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Name	Size	Permission
lib	[ DIR ]	drwxr-xr-x
LibYAML.bs	0 B	-rw-r--r--
LibYAML.c	6.84 KB	-rw-r--r--
LibYAML.o	75.68 KB	-rw-r--r--
LibYAML.xs	695 B	-rw-r--r--
MYMETA.json	837 B	-rw-r--r--
MYMETA.yml	487 B	-rw-r--r--
Makefile	28.34 KB	-rw-r--r--
Makefile.PL	802 B	-rw-r--r--
api.c	35.75 KB	-rw-r--r--
api.o	142.21 KB	-rw-r--r--
config.h	2.23 KB	-rw-r--r--
dumper.c	9.83 KB	-rw-r--r--
dumper.o	39.54 KB	-rw-r--r--
emitter.c	64.82 KB	-rw-r--r--
emitter.o	138.4 KB	-rw-r--r--
loader.c	13.76 KB	-rw-r--r--
loader.o	48.55 KB	-rw-r--r--
parser.c	43.98 KB	-rw-r--r--
parser.o	104.04 KB	-rw-r--r--
perl_libyaml.c	36.24 KB	-rw-r--r--
perl_libyaml.h	2.29 KB	-rw-r--r--
perl_libyaml.o	219.38 KB	-rw-r--r--
pm_to_blib	0 B	-rw-r--r--
ppport.h	170.76 KB	-rw-r--r--
ppport_sort.h	1012 B	-rw-r--r--
reader.c	16.29 KB	-rw-r--r--
reader.o	35.16 KB	-rw-r--r--
scanner.c	96.61 KB	-rw-r--r--
scanner.o	225.37 KB	-rw-r--r--
test.pl	97 B	-rw-r--r--
update.sh	673 B	-rwxr-xr-x
writer.c	3.95 KB	-rw-r--r--
writer.o	21.68 KB	-rw-r--r--
yaml.h	53.16 KB	-rw-r--r--
yaml_private.h	29.79 KB	-rw-r--r--

Code Editor : scanner.c

/*
 * 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               # ']'
 *      FLOW-MAPPING-START              # '{'
 *      FLOW-MAPPING-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)
 *          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
 *          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;

/* 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;

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;

/* Check for a comment. */

if (CHECK(parser->buffer, '#'))
            break;

/* Consume non-blank characters. */

while (!IS_BLANKZ(parser->buffer))
        {
            /* Check for "x:" + one of ',?[]{}' in the flow context. TODO: Fix the test "spec-08-13".
             * This is not completely according to the spec
             * See http://yaml.org/spec/1.1/#id907281 9.1.3. Plain
             */

if (parser->flow_level
                    && CHECK(parser->buffer, ':')
                    && (
                        CHECK_AT(parser->buffer, ',', 1)
                        || CHECK_AT(parser->buffer, '?', 1)
                        || CHECK_AT(parser->buffer, '[', 1)
                        || CHECK_AT(parser->buffer, ']', 1)
                        || CHECK_AT(parser->buffer, '{', 1)
                        || CHECK_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, '}'))))
                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 violates indentation");
                    goto error;
                }

/* Consume a space or a tab character. */

/* Check if it is a first line break. */

/* 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;
}

${this.title}

Code Editor : scanner.c