Adding upstream version 0.2.8.upstream/0.2.8

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 3575 insertions, 0 deletions

diff --git a/scanner.c b/scanner.c
new file mode 100644
index 0000000..1c3b500
--- /dev/null
+++ b/scanner.c
@@ -0,0 +1,3575 @@
+
+/*
+ * 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)
+ *          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)
+{
+    yaml_simple_key_t dummy_key;    /* Used to eliminate a compiler warning. */
+
+    if (parser->flow_level) {
+        parser->flow_level --;
+        dummy_key = POP(parser, parser->simple_keys);
+    }
+
+    return 1;
+}
+
+/*
+ * Push the current indentation level to the stack and set the new level
+ * the current column is greater than the indentation level.  In this case,
+ * append or insert the specified token into the token queue.
+ *
+ */
+
+static int
+yaml_parser_roll_indent(yaml_parser_t *parser, ptrdiff_t column,
+        ptrdiff_t number, yaml_token_type_t type, yaml_mark_t mark)
+{
+    yaml_token_t token;
+
+    /* In the flow context, do nothing. */
+
+    if (parser->flow_level)
+        return 1;
+
+    if (parser->indent < column)
+    {
+        /*
+         * Push the current indentation level to the stack and set the new
+         * indentation level.
+         */
+
+        if (!PUSH(parser, parser->indents, parser->indent))
+            return 0;
+
+        if (column > INT_MAX) {
+            parser->error = YAML_MEMORY_ERROR;
+            return 0;
+        }
+
+        parser->indent = column;
+
+        /* Create a token and insert it into the queue. */
+
+        TOKEN_INIT(token, type, mark, mark);
+
+        if (number == -1) {
+            if (!ENQUEUE(parser, parser->tokens, token))
+                return 0;
+        }
+        else {
+            if (!QUEUE_INSERT(parser,
+                        parser->tokens, number - parser->tokens_parsed, token))
+                return 0;
+        }
+    }
+
+    return 1;
+}
+
+/*
+ * Pop indentation levels from the indents stack until the current level
+ * becomes less or equal to the column.  For each indentation level, append
+ * the BLOCK-END token.
+ */
+
+
+static int
+yaml_parser_unroll_indent(yaml_parser_t *parser, ptrdiff_t column)
+{
+    yaml_token_t token;
+
+    /* In the flow context, do nothing. */
+
+    if (parser->flow_level)
+        return 1;
+
+    /* Loop through the indentation levels in the stack. */
+
+    while (parser->indent > column)
+    {
+        /* Create a token and append it to the queue. */
+
+        TOKEN_INIT(token, YAML_BLOCK_END_TOKEN, parser->mark, parser->mark);
+
+        if (!ENQUEUE(parser, parser->tokens, token))
+            return 0;
+
+        /* Pop the indentation level. */
+
+        parser->indent = POP(parser, parser->indents);
+    }
+
+    return 1;
+}
+
+/*
+ * Initialize the scanner and produce the STREAM-START token.
+ */
+
+static int
+yaml_parser_fetch_stream_start(yaml_parser_t *parser)
+{
+    yaml_simple_key_t simple_key = { 0, 0, 0, { 0, 0, 0 } };
+    yaml_token_t token;
+
+    /* Set the initial indentation. */
+
+    parser->indent = -1;
+
+    /* Initialize the simple key stack. */
+
+    if (!PUSH(parser, parser->simple_keys, simple_key))
+        return 0;
+
+    /* A simple key is allowed at the beginning of the stream. */
+
+    parser->simple_key_allowed = 1;
+
+    /* We have started. */
+
+    parser->stream_start_produced = 1;
+
+    /* Create the STREAM-START token and append it to the queue. */
+
+    STREAM_START_TOKEN_INIT(token, parser->encoding,
+            parser->mark, parser->mark);
+
+    if (!ENQUEUE(parser, parser->tokens, token))
+        return 0;
+
+    return 1;
+}
+
+/*
+ * Produce the STREAM-END token and shut down the scanner.
+ */
+
+static int
+yaml_parser_fetch_stream_end(yaml_parser_t *parser)
+{
+    yaml_token_t token;
+
+    /* Force new line. */
+
+    if (parser->mark.column != 0) {
+        parser->mark.column = 0;
+        parser->mark.line ++;
+    }
+
+    /* Reset the indentation level. */
+
+    if (!yaml_parser_unroll_indent(parser, -1))
+        return 0;
+
+    /* Reset simple keys. */
+
+    if (!yaml_parser_remove_simple_key(parser))
+        return 0;
+
+    parser->simple_key_allowed = 0;
+
+    /* Create the STREAM-END token and append it to the queue. */
+
+    STREAM_END_TOKEN_INIT(token, parser->mark, parser->mark);
+
+    if (!ENQUEUE(parser, parser->tokens, token))
+        return 0;
+
+    return 1;
+}
+
+/*
+ * Produce a VERSION-DIRECTIVE or TAG-DIRECTIVE token.
+ */
+
+static int
+yaml_parser_fetch_directive(yaml_parser_t *parser)
+{
+    yaml_token_t token;
+
+    /* Reset the indentation level. */
+
+    if (!yaml_parser_unroll_indent(parser, -1))
+        return 0;
+
+    /* Reset simple keys. */
+
+    if (!yaml_parser_remove_simple_key(parser))
+        return 0;
+
+    parser->simple_key_allowed = 0;
+
+    /* Create the YAML-DIRECTIVE or TAG-DIRECTIVE token. */
+
+    if (!yaml_parser_scan_directive(parser, &token))
+        return 0;
+
+    /* Append the token to the queue. */
+
+    if (!ENQUEUE(parser, parser->tokens, token)) {
+        yaml_token_delete(&token);
+        return 0;
+    }
+
+    return 1;
+}
+
+/*
+ * Produce the DOCUMENT-START or DOCUMENT-END token.
+ */
+
+static int
+yaml_parser_fetch_document_indicator(yaml_parser_t *parser,
+        yaml_token_type_t type)
+{
+    yaml_mark_t start_mark, end_mark;
+    yaml_token_t token;
+
+    /* Reset the indentation level. */
+
+    if (!yaml_parser_unroll_indent(parser, -1))
+        return 0;
+
+    /* Reset simple keys. */
+
+    if (!yaml_parser_remove_simple_key(parser))
+        return 0;
+
+    parser->simple_key_allowed = 0;
+
+    /* Consume the token. */
+
+    start_mark = parser->mark;
+
+    SKIP(parser);
+    SKIP(parser);
+    SKIP(parser);
+
+    end_mark = parser->mark;
+
+    /* Create the DOCUMENT-START or DOCUMENT-END token. */
+
+    TOKEN_INIT(token, type, start_mark, end_mark);
+
+    /* Append the token to the queue. */
+
+    if (!ENQUEUE(parser, parser->tokens, token))
+        return 0;
+
+    return 1;
+}
+
+/*
+ * Produce the FLOW-SEQUENCE-START or FLOW-MAPPING-START token.
+ */
+
+static int
+yaml_parser_fetch_flow_collection_start(yaml_parser_t *parser,
+        yaml_token_type_t type)
+{
+    yaml_mark_t start_mark, end_mark;
+    yaml_token_t token;
+
+    /* The indicators '[' and '{' may start a simple key. */
+
+    if (!yaml_parser_save_simple_key(parser))
+        return 0;
+
+    /* Increase the flow level. */
+
+    if (!yaml_parser_increase_flow_level(parser))
+        return 0;
+
+    /* A simple key may follow the indicators '[' and '{'. */
+
+    parser->simple_key_allowed = 1;
+
+    /* Consume the token. */
+
+    start_mark = parser->mark;
+    SKIP(parser);
+    end_mark = parser->mark;
+
+    /* Create the FLOW-SEQUENCE-START of FLOW-MAPPING-START token. */
+
+    TOKEN_INIT(token, type, start_mark, end_mark);
+
+    /* Append the token to the queue. */
+
+    if (!ENQUEUE(parser, parser->tokens, token))
+        return 0;
+
+    return 1;
+}
+
+/*
+ * Produce the FLOW-SEQUENCE-END or FLOW-MAPPING-END token.
+ */
+
+static int
+yaml_parser_fetch_flow_collection_end(yaml_parser_t *parser,
+        yaml_token_type_t type)
+{
+    yaml_mark_t start_mark, end_mark;
+    yaml_token_t token;
+
+    /* Reset any potential simple key on the current flow level. */
+
+    if (!yaml_parser_remove_simple_key(parser))
+        return 0;
+
+    /* Decrease the flow level. */
+
+    if (!yaml_parser_decrease_flow_level(parser))
+        return 0;
+
+    /* No simple keys after the indicators ']' and '}'. */
+
+    parser->simple_key_allowed = 0;
+
+    /* Consume the token. */
+
+    start_mark = parser->mark;
+    SKIP(parser);
+    end_mark = parser->mark;
+
+    /* Create the FLOW-SEQUENCE-END of FLOW-MAPPING-END token. */
+
+    TOKEN_INIT(token, type, start_mark, end_mark);
+
+    /* Append the token to the queue. */
+
+    if (!ENQUEUE(parser, parser->tokens, token))
+        return 0;
+
+    return 1;
+}
+
+/*
+ * Produce the FLOW-ENTRY token.
+ */
+
+static int
+yaml_parser_fetch_flow_entry(yaml_parser_t *parser)
+{
+    yaml_mark_t start_mark, end_mark;
+    yaml_token_t token;
+
+    /* Reset any potential simple keys on the current flow level. */
+
+    if (!yaml_parser_remove_simple_key(parser))
+        return 0;
+
+    /* Simple keys are allowed after ','. */
+
+    parser->simple_key_allowed = 1;
+
+    /* Consume the token. */
+
+    start_mark = parser->mark;
+    SKIP(parser);
+    end_mark = parser->mark;
+
+    /* Create the FLOW-ENTRY token and append it to the queue. */
+
+    TOKEN_INIT(token, YAML_FLOW_ENTRY_TOKEN, start_mark, end_mark);
+
+    if (!ENQUEUE(parser, parser->tokens, token))
+        return 0;
+
+    return 1;
+}
+
+/*
+ * Produce the BLOCK-ENTRY token.
+ */
+
+static int
+yaml_parser_fetch_block_entry(yaml_parser_t *parser)
+{
+    yaml_mark_t start_mark, end_mark;
+    yaml_token_t token;
+
+    /* Check if the scanner is in the block context. */
+
+    if (!parser->flow_level)
+    {
+        /* Check if we are allowed to start a new entry. */
+
+        if (!parser->simple_key_allowed) {
+            return yaml_parser_set_scanner_error(parser, NULL, parser->mark,
+                    "block sequence entries are not allowed in this context");
+        }
+
+        /* Add the BLOCK-SEQUENCE-START token if needed. */
+
+        if (!yaml_parser_roll_indent(parser, parser->mark.column, -1,
+                    YAML_BLOCK_SEQUENCE_START_TOKEN, parser->mark))
+            return 0;
+    }
+    else
+    {
+        /*
+         * It is an error for the '-' indicator to occur in the flow context,
+         * but we let the Parser detect and report about it because the Parser
+         * is able to point to the context.
+         */
+    }
+
+    /* Reset any potential simple keys on the current flow level. */
+
+    if (!yaml_parser_remove_simple_key(parser))
+        return 0;
+
+    /* Simple keys are allowed after '-'. */
+
+    parser->simple_key_allowed = 1;
+
+    /* Consume the token. */
+
+    start_mark = parser->mark;
+    SKIP(parser);
+    end_mark = parser->mark;
+
+    /* Create the BLOCK-ENTRY token and append it to the queue. */
+
+    TOKEN_INIT(token, YAML_BLOCK_ENTRY_TOKEN, start_mark, end_mark);
+
+    if (!ENQUEUE(parser, parser->tokens, token))
+        return 0;
+
+    return 1;
+}
+
+/*
+ * Produce the KEY token.
+ */
+
+static int
+yaml_parser_fetch_key(yaml_parser_t *parser)
+{
+    yaml_mark_t start_mark, end_mark;
+    yaml_token_t token;
+
+    /* In the block context, additional checks are required. */
+
+    if (!parser->flow_level)
+    {
+        /* Check if we are allowed to start a new key (not necessary simple). */
+
+        if (!parser->simple_key_allowed) {
+            return yaml_parser_set_scanner_error(parser, NULL, parser->mark,
+                    "mapping keys are not allowed in this context");
+        }
+
+        /* Add the BLOCK-MAPPING-START token if needed. */
+
+        if (!yaml_parser_roll_indent(parser, parser->mark.column, -1,
+                    YAML_BLOCK_MAPPING_START_TOKEN, parser->mark))
+            return 0;
+    }
+
+    /* Reset any potential simple keys on the current flow level. */
+
+    if (!yaml_parser_remove_simple_key(parser))
+        return 0;
+
+    /* Simple keys are allowed after '?' in the block context. */
+
+    parser->simple_key_allowed = (!parser->flow_level);
+
+    /* Consume the token. */
+
+    start_mark = parser->mark;
+    SKIP(parser);
+    end_mark = parser->mark;
+
+    /* Create the KEY token and append it to the queue. */
+
+    TOKEN_INIT(token, YAML_KEY_TOKEN, start_mark, end_mark);
+
+    if (!ENQUEUE(parser, parser->tokens, token))
+        return 0;
+
+    return 1;
+}
+
+/*
+ * Produce the VALUE token.
+ */
+
+static int
+yaml_parser_fetch_value(yaml_parser_t *parser)
+{
+    yaml_mark_t start_mark, end_mark;
+    yaml_token_t token;
+    yaml_simple_key_t *simple_key = parser->simple_keys.top-1;
+
+    /* Have we found a simple key? */
+
+    if (simple_key->possible)
+    {
+
+        /* Create the KEY token and insert it into the queue. */
+
+        TOKEN_INIT(token, YAML_KEY_TOKEN, simple_key->mark, simple_key->mark);
+
+        if (!QUEUE_INSERT(parser, parser->tokens,
+                    simple_key->token_number - parser->tokens_parsed, token))
+            return 0;
+
+        /* In the block context, we may need to add the BLOCK-MAPPING-START token. */
+
+        if (!yaml_parser_roll_indent(parser, simple_key->mark.column,
+                    simple_key->token_number,
+                    YAML_BLOCK_MAPPING_START_TOKEN, simple_key->mark))
+            return 0;
+
+        /* Remove the simple key. */
+
+        simple_key->possible = 0;
+
+        /* A simple key cannot follow another simple key. */
+
+        parser->simple_key_allowed = 0;
+    }
+    else
+    {
+        /* The ':' indicator follows a complex key. */
+
+        /* In the block context, extra checks are required. */
+
+        if (!parser->flow_level)
+        {
+            /* Check if we are allowed to start a complex value. */
+
+            if (!parser->simple_key_allowed) {
+                return yaml_parser_set_scanner_error(parser, NULL, parser->mark,
+                        "mapping values are not allowed in this context");
+            }
+
+            /* Add the BLOCK-MAPPING-START token if needed. */
+
+            if (!yaml_parser_roll_indent(parser, parser->mark.column, -1,
+                        YAML_BLOCK_MAPPING_START_TOKEN, parser->mark))
+                return 0;
+        }
+
+        /* Simple keys after ':' are allowed in the block context. */
+
+        parser->simple_key_allowed = (!parser->flow_level);
+    }
+
+    /* Consume the token. */
+
+    start_mark = parser->mark;
+    SKIP(parser);
+    end_mark = parser->mark;
+
+    /* Create the VALUE token and append it to the queue. */
+
+    TOKEN_INIT(token, YAML_VALUE_TOKEN, start_mark, end_mark);
+
+    if (!ENQUEUE(parser, parser->tokens, token))
+        return 0;
+
+    return 1;
+}
+
+/*
+ * Produce the ALIAS or ANCHOR token.
+ */
+
+static int
+yaml_parser_fetch_anchor(yaml_parser_t *parser, yaml_token_type_t type)
+{
+    yaml_token_t token;
+
+    /* An anchor or an alias could be a simple key. */
+
+    if (!yaml_parser_save_simple_key(parser))
+        return 0;
+
+    /* A simple key cannot follow an anchor or an alias. */
+
+    parser->simple_key_allowed = 0;
+
+    /* Create the ALIAS or ANCHOR token and append it to the queue. */
+
+    if (!yaml_parser_scan_anchor(parser, &token, type))
+        return 0;
+
+    if (!ENQUEUE(parser, parser->tokens, token)) {
+        yaml_token_delete(&token);
+        return 0;
+    }
+    return 1;
+}
+
+/*
+ * Produce the TAG token.
+ */
+
+static int
+yaml_parser_fetch_tag(yaml_parser_t *parser)
+{
+    yaml_token_t token;
+
+    /* A tag could be a simple key. */
+
+    if (!yaml_parser_save_simple_key(parser))
+        return 0;
+
+    /* A simple key cannot follow a tag. */
+
+    parser->simple_key_allowed = 0;
+
+    /* Create the TAG token and append it to the queue. */
+
+    if (!yaml_parser_scan_tag(parser, &token))
+        return 0;
+
+    if (!ENQUEUE(parser, parser->tokens, token)) {
+        yaml_token_delete(&token);
+        return 0;
+    }
+
+    return 1;
+}
+
+/*
+ * Produce the SCALAR(...,literal) or SCALAR(...,folded) tokens.
+ */
+
+static int
+yaml_parser_fetch_block_scalar(yaml_parser_t *parser, int literal)
+{
+    yaml_token_t token;
+
+    /* Remove any potential simple keys. */
+
+    if (!yaml_parser_remove_simple_key(parser))
+        return 0;
+
+    /* A simple key may follow a block scalar. */
+
+    parser->simple_key_allowed = 1;
+
+    /* Create the SCALAR token and append it to the queue. */
+
+    if (!yaml_parser_scan_block_scalar(parser, &token, literal))
+        return 0;
+
+    if (!ENQUEUE(parser, parser->tokens, token)) {
+        yaml_token_delete(&token);
+        return 0;
+    }
+
+    return 1;
+}
+
+/*
+ * Produce the SCALAR(...,single-quoted) or SCALAR(...,double-quoted) tokens.
+ */
+
+static int
+yaml_parser_fetch_flow_scalar(yaml_parser_t *parser, int single)
+{
+    yaml_token_t token;
+
+    /* A plain scalar could be a simple key. */
+
+    if (!yaml_parser_save_simple_key(parser))
+        return 0;
+
+    /* A simple key cannot follow a flow scalar. */
+
+    parser->simple_key_allowed = 0;
+
+    /* Create the SCALAR token and append it to the queue. */
+
+    if (!yaml_parser_scan_flow_scalar(parser, &token, single))
+        return 0;
+
+    if (!ENQUEUE(parser, parser->tokens, token)) {
+        yaml_token_delete(&token);
+        return 0;
+    }
+
+    return 1;
+}
+
+/*
+ * Produce the SCALAR(...,plain) token.
+ */
+
+static int
+yaml_parser_fetch_plain_scalar(yaml_parser_t *parser)
+{
+    yaml_token_t token;
+
+    /* A plain scalar could be a simple key. */
+
+    if (!yaml_parser_save_simple_key(parser))
+        return 0;
+
+    /* A simple key cannot follow a flow scalar. */
+
+    parser->simple_key_allowed = 0;
+
+    /* Create the SCALAR token and append it to the queue. */
+
+    if (!yaml_parser_scan_plain_scalar(parser, &token))
+        return 0;
+
+    if (!ENQUEUE(parser, parser->tokens, token)) {
+        yaml_token_delete(&token);
+        return 0;
+    }
+
+    return 1;
+}
+
+/*
+ * Eat whitespaces and comments until the next token is found.
+ */
+
+static int
+yaml_parser_scan_to_next_token(yaml_parser_t *parser)
+{
+    /* Until the next token is not found. */
+
+    while (1)
+    {
+        /* Allow the BOM mark to start a line. */
+
+        if (!CACHE(parser, 1)) return 0;
+
+        if (parser->mark.column == 0 && IS_BOM(parser->buffer))
+            SKIP(parser);
+
+        /*
+         * Eat whitespaces.
+         *
+         * Tabs are allowed:
+         *
+         *  - in the flow context;
+         *  - in the block context, but not at the beginning of the line or
+         *  after '-', '?', or ':' (complex value).
+         */
+
+        if (!CACHE(parser, 1)) return 0;
+
+        while (CHECK(parser->buffer,' ') ||
+                ((parser->flow_level || !parser->simple_key_allowed) &&
+                 CHECK(parser->buffer, '\t'))) {
+            SKIP(parser);
+            if (!CACHE(parser, 1)) return 0;
+        }
+
+        /* Eat a comment until a line break. */
+
+        if (CHECK(parser->buffer, '#')) {
+            while (!IS_BREAKZ(parser->buffer)) {
+                SKIP(parser);
+                if (!CACHE(parser, 1)) return 0;
+            }
+        }
+
+        /* If it is a line break, eat it. */
+
+        if (IS_BREAK(parser->buffer))
+        {
+            if (!CACHE(parser, 2)) return 0;
+            SKIP_LINE(parser);
+
+            /* In the block context, a new line may start a simple key. */
+
+            if (!parser->flow_level) {
+                parser->simple_key_allowed = 1;
+            }
+        }
+        else
+        {
+            /* We have found a token. */
+
+            break;
+        }
+    }
+
+    return 1;
+}
+
+/*
+ * Scan a YAML-DIRECTIVE or TAG-DIRECTIVE token.
+ *
+ * Scope:
+ *      %YAML    1.1    # a comment \n
+ *      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+ *      %TAG    !yaml!  tag:yaml.org,2002:  \n
+ *      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+ */
+
+int
+yaml_parser_scan_directive(yaml_parser_t *parser, yaml_token_t *token)
+{
+    yaml_mark_t start_mark, end_mark;
+    yaml_char_t *name = NULL;
+    int major, minor;
+    yaml_char_t *handle = NULL, *prefix = NULL;
+
+    /* Eat '%'. */
+
+    start_mark = parser->mark;
+
+    SKIP(parser);
+
+    /* Scan the directive name. */
+
+    if (!yaml_parser_scan_directive_name(parser, start_mark, &name))
+        goto error;
+
+    /* Is it a YAML directive? */
+
+    if (strcmp((char *)name, "YAML") == 0)
+    {
+        /* Scan the VERSION directive value. */
+
+        if (!yaml_parser_scan_version_directive_value(parser, start_mark,
+                    &major, &minor))
+            goto error;
+
+        end_mark = parser->mark;
+
+        /* Create a VERSION-DIRECTIVE token. */
+
+        VERSION_DIRECTIVE_TOKEN_INIT(*token, major, minor,
+                start_mark, end_mark);
+    }
+
+    /* Is it a TAG directive? */
+
+    else if (strcmp((char *)name, "TAG") == 0)
+    {
+        /* Scan the TAG directive value. */
+
+        if (!yaml_parser_scan_tag_directive_value(parser, start_mark,
+                    &handle, &prefix))
+            goto error;
+
+        end_mark = parser->mark;
+
+        /* Create a TAG-DIRECTIVE token. */
+
+        TAG_DIRECTIVE_TOKEN_INIT(*token, handle, prefix,
+                start_mark, end_mark);
+    }
+
+    /* Unknown directive. */
+
+    else
+    {
+        yaml_parser_set_scanner_error(parser, "while scanning a directive",
+                start_mark, "found unknown directive name");
+        goto error;
+    }
+
+    /* Eat the rest of the line including any comments. */
+
+    if (!CACHE(parser, 1)) goto error;
+
+    while (IS_BLANK(parser->buffer)) {
+        SKIP(parser);
+        if (!CACHE(parser, 1)) goto error;
+    }
+
+    if (CHECK(parser->buffer, '#')) {
+        while (!IS_BREAKZ(parser->buffer)) {
+            SKIP(parser);
+            if (!CACHE(parser, 1)) goto error;
+        }
+    }
+
+    /* Check if we are at the end of the line. */
+
+    if (!IS_BREAKZ(parser->buffer)) {
+        yaml_parser_set_scanner_error(parser, "while scanning a directive",
+                start_mark, "did not find expected comment or line break");
+        goto error;
+    }
+
+    /* Eat a line break. */
+
+    if (IS_BREAK(parser->buffer)) {
+        if (!CACHE(parser, 2)) goto error;
+        SKIP_LINE(parser);
+    }
+
+    yaml_free(name);
+
+    return 1;
+
+error:
+    yaml_free(prefix);
+    yaml_free(handle);
+    yaml_free(name);
+    return 0;
+}
+
+/*
+ * Scan the directive name.
+ *
+ * Scope:
+ *      %YAML   1.1     # a comment \n
+ *       ^^^^
+ *      %TAG    !yaml!  tag:yaml.org,2002:  \n
+ *       ^^^
+ */
+
+static int
+yaml_parser_scan_directive_name(yaml_parser_t *parser,
+        yaml_mark_t start_mark, yaml_char_t **name)
+{
+    yaml_string_t string = NULL_STRING;
+
+    if (!STRING_INIT(parser, string, INITIAL_STRING_SIZE)) goto error;
+
+    /* Consume the directive name. */
+
+    if (!CACHE(parser, 1)) goto error;
+
+    while (IS_ALPHA(parser->buffer))
+    {
+        if (!READ(parser, string)) goto error;
+        if (!CACHE(parser, 1)) goto error;
+    }
+
+    /* Check if the name is empty. */
+
+    if (string.start == string.pointer) {
+        yaml_parser_set_scanner_error(parser, "while scanning a directive",
+                start_mark, "could not find expected directive name");
+        goto error;
+    }
+
+    /* Check for an blank character after the name. */
+
+    if (!IS_BLANKZ(parser->buffer)) {
+        yaml_parser_set_scanner_error(parser, "while scanning a directive",
+                start_mark, "found unexpected non-alphabetical character");
+        goto error;
+    }
+
+    *name = string.start;
+
+    return 1;
+
+error:
+    STRING_DEL(parser, string);
+    return 0;
+}
+
+/*
+ * Scan the value of VERSION-DIRECTIVE.
+ *
+ * Scope:
+ *      %YAML   1.1     # a comment \n
+ *           ^^^^^^
+ */
+
+static int
+yaml_parser_scan_version_directive_value(yaml_parser_t *parser,
+        yaml_mark_t start_mark, int *major, int *minor)
+{
+    /* Eat whitespaces. */
+
+    if (!CACHE(parser, 1)) return 0;
+
+    while (IS_BLANK(parser->buffer)) {
+        SKIP(parser);
+        if (!CACHE(parser, 1)) return 0;
+    }
+
+    /* Consume the major version number. */
+
+    if (!yaml_parser_scan_version_directive_number(parser, start_mark, major))
+        return 0;
+
+    /* Eat '.'. */
+
+    if (!CHECK(parser->buffer, '.')) {
+        return yaml_parser_set_scanner_error(parser, "while scanning a %YAML directive",
+                start_mark, "did not find expected digit or '.' character");
+    }
+
+    SKIP(parser);
+
+    /* Consume the minor version number. */
+
+    if (!yaml_parser_scan_version_directive_number(parser, start_mark, minor))
+        return 0;
+
+    return 1;
+}
+
+#define MAX_NUMBER_LENGTH   9
+
+/*
+ * Scan the version number of VERSION-DIRECTIVE.
+ *
+ * Scope:
+ *      %YAML   1.1     # a comment \n
+ *              ^
+ *      %YAML   1.1     # a comment \n
+ *                ^
+ */
+
+static int
+yaml_parser_scan_version_directive_number(yaml_parser_t *parser,
+        yaml_mark_t start_mark, int *number)
+{
+    int value = 0;
+    size_t length = 0;
+
+    /* Repeat while the next character is digit. */
+
+    if (!CACHE(parser, 1)) return 0;
+
+    while (IS_DIGIT(parser->buffer))
+    {
+        /* Check if the number is too long. */
+
+        if (++length > MAX_NUMBER_LENGTH) {
+            return yaml_parser_set_scanner_error(parser, "while scanning a %YAML directive",
+                    start_mark, "found extremely long version number");
+        }
+
+        value = value*10 + AS_DIGIT(parser->buffer);
+
+        SKIP(parser);
+
+        if (!CACHE(parser, 1)) return 0;
+    }
+
+    /* Check if the number was present. */
+
+    if (!length) {
+        return yaml_parser_set_scanner_error(parser, "while scanning a %YAML directive",
+                start_mark, "did not find expected version number");
+    }
+
+    *number = value;
+
+    return 1;
+}
+
+/*
+ * Scan the value of a TAG-DIRECTIVE token.
+ *
+ * Scope:
+ *      %TAG    !yaml!  tag:yaml.org,2002:  \n
+ *          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+ */
+
+static int
+yaml_parser_scan_tag_directive_value(yaml_parser_t *parser,
+        yaml_mark_t start_mark, yaml_char_t **handle, yaml_char_t **prefix)
+{
+    yaml_char_t *handle_value = NULL;
+    yaml_char_t *prefix_value = NULL;
+
+    /* Eat whitespaces. */
+
+    if (!CACHE(parser, 1)) goto error;
+
+    while (IS_BLANK(parser->buffer)) {
+        SKIP(parser);
+        if (!CACHE(parser, 1)) goto error;
+    }
+
+    /* Scan a handle. */
+
+    if (!yaml_parser_scan_tag_handle(parser, 1, start_mark, &handle_value))
+        goto error;
+
+    /* Expect a whitespace. */
+
+    if (!CACHE(parser, 1)) goto error;
+
+    if (!IS_BLANK(parser->buffer)) {
+        yaml_parser_set_scanner_error(parser, "while scanning a %TAG directive",
+                start_mark, "did not find expected whitespace");
+        goto error;
+    }
+
+    /* Eat whitespaces. */
+
+    while (IS_BLANK(parser->buffer)) {
+        SKIP(parser);
+        if (!CACHE(parser, 1)) goto error;
+    }
+
+    /* Scan a prefix. */
+
+    if (!yaml_parser_scan_tag_uri(parser, 1, NULL, start_mark, &prefix_value))
+        goto error;
+
+    /* Expect a whitespace or line break. */
+
+    if (!CACHE(parser, 1)) goto error;
+
+    if (!IS_BLANKZ(parser->buffer)) {
+        yaml_parser_set_scanner_error(parser, "while scanning a %TAG directive",
+                start_mark, "did not find expected whitespace or line break");
+        goto error;
+    }
+
+    *handle = handle_value;
+    *prefix = prefix_value;
+
+    return 1;
+
+error:
+    yaml_free(handle_value);
+    yaml_free(prefix_value);
+    return 0;
+}
+
+static int
+yaml_parser_scan_anchor(yaml_parser_t *parser, yaml_token_t *token,
+        yaml_token_type_t type)
+{
+    int length = 0;
+    yaml_mark_t start_mark, end_mark;
+    yaml_string_t string = NULL_STRING;
+
+    if (!STRING_INIT(parser, string, INITIAL_STRING_SIZE)) goto error;
+
+    /* Eat the indicator character. */
+
+    start_mark = parser->mark;
+
+    SKIP(parser);
+
+    /* Consume the value. */
+
+    if (!CACHE(parser, 1)) goto error;
+
+    while (IS_ALPHA(parser->buffer)) {
+        if (!READ(parser, string)) goto error;
+        if (!CACHE(parser, 1)) goto error;
+        length ++;
+    }
+
+    end_mark = parser->mark;
+
+    /*
+     * Check if length of the anchor is greater than 0 and it is followed by
+     * a whitespace character or one of the indicators:
+     *
+     *      '?', ':', ',', ']', '}', '%', '@', '`'.
+     */
+
+    if (!length || !(IS_BLANKZ(parser->buffer) || CHECK(parser->buffer, '?')
+                || CHECK(parser->buffer, ':') || CHECK(parser->buffer, ',')
+                || CHECK(parser->buffer, ']') || CHECK(parser->buffer, '}')
+                || CHECK(parser->buffer, '%') || CHECK(parser->buffer, '@')
+                || CHECK(parser->buffer, '`'))) {
+        yaml_parser_set_scanner_error(parser, type == YAML_ANCHOR_TOKEN ?
+                "while scanning an anchor" : "while scanning an alias", start_mark,
+                "did not find expected alphabetic or numeric character");
+        goto error;
+    }
+
+    /* Create a token. */
+
+    if (type == YAML_ANCHOR_TOKEN) {
+        ANCHOR_TOKEN_INIT(*token, string.start, start_mark, end_mark);
+    }
+    else {
+        ALIAS_TOKEN_INIT(*token, string.start, start_mark, end_mark);
+    }
+
+    return 1;
+
+error:
+    STRING_DEL(parser, string);
+    return 0;
+}
+
+/*
+ * Scan a TAG token.
+ */
+
+static int
+yaml_parser_scan_tag(yaml_parser_t *parser, yaml_token_t *token)
+{
+    yaml_char_t *handle = NULL;
+    yaml_char_t *suffix = NULL;
+    yaml_mark_t start_mark, end_mark;
+
+    start_mark = parser->mark;
+
+    /* Check if the tag is in the canonical form. */
+
+    if (!CACHE(parser, 2)) goto error;
+
+    if (CHECK_AT(parser->buffer, '<', 1))
+    {
+        /* Set the handle to '' */
+
+        handle = YAML_MALLOC(1);
+        if (!handle) goto error;
+        handle[0] = '\0';
+
+        /* Eat '!<' */
+
+        SKIP(parser);
+        SKIP(parser);
+
+        /* Consume the tag value. */
+
+        if (!yaml_parser_scan_tag_uri(parser, 0, NULL, start_mark, &suffix))
+            goto error;
+
+        /* Check for '>' and eat it. */
+
+        if (!CHECK(parser->buffer, '>')) {
+            yaml_parser_set_scanner_error(parser, "while scanning a tag",
+                    start_mark, "did not find the expected '>'");
+            goto error;
+        }
+
+        SKIP(parser);
+    }
+    else
+    {
+        /* The tag has either the '!suffix' or the '!handle!suffix' form. */
+
+        /* First, try to scan a handle. */
+
+        if (!yaml_parser_scan_tag_handle(parser, 0, start_mark, &handle))
+            goto error;
+
+        /* Check if it is, indeed, handle. */
+
+        if (handle[0] == '!' && handle[1] != '\0' && handle[strlen((char *)handle)-1] == '!')
+        {
+            /* Scan the suffix now. */
+
+            if (!yaml_parser_scan_tag_uri(parser, 0, NULL, start_mark, &suffix))
+                goto error;
+        }
+        else
+        {
+            /* It wasn't a handle after all.  Scan the rest of the tag. */
+
+            if (!yaml_parser_scan_tag_uri(parser, 0, handle, start_mark, &suffix))
+                goto error;
+
+            /* Set the handle to '!'. */
+
+            yaml_free(handle);
+            handle = YAML_MALLOC(2);
+            if (!handle) goto error;
+            handle[0] = '!';
+            handle[1] = '\0';
+
+            /*
+             * A special case: the '!' tag.  Set the handle to '' and the
+             * suffix to '!'.
+             */
+
+            if (suffix[0] == '\0') {
+                yaml_char_t *tmp = handle;
+                handle = suffix;
+                suffix = tmp;
+            }
+        }
+    }
+
+    /* Check the character which ends the tag. */
+
+    if (!CACHE(parser, 1)) goto error;
+
+    if (!IS_BLANKZ(parser->buffer)) {
+        yaml_parser_set_scanner_error(parser, "while scanning a tag",
+                start_mark, "did not find expected whitespace or line break");
+        goto error;
+    }
+
+    end_mark = parser->mark;
+
+    /* Create a token. */
+
+    TAG_TOKEN_INIT(*token, handle, suffix, start_mark, end_mark);
+
+    return 1;
+
+error:
+    yaml_free(handle);
+    yaml_free(suffix);
+    return 0;
+}
+
+/*
+ * Scan a tag handle.
+ */
+
+static int
+yaml_parser_scan_tag_handle(yaml_parser_t *parser, int directive,
+        yaml_mark_t start_mark, yaml_char_t **handle)
+{
+    yaml_string_t string = NULL_STRING;
+
+    if (!STRING_INIT(parser, string, INITIAL_STRING_SIZE)) goto error;
+
+    /* Check the initial '!' character. */
+
+    if (!CACHE(parser, 1)) goto error;
+
+    if (!CHECK(parser->buffer, '!')) {
+        yaml_parser_set_scanner_error(parser, directive ?
+                "while scanning a tag directive" : "while scanning a tag",
+                start_mark, "did not find expected '!'");
+        goto error;
+    }
+
+    /* Copy the '!' character. */
+
+    if (!READ(parser, string)) goto error;
+
+    /* Copy all subsequent alphabetical and numerical characters. */
+
+    if (!CACHE(parser, 1)) goto error;
+
+    while (IS_ALPHA(parser->buffer))
+    {
+        if (!READ(parser, string)) goto error;
+        if (!CACHE(parser, 1)) goto error;
+    }
+
+    /* Check if the trailing character is '!' and copy it. */
+
+    if (CHECK(parser->buffer, '!'))
+    {
+        if (!READ(parser, string)) goto error;
+    }
+    else
+    {
+        /*
+         * It's either the '!' tag or not really a tag handle.  If it's a %TAG
+         * directive, it's an error.  If it's a tag token, it must be a part of
+         * URI.
+         */
+
+        if (directive && !(string.start[0] == '!' && string.start[1] == '\0')) {
+            yaml_parser_set_scanner_error(parser, "while parsing a tag directive",
+                    start_mark, "did not find expected '!'");
+            goto error;
+        }
+    }
+
+    *handle = string.start;
+
+    return 1;
+
+error:
+    STRING_DEL(parser, string);
+    return 0;
+}
+
+/*
+ * Scan a tag.
+ */
+
+static int
+yaml_parser_scan_tag_uri(yaml_parser_t *parser, int directive,
+        yaml_char_t *head, yaml_mark_t start_mark, yaml_char_t **uri)
+{
+    size_t length = head ? strlen((char *)head) : 0;
+    yaml_string_t string = NULL_STRING;
+
+    if (!STRING_INIT(parser, string, INITIAL_STRING_SIZE)) goto error;
+
+    /* Resize the string to include the head. */
+
+    while ((size_t)(string.end - string.start) <= length) {
+        if (!yaml_string_extend(&string.start, &string.pointer, &string.end)) {
+            parser->error = YAML_MEMORY_ERROR;
+            goto error;
+        }
+    }
+
+    /*
+     * Copy the head if needed.
+     *
+     * Note that we don't copy the leading '!' character.
+     */
+
+    if (length > 1) {
+        memcpy(string.start, head+1, length-1);
+        string.pointer += length-1;
+    }
+
+    /* Scan the tag. */
+
+    if (!CACHE(parser, 1)) goto error;
+
+    /*
+     * The set of characters that may appear in URI is as follows:
+     *
+     *      '0'-'9', 'A'-'Z', 'a'-'z', '_', '-', ';', '/', '?', ':', '@', '&',
+     *      '=', '+', '$', ',', '.', '!', '~', '*', '\'', '(', ')', '[', ']',
+     *      '%'.
+     */
+
+    while (IS_ALPHA(parser->buffer) || CHECK(parser->buffer, ';')
+            || CHECK(parser->buffer, '/') || CHECK(parser->buffer, '?')
+            || CHECK(parser->buffer, ':') || CHECK(parser->buffer, '@')
+            || CHECK(parser->buffer, '&') || CHECK(parser->buffer, '=')
+            || CHECK(parser->buffer, '+') || CHECK(parser->buffer, '$')
+            || CHECK(parser->buffer, ',') || CHECK(parser->buffer, '.')
+            || CHECK(parser->buffer, '!') || CHECK(parser->buffer, '~')
+            || CHECK(parser->buffer, '*') || CHECK(parser->buffer, '\'')
+            || CHECK(parser->buffer, '(') || CHECK(parser->buffer, ')')
+            || CHECK(parser->buffer, '[') || CHECK(parser->buffer, ']')
+            || CHECK(parser->buffer, '%'))
+    {
+        /* Check if it is a URI-escape sequence. */
+
+        if (CHECK(parser->buffer, '%')) {
+            if (!STRING_EXTEND(parser, string))
+                goto error;
+
+            if (!yaml_parser_scan_uri_escapes(parser,
+                        directive, start_mark, &string)) goto error;
+        }
+        else {
+            if (!READ(parser, string)) goto error;
+        }
+
+        length ++;
+        if (!CACHE(parser, 1)) goto error;
+    }
+
+    /* Check if the tag is non-empty. */
+
+    if (!length) {
+        if (!STRING_EXTEND(parser, string))
+            goto error;
+
+        yaml_parser_set_scanner_error(parser, directive ?
+                "while parsing a %TAG directive" : "while parsing a tag",
+                start_mark, "did not find expected tag URI");
+        goto error;
+    }
+
+    *uri = string.start;
+
+    return 1;
+
+error:
+    STRING_DEL(parser, string);
+    return 0;
+}
+
+/*
+ * Decode an URI-escape sequence corresponding to a single UTF-8 character.
+ */
+
+static int
+yaml_parser_scan_uri_escapes(yaml_parser_t *parser, int directive,
+        yaml_mark_t start_mark, yaml_string_t *string)
+{
+    int width = 0;
+
+    /* Decode the required number of characters. */
+
+    do {
+
+        unsigned char octet = 0;
+
+        /* Check for a URI-escaped octet. */
+
+        if (!CACHE(parser, 3)) return 0;
+
+        if (!(CHECK(parser->buffer, '%')
+                    && IS_HEX_AT(parser->buffer, 1)
+                    && IS_HEX_AT(parser->buffer, 2))) {
+            return yaml_parser_set_scanner_error(parser, directive ?
+                    "while parsing a %TAG directive" : "while parsing a tag",
+                    start_mark, "did not find URI escaped octet");
+        }
+
+        /* Get the octet. */
+
+        octet = (AS_HEX_AT(parser->buffer, 1) << 4) + AS_HEX_AT(parser->buffer, 2);
+
+        /* If it is the leading octet, determine the length of the UTF-8 sequence. */
+
+        if (!width)
+        {
+            width = (octet & 0x80) == 0x00 ? 1 :
+                    (octet & 0xE0) == 0xC0 ? 2 :
+                    (octet & 0xF0) == 0xE0 ? 3 :
+                    (octet & 0xF8) == 0xF0 ? 4 : 0;
+            if (!width) {
+                return yaml_parser_set_scanner_error(parser, directive ?
+                        "while parsing a %TAG directive" : "while parsing a tag",
+                        start_mark, "found an incorrect leading UTF-8 octet");
+            }
+        }
+        else
+        {
+            /* Check if the trailing octet is correct. */
+
+            if ((octet & 0xC0) != 0x80) {
+                return yaml_parser_set_scanner_error(parser, directive ?
+                        "while parsing a %TAG directive" : "while parsing a tag",
+                        start_mark, "found an incorrect trailing UTF-8 octet");
+            }
+        }
+
+        /* Copy the octet and move the pointers. */
+
+        *(string->pointer++) = octet;
+        SKIP(parser);
+        SKIP(parser);
+        SKIP(parser);
+
+    } while (--width);
+
+    return 1;
+}
+
+/*
+ * Scan a block scalar.
+ */
+
+static int
+yaml_parser_scan_block_scalar(yaml_parser_t *parser, yaml_token_t *token,
+        int literal)
+{
+    yaml_mark_t start_mark;
+    yaml_mark_t end_mark;
+    yaml_string_t string = NULL_STRING;
+    yaml_string_t leading_break = NULL_STRING;
+    yaml_string_t trailing_breaks = NULL_STRING;
+    int chomping = 0;
+    int increment = 0;
+    int indent = 0;
+    int leading_blank = 0;
+    int trailing_blank = 0;
+
+    if (!STRING_INIT(parser, string, INITIAL_STRING_SIZE)) goto error;
+    if (!STRING_INIT(parser, leading_break, INITIAL_STRING_SIZE)) goto error;
+    if (!STRING_INIT(parser, trailing_breaks, INITIAL_STRING_SIZE)) goto error;
+
+    /* Eat the indicator '|' or '>'. */
+
+    start_mark = parser->mark;
+
+    SKIP(parser);
+
+    /* Scan the additional block scalar indicators. */
+
+    if (!CACHE(parser, 1)) goto error;
+
+    /* Check for a chomping indicator. */
+
+    if (CHECK(parser->buffer, '+') || CHECK(parser->buffer, '-'))
+    {
+        /* Set the chomping method and eat the indicator. */
+
+        chomping = CHECK(parser->buffer, '+') ? +1 : -1;
+
+        SKIP(parser);
+
+        /* Check for an indentation indicator. */
+
+        if (!CACHE(parser, 1)) goto error;
+
+        if (IS_DIGIT(parser->buffer))
+        {
+            /* Check that the indentation is greater than 0. */
+
+            if (CHECK(parser->buffer, '0')) {
+                yaml_parser_set_scanner_error(parser, "while scanning a block scalar",
+                        start_mark, "found an indentation indicator equal to 0");
+                goto error;
+            }
+
+            /* Get the indentation level and eat the indicator. */
+
+            increment = AS_DIGIT(parser->buffer);
+
+            SKIP(parser);
+        }
+    }
+
+    /* Do the same as above, but in the opposite order. */
+
+    else if (IS_DIGIT(parser->buffer))
+    {
+        if (CHECK(parser->buffer, '0')) {
+            yaml_parser_set_scanner_error(parser, "while scanning a block scalar",
+                    start_mark, "found an indentation indicator equal to 0");
+            goto error;
+        }
+
+        increment = AS_DIGIT(parser->buffer);
+
+        SKIP(parser);
+
+        if (!CACHE(parser, 1)) goto error;
+
+        if (CHECK(parser->buffer, '+') || CHECK(parser->buffer, '-')) {
+            chomping = CHECK(parser->buffer, '+') ? +1 : -1;
+
+            SKIP(parser);
+        }
+    }
+
+    /* Eat whitespaces and comments to the end of the line. */
+
+    if (!CACHE(parser, 1)) goto error;
+
+    while (IS_BLANK(parser->buffer)) {
+        SKIP(parser);
+        if (!CACHE(parser, 1)) goto error;
+    }
+
+    if (CHECK(parser->buffer, '#')) {
+        while (!IS_BREAKZ(parser->buffer)) {
+            SKIP(parser);
+            if (!CACHE(parser, 1)) goto error;
+        }
+    }
+
+    /* Check if we are at the end of the line. */
+
+    if (!IS_BREAKZ(parser->buffer)) {
+        yaml_parser_set_scanner_error(parser, "while scanning a block scalar",
+                start_mark, "did not find expected comment or line break");
+        goto error;
+    }
+
+    /* Eat a line break. */
+
+    if (IS_BREAK(parser->buffer)) {
+        if (!CACHE(parser, 2)) goto error;
+        SKIP_LINE(parser);
+    }
+
+    end_mark = parser->mark;
+
+    /* Set the indentation level if it was specified. */
+
+    if (increment) {
+        indent = parser->indent >= 0 ? parser->indent+increment : increment;
+    }
+
+    /* Scan the leading line breaks and determine the indentation level if needed. */
+
+    if (!yaml_parser_scan_block_scalar_breaks(parser, &indent, &trailing_breaks,
+                start_mark, &end_mark)) goto error;
+
+    /* Scan the block scalar content. */
+
+    if (!CACHE(parser, 1)) goto error;
+
+    while ((int)parser->mark.column == indent && !IS_Z(parser->buffer))
+    {
+        /*
+         * We are at the beginning of a non-empty line.
+         */
+
+        /* Is it a trailing whitespace? */
+
+        trailing_blank = IS_BLANK(parser->buffer);
+
+        /* Check if we need to fold the leading line break. */
+
+        if (!literal && (*leading_break.start == '\n')
+                && !leading_blank && !trailing_blank)
+        {
+            /* Do we need to join the lines by space? */
+
+            if (*trailing_breaks.start == '\0') {
+                if (!STRING_EXTEND(parser, string)) goto error;
+                *(string.pointer ++) = ' ';
+            }
+
+            CLEAR(parser, leading_break);
+        }
+        else {
+            if (!JOIN(parser, string, leading_break)) goto error;
+            CLEAR(parser, leading_break);
+        }
+
+        /* Append the remaining line breaks. */
+
+        if (!JOIN(parser, string, trailing_breaks)) goto error;
+        CLEAR(parser, trailing_breaks);
+
+        /* Is it a leading whitespace? */
+
+        leading_blank = IS_BLANK(parser->buffer);
+
+        /* Consume the current line. */
+
+        while (!IS_BREAKZ(parser->buffer)) {
+            if (!READ(parser, string)) goto error;
+            if (!CACHE(parser, 1)) goto error;
+        }
+
+        /* Consume the line break. */
+
+        if (!CACHE(parser, 2)) goto error;
+
+        if (!READ_LINE(parser, leading_break)) goto error;
+
+        /* Eat the following indentation spaces and line breaks. */
+
+        if (!yaml_parser_scan_block_scalar_breaks(parser,
+                    &indent, &trailing_breaks, start_mark, &end_mark)) goto error;
+    }
+
+    /* Chomp the tail. */
+
+    if (chomping != -1) {
+        if (!JOIN(parser, string, leading_break)) goto error;
+    }
+    if (chomping == 1) {
+        if (!JOIN(parser, string, trailing_breaks)) goto error;
+    }
+
+    /* Create a token. */
+
+    SCALAR_TOKEN_INIT(*token, string.start, string.pointer-string.start,
+            literal ? YAML_LITERAL_SCALAR_STYLE : YAML_FOLDED_SCALAR_STYLE,
+            start_mark, end_mark);
+
+    STRING_DEL(parser, leading_break);
+    STRING_DEL(parser, trailing_breaks);
+
+    return 1;
+
+error:
+    STRING_DEL(parser, string);
+    STRING_DEL(parser, leading_break);
+    STRING_DEL(parser, trailing_breaks);
+
+    return 0;
+}
+
+/*
+ * Scan indentation spaces and line breaks for a block scalar.  Determine the
+ * indentation level if needed.
+ */
+
+static int
+yaml_parser_scan_block_scalar_breaks(yaml_parser_t *parser,
+        int *indent, yaml_string_t *breaks,
+        yaml_mark_t start_mark, yaml_mark_t *end_mark)
+{
+    int max_indent = 0;
+
+    *end_mark = parser->mark;
+
+    /* Eat the indentation spaces and line breaks. */
+
+    while (1)
+    {
+        /* Eat the indentation spaces. */
+
+        if (!CACHE(parser, 1)) return 0;
+
+        while ((!*indent || (int)parser->mark.column < *indent)
+                && IS_SPACE(parser->buffer)) {
+            SKIP(parser);
+            if (!CACHE(parser, 1)) return 0;
+        }
+
+        if ((int)parser->mark.column > max_indent)
+            max_indent = (int)parser->mark.column;
+
+        /* Check for a tab character messing the indentation. */
+
+        if ((!*indent || (int)parser->mark.column < *indent)
+                && IS_TAB(parser->buffer)) {
+            return yaml_parser_set_scanner_error(parser, "while scanning a block scalar",
+                    start_mark, "found a tab character where an indentation space is expected");
+        }
+
+        /* Have we found a non-empty line? */
+
+        if (!IS_BREAK(parser->buffer)) break;
+
+        /* Consume the line break. */
+
+        if (!CACHE(parser, 2)) return 0;
+        if (!READ_LINE(parser, *breaks)) return 0;
+        *end_mark = parser->mark;
+    }
+
+    /* Determine the indentation level if needed. */
+
+    if (!*indent) {
+        *indent = max_indent;
+        if (*indent < parser->indent + 1)
+            *indent = parser->indent + 1;
+        if (*indent < 1)
+            *indent = 1;
+    }
+
+   return 1;
+}
+
+/*
+ * Scan a quoted scalar.
+ */
+
+static int
+yaml_parser_scan_flow_scalar(yaml_parser_t *parser, yaml_token_t *token,
+        int single)
+{
+    yaml_mark_t start_mark;
+    yaml_mark_t end_mark;
+    yaml_string_t string = NULL_STRING;
+    yaml_string_t leading_break = NULL_STRING;
+    yaml_string_t trailing_breaks = NULL_STRING;
+    yaml_string_t whitespaces = NULL_STRING;
+    int leading_blanks;
+
+    if (!STRING_INIT(parser, string, INITIAL_STRING_SIZE)) goto error;
+    if (!STRING_INIT(parser, leading_break, INITIAL_STRING_SIZE)) goto error;
+    if (!STRING_INIT(parser, trailing_breaks, INITIAL_STRING_SIZE)) goto error;
+    if (!STRING_INIT(parser, whitespaces, INITIAL_STRING_SIZE)) goto error;
+
+    /* Eat the left quote. */
+
+    start_mark = parser->mark;
+
+    SKIP(parser);
+
+    /* Consume the content of the quoted scalar. */
+
+    while (1)
+    {
+        /* Check that there are no document indicators at the beginning of the line. */
+
+        if (!CACHE(parser, 4)) goto error;
+
+        if (parser->mark.column == 0 &&
+            ((CHECK_AT(parser->buffer, '-', 0) &&
+              CHECK_AT(parser->buffer, '-', 1) &&
+              CHECK_AT(parser->buffer, '-', 2)) ||
+             (CHECK_AT(parser->buffer, '.', 0) &&
+              CHECK_AT(parser->buffer, '.', 1) &&
+              CHECK_AT(parser->buffer, '.', 2))) &&
+            IS_BLANKZ_AT(parser->buffer, 3))
+        {
+            yaml_parser_set_scanner_error(parser, "while scanning a quoted scalar",
+                    start_mark, "found unexpected document indicator");
+            goto error;
+        }
+
+        /* Check for EOF. */
+
+        if (IS_Z(parser->buffer)) {
+            yaml_parser_set_scanner_error(parser, "while scanning a quoted scalar",
+                    start_mark, "found unexpected end of stream");
+            goto error;
+        }
+
+        /* Consume non-blank characters. */
+
+        if (!CACHE(parser, 2)) goto error;
+
+        leading_blanks = 0;
+
+        while (!IS_BLANKZ(parser->buffer))
+        {
+            /* Check for an escaped single quote. */
+
+            if (single && CHECK_AT(parser->buffer, '\'', 0)
+                    && CHECK_AT(parser->buffer, '\'', 1))
+            {
+                if (!STRING_EXTEND(parser, string)) goto error;
+                *(string.pointer++) = '\'';
+                SKIP(parser);
+                SKIP(parser);
+            }
+
+            /* Check for the right quote. */
+
+            else if (CHECK(parser->buffer, single ? '\'' : '"'))
+            {
+                break;
+            }
+
+            /* Check for an escaped line break. */
+
+            else if (!single && CHECK(parser->buffer, '\\')
+                    && IS_BREAK_AT(parser->buffer, 1))
+            {
+                if (!CACHE(parser, 3)) goto error;
+                SKIP(parser);
+                SKIP_LINE(parser);
+                leading_blanks = 1;
+                break;
+            }
+
+            /* Check for an escape sequence. */
+
+            else if (!single && CHECK(parser->buffer, '\\'))
+            {
+                size_t code_length = 0;
+
+                if (!STRING_EXTEND(parser, string)) goto error;
+
+                /* Check the escape character. */
+
+                switch (parser->buffer.pointer[1])
+                {
+                    case '0':
+                        *(string.pointer++) = '\0';
+                        break;
+
+                    case 'a':
+                        *(string.pointer++) = '\x07';
+                        break;
+
+                    case 'b':
+                        *(string.pointer++) = '\x08';
+                        break;
+
+                    case 't':
+                    case '\t':
+                        *(string.pointer++) = '\x09';
+                        break;
+
+                    case 'n':
+                        *(string.pointer++) = '\x0A';
+                        break;
+
+                    case 'v':
+                        *(string.pointer++) = '\x0B';
+                        break;
+
+                    case 'f':
+                        *(string.pointer++) = '\x0C';
+                        break;
+
+                    case 'r':
+                        *(string.pointer++) = '\x0D';
+                        break;
+
+                    case 'e':
+                        *(string.pointer++) = '\x1B';
+                        break;
+
+                    case ' ':
+                        *(string.pointer++) = '\x20';
+                        break;
+
+                    case '"':
+                        *(string.pointer++) = '"';
+                        break;
+
+                    case '\\':
+                        *(string.pointer++) = '\\';
+                        break;
+
+                    case '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;
+
+                    case '/':
+		        *(string.pointer++) = '/';  /* JSON -> YAML 1.2 */
+                        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. */
+
+        if (CHECK(parser->buffer, single ? '\'' : '"'))
+            break;
+
+        /* Consume blank characters. */
+
+        if (!CACHE(parser, 1)) goto error;
+
+        while (IS_BLANK(parser->buffer) || IS_BREAK(parser->buffer))
+        {
+            if (IS_BLANK(parser->buffer))
+            {
+                /* Consume a space or a tab character. */
+
+                if (!leading_blanks) {
+                    if (!READ(parser, whitespaces)) goto error;
+                }
+                else {
+                    SKIP(parser);
+                }
+            }
+            else
+            {
+                if (!CACHE(parser, 2)) goto error;
+
+                /* Check if it is a first line break. */
+
+                if (!leading_blanks)
+                {
+                    CLEAR(parser, whitespaces);
+                    if (!READ_LINE(parser, leading_break)) goto error;
+                    leading_blanks = 1;
+                }
+                else
+                {
+                    if (!READ_LINE(parser, trailing_breaks)) goto error;
+                }
+            }
+            if (!CACHE(parser, 1)) goto error;
+        }
+
+        /* Join the whitespaces or fold line breaks. */
+
+        if (leading_blanks)
+        {
+            /* Do we need to fold line breaks? */
+
+            if (leading_break.start[0] == '\n') {
+                if (trailing_breaks.start[0] == '\0') {
+                    if (!STRING_EXTEND(parser, string)) goto error;
+                    *(string.pointer++) = ' ';
+                }
+                else {
+                    if (!JOIN(parser, string, trailing_breaks)) goto error;
+                    CLEAR(parser, trailing_breaks);
+                }
+                CLEAR(parser, leading_break);
+            }
+            else {
+                if (!JOIN(parser, string, leading_break)) goto error;
+                if (!JOIN(parser, string, trailing_breaks)) goto error;
+                CLEAR(parser, leading_break);
+                CLEAR(parser, trailing_breaks);
+            }
+        }
+        else
+        {
+            if (!JOIN(parser, string, whitespaces)) goto error;
+            CLEAR(parser, whitespaces);
+        }
+    }
+
+    /* Eat the right quote. */
+
+    SKIP(parser);
+
+    end_mark = parser->mark;
+
+    /* Create a token. */
+
+    SCALAR_TOKEN_INIT(*token, string.start, string.pointer-string.start,
+            single ? YAML_SINGLE_QUOTED_SCALAR_STYLE : YAML_DOUBLE_QUOTED_SCALAR_STYLE,
+            start_mark, end_mark);
+
+    STRING_DEL(parser, leading_break);
+    STRING_DEL(parser, trailing_breaks);
+    STRING_DEL(parser, whitespaces);
+
+    return 1;
+
+error:
+    STRING_DEL(parser, string);
+    STRING_DEL(parser, leading_break);
+    STRING_DEL(parser, trailing_breaks);
+    STRING_DEL(parser, whitespaces);
+
+    return 0;
+}
+
+/*
+ * Scan a plain scalar.
+ */
+
+static int
+yaml_parser_scan_plain_scalar(yaml_parser_t *parser, yaml_token_t *token)
+{
+    yaml_mark_t start_mark;
+    yaml_mark_t end_mark;
+    yaml_string_t string = NULL_STRING;
+    yaml_string_t leading_break = NULL_STRING;
+    yaml_string_t trailing_breaks = NULL_STRING;
+    yaml_string_t whitespaces = NULL_STRING;
+    int leading_blanks = 0;
+    int indent = parser->indent+1;
+
+    if (!STRING_INIT(parser, string, INITIAL_STRING_SIZE)) goto error;
+    if (!STRING_INIT(parser, leading_break, INITIAL_STRING_SIZE)) goto error;
+    if (!STRING_INIT(parser, trailing_breaks, INITIAL_STRING_SIZE)) goto error;
+    if (!STRING_INIT(parser, whitespaces, INITIAL_STRING_SIZE)) goto error;
+
+    start_mark = end_mark = parser->mark;
+
+    /* Consume the content of the plain scalar. */
+
+    while (1)
+    {
+        /* Check for a document indicator. */
+
+        if (!CACHE(parser, 4)) goto error;
+
+        if (parser->mark.column == 0 &&
+            ((CHECK_AT(parser->buffer, '-', 0) &&
+              CHECK_AT(parser->buffer, '-', 1) &&
+              CHECK_AT(parser->buffer, '-', 2)) ||
+             (CHECK_AT(parser->buffer, '.', 0) &&
+              CHECK_AT(parser->buffer, '.', 1) &&
+              CHECK_AT(parser->buffer, '.', 2))) &&
+            IS_BLANKZ_AT(parser->buffer, 3)) break;
+
+        /* Check for a comment. */
+
+        if (CHECK(parser->buffer, '#'))
+            break;
+
+        /* Consume non-blank characters. */
+
+        while (!IS_BLANKZ(parser->buffer))
+        {
+            /* Check for 'x:x' in the flow context. TODO: Fix the test "spec-08-13". */
+
+            if (parser->flow_level
+                    && CHECK(parser->buffer, ':')
+                    && !IS_BLANKZ_AT(parser->buffer, 1)) {
+                yaml_parser_set_scanner_error(parser, "while scanning a plain scalar",
+                        start_mark, "found unexpected ':'");
+                goto error;
+            }
+
+            /* Check for indicators that may end a plain scalar. */
+
+            if ((CHECK(parser->buffer, ':') && IS_BLANKZ_AT(parser->buffer, 1))
+                    || (parser->flow_level &&
+                        (CHECK(parser->buffer, ',') || CHECK(parser->buffer, ':')
+                         || CHECK(parser->buffer, '?') || CHECK(parser->buffer, '[')
+                         || CHECK(parser->buffer, ']') || CHECK(parser->buffer, '{')
+                         || CHECK(parser->buffer, '}'))))
+                break;
+
+            /* Check if we need to join whitespaces and breaks. */
+
+            if (leading_blanks || whitespaces.start != whitespaces.pointer)
+            {
+                if (leading_blanks)
+                {
+                    /* Do we need to fold line breaks? */
+
+                    if (leading_break.start[0] == '\n') {
+                        if (trailing_breaks.start[0] == '\0') {
+                            if (!STRING_EXTEND(parser, string)) goto error;
+                            *(string.pointer++) = ' ';
+                        }
+                        else {
+                            if (!JOIN(parser, string, trailing_breaks)) goto error;
+                            CLEAR(parser, trailing_breaks);
+                        }
+                        CLEAR(parser, leading_break);
+                    }
+                    else {
+                        if (!JOIN(parser, string, leading_break)) goto error;
+                        if (!JOIN(parser, string, trailing_breaks)) goto error;
+                        CLEAR(parser, leading_break);
+                        CLEAR(parser, trailing_breaks);
+                    }
+
+                    leading_blanks = 0;
+                }
+                else
+                {
+                    if (!JOIN(parser, string, whitespaces)) goto error;
+                    CLEAR(parser, whitespaces);
+                }
+            }
+
+            /* Copy the character. */
+
+            if (!READ(parser, string)) goto error;
+
+            end_mark = parser->mark;
+
+            if (!CACHE(parser, 2)) goto error;
+        }
+
+        /* Is it the end? */
+
+        if (!(IS_BLANK(parser->buffer) || IS_BREAK(parser->buffer)))
+            break;
+
+        /* Consume blank characters. */
+
+        if (!CACHE(parser, 1)) goto error;
+
+        while (IS_BLANK(parser->buffer) || IS_BREAK(parser->buffer))
+        {
+            if (IS_BLANK(parser->buffer))
+            {
+                /* Check for tab characters that abuse indentation. */
+
+                if (leading_blanks && (int)parser->mark.column < indent
+                        && IS_TAB(parser->buffer)) {
+                    yaml_parser_set_scanner_error(parser, "while scanning a plain scalar",
+                            start_mark, "found a tab character that violates indentation");
+                    goto error;
+                }
+
+                /* Consume a space or a tab character. */
+
+                if (!leading_blanks) {
+                    if (!READ(parser, whitespaces)) goto error;
+                }
+                else {
+                    SKIP(parser);
+                }
+            }
+            else
+            {
+                if (!CACHE(parser, 2)) goto error;
+
+                /* Check if it is a first line break. */
+
+                if (!leading_blanks)
+                {
+                    CLEAR(parser, whitespaces);
+                    if (!READ_LINE(parser, leading_break)) goto error;
+                    leading_blanks = 1;
+                }
+                else
+                {
+                    if (!READ_LINE(parser, trailing_breaks)) goto error;
+                }
+            }
+            if (!CACHE(parser, 1)) goto error;
+        }
+
+        /* Check indentation level. */
+
+        if (!parser->flow_level && (int)parser->mark.column < indent)
+            break;
+    }
+
+    /* Create a token. */
+
+    SCALAR_TOKEN_INIT(*token, string.start, string.pointer-string.start,
+            YAML_PLAIN_SCALAR_STYLE, start_mark, end_mark);
+
+    /* Note that we change the 'simple_key_allowed' flag. */
+
+    if (leading_blanks) {
+        parser->simple_key_allowed = 1;
+    }
+
+    STRING_DEL(parser, leading_break);
+    STRING_DEL(parser, trailing_breaks);
+    STRING_DEL(parser, whitespaces);
+
+    return 1;
+
+error:
+    STRING_DEL(parser, string);
+    STRING_DEL(parser, leading_break);
+    STRING_DEL(parser, trailing_breaks);
+    STRING_DEL(parser, whitespaces);
+
+    return 0;
+}