK-MAPPING-START
   *          KEY
   *          SCALAR("key 1",plain)
   *          VALUE
   *          SCALAR("value 1",plain)
   *          KEY
   *          SCALAR("key 2",plain)
   *          VALUE
   *          SCALAR("value 2",plain)
   *          BLOCK-END
   *          BLOCK-END
   *          STREAM-END
   *
   *      2. Block mappings:
   *
   *          a simple key: a value   # The KEY token is produced here.
   *          ? a complex key
   *          : another value
   *          a mapping:
   *            key 1: value 1
   *            key 2: value 2
   *          a sequence:
   *            - item 1
   *            - item 2
   *
   *      Tokens:
   *
   *          STREAM-START(utf-8)
   *          BLOCK-MAPPING-START
   *          KEY
   *          SCALAR("a simple key",plain)
   *          VALUE
   *          SCALAR("a value",plain)
   *          KEY
   *          SCALAR("a complex key",plain)
   *          VALUE
   *          SCALAR("another value",plain)
   *          KEY
   *          SCALAR("a mapping",plain)
   *          BLOCK-MAPPING-START
   *          KEY
   *          SCALAR("key 1",plain)
   *          VALUE
   *          SCALAR("value 1",plain)
   *          KEY
   *          SCALAR("key 2",plain)
   *          VALUE
   *          SCALAR("value 2",plain)
   *          BLOCK-END
   *          KEY
   *          SCALAR("a sequence",plain)
   *          VALUE
   *          BLOCK-SEQUENCE-START
   *          BLOCK-ENTRY
   *          SCALAR("item 1",plain)
   *          BLOCK-ENTRY
   *          SCALAR("item 2",plain)
   *          BLOCK-END
   *          BLOCK-END
   *          STREAM-END
   *
   * YAML does not always require to start a new block collection from a new
   * line.  If the current line contains only '-', '?', and ':' indicators, a new
   * block collection may start at the current line.  The following examples
   * illustrate this case:
   *
   *      1. Collections in a sequence:
   *
   *          - - item 1
   *            - item 2
   *          - key 1: value 1
   *            key 2: value 2
   *          - ? complex key
   *            : complex value
   *
   *      Tokens:
   *
   *          STREAM-START(utf-8)
   *          BLOCK-SEQUENCE-START
   *          BLOCK-ENTRY
   *          BLOCK-SEQUENCE-START
   *          BLOCK-ENTRY
   *          SCALAR("item 1",plain)
   *          BLOCK-ENTRY
   *          SCALAR("item 2",plain)
   *          BLOCK-END
   *          BLOCK-ENTRY
   *          BLOCK-MAPPING-START
   *          KEY
   *          SCALAR("key 1",plain)
   *          VALUE
   *          SCALAR("value 1",plain)
   *          KEY
   *          SCALAR("key 2",plain)
   *          VALUE
   *          SCALAR("value 2",plain)
   *          BLOCK-END
   *          BLOCK-ENTRY
   *          BLOCK-MAPPING-START
   *          KEY
   *          SCALAR("complex key")
   *          VALUE
   *          SCALAR("complex value")
   *          BLOCK-END
   *          BLOCK-END
   *          STREAM-END
   *
   *      2. Collections in a mapping:
   *
   *          ? a sequence
   *          : - item 1
   *            - item 2
   *          ? a mapping
   *          : key 1: value 1
   *            key 2: value 2
   *
   *      Tokens:
   *
   *          STREAM-START(utf-8)
   *          BLOCK-MAPPING-START
   *          KEY
   *          SCALAR("a sequence",plain)
   *          VALUE
   *          BLOCK-SEQUENCE-START
   *          BLOCK-ENTRY
   *          SCALAR("item 1",plain)
   *          BLOCK-ENTRY
   *          SCALAR("item 2",plain)
   *          BLOCK-END
   *          KEY
   *          SCALAR("a mapping",plain)
   *          VALUE
   *          BLOCK-MAPPING-START
   *          KEY
   *          SCALAR("key 1",plain)
   *          VALUE
   *          SCALAR("value 1",plain)
   *          KEY
   *          SCALAR("key 2",plain)
   *          VALUE
   *          SCALAR("value 2",plain)
   *          BLOCK-END
   *          BLOCK-END
   *          STREAM-END
   *
   * YAML also permits non-indented sequences if they are included into a block
   * mapping.  In this case, the token BLOCK-SEQUENCE-START is not produced:
   *
   *      key:
   *      - item 1    # BLOCK-SEQUENCE-START is NOT produced here.
   *      - item 2
   *
   * Tokens:
   *
   *      STREAM-START(utf-8)
   *      BLOCK-MAPPING-START
   *      KEY
   *      SCALAR("key",plain)
   *      VALUE
   *      BLOCK-ENTRY
   *      SCALAR("item 1",plain)
   *      BLOCK-ENTRY
   *      SCALAR("item 2",plain)
   *      BLOCK-END
   */
  
  #include "yaml_private.h"
  
  /*
   * Ensure that the buffer contains the required number of characters.
   * Return 1 on success, 0 on failure (reader error or memory error).
   */
  
  #define CACHE(parser,length)                                                    \
      (parser->unread >= (length)                                                 \
          ? 1                                                                     \
          : yaml_parser_update_buffer(parser, (length)))
  
  /*
   * Advance the buffer pointer.
   */
  
  #define SKIP(parser)                                                            \
       (parser->mark.index ++,                                                    \
        parser->mark.column ++,                                                   \
        parser->unread --,                                                        \
        parser->buffer.pointer += WIDTH(parser->buffer))
  
  #define SKIP_LINE(parser)                                                       \
       (IS_CRLF(parser->buffer) ?                                                 \
        (parser->mark.index += 2,                                                 \
         parser->mark.column = 0,                                                 \
         parser->mark.line ++,                                                    \
         parser->unread -= 2,                                                     \
         parser->buffer.pointer += 2) :                                           \
        IS_BREAK(parser->buffer) ?                                                \
        (parser->mark.index ++,                                                   \
         parser->mark.column = 0,                                                 \
         parser->mark.line ++,                                                    \
         parser->unread --,                                                       \
         parser->buffer.pointer += WIDTH(parser->buffer)) : 0)
  
  /*
   * Copy a character to a string buffer and advance pointers.
   */
  
  #define READ(parser,string)                                                     \
       (STRING_EXTEND(parser,string) ?                                            \
           (COPY(string,parser->buffer),                                          \
            parser->mark.index ++,                                                \
            parser->mark.column ++,                                               \
            parser->unread --,                                                    \
            1) : 0)
  
  /*
   * Copy a line break character to a string buffer and advance pointers.
   */
  
  #define READ_LINE(parser,string)                                                \
      (STRING_EXTEND(parser,string) ?                                             \
      (((CHECK_AT(parser->buffer,'\r',0)                                          \
         && CHECK_AT(parser->buffer,'\n',1)) ?        /* CR LF -> LF */           \
       (*((string).pointer++) = (yaml_char_t) '\n',                               \
        parser->buffer.pointer += 2,                                              \
        parser->mark.index += 2,                                                  \
        parser->mark.column = 0,                                                  \
        parser->mark.line ++,                                                     \
        parser->unread -= 2) :                                                    \
       (CHECK_AT(parser->buffer,'\r',0)                                           \
        || CHECK_AT(parser->buffer,'\n',0)) ?         /* CR|LF -> LF */           \
       (*((string).pointer++) = (yaml_char_t) '\n',                               \
        parser->buffer.pointer ++,                                                \
        parser->mark.index ++,                                                    \
        parser->mark.column = 0,                                                  \
        parser->mark.line ++,                                                     \
        parser->unread --) :                                                      \
       (CHECK_AT(parser->buffer,'\xC2',0)                                         \
        && CHECK_AT(parser->buffer,'\x85',1)) ?       /* NEL -> LF */             \
       (*((string).pointer++) = (yaml_char_t) '\n',                               \
        parser->buffer.pointer += 2,                                              \
        parser->mark.index ++,                                                    \
        parser->mark.column = 0,                                                  \
        parser->mark.line ++,                                                     \
        parser->unread --) :                                                      \
       (CHECK_AT(parser->buffer,'\xE2',0) &&                                      \
        CHECK_AT(parser->buffer,'\x80',1) &&                                      \
        (CHECK_AT(parser->buffer,'\xA8',2) ||                                     \
         CHECK_AT(parser->buffer,'\xA9',2))) ?        /* LS|PS -> LS|PS */        \
       (*((string).pointer++) = *(parser->buffer.pointer++),                      \
        *((string).pointer++) = *(parser->buffer.pointer++),                      \
        *((string).pointer++) = *(parser->buffer.pointer++),                      \
        parser->mark.index ++,                                                    \
        parser->mark.column = 0,                                                  \
        parser->mark.line ++,                                                     \
        parser->unread --) : 0),                                                  \
      1) : 0)
  
  /*
   * Public API declarations.
   */
  
  YAML_DECLARE(int)
  yaml_parser_scan(yaml_parser_t *parser, yaml_token_t *token);
  
  /*
   * Error handling.
   */
  
  static int
  yaml_parser_set_scanner_error(yaml_parser_t *parser, const char *context,
          yaml_mark_t context_mark, const char *problem);
  
  /*
   * High-level token API.
   */
  
  YAML_DECLARE(int)
  yaml_parser_fetch_more_tokens(yaml_parser_t *parser);
  
  static int
  yaml_parser_fetch_next_token(yaml_parser_t *parser);
  
  /*
   * Potential simple keys.
   */
  
  static int
  yaml_parser_stale_simple_keys(yaml_parser_t *parser);
  
  static int
  yaml_parser_save_simple_key(yaml_parser_t *parser);
  
  static int
  yaml_parser_remove_simple_key(yaml_parser_t *parser);
  
  static int
  yaml_parser_increase_flow_level(yaml_parser_t *parser);
  
  static int
  yaml_parser_decrease_flow_level(yaml_parser_t *parser);
  
  /*
   * Indentation treatment.
   */
  
  static int
  yaml_parser_roll_indent(yaml_parser_t *parser, ptrdiff_t column,
          ptrdiff_t number, yaml_token_type_t type, yaml_mark_t mark);
  
  static int
  yaml_parser_unroll_indent(yaml_parser_t *parser, ptrdiff_t column);
  
  /*
   * Token fetchers.
   */
  
  static int
  yaml_parser_fetch_stream_start(yaml_parser_t *parser);
  
  static int
  yaml_parser_fetch_stream_end(yaml_parser_t *parser);
  
  static int
  yaml_parser_fetch_directive(yaml_parser_t *parser);
  
  static int
  yaml_parser_fetch_document_indicator(yaml_parser_t *parser,
          yaml_token_type_t type);
  
  static int
  yaml_parser_fetch_flow_collection_start(yaml_parser_t *parser,
          yaml_token_type_t type);
  
  static int
  yaml_parser_fetch_flow_collection_end(yaml_parser_t *parser,
          yaml_token_type_t type);
  
  static int
  yaml_parser_fetch_flow_entry(yaml_parser_t *parser);
  
  static int
  yaml_parser_fetch_block_entry(yaml_parser_t *parser);
  
  static int
  yaml_parser_fetch_key(yaml_parser_t *parser);
  
  static int
  yaml_parser_fetch_value(yaml_parser_t *parser);
  
  static int
  yaml_parser_fetch_anchor(yaml_parser_t *parser, yaml_token_type_t type);
  
  static int
  yaml_parser_fetch_tag(yaml_parser_t *parser);
  
  static int
  yaml_parser_fetch_block_scalar(yaml_parser_t *parser, int literal);
  
  static int
  yaml_parser_fetch_flow_scalar(yaml_parser_t *parser, int single);
  
  static int
  yaml_parser_fetch_plain_scalar(yaml_parser_t *parser);
  
  /*
   * Token scanners.
   */
  
  static int
  yaml_parser_scan_to_next_token(yaml_parser_t *parser);
  
  static int
  yaml_parser_scan_directive(yaml_parser_t *parser, yaml_token_t *token);
  
  static int
  yaml_parser_scan_directive_name(yaml_parser_t *parser,
          yaml_mark_t start_mark, yaml_char_t **name);
  
  static int
  yaml_parser_scan_version_directive_value(yaml_parser_t *parser,
          yaml_mark_t start_mark, int *major, int *minor);
  
  static int
  yaml_parser_scan_version_directive_number(yaml_parser_t *parser,
          yaml_mark_t start_mark, int *number);
  
  static int
  yaml_parser_scan_tag_directive_value(yaml_parser_t *parser,
          yaml_mark_t mark, yaml_char_t **handle, yaml_char_t **prefix);
  
  static int
  yaml_parser_scan_anchor(yaml_parser_t *parser, yaml_token_t *token,
          yaml_token_type_t type);
  
  static int
  yaml_parser_scan_tag(yaml_parser_t *parser, yaml_token_t *token);
  
  static int
  yaml_parser_scan_tag_handle(yaml_parser_t *parser, int directive,
          yaml_mark_t start_mark, yaml_char_t **handle);
  
  static int
  yaml_parser_scan_tag_uri(yaml_parser_t *parser, int directive,
          yaml_char_t *head, yaml_mark_t start_mark, yaml_char_t **uri);
  
  static int
  yaml_parser_scan_uri_escapes(yaml_parser_t *parser, int directive,
          yaml_mark_t start_mark, yaml_string_t *string);
  
  static int
  yaml_parser_scan_block_scalar(yaml_parser_t *parser, yaml_token_t *token,
          int literal);
  
  static int
  yaml_parser_scan_block_scalar_breaks(yaml_parser_t *parser,
          int *indent, yaml_string_t *breaks,
          yaml_mark_t start_mark, yaml_mark_t *end_mark);
  
  static int
  yaml_parser_scan_flow_scalar(yaml_parser_t *parser, yaml_token_t *token,
          int single);
  
  static int
  yaml_parser_scan_plain_scalar(yaml_parser_t *parser, yaml_token_t *token);
  
  /*
   * Get the next token.
   */
  
  YAML_DECLARE(int)
  yaml_parser_scan(yaml_parser_t *parser, yaml_token_t *token)
  {
      assert(parser); /* Non-NULL parser object is expected. */
      assert(token);  /* Non-NULL token object is expected. */
  
      /* Erase the token object. */
  
      memset(token, 0, sizeof(yaml_token_t));
  
      /* No tokens after STREAM-END or error. */
  
      if (parser->stream_end_produced || parser->error) {
          return 1;
      }
  
      /* Ensure that the tokens queue contains enough tokens. */
  
      if (!parser->token_available) {
          if (!yaml_parser_fetch_more_tokens(parser))
              return 0;
      }
  
      /* Fetch the next token from the queue. */
  
      *token = DEQUEUE(parser, parser->tokens);
      parser->token_available = 0;
      parser->tokens_parsed ++;
  
      if (token->type == YAML_STREAM_END_TOKEN) {
          parser->stream_end_produced = 1;
      }
  
      return 1;
  }
  
  /*
   * Set the scanner error and return 0.
   */
  
  static int
  yaml_parser_set_scanner_error(yaml_parser_t *parser, const char *context,
          yaml_mark_t context_mark, const char *problem)
  {
      parser->error = YAML_SCANNER_ERROR;
      parser->context = context;
      parser->context_mark = context_mark;
      parser->problem = problem;
      parser->problem_mark = parser->mark;
  
      return 0;
  }
  
  /*
   * Ensure that the tokens queue contains at least one token which can be
   * returned to the Parser.
   */
  
  YAML_DECLARE(int)
  yaml_parser_fetch_more_tokens(yaml_parser_t *parser)
  {
      int need_more_tokens;
  
      /* While we need more tokens to fetch, do it. */
  
      while (1)
      {
          /*
           * Check if we really need to fetch more tokens.
           */
  
          need_more_tokens = 0;
  
          if (parser->tokens.head == parser->tokens.tail)
          {
              /* Queue is empty. */
  
              need_more_tokens = 1;
          }
          else
          {
              yaml_simple_key_t *simple_key;
  
              /* Check if any potential simple key may occupy the head position. */
  
              if (!yaml_parser_stale_simple_keys(parser))
                  return 0;
  
              for (simple_key = parser->simple_keys.start;
                      simple_key != parser->simple_keys.top; simple_key++) {
                  if (simple_key->possible
                          && simple_key->token_number == parser->tokens_parsed) {
                      need_more_tokens = 1;
                      break;
                  }
              }
          }
  
          /* We are finished. */
  
          if (!need_more_tokens)
              break;
  
          /* Fetch the next token. */
  
          if (!yaml_parser_fetch_next_token(parser))
              return 0;
      }
  
      parser->token_available = 1;
  
      return 1;
  }
  
  /*
   * The dispatcher for token fetchers.
   */
  
  static int
  yaml_parser_fetch_next_token(yaml_parser_t *parser)
  {
      /* Ensure that the buffer is initialized. */
  
      if (!CACHE(parser, 1))
          return 0;
  
      /* Check if we just started scanning.  Fetch STREAM-START then. */
  
      if (!parser->stream_start_produced)
          return yaml_parser_fetch_stream_start(parser);
  
      /* Eat whitespaces and comments until we reach the next token. */
  
      if (!yaml_parser_scan_to_next_token(parser))
          return 0;
  
      /* Remove obsolete potential simple keys. */
  
      if (!yaml_parser_stale_simple_keys(parser))
          return 0;
  
      /* Check the indentation level against the current column. */
  
      if (!yaml_parser_unroll_indent(parser, parser->mark.column))
          return 0;
  
      /*
       * Ensure that the buffer contains at least 4 characters.  4 is the length
       * of the longest indicators ('--- ' and '... ').
       */
  
      if (!CACHE(parser, 4))
          return 0;
  
      /* Is it the end of the stream? */
  
      if (IS_Z(parser->buffer))
          return yaml_parser_fetch_stream_end(parser);
  
      /* Is it a directive? */
  
      if (parser->mark.column == 0 && CHECK(parser->buffer, '%'))
          return yaml_parser_fetch_directive(parser);
  
      /* Is it the document start indicator? */
  
      if (parser->mark.column == 0
              && CHECK_AT(parser->buffer, '-', 0)
              && CHECK_AT(parser->buffer, '-', 1)
              && CHECK_AT(parser->buffer, '-', 2)
              && IS_BLANKZ_AT(parser->buffer, 3))
          return yaml_parser_fetch_document_indicator(parser,
                  YAML_DOCUMENT_START_TOKEN);
  
      /* Is it the document end indicator? */
  
      if (parser->mark.column == 0
              && CHECK_AT(parser->buffer, '.', 0)
              && CHECK_AT(parser->buffer, '.', 1)
              && CHECK_AT(parser->buffer, '.', 2)
              && IS_BLANKZ_AT(parser->buffer, 3))
          return yaml_parser_fetch_document_indicator(parser,
                  YAML_DOCUMENT_END_TOKEN);
  
      /* Is it the flow sequence start indicator? */
  
      if (CHECK(parser->buffer, '['))
          return yaml_parser_fetch_flow_collection_start(parser,
                  YAML_FLOW_SEQUENCE_START_TOKEN);
  
      /* Is it the flow mapping start indicator? */
  
      if (CHECK(parser->buffer, '{'))
          return yaml_parser_fetch_flow_collection_start(parser,
                  YAML_FLOW_MAPPING_START_TOKEN);
  
      /* Is it the flow sequence end indicator? */
  
      if (CHECK(parser->buffer, ']'))
          return yaml_parser_fetch_flow_collection_end(parser,
                  YAML_FLOW_SEQUENCE_END_TOKEN);
  
      /* Is it the flow mapping end indicator? */
  
      if (CHECK(parser->buffer, '}'))
          return yaml_parser_fetch_flow_collection_end(parser,
                  YAML_FLOW_MAPPING_END_TOKEN);
  
      /* Is it the flow entry indicator? */
  
      if (CHECK(parser->buffer, ','))
          return yaml_parser_fetch_flow_entry(parser);
  
      /* Is it the block entry indicator? */
  
      if (CHECK(parser->buffer, '-') && IS_BLANKZ_AT(parser->buffer, 1))
          return yaml_parser_fetch_block_entry(parser);
  
      /* Is it the key indicator? */
  
      if (CHECK(parser->buffer, '?')
              && (parser->flow_level || IS_BLANKZ_AT(parser->buffer, 1)))
          return yaml_parser_fetch_key(parser);
  
      /* Is it the value indicator? */
  
      if (CHECK(parser->buffer, ':')
              && (parser->flow_level || IS_BLANKZ_AT(parser->buffer, 1)))
          return yaml_parser_fetch_value(parser);
  
      /* Is it an alias? */
  
      if (CHECK(parser->buffer, '*'))
          return yaml_parser_fetch_anchor(parser, YAML_ALIAS_TOKEN);
  
      /* Is it an anchor? */
  
      if (CHECK(parser->buffer, '&'))
          return yaml_parser_fetch_anchor(parser, YAML_ANCHOR_TOKEN);
  
      /* Is it a tag? */
  
      if (CHECK(parser->buffer, '!'))
          return yaml_parser_fetch_tag(parser);
  
      /* Is it a literal scalar? */
  
      if (CHECK(parser->buffer, '|') && !parser->flow_level)
          return yaml_parser_fetch_block_scalar(parser, 1);
  
      /* Is it a folded scalar? */
  
      if (CHECK(parser->buffer, '>') && !parser->flow_level)
          return yaml_parser_fetch_block_scalar(parser, 0);
  
      /* Is it a single-quoted scalar? */
  
      if (CHECK(parser->buffer, '\''))
          return yaml_parser_fetch_flow_scalar(parser, 1);
  
      /* Is it a double-quoted scalar? */
  
      if (CHECK(parser->buffer, '"'))
          return yaml_parser_fetch_flow_scalar(parser, 0);
  
      /*
       * Is it a plain scalar?
       *
       * A plain scalar may start with any non-blank characters except
       *
       *      '-', '?', ':', ',', '[', ']', '{', '}',
       *      '#', '&', '*', '!', '|', '>', '\'', '\"',
       *      '%', '@', '`'.
       *
       * In the block context (and, for the '-' indicator, in the flow context
       * too), it may also start with the characters
       *
       *      '-', '?', ':'
       *
       * if it is followed by a non-space character.
       *
       * The last rule is more restrictive than the specification requires.
       */
  
      if (!(IS_BLANKZ(parser->buffer) || CHECK(parser->buffer, '-')
                  || CHECK(parser->buffer, '?') || CHECK(parser->buffer, ':')
                  || CHECK(parser->buffer, ',') || CHECK(parser->buffer, '[')
                  || CHECK(parser->buffer, ']') || CHECK(parser->buffer, '{')
                  || CHECK(parser->buffer, '}') || CHECK(parser->buffer, '#')
                  || CHECK(parser->buffer, '&') || CHECK(parser->buffer, '*')
                  || CHECK(parser->buffer, '!') || CHECK(parser->buffer, '|')
                  || CHECK(parser->buffer, '>') || CHECK(parser->buffer, '\'')
                  || CHECK(parser->buffer, '"') || CHECK(parser->buffer, '%')
                  || CHECK(parser->buffer, '@') || CHECK(parser->buffer, '`')) ||
              (CHECK(parser->buffer, '-') && !IS_BLANK_AT(parser->buffer, 1)) ||
              (!parser->flow_level &&
               (CHECK(parser->buffer, '?') || CHECK(parser->buffer, ':'))
               && !IS_BLANKZ_AT(parser->buffer, 1)))
          return yaml_parser_fetch_plain_scalar(parser);
  
      /*
       * If we don't determine the token type so far, it is an error.
       */
  
      return yaml_parser_set_scanner_error(parser,
              "while scanning for the next token", parser->mark,
              "found character that cannot start any token");
  }
  
  /*
   * Check the list of potential simple keys and remove the positions that
   * cannot contain simple keys anymore.
   */
  
  static int
  yaml_parser_stale_simple_keys(yaml_parser_t *parser)
  {
      yaml_simple_key_t *simple_key;
  
      /* Check for a potential simple key for each flow level. */
  
      for (simple_key = parser->simple_keys.start;
              simple_key != parser->simple_keys.top; simple_key ++)
      {
          /*
           * The specification requires that a simple key
           *
           *  - is limited to a single line,
           *  - is shorter than 1024 characters.
           */
  
          if (simple_key->possible
                  && (simple_key->mark.line < parser->mark.line
                      || simple_key->mark.index+1024 < parser->mark.index)) {
  
              /* Check if the potential simple key to be removed is required. */
  
              if (simple_key->required) {
                  return yaml_parser_set_scanner_error(parser,
                          "while scanning a simple key", simple_key->mark,
                          "could not find expected ':'");
              }
  
              simple_key->possible = 0;
          }
      }
  
      return 1;
  }
  
  /*
   * Check if a simple key may start at the current position and add it if
   * needed.
   */
  
  static int
  yaml_parser_save_simple_key(yaml_parser_t *parser)
  {
      /*
       * A simple key is required at the current position if the scanner is in
       * the block context and the current column coincides with the indentation
       * level.
       */
  
      int required = (!parser->flow_level
              && parser->indent == (ptrdiff_t)parser->mark.column);
  
      /*
       * If the current position may start a simple key, save it.
       */
  
      if (parser->simple_key_allowed)
      {
          yaml_simple_key_t simple_key;
          simple_key.possible = 1;
          simple_key.required = required;
          simple_key.token_number =
              parser->tokens_parsed + (parser->tokens.tail - parser->tokens.head);
          simple_key.mark = parser->mark;
  
          if (!yaml_parser_remove_simple_key(parser)) return 0;
  
          *(parser->simple_keys.top-1) = simple_key;
      }
  
      return 1;
  }
  
  /*
   * Remove a potential simple key at the current flow level.
   */
  
  static int
  yaml_parser_remove_simple_key(yaml_parser_t *parser)
  {
      yaml_simple_key_t *simple_key = parser->simple_keys.top-1;
  
      if (simple_key->possible)
      {
          /* If the key is required, it is an error. */
  
          if (simple_key->required) {
              return yaml_parser_set_scanner_error(parser,
                      "while scanning a simple key", simple_key->mark,
                      "could not find expected ':'");
          }
      }
  
      /* Remove the key from the stack. */
  
      simple_key->possible = 0;
  
      return 1;
  }
  
  /*
   * Increase the flow level and resize the simple key list if needed.
   */
  
  static int
  yaml_parser_increase_flow_level(yaml_parser_t *parser)
  {
      yaml_simple_key_t empty_simple_key = { 0, 0, 0, { 0, 0, 0 } };
  
      /* Reset the simple key on the next level. */
  
      if (!PUSH(parser, parser->simple_keys, empty_simple_key))
          return 0;
  
      /* Increase the flow level. */
  
      if (parser->flow_level == INT_MAX) {
          parser->error = YAML_MEMORY_ERROR;
          return 0;
      }
  
      parser->flow_level++;
  
      return 1;
  }
  
  /*
   * Decrease the flow level.
   */
  
  static int
  yaml_parser_decrease_flow_level(yaml_parser_t *parser)
  {
      if (parser->flow_level) {
          parser->flow_level --;
          (void)POP(parser, parser->simple_keys);
      }
  
      return 1;
  }
  
  /*
   * Push the current indentation level to the stack and set the new level
   * the current column is greater than the indentation level.  In this case,
   * append or insert the specified token into the token queue.
   *
   */
  
  static int
  yaml_parser_roll_indent(yaml_parser_t *parser, ptrdiff_t column,
          ptrdiff_t number, yaml_token_type_t type, yaml_mark_t mark)
  {
      yaml_token_t token;
  
      /* In the flow context, do nothing. */
  
      if (parser->flow_level)
          return 1;
  
      if (parser->indent < column)
      {
          /*
           * Push the current indentation level to the stack and set the new
           * indentation level.
           */
  
          if (!PUSH(parser, parser->indents, parser->indent))
              return 0;
  
          if (column > INT_MAX) {
              parser->error = YAML_MEMORY_ERROR;
              return 0;
          }
  
          parser->indent = column;
  
          /* Create a token and insert it into the queue. */
  
          TOKEN_INIT(token, type, mark, mark);
  
          if (number == -1) {
              if (!ENQUEUE(parser, parser->tokens, token))
                  return 0;
          }
          else {
              if (!QUEUE_INSERT(parser,
                          parser->tokens, number - parser->tokens_parsed, token))
                  return 0;
          }
      }
  
      return 1;
  }
  
  /*
   * Pop indentation levels from the indents stack until the current level
   * becomes less or equal to the column.  For each indentation level, append
   * the BLOCK-END token.
   */
  
  
  static int
  yaml_parser_unroll_indent(yaml_parser_t *parser, ptrdiff_t column)
  {
      yaml_token_t token;
  
      /* In the flow context, do nothing. */
  
      if (parser->flow_level)
          return 1;
  
      /* Loop through the indentation levels in the stack. */
  
      while (parser->indent > column)
      {
          /* Create a token and append it to the queue. */
  
          TOKEN_INIT(token, YAML_BLOCK_END_TOKEN, parser->mark, parser->mark);
  
          if (!ENQUEUE(parser, parser->tokens, token))
              return 0;
  
          /* Pop the indentation level. */
  
          parser->indent = POP(parser, parser->indents);
      }
  
      return 1;
  }
  
  /*
   * Initialize the scanner and produce the STREAM-START token.
   */
  
  static int
  yaml_parser_fetch_stream_start(yaml_parser_t *parser)
  {
      yaml_simple_key_t simple_key = { 0, 0, 0, { 0, 0, 0 } };
      yaml_token_t token;
  
      /* Set the initial indentation. */
  
      parser->indent = -1;
  
      /* Initialize the simple key stack. */
  
      if (!PUSH(parser, parser->simple_keys, simple_key))
          return 0;
  
      /* A simple key is allowed at the beginning of the stream. */
  
      parser->simple_key_allowed = 1;
  
      /* We have started. */
  
      parser->stream_start_produced = 1;
  
      /* Create the STREAM-START token and append it to the queue. */
  
      STREAM_START_TOKEN_INIT(token, parser->encoding,
              parser->mark, parser->mark);
  
      if (!ENQUEUE(parser, parser->tokens, token))
          return 0;
  
      return 1;
  }
  
  /*
   * Produce the STREAM-END token and shut down the scanner.
   */
  
  static int
  yaml_parser_fetch_stream_end(yaml_parser_t *parser)
  {
      yaml_token_t token;
  
      /* Force new line. */
  
      if (parser->mark.column != 0) {
          parser->mark.column = 0;
          parser->mark.line ++;
      }
  
      /* Reset the indentation level. */
  
      if (!yaml_parser_unroll_indent(parser, -1))
          return 0;
  
      /* Reset simple keys. */
  
      if (!yaml_parser_remove_simple_key(parser))
          return 0;
  
      parser->simple_key_allowed = 0;
  
      /* Create the STREAM-END token and append it to the queue. */
  
      STREAM_END_TOKEN_INIT(token, parser->mark, parser->mark);
  
      if (!ENQUEUE(parser, parser->tokens, token))
          return 0;
  
      return 1;
  }
  
  /*
   * Produce a VERSION-DIRECTIVE or TAG-DIRECTIVE token.
   */
  
  static int
  yaml_parser_fetch_directive(yaml_parser_t *parser)
  {
      yaml_token_t token;
  
      /* Reset the indentation level. */
  
      if (!yaml_parser_unroll_indent(parser, -1))
          return 0;
  
      /* Reset simple keys. */
  
      if (!yaml_parser_remove_simple_key(parser))
          return 0;
  
      parser->simple_key_allowed = 0;
  
      /* Create the YAML-DIRECTIVE or TAG-DIRECTIVE token. */
  
      if (!yaml_parser_scan_directive(parser, &token))
          return 0;
  
      /* Append the token to the queue. */
  
      if (!ENQUEUE(parser, parser->tokens, token)) {
          yaml_token_delete(&token);
          return 0;
      }
  
      return 1;
  }
  
  /*
   * Produce the DOCUMENT-START or DOCUMENT-END token.
   */
  
  static int
  yaml_parser_fetch_document_indicator(yaml_parser_t *parser,
          yaml_token_type_t type)
  {
      yaml_mark_t start_mark, end_mark;
      yaml_token_t token;
  
      /* Reset the indentation level. */
  
      if (!yaml_parser_unroll_indent(parser, -1))
          return 0;
  
      /* Reset simple keys. */
  
      if (!yaml_parser_remove_simple_key(parser))
          return 0;
  
      parser->simple_key_allowed = 0;
  
      /* Consume the token. */
  
      start_mark = parser->mark;
  
      SKIP(parser);
      SKIP(parser);
      SKIP(parser);
  
      end_mark = parser->mark;
  
      /* Create the DOCUMENT-START or DOCUMENT-END token. */
  
      TOKEN_INIT(token, type, start_mark, end_mark);
  
      /* Append the token to the queue. */
  
      if (!ENQUEUE(parser, parser->tokens, token))
          return 0;
  
      return 1;
  }
  
  /*
   * Produce the FLOW-SEQUENCE-START or FLOW-MAPPING-START token.
   */
  
  static int
  yaml_parser_fetch_flow_collection_start(yaml_parser_t *parser,
          yaml_token_type_t type)
  {
      yaml_mark_t start_mark, end_mark;
      yaml_token_t token;
  
      /* The indicators '[' and '{' may start a simple key. */
  
      if (!yaml_parser_save_simple_key(parser))
          return 0;
  
      /* Increase the flow level. */
  
      if (!yaml_parser_increase_flow_level(parser))
          return 0;
  
      /* A simple key may follow the indicators '[' and '{'. */
  
      parser->simple_key_allowed = 1;
  
      /* Consume the token. */
  
      start_mark = parser->mark;
      SKIP(parser);
      end_mark = parser->mark;
  
      /* Create the FLOW-SEQUENCE-START of FLOW-MAPPING-START token. */
  
      TOKEN_INIT(token, type, start_mark, end_mark);
  
      /* Append the token to the queue. */
  
      if (!ENQUEUE(parser, parser->tokens, token))
          return 0;
  
      return 1;
  }
  
  /*
   * Produce the FLOW-SEQUENCE-END or FLOW-MAPPING-END token.
   */
  
  static int
  yaml_parser_fetch_flow_collection_end(yaml_parser_t *parser,
          yaml_token_type_t type)
  {
      yaml_mark_t start_mark, end_mark;
      yaml_token_t token;
  
      /* Reset any potential simple key on the current flow level. */
  
      if (!yaml_parser_remove_simple_key(parser))
          return 0;
  
      /* Decrease the flow level. */
  
      if (!yaml_parser_decrease_flow_level(parser))
          return 0;
  
      /* No simple keys after the indicators ']' and '}'. */
  
      parser->simple_key_allowed = 0;
  
      /* Consume the token. */
  
      start_mark = parser->mark;
      SKIP(parser);
      end_mark = parser->mark;
  
      /* Create the FLOW-SEQUENCE-END of FLOW-MAPPING-END token. */
  
      TOKEN_INIT(token, type, start_mark, end_mark);
  
      /* Append the token to the queue. */
  
      if (!ENQUEUE(parser, parser->tokens, token))
          return 0;
  
      return 1;
  }
  
  /*
   * Produce the FLOW-ENTRY token.
   */
  
  static int
  yaml_parser_fetch_flow_entry(yaml_parser_t *parser)
  {
      yaml_mark_t start_mark, end_mark;
      yaml_token_t token;
  
      /* Reset any potential simple keys on the current flow level. */
  
      if (!yaml_parser_remove_simple_key(parser))
          return 0;
  
      /* Simple keys are allowed after ','. */
  
      parser->simple_key_allowed = 1;
  
      /* Consume the token. */
  
      start_mark = parser->mark;
      SKIP(parser);
      end_mark = parser->mark;
  
      /* Create the FLOW-ENTRY token and append it to the queue. */
  
      TOKEN_INIT(token, YAML_FLOW_ENTRY_TOKEN, start_mark, end_mark);
  
      if (!ENQUEUE(parser, parser->tokens, token))
          return 0;
  
      return 1;
  }
  
  /*
   * Produce the BLOCK-ENTRY token.
   */
  
  static int
  yaml_parser_fetch_block_entry(yaml_parser_t *parser)
  {
      yaml_mark_t start_mark, end_mark;
      yaml_token_t token;
  
      /* Check if the scanner is in the block context. */
  
      if (!parser->flow_level)
      {
          /* Check if we are allowed to start a new entry. */
  
          if (!parser->simple_key_allowed) {
              return yaml_parser_set_scanner_error(parser, NULL, parser->mark,
                      "block sequence entries are not allowed in this context");
          }
  
          /* Add the BLOCK-SEQUENCE-START token if needed. */
  
          if (!yaml_parser_roll_indent(parser, parser->mark.column, -1,
                      YAML_BLOCK_SEQUENCE_START_TOKEN, parser->mark))
              return 0;
      }
      else
      {
          /*
           * It is an error for the '-' indicator to occur in the flow context,
           * but we let the Parser detect and report about it because the Parser
           * is able to point to the context.
           */
      }
  
      /* Reset any potential simple keys on the current flow level. */
  
      if (!yaml_parser_remove_simple_key(parser))
          return 0;
  
      /* Simple keys are allowed after '-'. */
  
      parser->simple_key_allowed = 1;
  
      /* Consume the token. */
  
      start_mark = parser->mark;
      SKIP(parser);
      end_mark = parser->mark;
  
      /* Create the BLOCK-ENTRY token and append it to the queue. */
  
      TOKEN_INIT(token, YAML_BLOCK_ENTRY_TOKEN, start_mark, end_mark);
  
      if (!ENQUEUE(parser, parser->tokens, token))
          return 0;
  
      return 1;
  }
  
  /*
   * Produce the KEY token.
   */
  
  static int
  yaml_parser_fetch_key(yaml_parser_t *parser)
  {
      yaml_mark_t start_mark, end_mark;
      yaml_token_t token;
  
      /* In the block context, additional checks are required. */
  
      if (!parser->flow_level)
      {
          /* Check if we are allowed to start a new key (not necessary simple). */
  
          if (!parser->simple_key_allowed) {
              return yaml_parser_set_scanner_error(parser, NULL, parser->mark,
                      "mapping keys are not allowed in this context");
          }
  
          /* Add the BLOCK-MAPPING-START token if needed. */
  
          if (!yaml_parser_roll_indent(parser, parser->mark.column, -1,
                      YAML_BLOCK_MAPPING_START_TOKEN, parser->mark))
              return 0;
      }
  
      /* Reset any potential simple keys on the current flow level. */
  
      if (!yaml_parser_remove_simple_key(parser))
          return 0;
  
      /* Simple keys are allowed after '?' in the block context. */
  
      parser->simple_key_allowed = (!parser->flow_level);
  
      /* Consume the token. */
  
      start_mark = parser->mark;
      SKIP(parser);
      end_mark = parser->mark;
  
      /* Create the KEY token and append it to the queue. */
  
      TOKEN_INIT(token, YAML_KEY_TOKEN, start_mark, end_mark);
  
      if (!ENQUEUE(parser, parser->tokens, token))
          return 0;
  
      return 1;
  }
  
  /*
   * Produce the VALUE token.
   */
  
  static int
  yaml_parser_fetch_value(yaml_parser_t *parser)
  {
      yaml_mark_t start_mark, end_mark;
      yaml_token_t token;
      yaml_simple_key_t *simple_key = parser->simple_keys.top-1;
  
      /* Have we found a simple key? */
  
      if (simple_key->possible)
      {
  
          /* Create the KEY token and insert it into the queue. */
  
          TOKEN_INIT(token, YAML_KEY_TOKEN, simple_key->mark, simple_key->mark);
  
          if (!QUEUE_INSERT(parser, parser->tokens,
                      simple_key->token_number - parser->tokens_parsed, token))
              return 0;
  
          /* In the block context, we may need to add the BLOCK-MAPPING-START token. */
  
          if (!yaml_parser_roll_indent(parser, simple_key->mark.column,
                      simple_key->token_number,
                      YAML_BLOCK_MAPPING_START_TOKEN, simple_key->mark))
              return 0;
  
          /* Remove the simple key. */
  
          simple_key->possible = 0;
  
          /* A simple key cannot follow another simple key. */
  
          parser->simple_key_allowed = 0;
      }
      else
      {
          /* The ':' indicator follows a complex key. */
  
          /* In the block context, extra checks are required. */
  
          if (!parser->flow_level)
          {
              /* Check if we are allowed to start a complex value. */
  
              if (!parser->simple_key_allowed) {
                  return yaml_parser_set_scanner_error(parser, NULL, parser->mark,
                          "mapping values are not allowed in this context");
              }
  
              /* Add the BLOCK-MAPPING-START token if needed. */
  
              if (!yaml_parser_roll_indent(parser, parser->mark.column, -1,
                          YAML_BLOCK_MAPPING_START_TOKEN, parser->mark))
                  return 0;
          }
  
          /* Simple keys after ':' are allowed in the block context. */
  
          parser->simple_key_allowed = (!parser->flow_level);
      }
  
      /* Consume the token. */
  
      start_mark = parser->mark;
      SKIP(parser);
      end_mark = parser->mark;
  
      /* Create the VALUE token and append it to the queue. */
  
      TOKEN_INIT(token, YAML_VALUE_TOKEN, start_mark, end_mark);
  
      if (!ENQUEUE(parser, parser->tokens, token))
          return 0;
  
      return 1;
  }
  
  /*
   * Produce the ALIAS or ANCHOR token.
   */
  
  static int
  yaml_parser_fetch_anchor(yaml_parser_t *parser, yaml_token_type_t type)
  {
      yaml_token_t token;
  
      /* An anchor or an alias could be a simple key. */
  
      if (!yaml_parser_save_simple_key(parser))
          return 0;
  
      /* A simple key cannot follow an anchor or an alias. */
  
      parser->simple_key_allowed = 0;
  
      /* Create the ALIAS or ANCHOR token and append it to the queue. */
  
      if (!yaml_parser_scan_anchor(parser, &token, type))
          return 0;
  
      if (!ENQUEUE(parser, parser->tokens, token)) {
          yaml_token_delete(&token);
          return 0;
      }
      return 1;
  }
  
  /*
   * Produce the TAG token.
   */
  
  static int
  yaml_parser_fetch_tag(yaml_parser_t *parser)
  {
      yaml_token_t token;
  
      /* A tag could be a simple key. */
  
      if (!yaml_parser_save_simple_key(parser))
          return 0;
  
      /* A simple key cannot follow a tag. */
  
      parser->simple_key_allowed = 0;
  
      /* Create the TAG token and append it to the queue. */
  
      if (!yaml_parser_scan_tag(parser, &token))
          return 0;
  
      if (!ENQUEUE(parser, parser->tokens, token)) {
          yaml_token_delete(&token);
          return 0;
      }
  
      return 1;
  }
  
  /*
   * Produce the SCALAR(...,literal) or SCALAR(...,folded) tokens.
   */
  
  static int
  yaml_parser_fetch_block_scalar(yaml_parser_t *parser, int literal)
  {
      yaml_token_t token;
  
      /* Remove any potential simple keys. */
  
      if (!yaml_parser_remove_simple_key(parser))
          return 0;
  
      /* A simple key may follow a block scalar. */
  
      parser->simple_key_allowed = 1;
  
      /* Create the SCALAR token and append it to the queue. */
  
      if (!yaml_parser_scan_block_scalar(parser, &token, literal))
          return 0;
  
      if (!ENQUEUE(parser, parser->tokens, token)) {
          yaml_token_delete(&token);
          return 0;
      }
  
      return 1;
  }
  
  /*
   * Produce the SCALAR(...,single-quoted) or SCALAR(...,double-quoted) tokens.
   */
  
  static int
  yaml_parser_fetch_flow_scalar(yaml_parser_t *parser, int single)
  {
      yaml_token_t token;
  
      /* A plain scalar could be a simple key. */
  
      if (!yaml_parser_save_simple_key(parser))
          return 0;
  
      /* A simple key cannot follow a flow scalar. */
  
      parser->simple_key_allowed = 0;
  
      /* Create the SCALAR token and append it to the queue. */
  
      if (!yaml_parser_scan_flow_scalar(parser, &token, single))
          return 0;
  
      if (!ENQUEUE(parser, parser->tokens, token)) {
          yaml_token_delete(&token);
          return 0;
      }
  
      return 1;
  }
  
  /*
   * Produce the SCALAR(...,plain) token.
   */
  
  static int
  yaml_parser_fetch_plain_scalar(yaml_parser_t *parser)
  {
      yaml_token_t token;
  
      /* A plain scalar could be a simple key. */
  
      if (!yaml_parser_save_simple_key(parser))
          return 0;
  
      /* A simple key cannot follow a flow scalar. */
  
      parser->simple_key_allowed = 0;
  
      /* Create the SCALAR token and append it to the queue. */
  
      if (!yaml_parser_scan_plain_scalar(parser, &token))
          return 0;
  
      if (!ENQUEUE(parser, parser->tokens, token)) {
          yaml_token_delete(&token);
          return 0;
      }
  
      return 1;
  }
  
  /*
   * Eat whitespaces and comments until the next token is found.
   */
  
  static int
  yaml_parser_scan_to_next_token(yaml_parser_t *parser)
  {
      /* Until the next token is not found. */
  
      while (1)
      {
          /* Allow the BOM mark to start a line. */
  
          if (!CACHE(parser, 1)) return 0;
  
          if (parser->mark.column == 0 && IS_BOM(parser->buffer))
              SKIP(parser);
  
          /*
           * Eat whitespaces.
           *
           * Tabs are allowed:
           *
           *  - in the flow context;
           *  - in the block context, but not at the beginning of the line or
           *  after '-', '?', or ':' (complex value).
           */
  
          if (!CACHE(parser, 1)) return 0;
  
          while (CHECK(parser->buffer,' ') ||
                  ((parser->flow_level || !parser->simple_key_allowed) &&
                   CHECK(parser->buffer, '\t'))) {
              SKIP(parser);
              if (!CACHE(parser, 1)) return 0;
          }
  
          /* Eat a comment until a line break. */
  
          if (CHECK(parser->buffer, '#')) {
              while (!IS_BREAKZ(parser->buffer)) {
                  SKIP(parser);
                  if (!CACHE(parser, 1)) return 0;
              }
          }
  
          /* If it is a line break, eat it. */
  
          if (IS_BREAK(parser->buffer))
          {
              if (!CACHE(parser, 2)) return 0;
              SKIP_LINE(parser);
  
              /* In the block context, a new line may start a simple key. */
  
              if (!parser->flow_level) {
                  parser->simple_key_allowed = 1;
              }
          }
          else
          {
              /* We have found a token. */
  
              break;
          }
      }
  
      return 1;
  }
  
  /*
   * Scan a YAML-DIRECTIVE or TAG-DIRECTIVE token.
   *
   * Scope:
   *      %YAML    1.1    # a comment \n
   *      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   *      %TAG    !yaml!  tag:yaml.org,2002:  \n
   *      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   */
  
  int
  yaml_parser_scan_directive(yaml_parser_t *parser, yaml_token_t *token)
  {
      yaml_mark_t start_mark, end_mark;
      yaml_char_t *name = NULL;
      int major, minor;
      yaml_char_t *handle = NULL, *prefix = NULL;
  
      /* Eat '%'. */
  
      start_mark = parser->mark;
  
      SKIP(parser);
  
      /* Scan the directive name. */
  
      if (!yaml_parser_scan_directive_name(parser, start_mark, &name))
          goto error;
  
      /* Is it a YAML directive? */
  
      if (strcmp((char *)name, "YAML") == 0)
      {
          /* Scan the VERSION directive value. */
  
          if (!yaml_parser_scan_version_directive_value(parser, start_mark,
                      &major, &minor))
              goto error;
  
          end_mark = parser->mark;
  
          /* Create a VERSION-DIRECTIVE token. */
  
          VERSION_DIRECTIVE_TOKEN_INIT(*token, major, minor,
                  start_mark, end_mark);
      }
  
      /* Is it a TAG directive? */
  
      else if (strcmp((char *)name, "TAG") == 0)
      {
          /* Scan the TAG directive value. */
  
          if (!yaml_parser_scan_tag_directive_value(parser, start_mark,
                      &handle, &prefix))
              goto error;
  
          end_mark = parser->mark;
  
          /* Create a TAG-DIRECTIVE token. */
  
          TAG_DIRECTIVE_TOKEN_INIT(*token, handle, prefix,
                  start_mark, end_mark);
      }
  
      /* Unknown directive. */
  
      else
      {
          yaml_parser_set_scanner_error(parser, "while scanning a directive",
                  start_mark, "found unknown directive name");
          goto error;
      }
  
      /* Eat the rest of the line including any comments. */
  
      if (!CACHE(parser, 1)) goto error;
  
      while (IS_BLANK(parser->buffer)) {
          SKIP(parser);
          if (!CACHE(parser, 1)) goto error;
      }
  
      if (CHECK(parser->buffer, '#')) {
          while (!IS_BREAKZ(parser->buffer)) {
              SKIP(parser);
              if (!CACHE(parser, 1)) goto error;
          }
      }
  
      /* Check if we are at the end of the line. */
  
      if (!IS_BREAKZ(parser->buffer)) {
          yaml_parser_set_scanner_error(parser, "while scanning a directive",
                  start_mark, "did not find expected comment or line break");
          goto error;
      }
  
      /* Eat a line break. */
  
      if (IS_BREAK(parser->buffer)) {
          if (!CACHE(parser, 2)) goto error;
          SKIP_LINE(parser);
      }
  
      yaml_free(name);
  
      return 1;
  
  error:
      yaml_free(prefix);
      yaml_free(handle);
      yaml_free(name);
      return 0;
  }
  
  /*
   * Scan the directive name.
   *
   * Scope:
   *      %YAML   1.1     # a comment \n
   *       ^^^^
   *      %TAG    !yaml!  tag:yaml.org,2002:  \n
   *       ^^^
   */
  
  static int
  yaml_parser_scan_directive_name(yaml_parser_t *parser,
          yaml_mark_t start_mark, yaml_char_t **name)
  {
      yaml_string_t string = NULL_STRING;
  
      if (!STRING_INIT(parser, string, INITIAL_STRING_SIZE)) goto error;
  
      /* Consume the directive name. */
  
      if (!CACHE(parser, 1)) goto error;
  
      while (IS_ALPHA(parser->buffer))
      {
          if (!READ(parser, string)) goto error;
          if (!CACHE(parser, 1)) goto error;
      }
  
      /* Check if the name is empty. */
  
      if (string.start == string.pointer) {
          yaml_parser_set_scanner_error(parser, "while scanning a directive",
                  start_mark, "could not find expected directive name");
          goto error;
      }
  
      /* Check for an blank character after the name. */
  
      if (!IS_BLANKZ(parser->buffer)) {
          yaml_parser_set_scanner_error(parser, "while scanning a directive",
                  start_mark, "found unexpected non-alphabetical character");
          goto error;
      }
  
      *name = string.start;
  
      return 1;
  
  error:
      STRING_DEL(parser, string);
      return 0;
  }
  
  /*
   * Scan the value of VERSION-DIRECTIVE.
   *
   * Scope:
   *      %YAML   1.1     # a comment \n
   *           ^^^^^^
   */
  
  static int
  yaml_parser_scan_version_directive_value(yaml_parser_t *parser,
          yaml_mark_t start_mark, int *major, int *minor)
  {
      /* Eat whitespaces. */
  
      if (!CACHE(parser, 1)) return 0;
  
      while (IS_BLANK(parser->buffer)) {
          SKIP(parser);
          if (!CACHE(parser, 1)) return 0;
      }
  
      /* Consume the major version number. */
  
      if (!yaml_parser_scan_version_directive_number(parser, start_mark, major))
          return 0;
  
      /* Eat '.'. */
  
      if (!CHECK(parser->buffer, '.')) {
          return yaml_parser_set_scanner_error(parser, "while scanning a %YAML directive",
                  start_mark, "did not find expected digit or '.' character");
      }
  
      SKIP(parser);
  
      /* Consume the minor version number. */
  
      if (!yaml_parser_scan_version_directive_number(parser, start_mark, minor))
          return 0;
  
      return 1;
  }
  
  #define MAX_NUMBER_LENGTH   9
  
  /*
   * Scan the version number of VERSION-DIRECTIVE.
   *
   * Scope:
   *      %YAML   1.1     # a comment \n
   *              ^
   *      %YAML   1.1     # a comment \n
   *                ^
   */
  
  static int
  yaml_parser_scan_version_directive_number(yaml_parser_t *parser,
          yaml_mark_t start_mark, int *number)
  {
      int value = 0;
      size_t length = 0;
  
      /* Repeat while the next character is digit. */
  
      if (!CACHE(parser, 1)) return 0;
  
      while (IS_DIGIT(parser->buffer))
      {
          /* Check if the number is too long. */
  
          if (++length > MAX_NUMBER_LENGTH) {
              return yaml_parser_set_scanner_error(parser, "while scanning a %YAML directive",
                      start_mark, "found extremely long version number");
          }
  
          value = value*10 + AS_DIGIT(parser->buffer);
  
          SKIP(parser);
  
          if (!CACHE(parser, 1)) return 0;
      }
  
      /* Check if the number was present. */
  
      if (!length) {
          return yaml_parser_set_scanner_error(parser, "while scanning a %YAML directive",
                  start_mark, "did not find expected version number");
      }
  
      *number = value;
  
      return 1;
  }
  
  /*
   * Scan the value of a TAG-DIRECTIVE token.
   *
   * Scope:
   *      %TAG    !yaml!  tag:yaml.org,2002:  \n
   *          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   */
  
  static int
  yaml_parser_scan_tag_directive_value(yaml_parser_t *parser,
          yaml_mark_t start_mark, yaml_char_t **handle, yaml_char_t **prefix)
  {
      yaml_char_t *handle_value = NULL;
      yaml_char_t *prefix_value = NULL;
  
      /* Eat whitespaces. */
  
      if (!CACHE(parser, 1)) goto error;
  
      while (IS_BLANK(parser->buffer)) {
          SKIP(parser);
          if (!CACHE(parser, 1)) goto error;
      }
  
      /* Scan a handle. */
  
      if (!yaml_parser_scan_tag_handle(parser, 1, start_mark, &handle_value))
          goto error;
  
      /* Expect a whitespace. */
  
      if (!CACHE(parser, 1)) goto error;
  
      if (!IS_BLANK(parser->buffer)) {
          yaml_parser_set_scanner_error(parser, "while scanning a %TAG directive",
                  start_mark, "did not find expected whitespace");
          goto error;
      }
  
      /* Eat whitespaces. */
  
      while (IS_BLANK(parser->buffer)) {
          SKIP(parser);
          if (!CACHE(parser, 1)) goto error;
      }
  
      /* Scan a prefix. */
  
      if (!yaml_parser_scan_tag_uri(parser, 1, NULL, start_mark, &prefix_value))
          goto error;
  
      /* Expect a whitespace or line break. */
  
      if (!CACHE(parser, 1)) goto error;
  
      if (!IS_BLANKZ(parser->buffer)) {
          yaml_parser_set_scanner_error(parser, "while scanning a %TAG directive",
                  start_mark, "did not find expected whitespace or line break");
          goto error;
      }
  
      *handle = handle_value;
      *prefix = prefix_value;
  
      return 1;
  
  error:
      yaml_free(handle_value);
      yaml_free(prefix_value);
      return 0;
  }
  
  static int
  yaml_parser_scan_anchor(yaml_parser_t *parser, yaml_token_t *token,
          yaml_token_type_t type)
  {
      int length = 0;
      yaml_mark_t start_mark, end_mark;
      yaml_string_t string = NULL_STRING;
  
      if (!STRING_INIT(parser, string, INITIAL_STRING_SIZE)) goto error;
  
      /* Eat the indicator character. */
  
      start_mark = parser->mark;
  
      SKIP(parser);
  
      /* Consume the value. */
  
      if (!CACHE(parser, 1)) goto error;
  
      while (IS_ALPHA(parser->buffer)) {
          if (!READ(parser, string)) goto error;
          if (!CACHE(parser, 1)) goto error;
          length ++;
      }
  
      end_mark = parser->mark;
  
      /*
       * Check if length of the anchor is greater than 0 and it is followed by
       * a whitespace character or one of the indicators:
       *
       *      '?', ':', ',', ']', '}', '%', '@', '`'.
       */
  
      if (!length || !(IS_BLANKZ(parser->buffer) || CHECK(parser->buffer, '?')
                  || CHECK(parser->buffer, ':') || CHECK(parser->buffer, ',')
                  || CHECK(parser->buffer, ']') || CHECK(parser->buffer, '}')
                  || CHECK(parser->buffer, '%') || CHECK(parser->buffer, '@')
                  || CHECK(parser->buffer, '`'))) {
          yaml_parser_set_scanner_error(parser, type == YAML_ANCHOR_TOKEN ?
                  "while scanning an anchor" : "while scanning an alias", start_mark,
                  "did not find expected alphabetic or numeric character");
          goto error;
      }
  
      /* Create a token. */
  
      if (type == YAML_ANCHOR_TOKEN) {
          ANCHOR_TOKEN_INIT(*token, string.start, start_mark, end_mark);
      }
      else {
          ALIAS_TOKEN_INIT(*token, string.start, start_mark, end_mark);
      }
  
      return 1;
  
  error:
      STRING_DEL(parser, string);
      return 0;
  }
  
  /*
   * Scan a TAG token.
   */
  
  static int
  yaml_parser_scan_tag(yaml_parser_t *parser, yaml_token_t *token)
  {
      yaml_char_t *handle = NULL;
      yaml_char_t *suffix = NULL;
      yaml_mark_t start_mark, end_mark;
  
      start_mark = parser->mark;
  
      /* Check if the tag is in the canonical form. */
  
      if (!CACHE(parser, 2)) goto error;
  
      if (CHECK_AT(parser->buffer, '<', 1))
      {
          /* Set the handle to '' */
  
          handle = YAML_MALLOC(1);
          if (!handle) goto error;
          handle[0] = '\0';
  
          /* Eat '!<' */
  
          SKIP(parser);
          SKIP(parser);
  
          /* Consume the tag value. */
  
          if (!yaml_parser_scan_tag_uri(parser, 0, NULL, start_mark, &suffix))
              goto error;
  
          /* Check for '>' and eat it. */
  
          if (!CHECK(parser->buffer, '>')) {
              yaml_parser_set_scanner_error(parser, "while scanning a tag",
                      start_mark, "did not find the expected '>'");
              goto error;
          }
  
          SKIP(parser);
      }
      else
      {
          /* The tag has either the '!suffix' or the '!handle!suffix' form. */
  
          /* First, try to scan a handle. */
  
          if (!yaml_parser_scan_tag_handle(parser, 0, start_mark, &handle))
              goto error;
  
          /* Check if it is, indeed, handle. */
  
          if (handle[0] == '!' && handle[1] != '\0' && handle[strlen((char *)handle)-1] == '!')
          {
              /* Scan the suffix now. */
  
              if (!yaml_parser_scan_tag_uri(parser, 0, NULL, start_mark, &suffix))
                  goto error;
          }
          else
          {
              /* It wasn't a handle after all.  Scan the rest of the tag. */
  
              if (!yaml_parser_scan_tag_uri(parser, 0, handle, start_mark, &suffix))
                  goto error;
  
              /* Set the handle to '!'. */
  
              yaml_free(handle);
              handle = YAML_MALLOC(2);
              if (!handle) goto error;
              handle[0] = '!';
              handle[1] = '\0';
  
              /*
               * A special case: the '!' tag.  Set the handle to '' and the
               * suffix to '!'.
               */
  
              if (suffix[0] == '\0') {
                  yaml_char_t *tmp = handle;
                  handle = suffix;
                  suffix = tmp;
              }
          }
      }
  
      /* Check the character which ends the tag. */
  
      if (!CACHE(parser, 1)) goto error;
  
      if (!IS_BLANKZ(parser->buffer)) {
          yaml_parser_set_scanner_error(parser, "while scanning a tag",
                  start_mark, "did not find expected whitespace or line break");
          goto error;
      }
  
      end_mark = parser->mark;
  
      /* Create a token. */
  
      TAG_TOKEN_INIT(*token, handle, suffix, start_mark, end_mark);
  
      return 1;
  
  error:
      yaml_free(handle);
      yaml_free(suffix);
      return 0;
  }
  
  /*
   * Scan a tag handle.
   */
  
  static int
  yaml_parser_scan_tag_handle(yaml_parser_t *parser, int directive,
          yaml_mark_t start_mark, yaml_char_t **handle)
  {
      yaml_string_t string = NULL_STRING;
  
      if (!STRING_INIT(parser, string, INITIAL_STRING_SIZE)) goto error;
  
      /* Check the initial '!' character. */
  
      if (!CACHE(parser, 1)) goto error;
  
      if (!CHECK(parser->buffer, '!')) {
          yaml_parser_set_scanner_error(parser, directive ?
                  "while scanning a tag directive" : "while scanning a tag",
                  start_mark, "did not find expected '!'");
          goto error;
      }
  
      /* Copy the '!' character. */
  
      if (!READ(parser, string)) goto error;
  
      /* Copy all subsequent alphabetical and numerical characters. */
  
      if (!CACHE(parser, 1)) goto error;
  
      while (IS_ALPHA(parser->buffer))
      {
          if (!READ(parser, string)) goto error;
          if (!CACHE(parser, 1)) goto error;
      }
  
      /* Check if the trailing character is '!' and copy it. */
  
      if (CHECK(parser->buffer, '!'))
      {
          if (!READ(parser, string)) goto error;
      }
      else
      {
          /*
           * It's either the '!' tag or not really a tag handle.  If it's a %TAG
           * directive, it's an error.  If it's a tag token, it must be a part of
           * URI.
           */
  
          if (directive && !(string.start[0] == '!' && string.start[1] == '\0')) {
              yaml_parser_set_scanner_error(parser, "while parsing a tag directive",
                      start_mark, "did not find expected '!'");
              goto error;
          }
      }
  
      *handle = string.start;
  
      return 1;
  
  error:
      STRING_DEL(parser, string);
      return 0;
  }
  
  /*
   * Scan a tag.
   */
  
  static int
  yaml_parser_scan_tag_uri(yaml_parser_t *parser, int directive,
          yaml_char_t *head, yaml_mark_t start_mark, yaml_char_t **uri)
  {
      size_t length = head ? strlen((char *)head) : 0;
      yaml_string_t string = NULL_STRING;
  
      if (!STRING_INIT(parser, string, INITIAL_STRING_SIZE)) goto error;
  
      /* Resize the string to include the head. */
  
      while ((size_t)(string.end - string.start) <= length) {
          if (!yaml_string_extend(&string.start, &string.pointer, &string.end)) {
              parser->error = YAML_MEMORY_ERROR;
              goto error;
          }
      }
  
      /*
       * Copy the head if needed.
       *
       * Note that we don't copy the leading '!' character.
       */
  
      if (length > 1) {
          memcpy(string.start, head+1, length-1);
          string.pointer += length-1;
      }
  
      /* Scan the tag. */
  
      if (!CACHE(parser, 1)) goto error;
  
      /*
       * The set of characters that may appear in URI is as follows:
       *
       *      '0'-'9', 'A'-'Z', 'a'-'z', '_', '-', ';', '/', '?', ':', '@', '&',
       *      '=', '+', '$', ',', '.', '!', '~', '*', '\'', '(', ')', '[', ']',
       *      '%'.
       */
  
      while (IS_ALPHA(parser->buffer) || CHECK(parser->buffer, ';')
              || CHECK(parser->buffer, '/') || CHECK(parser->buffer, '?')
              || CHECK(parser->buffer, ':') || CHECK(parser->buffer, '@')
              || CHECK(parser->buffer, '&') || CHECK(parser->buffer, '=')
              || CHECK(parser->buffer, '+') || CHECK(parser->buffer, '$')
              || CHECK(parser->buffer, ',') || CHECK(parser->buffer, '.')
              || CHECK(parser->buffer, '!') || CHECK(parser->buffer, '~')
              || CHECK(parser->buffer, '*') || CHECK(parser->buffer, '\'')
              || CHECK(parser->buffer, '(') || CHECK(parser->buffer, ')')
              || CHECK(parser->buffer, '[') || CHECK(parser->buffer, ']')
              || CHECK(parser->buffer, '%'))
      {
          /* Check if it is a URI-escape sequence. */
  
          if (CHECK(parser->buffer, '%')) {
              if (!STRING_EXTEND(parser, string))
                  goto error;
  
              if (!yaml_parser_scan_uri_escapes(parser,
                          directive, start_mark, &string)) goto error;
          }
          else {
              if (!READ(parser, string)) goto error;
          }
  
          length ++;
          if (!CACHE(parser, 1)) goto error;
      }
  
      /* Check if the tag is non-empty. */
  
      if (!length) {
          if (!STRING_EXTEND(parser, string))
              goto error;
  
          yaml_parser_set_scanner_error(parser, directive ?
                  "while parsing a %TAG directive" : "while parsing a tag",
                  start_mark, "did not find expected tag URI");
          goto error;
      }
  
      *uri = string.start;
  
      return 1;
  
  error:
      STRING_DEL(parser, string);
      return 0;
  }
  
  /*
   * Decode an URI-escape sequence corresponding to a single UTF-8 character.
   */
  
  static int
  yaml_parser_scan_uri_escapes(yaml_parser_t *parser, int directive,
          yaml_mark_t start_mark, yaml_string_t *string)
  {
      int width = 0;
  
      /* Decode the required number of characters. */
  
      do {
  
          unsigned char octet = 0;
  
          /* Check for a URI-escaped octet. */
  
          if (!CACHE(parser, 3)) return 0;
  
          if (!(CHECK(parser->buffer, '%')
                      && IS_HEX_AT(parser->buffer, 1)
                      && IS_HEX_AT(parser->buffer, 2))) {
              return yaml_parser_set_scanner_error(parser, directive ?
                      "while parsing a %TAG directive" : "while parsing a tag",
                      start_mark, "did not find URI escaped octet");
          }
  
          /* Get the octet. */
  
          octet = (AS_HEX_AT(parser->buffer, 1) << 4) + AS_HEX_AT(parser->buffer, 2);
  
          /* If it is the leading octet, determine the length of the UTF-8 sequence. */
  
          if (!width)
          {
              width = (octet & 0x80) == 0x00 ? 1 :
                      (octet & 0xE0) == 0xC0 ? 2 :
                      (octet & 0xF0) == 0xE0 ? 3 :
                      (octet & 0xF8) == 0xF0 ? 4 : 0;
              if (!width) {
                  return yaml_parser_set_scanner_error(parser, directive ?
                          "while parsing a %TAG directive" : "while parsing a tag",
                          start_mark, "found an incorrect leading UTF-8 octet");
              }
          }
          else
          {
              /* Check if the trailing octet is correct. */
  
              if ((octet & 0xC0) != 0x80) {
                  return yaml_parser_set_scanner_error(parser, directive ?
                          "while parsing a %TAG directive" : "while parsing a tag",
                          start_mark, "found an incorrect trailing UTF-8 octet");
              }
          }
  
          /* Copy the octet and move the pointers. */
  
          *(string->pointer++) = octet;
          SKIP(parser);
          SKIP(parser);
          SKIP(parser);
  
      } while (--width);
  
      return 1;
  }
  
  /*
   * Scan a block scalar.
   */
  
  static int
  yaml_parser_scan_block_scalar(yaml_parser_t *parser, yaml_token_t *token,
          int literal)
  {
      yaml_mark_t start_mark;
      yaml_mark_t end_mark;
      yaml_string_t string = NULL_STRING;
      yaml_string_t leading_break = NULL_STRING;
      yaml_string_t trailing_breaks = NULL_STRING;
      int chomping = 0;
      int increment = 0;
      int indent = 0;
      int leading_blank = 0;
      int trailing_blank = 0;
  
      if (!STRING_INIT(parser, string, INITIAL_STRING_SIZE)) goto error;
      if (!STRING_INIT(parser, leading_break, INITIAL_STRING_SIZE)) goto error;
      if (!STRING_INIT(parser, trailing_breaks, INITIAL_STRING_SIZE)) goto error;
  
      /* Eat the indicator '|' or '>'. */
  
      start_mark = parser->mark;
  
      SKIP(parser);
  
      /* Scan the additional block scalar indicators. */
  
      if (!CACHE(parser, 1)) goto error;
  
      /* Check for a chomping indicator. */
  
      if (CHECK(parser->buffer, '+') || CHECK(parser->buffer, '-'))
      {
          /* Set the chomping method and eat the indicator. */
  
          chomping = CHECK(parser->buffer, '+') ? +1 : -1;
  
          SKIP(parser);
  
          /* Check for an indentation indicator. */
  
          if (!CACHE(parser, 1)) goto error;
  
          if (IS_DIGIT(parser->buffer))
          {
              /* Check that the indentation is greater than 0. */
  
              if (CHECK(parser->buffer, '0')) {
                  yaml_parser_set_scanner_error(parser, "while scanning a block scalar",
                          start_mark, "found an indentation indicator equal to 0");
                  goto error;
              }
  
              /* Get the indentation level and eat the indicator. */
  
              increment = AS_DIGIT(parser->buffer);
  
              SKIP(parser);
          }
      }
  
      /* Do the same as above, but in the opposite order. */
  
      else if (IS_DIGIT(parser->buffer))
      {
          if (CHECK(parser->buffer, '0')) {
              yaml_parser_set_scanner_error(parser, "while scanning a block scalar",
                      start_mark, "found an indentation indicator equal to 0");
              goto error;
          }
  
          increment = AS_DIGIT(parser->buffer);
  
          SKIP(parser);
  
          if (!CACHE(parser, 1)) goto error;
  
          if (CHECK(parser->buffer, '+') || CHECK(parser->buffer, '-')) {
              chomping = CHECK(parser->buffer, '+') ? +1 : -1;
  
              SKIP(parser);
          }
      }
  
      /* Eat whitespaces and comments to the end of the line. */
  
      if (!CACHE(parser, 1)) goto error;
  
      while (IS_BLANK(parser->buffer)) {
          SKIP(parser);
          if (!CACHE(parser, 1)) goto error;
      }
  
      if (CHECK(parser->buffer, '#')) {
          while (!IS_BREAKZ(parser->buffer)) {
              SKIP(parser);
              if (!CACHE(parser, 1)) goto error;
          }
      }
  
      /* Check if we are at the end of the line. */
  
      if (!IS_BREAKZ(parser->buffer)) {
          yaml_parser_set_scanner_error(parser, "while scanning a block scalar",
                  start_mark, "did not find expected comment or line break");
          goto error;
      }
  
      /* Eat a line break. */
  
      if (IS_BREAK(parser->buffer)) {
          if (!CACHE(parser, 2)) goto error;
          SKIP_LINE(parser);
      }
  
      end_mark = parser->mark;
  
      /* Set the indentation level if it was specified. */
  
      if (increment) {
          indent = parser->indent >= 0 ? parser->indent+increment : increment;
      }
  
      /* Scan the leading line breaks and determine the indentation level if needed. */
  
      if (!yaml_parser_scan_block_scalar_breaks(parser, &indent, &trailing_breaks,
                  start_mark, &end_mark)) goto error;
  
      /* Scan the block scalar content. */
  
      if (!CACHE(parser, 1)) goto error;
  
      while ((int)parser->mark.column == indent && !IS_Z(parser->buffer))
      {
          /*
           * We are at the beginning of a non-empty line.
           */
  
          /* Is it a trailing whitespace? */
  
          trailing_blank = IS_BLANK(parser->buffer);
  
          /* Check if we need to fold the leading line break. */
  
          if (!literal && (*leading_break.start == '\n')
                  && !leading_blank && !trailing_blank)
          {
              /* Do we need to join the lines by space? */
  
              if (*trailing_breaks.start == '\0') {
                  if (!STRING_EXTEND(parser, string)) goto error;
                  *(string.pointer ++) = ' ';
              }
  
              CLEAR(parser, leading_break);
          }
          else {
              if (!JOIN(parser, string, leading_break)) goto error;
              CLEAR(parser, leading_break);
          }
  
          /* Append the remaining line breaks. */
  
          if (!JOIN(parser, string, trailing_breaks)) goto error;
          CLEAR(parser, trailing_breaks);
  
          /* Is it a leading whitespace? */
  
          leading_blank = IS_BLANK(parser->buffer);
  
          /* Consume the current line. */
  
          while (!IS_BREAKZ(parser->buffer)) {
              if (!READ(parser, string)) goto error;
              if (!CACHE(parser, 1)) goto error;
          }
  
          /* Consume the line break. */
  
          if (!CACHE(parser, 2)) goto error;
  
          if (!READ_LINE(parser, leading_break)) goto error;
  
          /* Eat the following indentation spaces and line breaks. */
  
          if (!yaml_parser_scan_block_scalar_breaks(parser,
                      &indent, &trailing_breaks, start_mark, &end_mark)) goto error;
      }
  
      /* Chomp the tail. */
  
      if (chomping != -1) {
          if (!JOIN(parser, string, leading_break)) goto error;
      }
      if (chomping == 1) {
          if (!JOIN(parser, string, trailing_breaks)) goto error;
      }
  
      /* Create a token. */
  
      SCALAR_TOKEN_INIT(*token, string.start, string.pointer-string.start,
              literal ? YAML_LITERAL_SCALAR_STYLE : YAML_FOLDED_SCALAR_STYLE,
              start_mark, end_mark);
  
      STRING_DEL(parser, leading_break);
      STRING_DEL(parser, trailing_breaks);
  
      return 1;
  
  error:
      STRING_DEL(parser, string);
      STRING_DEL(parser, leading_break);
      STRING_DEL(parser, trailing_breaks);
  
      return 0;
  }
  
  /*
   * Scan indentation spaces and line breaks for a block scalar.  Determine the
   * indentation level if needed.
   */
  
  static int
  yaml_parser_scan_block_scalar_breaks(yaml_parser_t *parser,
          int *indent, yaml_string_t *breaks,
          yaml_mark_t start_mark, yaml_mark_t *end_mark)
  {
      int max_indent = 0;
  
      *end_mark = parser->mark;
  
      /* Eat the indentation spaces and line breaks. */
  
      while (1)
      {
          /* Eat the indentation spaces. */
  
          if (!CACHE(parser, 1)) return 0;
  
          while ((!*indent || (int)parser->mark.column < *indent)
                  && IS_SPACE(parser->buffer)) {
              SKIP(parser);
              if (!CACHE(parser, 1)) return 0;
          }
  
          if ((int)parser->mark.column > max_indent)
              max_indent = (int)parser->mark.column;
  
          /* Check for a tab character messing the indentation. */
  
          if ((!*indent || (int)parser->mark.column < *indent)
                  && IS_TAB(parser->buffer)) {
              return yaml_parser_set_scanner_error(parser, "while scanning a block scalar",
                      start_mark, "found a tab character where an indentation space is expected");
          }
  
          /* Have we found a non-empty line? */
  
          if (!IS_BREAK(parser->buffer)) break;
  
          /* Consume the line break. */
  
          if (!CACHE(parser, 2)) return 0;
          if (!READ_LINE(parser, *breaks)) return 0;
          *end_mark = parser->mark;
      }
  
      /* Determine the indentation level if needed. */
  
      if (!*indent) {
          *indent = max_indent;
          if (*indent < parser->indent + 1)
              *indent = parser->indent + 1;
          if (*indent < 1)
              *indent = 1;
      }
  
     return 1;
  }
  
  /*
   * Scan a quoted scalar.
   */
  
  static int
  yaml_parser_scan_flow_scalar(yaml_parser_t *parser, yaml_token_t *token,
          int single)
  {
      yaml_mark_t start_mark;
      yaml_mark_t end_mark;
      yaml_string_t string = NULL_STRING;
      yaml_string_t leading_break = NULL_STRING;
      yaml_string_t trailing_breaks = NULL_STRING;
      yaml_string_t whitespaces = NULL_STRING;
      int leading_blanks;
  
      if (!STRING_INIT(parser, string, INITIAL_STRING_SIZE)) goto error;
      if (!STRING_INIT(parser, leading_break, INITIAL_STRING_SIZE)) goto error;
      if (!STRING_INIT(parser, trailing_breaks, INITIAL_STRING_SIZE)) goto error;
      if (!STRING_INIT(parser, whitespaces, INITIAL_STRING_SIZE)) goto error;
  
      /* Eat the left quote. */
  
      start_mark = parser->mark;
  
      SKIP(parser);
  
      /* Consume the content of the quoted scalar. */
  
      while (1)
      {
          /* Check that there are no document indicators at the beginning of the line. */
  
          if (!CACHE(parser, 4)) goto error;
  
          if (parser->mark.column == 0 &&
              ((CHECK_AT(parser->buffer, '-', 0) &&
                CHECK_AT(parser->buffer, '-', 1) &&
                CHECK_AT(parser->buffer, '-', 2)) ||
               (CHECK_AT(parser->buffer, '.', 0) &&
                CHECK_AT(parser->buffer, '.', 1) &&
                CHECK_AT(parser->buffer, '.', 2))) &&
              IS_BLANKZ_AT(parser->buffer, 3))
          {
              yaml_parser_set_scanner_error(parser, "while scanning a quoted scalar",
                      start_mark, "found unexpected document indicator");
              goto error;
          }
  
          /* Check for EOF. */
  
          if (IS_Z(parser->buffer)) {
              yaml_parser_set_scanner_error(parser, "while scanning a quoted scalar",
                      start_mark, "found unexpected end of stream");
              goto error;
          }
  
          /* Consume non-blank characters. */
  
          if (!CACHE(parser, 2)) goto error;
  
          leading_blanks = 0;
  
          while (!IS_BLANKZ(parser->buffer))
          {
              /* Check for an escaped single quote. */
  
              if (single && CHECK_AT(parser->buffer, '\'', 0)
                      && CHECK_AT(parser->buffer, '\'', 1))
              {
                  if (!STRING_EXTEND(parser, string)) goto error;
                  *(string.pointer++) = '\'';
                  SKIP(parser);
                  SKIP(parser);
              }
  
              /* Check for the right quote. */
  
              else if (CHECK(parser->buffer, single ? '\'' : '"'))
              {
                  break;
              }
  
              /* Check for an escaped line break. */
  
              else if (!single && CHECK(parser->buffer, '\\')
                      && IS_BREAK_AT(parser->buffer, 1))
              {
                  if (!CACHE(parser, 3)) goto error;
                  SKIP(parser);
                  SKIP_LINE(parser);
                  leading_blanks = 1;
                  break;
              }
  
              /* Check for an escape sequence. */
  
              else if (!single && CHECK(parser->buffer, '\\'))
              {
                  size_t code_length = 0;
  
                  if (!STRING_EXTEND(parser, string)) goto error;
  
                  /* Check the escape character. */
  
                  switch (parser->buffer.pointer[1])
                  {
                      case '0':
                          *(string.pointer++) = '\0';
                          break;
  
                      case 'a':
                          *(string.pointer++) = '\x07';
                          break;
  
                      case 'b':
                          *(string.pointer++) = '\x08';
                          break;
  
                      case 't':
                      case '\t':
                          *(string.pointer++) = '\x09';
                          break;
  
                      case 'n':
                          *(string.pointer++) = '\x0A';
                          break;
  
                      case 'v':
                          *(string.pointer++) = '\x0B';
                          break;
  
                      case 'f':
                          *(string.pointer++) = '\x0C';
                          break;
  
                      case 'r':
                          *(string.pointer++) = '\x0D';
                          break;
  
                      case 'e':
                          *(string.pointer++) = '\x1B';
                          break;
  
                      case ' ':
                          *(string.pointer++) = '\x20';
                          break;
  
                      case '"':
                          *(string.pointer++) = '"';
                          break;
  
                      case '/':
                          *(string.pointer++) = '/';
                          break;
  
                      case '\\':
                          *(string.pointer++) = '\\';
                          break;
  
                      case 'N':   /* NEL (#x85) */
                          *(string.pointer++) = '\xC2';
                          *(string.pointer++) = '\x85';
                          break;
  
                      case '_':   /* #xA0 */
                          *(string.pointer++) = '\xC2';
                          *(string.pointer++) = '\xA0';
                          break;
  
                      case 'L':   /* LS (#x2028) */
                          *(string.pointer++) = '\xE2';
                          *(string.pointer++) = '\x80';
                          *(string.pointer++) = '\xA8';
                          break;
  
                      case 'P':   /* PS (#x2029) */
                          *(string.pointer++) = '\xE2';
                          *(string.pointer++) = '\x80';
                          *(string.pointer++) = '\xA9';
                          break;
  
                      case 'x':
                          code_length = 2;
                          break;
  
                      case 'u':
                          code_length = 4;
                          break;
  
                      case 'U':
                          code_length = 8;
                          break;
  
                      default:
                          yaml_parser_set_scanner_error(parser, "while parsing a quoted scalar",
                                  start_mark, "found unknown escape character");
                          goto error;
                  }
  
                  SKIP(parser);
                  SKIP(parser);
  
                  /* Consume an arbitrary escape code. */
  
                  if (code_length)
                  {
                      unsigned int value = 0;
                      size_t k;
  
                      /* Scan the character value. */
  
                      if (!CACHE(parser, code_length)) goto error;
  
                      for (k = 0; k < code_length; k ++) {
                          if (!IS_HEX_AT(parser->buffer, k)) {
                              yaml_parser_set_scanner_error(parser, "while parsing a quoted scalar",
                                      start_mark, "did not find expected hexdecimal number");
                              goto error;
                          }
                          value = (value << 4) + AS_HEX_AT(parser->buffer, k);
                      }
  
                      /* Check the value and write the character. */
  
                      if ((value >= 0xD800 && value <= 0xDFFF) || value > 0x10FFFF) {
                          yaml_parser_set_scanner_error(parser, "while parsing a quoted scalar",
                                  start_mark, "found invalid Unicode character escape code");
                          goto error;
                      }
  
                      if (value <= 0x7F) {
                          *(string.pointer++) = value;
                      }
                      else if (value <= 0x7FF) {
                          *(string.pointer++) = 0xC0 + (value >> 6);
                          *(string.pointer++) = 0x80 + (value & 0x3F);
                      }
                      else if (value <= 0xFFFF) {
                          *(string.pointer++) = 0xE0 + (value >> 12);
                          *(string.pointer++) = 0x80 + ((value >> 6) & 0x3F);
                          *(string.pointer++) = 0x80 + (value & 0x3F);
                      }
                      else {
                          *(string.pointer++) = 0xF0 + (value >> 18);
                          *(string.pointer++) = 0x80 + ((value >> 12) & 0x3F);
                          *(string.pointer++) = 0x80 + ((value >> 6) & 0x3F);
                          *(string.pointer++) = 0x80 + (value & 0x3F);
                      }
  
                      /* Advance the pointer. */
  
                      for (k = 0; k < code_length; k ++) {
                          SKIP(parser);
                      }
                  }
              }
  
              else
              {
                  /* It is a non-escaped non-blank character. */
  
                  if (!READ(parser, string)) goto error;
              }
  
              if (!CACHE(parser, 2)) goto error;
          }
  
          /* Check if we are at the end of the scalar. */
  
          /* Fix for crash unitialized value crash
           * Credit for the bug and input is to OSS Fuzz
           * Credit for the fix to Alex Gaynor
           */
          if (!CACHE(parser, 1)) goto error;
          if (CHECK(parser->buffer, single ? '\'' : '"'))
              break;
  
          /* Consume blank characters. */
  
          if (!CACHE(parser, 1)) goto error;
  
          while (IS_BLANK(parser->buffer) || IS_BREAK(parser->buffer))
          {
              if (IS_BLANK(parser->buffer))
              {
                  /* Consume a space or a tab character. */
  
                  if (!leading_blanks) {
                      if (!READ(parser, whitespaces)) goto error;
                  }
                  else {
                      SKIP(parser);
                  }
              }
              else
              {
                  if (!CACHE(parser, 2)) goto error;
  
                  /* Check if it is a first line break. */
  
                  if (!leading_blanks)
                  {
                      CLEAR(parser, whitespaces);
                      if (!READ_LINE(parser, leading_break)) goto error;
                      leading_blanks = 1;
                  }
                  else
                  {
                      if (!READ_LINE(parser, trailing_breaks)) goto error;
                  }
              }
              if (!CACHE(parser, 1)) goto error;
          }
  
          /* Join the whitespaces or fold line breaks. */
  
          if (leading_blanks)
          {
              /* Do we need to fold line breaks? */
  
              if (leading_break.start[0] == '\n') {
                  if (trailing_breaks.start[0] == '\0') {
                      if (!STRING_EXTEND(parser, string)) goto error;
                      *(string.pointer++) = ' ';
                  }
                  else {
                      if (!JOIN(parser, string, trailing_breaks)) goto error;
                      CLEAR(parser, trailing_breaks);
                  }
                  CLEAR(parser, leading_break);
              }
              else {
                  if (!JOIN(parser, string, leading_break)) goto error;
                  if (!JOIN(parser, string, trailing_breaks)) goto error;
                  CLEAR(parser, leading_break);
                  CLEAR(parser, trailing_breaks);
              }
          }
          else
          {
              if (!JOIN(parser, string, whitespaces)) goto error;
              CLEAR(parser, whitespaces);
          }
      }
  
      /* Eat the right quote. */
  
      SKIP(parser);
  
      end_mark = parser->mark;
  
      /* Create a token. */
  
      SCALAR_TOKEN_INIT(*token, string.start, string.pointer-string.start,
              single ? YAML_SINGLE_QUOTED_SCALAR_STYLE : YAML_DOUBLE_QUOTED_SCALAR_STYLE,
              start_mark, end_mark);
  
      STRING_DEL(parser, leading_break);
      STRING_DEL(parser, trailing_breaks);
      STRING_DEL(parser, whitespaces);
  
      return 1;
  
  error:
      STRING_DEL(parser, string);
      STRING_DEL(parser, leading_break);
      STRING_DEL(parser, trailing_breaks);
      STRING_DEL(parser, whitespaces);
  
      return 0;
  }
  
  /*
   * Scan a plain scalar.
   */
  
  static int
  yaml_parser_scan_plain_scalar(yaml_parser_t *parser, yaml_token_t *token)
  {
      yaml_mark_t start_mark;
      yaml_mark_t end_mark;
      yaml_string_t string = NULL_STRING;
      yaml_string_t leading_break = NULL_STRING;
      yaml_string_t trailing_breaks = NULL_STRING;
      yaml_string_t whitespaces = NULL_STRING;
      int leading_blanks = 0;
      int indent = parser->indent+1;
  
      if (!STRING_INIT(parser, string, INITIAL_STRING_SIZE)) goto error;
      if (!STRING_INIT(parser, leading_break, INITIAL_STRING_SIZE)) goto error;
      if (!STRING_INIT(parser, trailing_breaks, INITIAL_STRING_SIZE)) goto error;
      if (!STRING_INIT(parser, whitespaces, INITIAL_STRING_SIZE)) goto error;
  
      start_mark = end_mark = parser->mark;
  
      /* Consume the content of the plain scalar. */
  
      while (1)
      {
          /* Check for a document indicator. */
  
          if (!CACHE(parser, 4)) goto error;
  
          if (parser->mark.column == 0 &&
              ((CHECK_AT(parser->buffer, '-', 0) &&
                CHECK_AT(parser->buffer, '-', 1) &&
                CHECK_AT(parser->buffer, '-', 2)) ||
               (CHECK_AT(parser->buffer, '.', 0) &&
                CHECK_AT(parser->buffer, '.', 1) &&
                CHECK_AT(parser->buffer, '.', 2))) &&
              IS_BLANKZ_AT(parser->buffer, 3)) break;
  
          /* Check for a comment. */
  
          if (CHECK(parser->buffer, '#'))
              break;
  
          /* Consume non-blank characters. */
  
          while (!IS_BLANKZ(parser->buffer))
          {
              /* Check for 'x:x' in the flow context. TODO: Fix the test "spec-08-13". */
  
              if (parser->flow_level
                      && CHECK(parser->buffer, ':')
                      && !IS_BLANKZ_AT(parser->buffer, 1)) {
                  yaml_parser_set_scanner_error(parser, "while scanning a plain scalar",
                          start_mark, "found unexpected ':'");
                  goto error;
              }
  
              /* Check for indicators that may end a plain scalar. */
  
              if ((CHECK(parser->buffer, ':') && IS_BLANKZ_AT(parser->buffer, 1))
                      || (parser->flow_level &&
                          (CHECK(parser->buffer, ',') || CHECK(parser->buffer, ':')
                           || CHECK(parser->buffer, '?') || CHECK(parser->buffer, '[')
                           || CHECK(parser->buffer, ']') || CHECK(parser->buffer, '{')
                           || CHECK(parser->buffer, '}'))))
                  break;
  
              /* Check if we need to join whitespaces and breaks. */
  
              if (leading_blanks || whitespaces.start != whitespaces.pointer)
              {
                  if (leading_blanks)
                  {
                      /* Do we need to fold line breaks? */
  
                      if (leading_break.start[0] == '\n') {
                          if (trailing_breaks.start[0] == '\0') {
                              if (!STRING_EXTEND(parser, string)) goto error;
                              *(string.pointer++) = ' ';
                          }
                          else {
                              if (!JOIN(parser, string, trailing_breaks)) goto error;
                              CLEAR(parser, trailing_breaks);
                          }
                          CLEAR(parser, leading_break);
                      }
                      else {
                          if (!JOIN(parser, string, leading_break)) goto error;
                          if (!JOIN(parser, string, trailing_breaks)) goto error;
                          CLEAR(parser, leading_break);
                          CLEAR(parser, trailing_breaks);
                      }
  
                      leading_blanks = 0;
                  }
                  else
                  {
                      if (!JOIN(parser, string, whitespaces)) goto error;
                      CLEAR(parser, whitespaces);
                  }
              }
  
              /* Copy the character. */
  
              if (!READ(parser, string)) goto error;
  
              end_mark = parser->mark;
  
              if (!CACHE(parser, 2)) goto error;
          }
  
          /* Is it the end? */
  
          if (!(IS_BLANK(parser->buffer) || IS_BREAK(parser->buffer)))
              break;
  
          /* Consume blank characters. */
  
          if (!CACHE(parser, 1)) goto error;
  
          while (IS_BLANK(parser->buffer) || IS_BREAK(parser->buffer))
          {
              if (IS_BLANK(parser->buffer))
              {
                  /* Check for tab characters that abuse indentation. */
  
                  if (leading_blanks && (int)parser->mark.column < indent
                          && IS_TAB(parser->buffer)) {
                      yaml_parser_set_scanner_error(parser, "while scanning a plain scalar",
                              start_mark, "found a tab character that violate indentation");
                      goto error;
                  }
  
                  /* Consume a space or a tab character. */
  
                  if (!leading_blanks) {
                      if (!READ(parser, whitespaces)) goto error;
                  }
                  else {
                      SKIP(parser);
                  }
              }
              else
              {
                  if (!CACHE(parser, 2)) goto error;
  
                  /* Check if it is a first line break. */
  
                  if (!leading_blanks)
                  {
                      CLEAR(parser, whitespaces);
                      if (!READ_LINE(parser, leading_break)) goto error;
                      leading_blanks = 1;
                  }
                  else
                  {
                      if (!READ_LINE(parser, trailing_breaks)) goto error;
                  }
              }
              if (!CACHE(parser, 1)) goto error;
          }
  
          /* Check indentation level. */
  
          if (!parser->flow_level && (int)parser->mark.column < indent)
              break;
      }
  
      /* Create a token. */
  
      SCALAR_TOKEN_INIT(*token, string.start, string.pointer-string.start,
              YAML_PLAIN_SCALAR_STYLE, start_mark, end_mark);
  
      /* Note that we change the 'simple_key_allowed' flag. */
  
      if (leading_blanks) {
          parser->simple_key_allowed = 1;
      }
  
      STRING_DEL(parser, leading_break);
      STRING_DEL(parser, trailing_breaks);
      STRING_DEL(parser, whitespaces);
  
      return 1;
  
  error:
      STRING_DEL(parser, string);
      STRING_DEL(parser, leading_break);
      STRING_DEL(parser, trailing_breaks);
      STRING_DEL(parser, whitespaces);
  
      return 0;
  }
  