yakumo_izuru/aya: vendor/gopkg.in/yaml.v2/scannerc.go comparison

comparison vendor/gopkg.in/yaml.v2/scannerc.go @ 66:787b5ee0289d draft

Use vendored modules Signed-off-by: Izuru Yakumo <yakumo.izuru@chaotic.ninja>

author	yakumo.izuru
date	Sun, 23 Jul 2023 13:18:53 +0000
parents
children

comparison

equal deleted inserted replaced

-:6d985efa0f7a
+:787b5ee0289d
+package yaml
+import (
+	"bytes"
+	"fmt"
+)
+// Introduction
+// ************
+//
+// The following notes assume that you are familiar with the YAML specification
+// (http://yaml.org/spec/1.2/spec.html).  We mostly follow it, although in
+// some cases we are less restrictive that it requires.
+//
+// The process of transforming a YAML stream into a sequence of events is
+// divided on two steps: Scanning and Parsing.
+//
+// The Scanner transforms the input stream into a sequence of tokens, while the
+// parser transform the sequence of tokens produced by the Scanner into a
+// sequence of parsing events.
+//
+// The Scanner is rather clever and complicated. The Parser, on the contrary,
+// is a straightforward implementation of a recursive-descendant parser (or,
+// LL(1) parser, as it is usually called).
+//
+// Actually there are two issues of Scanning that might be called "clever", the
+// rest is quite straightforward.  The issues are "block collection start" and
+// "simple keys".  Both issues are explained below in details.
+//
+// Here the Scanning step is explained and implemented.  We start with the list
+// of all the tokens produced by the Scanner together with short descriptions.
+//
+// Now, tokens:
+//
+//      STREAM-START(encoding)          # The stream start.
+//      STREAM-END                      # The stream end.
+//      VERSION-DIRECTIVE(major,minor)  # The '%YAML' directive.
+//      TAG-DIRECTIVE(handle,prefix)    # The '%TAG' directive.
+//      DOCUMENT-START                  # '---'
+//      DOCUMENT-END                    # '...'
+//      BLOCK-SEQUENCE-START            # Indentation increase denoting a block
+//      BLOCK-MAPPING-START             # sequence or a block mapping.
+//      BLOCK-END                       # Indentation decrease.
+//      FLOW-SEQUENCE-START             # '['
+//      FLOW-SEQUENCE-END               # ']'
+//      BLOCK-SEQUENCE-START            # '{'
+//      BLOCK-SEQUENCE-END              # '}'
+//      BLOCK-ENTRY                     # '-'
+//      FLOW-ENTRY                      # ','
+//      KEY                             # '?' or nothing (simple keys).
+//      VALUE                           # ':'
+//      ALIAS(anchor)                   # '*anchor'
+//      ANCHOR(anchor)                  # '&anchor'
+//      TAG(handle,suffix)              # '!handle!suffix'
+//      SCALAR(value,style)             # A scalar.
+//
+// The following two tokens are "virtual" tokens denoting the beginning and the
+// end of the stream:
+//
+//      STREAM-START(encoding)
+//      STREAM-END
+//
+// We pass the information about the input stream encoding with the
+// STREAM-START token.
+//
+// The next two tokens are responsible for tags:
+//
+//      VERSION-DIRECTIVE(major,minor)
+//      TAG-DIRECTIVE(handle,prefix)
+//
+// Example:
+//
+//      %YAML   1.1
+//      %TAG    !   !foo
+//      %TAG    !yaml!  tag:yaml.org,2002:
+//      ---
+//
+// The correspoding 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
+//
+// Ensure that the buffer contains the required number of characters.
+// Return true on success, false on failure (reader error or memory error).
+func cache(parser *yaml_parser_t, length int) bool {
+	// [Go] This was inlined: !cache(A, B) -> unread < B && !update(A, B)
+	return parser.unread >= length || yaml_parser_update_buffer(parser, length)
+}
+// Advance the buffer pointer.
+func skip(parser *yaml_parser_t) {
+	parser.mark.index++
+	parser.mark.column++
+	parser.unread--
+	parser.buffer_pos += width(parser.buffer[parser.buffer_pos])
+}
+func skip_line(parser *yaml_parser_t) {
+	if is_crlf(parser.buffer, parser.buffer_pos) {
+		parser.mark.index += 2
+		parser.mark.column = 0
+		parser.mark.line++
+		parser.unread -= 2
+		parser.buffer_pos += 2
+	} else if is_break(parser.buffer, parser.buffer_pos) {
+		parser.mark.index++
+		parser.mark.column = 0
+		parser.mark.line++
+		parser.unread--
+		parser.buffer_pos += width(parser.buffer[parser.buffer_pos])
+	}
+}
+// Copy a character to a string buffer and advance pointers.
+func read(parser *yaml_parser_t, s []byte) []byte {
+	w := width(parser.buffer[parser.buffer_pos])
+	if w == 0 {
+		panic("invalid character sequence")
+	}
+	if len(s) == 0 {
+		s = make([]byte, 0, 32)
+	}
+	if w == 1 && len(s)+w <= cap(s) {
+		s = s[:len(s)+1]
+		s[len(s)-1] = parser.buffer[parser.buffer_pos]
+		parser.buffer_pos++
+	} else {
+		s = append(s, parser.buffer[parser.buffer_pos:parser.buffer_pos+w]...)
+		parser.buffer_pos += w
+	}
+	parser.mark.index++
+	parser.mark.column++
+	parser.unread--
+	return s
+}
+// Copy a line break character to a string buffer and advance pointers.
+func read_line(parser *yaml_parser_t, s []byte) []byte {
+	buf := parser.buffer
+	pos := parser.buffer_pos
+	switch {
+	case buf[pos] == '\r' && buf[pos+1] == '\n':
+		// CR LF . LF
+		s = append(s, '\n')
+		parser.buffer_pos += 2
+		parser.mark.index++
+		parser.unread--
+	case buf[pos] == '\r' || buf[pos] == '\n':
+		// CR|LF . LF
+		s = append(s, '\n')
+		parser.buffer_pos += 1
+	case buf[pos] == '\xC2' && buf[pos+1] == '\x85':
+		// NEL . LF
+		s = append(s, '\n')
+		parser.buffer_pos += 2
+	case buf[pos] == '\xE2' && buf[pos+1] == '\x80' && (buf[pos+2] == '\xA8' || buf[pos+2] == '\xA9'):
+		// LS|PS . LS|PS
+		s = append(s, buf[parser.buffer_pos:pos+3]...)
+		parser.buffer_pos += 3
+	default:
+		return s
+	}
+	parser.mark.index++
+	parser.mark.column = 0
+	parser.mark.line++
+	parser.unread--
+	return s
+}
+// Get the next token.
+func yaml_parser_scan(parser *yaml_parser_t, token *yaml_token_t) bool {
+	// Erase the token object.
+	*token = yaml_token_t{} // [Go] Is this necessary?
+	// No tokens after STREAM-END or error.
+	if parser.stream_end_produced || parser.error != yaml_NO_ERROR {
+		return true
+	}
+	// Ensure that the tokens queue contains enough tokens.
+	if !parser.token_available {
+		if !yaml_parser_fetch_more_tokens(parser) {
+			return false
+		}
+	}
+	// Fetch the next token from the queue.
+	*token = parser.tokens[parser.tokens_head]
+	parser.tokens_head++
+	parser.tokens_parsed++
+	parser.token_available = false
+	if token.typ == yaml_STREAM_END_TOKEN {
+		parser.stream_end_produced = true
+	}
+	return true
+}
+// Set the scanner error and return false.
+func yaml_parser_set_scanner_error(parser *yaml_parser_t, context string, context_mark yaml_mark_t, problem string) bool {
+	parser.error = yaml_SCANNER_ERROR
+	parser.context = context
+	parser.context_mark = context_mark
+	parser.problem = problem
+	parser.problem_mark = parser.mark
+	return false
+}
+func yaml_parser_set_scanner_tag_error(parser *yaml_parser_t, directive bool, context_mark yaml_mark_t, problem string) bool {
+	context := "while parsing a tag"
+	if directive {
+		context = "while parsing a %TAG directive"
+	}
+	return yaml_parser_set_scanner_error(parser, context, context_mark, problem)
+}
+func trace(args ...interface{}) func() {
+	pargs := append([]interface{}{"+++"}, args...)
+	fmt.Println(pargs...)
+	pargs = append([]interface{}{"---"}, args...)
+	return func() { fmt.Println(pargs...) }
+}
+// Ensure that the tokens queue contains at least one token which can be
+// returned to the Parser.
+func yaml_parser_fetch_more_tokens(parser *yaml_parser_t) bool {
+	// While we need more tokens to fetch, do it.
+	for {
+		if parser.tokens_head != len(parser.tokens) {
+			// If queue is non-empty, check if any potential simple key may
+			// occupy the head position.
+			head_tok_idx, ok := parser.simple_keys_by_tok[parser.tokens_parsed]
+			if !ok {
+				break
+			} else if valid, ok := yaml_simple_key_is_valid(parser, &parser.simple_keys[head_tok_idx]); !ok {
+				return false
+			} else if !valid {
+				break
+			}
+		}
+		// Fetch the next token.
+		if !yaml_parser_fetch_next_token(parser) {
+			return false
+		}
+	}
+	parser.token_available = true
+	return true
+}
+// The dispatcher for token fetchers.
+func yaml_parser_fetch_next_token(parser *yaml_parser_t) bool {
+	// Ensure that the buffer is initialized.
+	if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+		return false
+	}
+	// 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 false
+	}
+	// Check the indentation level against the current column.
+	if !yaml_parser_unroll_indent(parser, parser.mark.column) {
+		return false
+	}
+	// Ensure that the buffer contains at least 4 characters.  4 is the length
+	// of the longest indicators ('--- ' and '... ').
+	if parser.unread < 4 && !yaml_parser_update_buffer(parser, 4) {
+		return false
+	}
+	// Is it the end of the stream?
+	if is_z(parser.buffer, parser.buffer_pos) {
+		return yaml_parser_fetch_stream_end(parser)
+	}
+	// Is it a directive?
+	if parser.mark.column == 0 && parser.buffer[parser.buffer_pos] == '%' {
+		return yaml_parser_fetch_directive(parser)
+	}
+	buf := parser.buffer
+	pos := parser.buffer_pos
+	// Is it the document start indicator?
+	if parser.mark.column == 0 && buf[pos] == '-' && buf[pos+1] == '-' && buf[pos+2] == '-' && is_blankz(buf, pos+3) {
+		return yaml_parser_fetch_document_indicator(parser, yaml_DOCUMENT_START_TOKEN)
+	}
+	// Is it the document end indicator?
+	if parser.mark.column == 0 && buf[pos] == '.' && buf[pos+1] == '.' && buf[pos+2] == '.' && is_blankz(buf, pos+3) {
+		return yaml_parser_fetch_document_indicator(parser, yaml_DOCUMENT_END_TOKEN)
+	}
+	// Is it the flow sequence start indicator?
+	if buf[pos] == '[' {
+		return yaml_parser_fetch_flow_collection_start(parser, yaml_FLOW_SEQUENCE_START_TOKEN)
+	}
+	// Is it the flow mapping start indicator?
+	if parser.buffer[parser.buffer_pos] == '{' {
+		return yaml_parser_fetch_flow_collection_start(parser, yaml_FLOW_MAPPING_START_TOKEN)
+	}
+	// Is it the flow sequence end indicator?
+	if parser.buffer[parser.buffer_pos] == ']' {
+		return yaml_parser_fetch_flow_collection_end(parser,
+			yaml_FLOW_SEQUENCE_END_TOKEN)
+	}
+	// Is it the flow mapping end indicator?
+	if parser.buffer[parser.buffer_pos] == '}' {
+		return yaml_parser_fetch_flow_collection_end(parser,
+			yaml_FLOW_MAPPING_END_TOKEN)
+	}
+	// Is it the flow entry indicator?
+	if parser.buffer[parser.buffer_pos] == ',' {
+		return yaml_parser_fetch_flow_entry(parser)
+	}
+	// Is it the block entry indicator?
+	if parser.buffer[parser.buffer_pos] == '-' && is_blankz(parser.buffer, parser.buffer_pos+1) {
+		return yaml_parser_fetch_block_entry(parser)
+	}
+	// Is it the key indicator?
+	if parser.buffer[parser.buffer_pos] == '?' && (parser.flow_level > 0 || is_blankz(parser.buffer, parser.buffer_pos+1)) {
+		return yaml_parser_fetch_key(parser)
+	}
+	// Is it the value indicator?
+	if parser.buffer[parser.buffer_pos] == ':' && (parser.flow_level > 0 || is_blankz(parser.buffer, parser.buffer_pos+1)) {
+		return yaml_parser_fetch_value(parser)
+	}
+	// Is it an alias?
+	if parser.buffer[parser.buffer_pos] == '*' {
+		return yaml_parser_fetch_anchor(parser, yaml_ALIAS_TOKEN)
+	}
+	// Is it an anchor?
+	if parser.buffer[parser.buffer_pos] == '&' {
+		return yaml_parser_fetch_anchor(parser, yaml_ANCHOR_TOKEN)
+	}
+	// Is it a tag?
+	if parser.buffer[parser.buffer_pos] == '!' {
+		return yaml_parser_fetch_tag(parser)
+	}
+	// Is it a literal scalar?
+	if parser.buffer[parser.buffer_pos] == '|' && parser.flow_level == 0 {
+		return yaml_parser_fetch_block_scalar(parser, true)
+	}
+	// Is it a folded scalar?
+	if parser.buffer[parser.buffer_pos] == '>' && parser.flow_level == 0 {
+		return yaml_parser_fetch_block_scalar(parser, false)
+	}
+	// Is it a single-quoted scalar?
+	if parser.buffer[parser.buffer_pos] == '\'' {
+		return yaml_parser_fetch_flow_scalar(parser, true)
+	}
+	// Is it a double-quoted scalar?
+	if parser.buffer[parser.buffer_pos] == '"' {
+		return yaml_parser_fetch_flow_scalar(parser, false)
+	}
+	// 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.
+	// [Go] Make this logic more reasonable.
+	//switch parser.buffer[parser.buffer_pos] {
+	//case '-', '?', ':', ',', '?', '-', ',', ':', ']', '[', '}', '{', '&', '#', '!', '*', '>', '|', '"', '\'', '@', '%', '-', '`':
+	//}
+	if !(is_blankz(parser.buffer, parser.buffer_pos) || parser.buffer[parser.buffer_pos] == '-' ||
+		parser.buffer[parser.buffer_pos] == '?' || parser.buffer[parser.buffer_pos] == ':' ||
+		parser.buffer[parser.buffer_pos] == ',' || parser.buffer[parser.buffer_pos] == '[' ||
+		parser.buffer[parser.buffer_pos] == ']' || parser.buffer[parser.buffer_pos] == '{' ||
+		parser.buffer[parser.buffer_pos] == '}' || parser.buffer[parser.buffer_pos] == '#' ||
+		parser.buffer[parser.buffer_pos] == '&' || parser.buffer[parser.buffer_pos] == '*' ||
+		parser.buffer[parser.buffer_pos] == '!' || parser.buffer[parser.buffer_pos] == '|' ||
+		parser.buffer[parser.buffer_pos] == '>' || parser.buffer[parser.buffer_pos] == '\'' ||
+		parser.buffer[parser.buffer_pos] == '"' || parser.buffer[parser.buffer_pos] == '%' ||
+		parser.buffer[parser.buffer_pos] == '@' || parser.buffer[parser.buffer_pos] == '`') ||
+		(parser.buffer[parser.buffer_pos] == '-' && !is_blank(parser.buffer, parser.buffer_pos+1)) ||
+		(parser.flow_level == 0 &&
+			(parser.buffer[parser.buffer_pos] == '?' || parser.buffer[parser.buffer_pos] == ':') &&
+			!is_blankz(parser.buffer, parser.buffer_pos+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")
+}
+func yaml_simple_key_is_valid(parser *yaml_parser_t, simple_key *yaml_simple_key_t) (valid, ok bool) {
+	if !simple_key.possible {
+		return false, true
+	}
+	// The 1.2 specification says:
+	//
+	//     "If the ? indicator is omitted, parsing needs to see past the
+	//     implicit key to recognize it as such. To limit the amount of
+	//     lookahead required, the “:” indicator must appear at most 1024
+	//     Unicode characters beyond the start of the key. In addition, the key
+	//     is restricted to a single line."
+	//
+	if 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 false, yaml_parser_set_scanner_error(parser,
+				"while scanning a simple key", simple_key.mark,
+				"could not find expected ':'")
+		}
+		simple_key.possible = false
+		return false, true
+	}
+	return true, true
+}
+// Check if a simple key may start at the current position and add it if
+// needed.
+func yaml_parser_save_simple_key(parser *yaml_parser_t) bool {
+	// 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.
+	required := parser.flow_level == 0 && parser.indent == parser.mark.column
+	//
+	// If the current position may start a simple key, save it.
+	//
+	if parser.simple_key_allowed {
+		simple_key := yaml_simple_key_t{
+			possible:     true,
+			required:     required,
+			token_number: parser.tokens_parsed + (len(parser.tokens) - parser.tokens_head),
+			mark:         parser.mark,
+		}
+		if !yaml_parser_remove_simple_key(parser) {
+			return false
+		}
+		parser.simple_keys[len(parser.simple_keys)-1] = simple_key
+		parser.simple_keys_by_tok[simple_key.token_number] = len(parser.simple_keys) - 1
+	}
+	return true
+}
+// Remove a potential simple key at the current flow level.
+func yaml_parser_remove_simple_key(parser *yaml_parser_t) bool {
+	i := len(parser.simple_keys) - 1
+	if parser.simple_keys[i].possible {
+		// If the key is required, it is an error.
+		if parser.simple_keys[i].required {
+			return yaml_parser_set_scanner_error(parser,
+				"while scanning a simple key", parser.simple_keys[i].mark,
+				"could not find expected ':'")
+		}
+		// Remove the key from the stack.
+		parser.simple_keys[i].possible = false
+		delete(parser.simple_keys_by_tok, parser.simple_keys[i].token_number)
+	}
+	return true
+}
+// max_flow_level limits the flow_level
+const max_flow_level = 10000
+// Increase the flow level and resize the simple key list if needed.
+func yaml_parser_increase_flow_level(parser *yaml_parser_t) bool {
+	// Reset the simple key on the next level.
+	parser.simple_keys = append(parser.simple_keys, yaml_simple_key_t{
+		possible:     false,
+		required:     false,
+		token_number: parser.tokens_parsed + (len(parser.tokens) - parser.tokens_head),
+		mark:         parser.mark,
+	})
+	// Increase the flow level.
+	parser.flow_level++
+	if parser.flow_level > max_flow_level {
+		return yaml_parser_set_scanner_error(parser,
+			"while increasing flow level", parser.simple_keys[len(parser.simple_keys)-1].mark,
+			fmt.Sprintf("exceeded max depth of %d", max_flow_level))
+	}
+	return true
+}
+// Decrease the flow level.
+func yaml_parser_decrease_flow_level(parser *yaml_parser_t) bool {
+	if parser.flow_level > 0 {
+		parser.flow_level--
+		last := len(parser.simple_keys) - 1
+		delete(parser.simple_keys_by_tok, parser.simple_keys[last].token_number)
+		parser.simple_keys = parser.simple_keys[:last]
+	}
+	return true
+}
+// max_indents limits the indents stack size
+const max_indents = 10000
+// 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.
+func yaml_parser_roll_indent(parser *yaml_parser_t, column, number int, typ yaml_token_type_t, mark yaml_mark_t) bool {
+	// In the flow context, do nothing.
+	if parser.flow_level > 0 {
+		return true
+	}
+	if parser.indent < column {
+		// Push the current indentation level to the stack and set the new
+		// indentation level.
+		parser.indents = append(parser.indents, parser.indent)
+		parser.indent = column
+		if len(parser.indents) > max_indents {
+			return yaml_parser_set_scanner_error(parser,
+				"while increasing indent level", parser.simple_keys[len(parser.simple_keys)-1].mark,
+				fmt.Sprintf("exceeded max depth of %d", max_indents))
+		}
+		// Create a token and insert it into the queue.
+		token := yaml_token_t{
+			typ:        typ,
+			start_mark: mark,
+			end_mark:   mark,
+		}
+		if number > -1 {
+			number -= parser.tokens_parsed
+		}
+		yaml_insert_token(parser, number, &token)
+	}
+	return true
+}
+// 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.
+func yaml_parser_unroll_indent(parser *yaml_parser_t, column int) bool {
+	// In the flow context, do nothing.
+	if parser.flow_level > 0 {
+		return true
+	}
+	// Loop through the indentation levels in the stack.
+	for parser.indent > column {
+		// Create a token and append it to the queue.
+		token := yaml_token_t{
+			typ:        yaml_BLOCK_END_TOKEN,
+			start_mark: parser.mark,
+			end_mark:   parser.mark,
+		}
+		yaml_insert_token(parser, -1, &token)
+		// Pop the indentation level.
+		parser.indent = parser.indents[len(parser.indents)-1]
+		parser.indents = parser.indents[:len(parser.indents)-1]
+	}
+	return true
+}
+// Initialize the scanner and produce the STREAM-START token.
+func yaml_parser_fetch_stream_start(parser *yaml_parser_t) bool {
+	// Set the initial indentation.
+	parser.indent = -1
+	// Initialize the simple key stack.
+	parser.simple_keys = append(parser.simple_keys, yaml_simple_key_t{})
+	parser.simple_keys_by_tok = make(map[int]int)
+	// A simple key is allowed at the beginning of the stream.
+	parser.simple_key_allowed = true
+	// We have started.
+	parser.stream_start_produced = true
+	// Create the STREAM-START token and append it to the queue.
+	token := yaml_token_t{
+		typ:        yaml_STREAM_START_TOKEN,
+		start_mark: parser.mark,
+		end_mark:   parser.mark,
+		encoding:   parser.encoding,
+	}
+	yaml_insert_token(parser, -1, &token)
+	return true
+}
+// Produce the STREAM-END token and shut down the scanner.
+func yaml_parser_fetch_stream_end(parser *yaml_parser_t) bool {
+	// 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 false
+	}
+	// Reset simple keys.
+	if !yaml_parser_remove_simple_key(parser) {
+		return false
+	}
+	parser.simple_key_allowed = false
+	// Create the STREAM-END token and append it to the queue.
+	token := yaml_token_t{
+		typ:        yaml_STREAM_END_TOKEN,
+		start_mark: parser.mark,
+		end_mark:   parser.mark,
+	}
+	yaml_insert_token(parser, -1, &token)
+	return true
+}
+// Produce a VERSION-DIRECTIVE or TAG-DIRECTIVE token.
+func yaml_parser_fetch_directive(parser *yaml_parser_t) bool {
+	// Reset the indentation level.
+	if !yaml_parser_unroll_indent(parser, -1) {
+		return false
+	}
+	// Reset simple keys.
+	if !yaml_parser_remove_simple_key(parser) {
+		return false
+	}
+	parser.simple_key_allowed = false
+	// Create the YAML-DIRECTIVE or TAG-DIRECTIVE token.
+	token := yaml_token_t{}
+	if !yaml_parser_scan_directive(parser, &token) {
+		return false
+	}
+	// Append the token to the queue.
+	yaml_insert_token(parser, -1, &token)
+	return true
+}
+// Produce the DOCUMENT-START or DOCUMENT-END token.
+func yaml_parser_fetch_document_indicator(parser *yaml_parser_t, typ yaml_token_type_t) bool {
+	// Reset the indentation level.
+	if !yaml_parser_unroll_indent(parser, -1) {
+		return false
+	}
+	// Reset simple keys.
+	if !yaml_parser_remove_simple_key(parser) {
+		return false
+	}
+	parser.simple_key_allowed = false
+	// 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 := yaml_token_t{
+		typ:        typ,
+		start_mark: start_mark,
+		end_mark:   end_mark,
+	}
+	// Append the token to the queue.
+	yaml_insert_token(parser, -1, &token)
+	return true
+}
+// Produce the FLOW-SEQUENCE-START or FLOW-MAPPING-START token.
+func yaml_parser_fetch_flow_collection_start(parser *yaml_parser_t, typ yaml_token_type_t) bool {
+	// The indicators '[' and '{' may start a simple key.
+	if !yaml_parser_save_simple_key(parser) {
+		return false
+	}
+	// Increase the flow level.
+	if !yaml_parser_increase_flow_level(parser) {
+		return false
+	}
+	// A simple key may follow the indicators '[' and '{'.
+	parser.simple_key_allowed = true
+	// Consume the token.
+	start_mark := parser.mark
+	skip(parser)
+	end_mark := parser.mark
+	// Create the FLOW-SEQUENCE-START of FLOW-MAPPING-START token.
+	token := yaml_token_t{
+		typ:        typ,
+		start_mark: start_mark,
+		end_mark:   end_mark,
+	}
+	// Append the token to the queue.
+	yaml_insert_token(parser, -1, &token)
+	return true
+}
+// Produce the FLOW-SEQUENCE-END or FLOW-MAPPING-END token.
+func yaml_parser_fetch_flow_collection_end(parser *yaml_parser_t, typ yaml_token_type_t) bool {
+	// Reset any potential simple key on the current flow level.
+	if !yaml_parser_remove_simple_key(parser) {
+		return false
+	}
+	// Decrease the flow level.
+	if !yaml_parser_decrease_flow_level(parser) {
+		return false
+	}
+	// No simple keys after the indicators ']' and '}'.
+	parser.simple_key_allowed = false
+	// Consume the token.
+	start_mark := parser.mark
+	skip(parser)
+	end_mark := parser.mark
+	// Create the FLOW-SEQUENCE-END of FLOW-MAPPING-END token.
+	token := yaml_token_t{
+		typ:        typ,
+		start_mark: start_mark,
+		end_mark:   end_mark,
+	}
+	// Append the token to the queue.
+	yaml_insert_token(parser, -1, &token)
+	return true
+}
+// Produce the FLOW-ENTRY token.
+func yaml_parser_fetch_flow_entry(parser *yaml_parser_t) bool {
+	// Reset any potential simple keys on the current flow level.
+	if !yaml_parser_remove_simple_key(parser) {
+		return false
+	}
+	// Simple keys are allowed after ','.
+	parser.simple_key_allowed = true
+	// 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 := yaml_token_t{
+		typ:        yaml_FLOW_ENTRY_TOKEN,
+		start_mark: start_mark,
+		end_mark:   end_mark,
+	}
+	yaml_insert_token(parser, -1, &token)
+	return true
+}
+// Produce the BLOCK-ENTRY token.
+func yaml_parser_fetch_block_entry(parser *yaml_parser_t) bool {
+	// Check if the scanner is in the block context.
+	if parser.flow_level == 0 {
+		// Check if we are allowed to start a new entry.
+		if !parser.simple_key_allowed {
+			return yaml_parser_set_scanner_error(parser, "", 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 false
+		}
+	} 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 false
+	}
+	// Simple keys are allowed after '-'.
+	parser.simple_key_allowed = true
+	// 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 := yaml_token_t{
+		typ:        yaml_BLOCK_ENTRY_TOKEN,
+		start_mark: start_mark,
+		end_mark:   end_mark,
+	}
+	yaml_insert_token(parser, -1, &token)
+	return true
+}
+// Produce the KEY token.
+func yaml_parser_fetch_key(parser *yaml_parser_t) bool {
+	// In the block context, additional checks are required.
+	if parser.flow_level == 0 {
+		// Check if we are allowed to start a new key (not nessesary simple).
+		if !parser.simple_key_allowed {
+			return yaml_parser_set_scanner_error(parser, "", 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 false
+		}
+	}
+	// Reset any potential simple keys on the current flow level.
+	if !yaml_parser_remove_simple_key(parser) {
+		return false
+	}
+	// Simple keys are allowed after '?' in the block context.
+	parser.simple_key_allowed = parser.flow_level == 0
+	// Consume the token.
+	start_mark := parser.mark
+	skip(parser)
+	end_mark := parser.mark
+	// Create the KEY token and append it to the queue.
+	token := yaml_token_t{
+		typ:        yaml_KEY_TOKEN,
+		start_mark: start_mark,
+		end_mark:   end_mark,
+	}
+	yaml_insert_token(parser, -1, &token)
+	return true
+}
+// Produce the VALUE token.
+func yaml_parser_fetch_value(parser *yaml_parser_t) bool {
+	simple_key := &parser.simple_keys[len(parser.simple_keys)-1]
+	// Have we found a simple key?
+	if valid, ok := yaml_simple_key_is_valid(parser, simple_key); !ok {
+		return false
+	} else if valid {
+		// Create the KEY token and insert it into the queue.
+		token := yaml_token_t{
+			typ:        yaml_KEY_TOKEN,
+			start_mark: simple_key.mark,
+			end_mark:   simple_key.mark,
+		}
+		yaml_insert_token(parser, simple_key.token_number-parser.tokens_parsed, &token)
+		// 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 false
+		}
+		// Remove the simple key.
+		simple_key.possible = false
+		delete(parser.simple_keys_by_tok, simple_key.token_number)
+		// A simple key cannot follow another simple key.
+		parser.simple_key_allowed = false
+	} else {
+		// The ':' indicator follows a complex key.
+		// In the block context, extra checks are required.
+		if parser.flow_level == 0 {
+			// Check if we are allowed to start a complex value.
+			if !parser.simple_key_allowed {
+				return yaml_parser_set_scanner_error(parser, "", 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 false
+			}
+		}
+		// Simple keys after ':' are allowed in the block context.
+		parser.simple_key_allowed = parser.flow_level == 0
+	}
+	// Consume the token.
+	start_mark := parser.mark
+	skip(parser)
+	end_mark := parser.mark
+	// Create the VALUE token and append it to the queue.
+	token := yaml_token_t{
+		typ:        yaml_VALUE_TOKEN,
+		start_mark: start_mark,
+		end_mark:   end_mark,
+	}
+	yaml_insert_token(parser, -1, &token)
+	return true
+}
+// Produce the ALIAS or ANCHOR token.
+func yaml_parser_fetch_anchor(parser *yaml_parser_t, typ yaml_token_type_t) bool {
+	// An anchor or an alias could be a simple key.
+	if !yaml_parser_save_simple_key(parser) {
+		return false
+	}
+	// A simple key cannot follow an anchor or an alias.
+	parser.simple_key_allowed = false
+	// Create the ALIAS or ANCHOR token and append it to the queue.
+	var token yaml_token_t
+	if !yaml_parser_scan_anchor(parser, &token, typ) {
+		return false
+	}
+	yaml_insert_token(parser, -1, &token)
+	return true
+}
+// Produce the TAG token.
+func yaml_parser_fetch_tag(parser *yaml_parser_t) bool {
+	// A tag could be a simple key.
+	if !yaml_parser_save_simple_key(parser) {
+		return false
+	}
+	// A simple key cannot follow a tag.
+	parser.simple_key_allowed = false
+	// Create the TAG token and append it to the queue.
+	var token yaml_token_t
+	if !yaml_parser_scan_tag(parser, &token) {
+		return false
+	}
+	yaml_insert_token(parser, -1, &token)
+	return true
+}
+// Produce the SCALAR(...,literal) or SCALAR(...,folded) tokens.
+func yaml_parser_fetch_block_scalar(parser *yaml_parser_t, literal bool) bool {
+	// Remove any potential simple keys.
+	if !yaml_parser_remove_simple_key(parser) {
+		return false
+	}
+	// A simple key may follow a block scalar.
+	parser.simple_key_allowed = true
+	// Create the SCALAR token and append it to the queue.
+	var token yaml_token_t
+	if !yaml_parser_scan_block_scalar(parser, &token, literal) {
+		return false
+	}
+	yaml_insert_token(parser, -1, &token)
+	return true
+}
+// Produce the SCALAR(...,single-quoted) or SCALAR(...,double-quoted) tokens.
+func yaml_parser_fetch_flow_scalar(parser *yaml_parser_t, single bool) bool {
+	// A plain scalar could be a simple key.
+	if !yaml_parser_save_simple_key(parser) {
+		return false
+	}
+	// A simple key cannot follow a flow scalar.
+	parser.simple_key_allowed = false
+	// Create the SCALAR token and append it to the queue.
+	var token yaml_token_t
+	if !yaml_parser_scan_flow_scalar(parser, &token, single) {
+		return false
+	}
+	yaml_insert_token(parser, -1, &token)
+	return true
+}
+// Produce the SCALAR(...,plain) token.
+func yaml_parser_fetch_plain_scalar(parser *yaml_parser_t) bool {
+	// A plain scalar could be a simple key.
+	if !yaml_parser_save_simple_key(parser) {
+		return false
+	}
+	// A simple key cannot follow a flow scalar.
+	parser.simple_key_allowed = false
+	// Create the SCALAR token and append it to the queue.
+	var token yaml_token_t
+	if !yaml_parser_scan_plain_scalar(parser, &token) {
+		return false
+	}
+	yaml_insert_token(parser, -1, &token)
+	return true
+}
+// Eat whitespaces and comments until the next token is found.
+func yaml_parser_scan_to_next_token(parser *yaml_parser_t) bool {
+	// Until the next token is not found.
+	for {
+		// Allow the BOM mark to start a line.
+		if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+			return false
+		}
+		if parser.mark.column == 0 && is_bom(parser.buffer, parser.buffer_pos) {
+			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 parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+			return false
+		}
+		for parser.buffer[parser.buffer_pos] == ' ' || ((parser.flow_level > 0 || !parser.simple_key_allowed) && parser.buffer[parser.buffer_pos] == '\t') {
+			skip(parser)
+			if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+				return false
+			}
+		}
+		// Eat a comment until a line break.
+		if parser.buffer[parser.buffer_pos] == '#' {
+			for !is_breakz(parser.buffer, parser.buffer_pos) {
+				skip(parser)
+				if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+					return false
+				}
+			}
+		}
+		// If it is a line break, eat it.
+		if is_break(parser.buffer, parser.buffer_pos) {
+			if parser.unread < 2 && !yaml_parser_update_buffer(parser, 2) {
+				return false
+			}
+			skip_line(parser)
+			// In the block context, a new line may start a simple key.
+			if parser.flow_level == 0 {
+				parser.simple_key_allowed = true
+			}
+		} else {
+			break // We have found a token.
+		}
+	}
+	return true
+}
+// Scan a YAML-DIRECTIVE or TAG-DIRECTIVE token.
+//
+// Scope:
+//      %YAML    1.1    # a comment \n
+//      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//      %TAG    !yaml!  tag:yaml.org,2002:  \n
+//      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+func yaml_parser_scan_directive(parser *yaml_parser_t, token *yaml_token_t) bool {
+	// Eat '%'.
+	start_mark := parser.mark
+	skip(parser)
+	// Scan the directive name.
+	var name []byte
+	if !yaml_parser_scan_directive_name(parser, start_mark, &name) {
+		return false
+	}
+	// Is it a YAML directive?
+	if bytes.Equal(name, []byte("YAML")) {
+		// Scan the VERSION directive value.
+		var major, minor int8
+		if !yaml_parser_scan_version_directive_value(parser, start_mark, &major, &minor) {
+			return false
+		}
+		end_mark := parser.mark
+		// Create a VERSION-DIRECTIVE token.
+		*token = yaml_token_t{
+			typ:        yaml_VERSION_DIRECTIVE_TOKEN,
+			start_mark: start_mark,
+			end_mark:   end_mark,
+			major:      major,
+			minor:      minor,
+		}
+		// Is it a TAG directive?
+	} else if bytes.Equal(name, []byte("TAG")) {
+		// Scan the TAG directive value.
+		var handle, prefix []byte
+		if !yaml_parser_scan_tag_directive_value(parser, start_mark, &handle, &prefix) {
+			return false
+		}
+		end_mark := parser.mark
+		// Create a TAG-DIRECTIVE token.
+		*token = yaml_token_t{
+			typ:        yaml_TAG_DIRECTIVE_TOKEN,
+			start_mark: start_mark,
+			end_mark:   end_mark,
+			value:      handle,
+			prefix:     prefix,
+		}
+		// Unknown directive.
+	} else {
+		yaml_parser_set_scanner_error(parser, "while scanning a directive",
+			start_mark, "found unknown directive name")
+		return false
+	}
+	// Eat the rest of the line including any comments.
+	if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+		return false
+	}
+	for is_blank(parser.buffer, parser.buffer_pos) {
+		skip(parser)
+		if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+			return false
+		}
+	}
+	if parser.buffer[parser.buffer_pos] == '#' {
+		for !is_breakz(parser.buffer, parser.buffer_pos) {
+			skip(parser)
+			if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+				return false
+			}
+		}
+	}
+	// Check if we are at the end of the line.
+	if !is_breakz(parser.buffer, parser.buffer_pos) {
+		yaml_parser_set_scanner_error(parser, "while scanning a directive",
+			start_mark, "did not find expected comment or line break")
+		return false
+	}
+	// Eat a line break.
+	if is_break(parser.buffer, parser.buffer_pos) {
+		if parser.unread < 2 && !yaml_parser_update_buffer(parser, 2) {
+			return false
+		}
+		skip_line(parser)
+	}
+	return true
+}
+// Scan the directive name.
+//
+// Scope:
+//      %YAML   1.1     # a comment \n
+//       ^^^^
+//      %TAG    !yaml!  tag:yaml.org,2002:  \n
+//       ^^^
+//
+func yaml_parser_scan_directive_name(parser *yaml_parser_t, start_mark yaml_mark_t, name *[]byte) bool {
+	// Consume the directive name.
+	if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+		return false
+	}
+	var s []byte
+	for is_alpha(parser.buffer, parser.buffer_pos) {
+		s = read(parser, s)
+		if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+			return false
+		}
+	}
+	// Check if the name is empty.
+	if len(s) == 0 {
+		yaml_parser_set_scanner_error(parser, "while scanning a directive",
+			start_mark, "could not find expected directive name")
+		return false
+	}
+	// Check for an blank character after the name.
+	if !is_blankz(parser.buffer, parser.buffer_pos) {
+		yaml_parser_set_scanner_error(parser, "while scanning a directive",
+			start_mark, "found unexpected non-alphabetical character")
+		return false
+	}
+	*name = s
+	return true
+}
+// Scan the value of VERSION-DIRECTIVE.
+//
+// Scope:
+//      %YAML   1.1     # a comment \n
+//           ^^^^^^
+func yaml_parser_scan_version_directive_value(parser *yaml_parser_t, start_mark yaml_mark_t, major, minor *int8) bool {
+	// Eat whitespaces.
+	if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+		return false
+	}
+	for is_blank(parser.buffer, parser.buffer_pos) {
+		skip(parser)
+		if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+			return false
+		}
+	}
+	// Consume the major version number.
+	if !yaml_parser_scan_version_directive_number(parser, start_mark, major) {
+		return false
+	}
+	// Eat '.'.
+	if parser.buffer[parser.buffer_pos] != '.' {
+		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 false
+	}
+	return true
+}
+const max_number_length = 2
+// Scan the version number of VERSION-DIRECTIVE.
+//
+// Scope:
+//      %YAML   1.1     # a comment \n
+//              ^
+//      %YAML   1.1     # a comment \n
+//                ^
+func yaml_parser_scan_version_directive_number(parser *yaml_parser_t, start_mark yaml_mark_t, number *int8) bool {
+	// Repeat while the next character is digit.
+	if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+		return false
+	}
+	var value, length int8
+	for is_digit(parser.buffer, parser.buffer_pos) {
+		// Check if the number is too long.
+		length++
+		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 + int8(as_digit(parser.buffer, parser.buffer_pos))
+		skip(parser)
+		if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+			return false
+		}
+	}
+	// Check if the number was present.
+	if length == 0 {
+		return yaml_parser_set_scanner_error(parser, "while scanning a %YAML directive",
+			start_mark, "did not find expected version number")
+	}
+	*number = value
+	return true
+}
+// Scan the value of a TAG-DIRECTIVE token.
+//
+// Scope:
+//      %TAG    !yaml!  tag:yaml.org,2002:  \n
+//          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+func yaml_parser_scan_tag_directive_value(parser *yaml_parser_t, start_mark yaml_mark_t, handle, prefix *[]byte) bool {
+	var handle_value, prefix_value []byte
+	// Eat whitespaces.
+	if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+		return false
+	}
+	for is_blank(parser.buffer, parser.buffer_pos) {
+		skip(parser)
+		if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+			return false
+		}
+	}
+	// Scan a handle.
+	if !yaml_parser_scan_tag_handle(parser, true, start_mark, &handle_value) {
+		return false
+	}
+	// Expect a whitespace.
+	if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+		return false
+	}
+	if !is_blank(parser.buffer, parser.buffer_pos) {
+		yaml_parser_set_scanner_error(parser, "while scanning a %TAG directive",
+			start_mark, "did not find expected whitespace")
+		return false
+	}
+	// Eat whitespaces.
+	for is_blank(parser.buffer, parser.buffer_pos) {
+		skip(parser)
+		if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+			return false
+		}
+	}
+	// Scan a prefix.
+	if !yaml_parser_scan_tag_uri(parser, true, nil, start_mark, &prefix_value) {
+		return false
+	}
+	// Expect a whitespace or line break.
+	if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+		return false
+	}
+	if !is_blankz(parser.buffer, parser.buffer_pos) {
+		yaml_parser_set_scanner_error(parser, "while scanning a %TAG directive",
+			start_mark, "did not find expected whitespace or line break")
+		return false
+	}
+	*handle = handle_value
+	*prefix = prefix_value
+	return true
+}
+func yaml_parser_scan_anchor(parser *yaml_parser_t, token *yaml_token_t, typ yaml_token_type_t) bool {
+	var s []byte
+	// Eat the indicator character.
+	start_mark := parser.mark
+	skip(parser)
+	// Consume the value.
+	if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+		return false
+	}
+	for is_alpha(parser.buffer, parser.buffer_pos) {
+		s = read(parser, s)
+		if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+			return false
+		}
+	}
+	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 len(s) == 0 ||
+		!(is_blankz(parser.buffer, parser.buffer_pos) || parser.buffer[parser.buffer_pos] == '?' ||
+			parser.buffer[parser.buffer_pos] == ':' || parser.buffer[parser.buffer_pos] == ',' ||
+			parser.buffer[parser.buffer_pos] == ']' || parser.buffer[parser.buffer_pos] == '}' ||
+			parser.buffer[parser.buffer_pos] == '%' || parser.buffer[parser.buffer_pos] == '@' ||
+			parser.buffer[parser.buffer_pos] == '`') {
+		context := "while scanning an alias"
+		if typ == yaml_ANCHOR_TOKEN {
+			context = "while scanning an anchor"
+		}
+		yaml_parser_set_scanner_error(parser, context, start_mark,
+			"did not find expected alphabetic or numeric character")
+		return false
+	}
+	// Create a token.
+	*token = yaml_token_t{
+		typ:        typ,
+		start_mark: start_mark,
+		end_mark:   end_mark,
+		value:      s,
+	}
+	return true
+}
+/*
+* Scan a TAG token.
+*/
+func yaml_parser_scan_tag(parser *yaml_parser_t, token *yaml_token_t) bool {
+	var handle, suffix []byte
+	start_mark := parser.mark
+	// Check if the tag is in the canonical form.
+	if parser.unread < 2 && !yaml_parser_update_buffer(parser, 2) {
+		return false
+	}
+	if parser.buffer[parser.buffer_pos+1] == '<' {
+		// Keep the handle as ''
+		// Eat '!<'
+		skip(parser)
+		skip(parser)
+		// Consume the tag value.
+		if !yaml_parser_scan_tag_uri(parser, false, nil, start_mark, &suffix) {
+			return false
+		}
+		// Check for '>' and eat it.
+		if parser.buffer[parser.buffer_pos] != '>' {
+			yaml_parser_set_scanner_error(parser, "while scanning a tag",
+				start_mark, "did not find the expected '>'")
+			return false
+		}
+		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, false, start_mark, &handle) {
+			return false
+		}
+		// Check if it is, indeed, handle.
+		if handle[0] == '!' && len(handle) > 1 && handle[len(handle)-1] == '!' {
+			// Scan the suffix now.
+			if !yaml_parser_scan_tag_uri(parser, false, nil, start_mark, &suffix) {
+				return false
+			}
+		} else {
+			// It wasn't a handle after all.  Scan the rest of the tag.
+			if !yaml_parser_scan_tag_uri(parser, false, handle, start_mark, &suffix) {
+				return false
+			}
+			// Set the handle to '!'.
+			handle = []byte{'!'}
+			// A special case: the '!' tag.  Set the handle to '' and the
+			// suffix to '!'.
+			if len(suffix) == 0 {
+				handle, suffix = suffix, handle
+			}
+		}
+	}
+	// Check the character which ends the tag.
+	if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+		return false
+	}
+	if !is_blankz(parser.buffer, parser.buffer_pos) {
+		yaml_parser_set_scanner_error(parser, "while scanning a tag",
+			start_mark, "did not find expected whitespace or line break")
+		return false
+	}
+	end_mark := parser.mark
+	// Create a token.
+	*token = yaml_token_t{
+		typ:        yaml_TAG_TOKEN,
+		start_mark: start_mark,
+		end_mark:   end_mark,
+		value:      handle,
+		suffix:     suffix,
+	}
+	return true
+}
+// Scan a tag handle.
+func yaml_parser_scan_tag_handle(parser *yaml_parser_t, directive bool, start_mark yaml_mark_t, handle *[]byte) bool {
+	// Check the initial '!' character.
+	if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+		return false
+	}
+	if parser.buffer[parser.buffer_pos] != '!' {
+		yaml_parser_set_scanner_tag_error(parser, directive,
+			start_mark, "did not find expected '!'")
+		return false
+	}
+	var s []byte
+	// Copy the '!' character.
+	s = read(parser, s)
+	// Copy all subsequent alphabetical and numerical characters.
+	if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+		return false
+	}
+	for is_alpha(parser.buffer, parser.buffer_pos) {
+		s = read(parser, s)
+		if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+			return false
+		}
+	}
+	// Check if the trailing character is '!' and copy it.
+	if parser.buffer[parser.buffer_pos] == '!' {
+		s = read(parser, s)
+	} 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(s) != "!" {
+			yaml_parser_set_scanner_tag_error(parser, directive,
+				start_mark, "did not find expected '!'")
+			return false
+		}
+	}
+	*handle = s
+	return true
+}
+// Scan a tag.
+func yaml_parser_scan_tag_uri(parser *yaml_parser_t, directive bool, head []byte, start_mark yaml_mark_t, uri *[]byte) bool {
+	//size_t length = head ? strlen((char *)head) : 0
+	var s []byte
+	hasTag := len(head) > 0
+	// Copy the head if needed.
+	//
+	// Note that we don't copy the leading '!' character.
+	if len(head) > 1 {
+		s = append(s, head[1:]...)
+	}
+	// Scan the tag.
+	if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+		return false
+	}
+	// The set of characters that may appear in URI is as follows:
+	//
+	//      '0'-'9', 'A'-'Z', 'a'-'z', '_', '-', ';', '/', '?', ':', '@', '&',
+	//      '=', '+', '$', ',', '.', '!', '~', '*', '\'', '(', ')', '[', ']',
+	//      '%'.
+	// [Go] Convert this into more reasonable logic.
+	for is_alpha(parser.buffer, parser.buffer_pos) || parser.buffer[parser.buffer_pos] == ';' ||
+		parser.buffer[parser.buffer_pos] == '/' || parser.buffer[parser.buffer_pos] == '?' ||
+		parser.buffer[parser.buffer_pos] == ':' || parser.buffer[parser.buffer_pos] == '@' ||
+		parser.buffer[parser.buffer_pos] == '&' || parser.buffer[parser.buffer_pos] == '=' ||
+		parser.buffer[parser.buffer_pos] == '+' || parser.buffer[parser.buffer_pos] == '$' ||
+		parser.buffer[parser.buffer_pos] == ',' || parser.buffer[parser.buffer_pos] == '.' ||
+		parser.buffer[parser.buffer_pos] == '!' || parser.buffer[parser.buffer_pos] == '~' ||
+		parser.buffer[parser.buffer_pos] == '*' || parser.buffer[parser.buffer_pos] == '\'' ||
+		parser.buffer[parser.buffer_pos] == '(' || parser.buffer[parser.buffer_pos] == ')' ||
+		parser.buffer[parser.buffer_pos] == '[' || parser.buffer[parser.buffer_pos] == ']' ||
+		parser.buffer[parser.buffer_pos] == '%' {
+		// Check if it is a URI-escape sequence.
+		if parser.buffer[parser.buffer_pos] == '%' {
+			if !yaml_parser_scan_uri_escapes(parser, directive, start_mark, &s) {
+				return false
+			}
+		} else {
+			s = read(parser, s)
+		}
+		if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+			return false
+		}
+		hasTag = true
+	}
+	if !hasTag {
+		yaml_parser_set_scanner_tag_error(parser, directive,
+			start_mark, "did not find expected tag URI")
+		return false
+	}
+	*uri = s
+	return true
+}
+// Decode an URI-escape sequence corresponding to a single UTF-8 character.
+func yaml_parser_scan_uri_escapes(parser *yaml_parser_t, directive bool, start_mark yaml_mark_t, s *[]byte) bool {
+	// Decode the required number of characters.
+	w := 1024
+	for w > 0 {
+		// Check for a URI-escaped octet.
+		if parser.unread < 3 && !yaml_parser_update_buffer(parser, 3) {
+			return false
+		}
+		if !(parser.buffer[parser.buffer_pos] == '%' &&
+			is_hex(parser.buffer, parser.buffer_pos+1) &&
+			is_hex(parser.buffer, parser.buffer_pos+2)) {
+			return yaml_parser_set_scanner_tag_error(parser, directive,
+				start_mark, "did not find URI escaped octet")
+		}
+		// Get the octet.
+		octet := byte((as_hex(parser.buffer, parser.buffer_pos+1) << 4) + as_hex(parser.buffer, parser.buffer_pos+2))
+		// If it is the leading octet, determine the length of the UTF-8 sequence.
+		if w == 1024 {
+			w = width(octet)
+			if w == 0 {
+				return yaml_parser_set_scanner_tag_error(parser, directive,
+					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_tag_error(parser, directive,
+					start_mark, "found an incorrect trailing UTF-8 octet")
+			}
+		}
+		// Copy the octet and move the pointers.
+		*s = append(*s, octet)
+		skip(parser)
+		skip(parser)
+		skip(parser)
+		w--
+	}
+	return true
+}
+// Scan a block scalar.
+func yaml_parser_scan_block_scalar(parser *yaml_parser_t, token *yaml_token_t, literal bool) bool {
+	// Eat the indicator '|' or '>'.
+	start_mark := parser.mark
+	skip(parser)
+	// Scan the additional block scalar indicators.
+	if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+		return false
+	}
+	// Check for a chomping indicator.
+	var chomping, increment int
+	if parser.buffer[parser.buffer_pos] == '+' || parser.buffer[parser.buffer_pos] == '-' {
+		// Set the chomping method and eat the indicator.
+		if parser.buffer[parser.buffer_pos] == '+' {
+			chomping = +1
+		} else {
+			chomping = -1
+		}
+		skip(parser)
+		// Check for an indentation indicator.
+		if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+			return false
+		}
+		if is_digit(parser.buffer, parser.buffer_pos) {
+			// Check that the indentation is greater than 0.
+			if parser.buffer[parser.buffer_pos] == '0' {
+				yaml_parser_set_scanner_error(parser, "while scanning a block scalar",
+					start_mark, "found an indentation indicator equal to 0")
+				return false
+			}
+			// Get the indentation level and eat the indicator.
+			increment = as_digit(parser.buffer, parser.buffer_pos)
+			skip(parser)
+		}
+	} else if is_digit(parser.buffer, parser.buffer_pos) {
+		// Do the same as above, but in the opposite order.
+		if parser.buffer[parser.buffer_pos] == '0' {
+			yaml_parser_set_scanner_error(parser, "while scanning a block scalar",
+				start_mark, "found an indentation indicator equal to 0")
+			return false
+		}
+		increment = as_digit(parser.buffer, parser.buffer_pos)
+		skip(parser)
+		if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+			return false
+		}
+		if parser.buffer[parser.buffer_pos] == '+' || parser.buffer[parser.buffer_pos] == '-' {
+			if parser.buffer[parser.buffer_pos] == '+' {
+				chomping = +1
+			} else {
+				chomping = -1
+			}
+			skip(parser)
+		}
+	}
+	// Eat whitespaces and comments to the end of the line.
+	if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+		return false
+	}
+	for is_blank(parser.buffer, parser.buffer_pos) {
+		skip(parser)
+		if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+			return false
+		}
+	}
+	if parser.buffer[parser.buffer_pos] == '#' {
+		for !is_breakz(parser.buffer, parser.buffer_pos) {
+			skip(parser)
+			if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+				return false
+			}
+		}
+	}
+	// Check if we are at the end of the line.
+	if !is_breakz(parser.buffer, parser.buffer_pos) {
+		yaml_parser_set_scanner_error(parser, "while scanning a block scalar",
+			start_mark, "did not find expected comment or line break")
+		return false
+	}
+	// Eat a line break.
+	if is_break(parser.buffer, parser.buffer_pos) {
+		if parser.unread < 2 && !yaml_parser_update_buffer(parser, 2) {
+			return false
+		}
+		skip_line(parser)
+	}
+	end_mark := parser.mark
+	// Set the indentation level if it was specified.
+	var indent int
+	if increment > 0 {
+		if parser.indent >= 0 {
+			indent = parser.indent + increment
+		} else {
+			indent = increment
+		}
+	}
+	// Scan the leading line breaks and determine the indentation level if needed.
+	var s, leading_break, trailing_breaks []byte
+	if !yaml_parser_scan_block_scalar_breaks(parser, &indent, &trailing_breaks, start_mark, &end_mark) {
+		return false
+	}
+	// Scan the block scalar content.
+	if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+		return false
+	}
+	var leading_blank, trailing_blank bool
+	for parser.mark.column == indent && !is_z(parser.buffer, parser.buffer_pos) {
+		// We are at the beginning of a non-empty line.
+		// Is it a trailing whitespace?
+		trailing_blank = is_blank(parser.buffer, parser.buffer_pos)
+		// Check if we need to fold the leading line break.
+		if !literal && !leading_blank && !trailing_blank && len(leading_break) > 0 && leading_break[0] == '\n' {
+			// Do we need to join the lines by space?
+			if len(trailing_breaks) == 0 {
+				s = append(s, ' ')
+			}
+		} else {
+			s = append(s, leading_break...)
+		}
+		leading_break = leading_break[:0]
+		// Append the remaining line breaks.
+		s = append(s, trailing_breaks...)
+		trailing_breaks = trailing_breaks[:0]
+		// Is it a leading whitespace?
+		leading_blank = is_blank(parser.buffer, parser.buffer_pos)
+		// Consume the current line.
+		for !is_breakz(parser.buffer, parser.buffer_pos) {
+			s = read(parser, s)
+			if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+				return false
+			}
+		}
+		// Consume the line break.
+		if parser.unread < 2 && !yaml_parser_update_buffer(parser, 2) {
+			return false
+		}
+		leading_break = read_line(parser, leading_break)
+		// Eat the following indentation spaces and line breaks.
+		if !yaml_parser_scan_block_scalar_breaks(parser, &indent, &trailing_breaks, start_mark, &end_mark) {
+			return false
+		}
+	}
+	// Chomp the tail.
+	if chomping != -1 {
+		s = append(s, leading_break...)
+	}
+	if chomping == 1 {
+		s = append(s, trailing_breaks...)
+	}
+	// Create a token.
+	*token = yaml_token_t{
+		typ:        yaml_SCALAR_TOKEN,
+		start_mark: start_mark,
+		end_mark:   end_mark,
+		value:      s,
+		style:      yaml_LITERAL_SCALAR_STYLE,
+	}
+	if !literal {
+		token.style = yaml_FOLDED_SCALAR_STYLE
+	}
+	return true
+}
+// Scan indentation spaces and line breaks for a block scalar.  Determine the
+// indentation level if needed.
+func yaml_parser_scan_block_scalar_breaks(parser *yaml_parser_t, indent *int, breaks *[]byte, start_mark yaml_mark_t, end_mark *yaml_mark_t) bool {
+	*end_mark = parser.mark
+	// Eat the indentation spaces and line breaks.
+	max_indent := 0
+	for {
+		// Eat the indentation spaces.
+		if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+			return false
+		}
+		for (*indent == 0 || parser.mark.column < *indent) && is_space(parser.buffer, parser.buffer_pos) {
+			skip(parser)
+			if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+				return false
+			}
+		}
+		if parser.mark.column > max_indent {
+			max_indent = parser.mark.column
+		}
+		// Check for a tab character messing the indentation.
+		if (*indent == 0 || parser.mark.column < *indent) && is_tab(parser.buffer, parser.buffer_pos) {
+			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, parser.buffer_pos) {
+			break
+		}
+		// Consume the line break.
+		if parser.unread < 2 && !yaml_parser_update_buffer(parser, 2) {
+			return false
+		}
+		// [Go] Should really be returning breaks instead.
+		*breaks = read_line(parser, *breaks)
+		*end_mark = parser.mark
+	}
+	// Determine the indentation level if needed.
+	if *indent == 0 {
+		*indent = max_indent
+		if *indent < parser.indent+1 {
+			*indent = parser.indent + 1
+		}
+		if *indent < 1 {
+			*indent = 1
+		}
+	}
+	return true
+}
+// Scan a quoted scalar.
+func yaml_parser_scan_flow_scalar(parser *yaml_parser_t, token *yaml_token_t, single bool) bool {
+	// Eat the left quote.
+	start_mark := parser.mark
+	skip(parser)
+	// Consume the content of the quoted scalar.
+	var s, leading_break, trailing_breaks, whitespaces []byte
+	for {
+		// Check that there are no document indicators at the beginning of the line.
+		if parser.unread < 4 && !yaml_parser_update_buffer(parser, 4) {
+			return false
+		}
+		if parser.mark.column == 0 &&
+			((parser.buffer[parser.buffer_pos+0] == '-' &&
+				parser.buffer[parser.buffer_pos+1] == '-' &&
+				parser.buffer[parser.buffer_pos+2] == '-') ||
+				(parser.buffer[parser.buffer_pos+0] == '.' &&
+					parser.buffer[parser.buffer_pos+1] == '.' &&
+					parser.buffer[parser.buffer_pos+2] == '.')) &&
+			is_blankz(parser.buffer, parser.buffer_pos+3) {
+			yaml_parser_set_scanner_error(parser, "while scanning a quoted scalar",
+				start_mark, "found unexpected document indicator")
+			return false
+		}
+		// Check for EOF.
+		if is_z(parser.buffer, parser.buffer_pos) {
+			yaml_parser_set_scanner_error(parser, "while scanning a quoted scalar",
+				start_mark, "found unexpected end of stream")
+			return false
+		}
+		// Consume non-blank characters.
+		leading_blanks := false
+		for !is_blankz(parser.buffer, parser.buffer_pos) {
+			if single && parser.buffer[parser.buffer_pos] == '\'' && parser.buffer[parser.buffer_pos+1] == '\'' {
+				// Is is an escaped single quote.
+				s = append(s, '\'')
+				skip(parser)
+				skip(parser)
+			} else if single && parser.buffer[parser.buffer_pos] == '\'' {
+				// It is a right single quote.
+				break
+			} else if !single && parser.buffer[parser.buffer_pos] == '"' {
+				// It is a right double quote.
+				break
+			} else if !single && parser.buffer[parser.buffer_pos] == '\\' && is_break(parser.buffer, parser.buffer_pos+1) {
+				// It is an escaped line break.
+				if parser.unread < 3 && !yaml_parser_update_buffer(parser, 3) {
+					return false
+				}
+				skip(parser)
+				skip_line(parser)
+				leading_blanks = true
+				break
+			} else if !single && parser.buffer[parser.buffer_pos] == '\\' {
+				// It is an escape sequence.
+				code_length := 0
+				// Check the escape character.
+				switch parser.buffer[parser.buffer_pos+1] {
+				case '0':
+					s = append(s, 0)
+				case 'a':
+					s = append(s, '\x07')
+				case 'b':
+					s = append(s, '\x08')
+				case 't', '\t':
+					s = append(s, '\x09')
+				case 'n':
+					s = append(s, '\x0A')
+				case 'v':
+					s = append(s, '\x0B')
+				case 'f':
+					s = append(s, '\x0C')
+				case 'r':
+					s = append(s, '\x0D')
+				case 'e':
+					s = append(s, '\x1B')
+				case ' ':
+					s = append(s, '\x20')
+				case '"':
+					s = append(s, '"')
+				case '\'':
+					s = append(s, '\'')
+				case '\\':
+					s = append(s, '\\')
+				case 'N': // NEL (#x85)
+					s = append(s, '\xC2')
+					s = append(s, '\x85')
+				case '_': // #xA0
+					s = append(s, '\xC2')
+					s = append(s, '\xA0')
+				case 'L': // LS (#x2028)
+					s = append(s, '\xE2')
+					s = append(s, '\x80')
+					s = append(s, '\xA8')
+				case 'P': // PS (#x2029)
+					s = append(s, '\xE2')
+					s = append(s, '\x80')
+					s = append(s, '\xA9')
+				case 'x':
+					code_length = 2
+				case 'u':
+					code_length = 4
+				case 'U':
+					code_length = 8
+				default:
+					yaml_parser_set_scanner_error(parser, "while parsing a quoted scalar",
+						start_mark, "found unknown escape character")
+					return false
+				}
+				skip(parser)
+				skip(parser)
+				// Consume an arbitrary escape code.
+				if code_length > 0 {
+					var value int
+					// Scan the character value.
+					if parser.unread < code_length && !yaml_parser_update_buffer(parser, code_length) {
+						return false
+					}
+					for k := 0; k < code_length; k++ {
+						if !is_hex(parser.buffer, parser.buffer_pos+k) {
+							yaml_parser_set_scanner_error(parser, "while parsing a quoted scalar",
+								start_mark, "did not find expected hexdecimal number")
+							return false
+						}
+						value = (value << 4) + as_hex(parser.buffer, parser.buffer_pos+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")
+						return false
+					}
+					if value <= 0x7F {
+						s = append(s, byte(value))
+					} else if value <= 0x7FF {
+						s = append(s, byte(0xC0+(value>>6)))
+						s = append(s, byte(0x80+(value&0x3F)))
+					} else if value <= 0xFFFF {
+						s = append(s, byte(0xE0+(value>>12)))
+						s = append(s, byte(0x80+((value>>6)&0x3F)))
+						s = append(s, byte(0x80+(value&0x3F)))
+					} else {
+						s = append(s, byte(0xF0+(value>>18)))
+						s = append(s, byte(0x80+((value>>12)&0x3F)))
+						s = append(s, byte(0x80+((value>>6)&0x3F)))
+						s = append(s, byte(0x80+(value&0x3F)))
+					}
+					// Advance the pointer.
+					for k := 0; k < code_length; k++ {
+						skip(parser)
+					}
+				}
+			} else {
+				// It is a non-escaped non-blank character.
+				s = read(parser, s)
+			}
+			if parser.unread < 2 && !yaml_parser_update_buffer(parser, 2) {
+				return false
+			}
+		}
+		if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+			return false
+		}
+		// Check if we are at the end of the scalar.
+		if single {
+			if parser.buffer[parser.buffer_pos] == '\'' {
+				break
+			}
+		} else {
+			if parser.buffer[parser.buffer_pos] == '"' {
+				break
+			}
+		}
+		// Consume blank characters.
+		for is_blank(parser.buffer, parser.buffer_pos) || is_break(parser.buffer, parser.buffer_pos) {
+			if is_blank(parser.buffer, parser.buffer_pos) {
+				// Consume a space or a tab character.
+				if !leading_blanks {
+					whitespaces = read(parser, whitespaces)
+				} else {
+					skip(parser)
+				}
+			} else {
+				if parser.unread < 2 && !yaml_parser_update_buffer(parser, 2) {
+					return false
+				}
+				// Check if it is a first line break.
+				if !leading_blanks {
+					whitespaces = whitespaces[:0]
+					leading_break = read_line(parser, leading_break)
+					leading_blanks = true
+				} else {
+					trailing_breaks = read_line(parser, trailing_breaks)
+				}
+			}
+			if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+				return false
+			}
+		}
+		// Join the whitespaces or fold line breaks.
+		if leading_blanks {
+			// Do we need to fold line breaks?
+			if len(leading_break) > 0 && leading_break[0] == '\n' {
+				if len(trailing_breaks) == 0 {
+					s = append(s, ' ')
+				} else {
+					s = append(s, trailing_breaks...)
+				}
+			} else {
+				s = append(s, leading_break...)
+				s = append(s, trailing_breaks...)
+			}
+			trailing_breaks = trailing_breaks[:0]
+			leading_break = leading_break[:0]
+		} else {
+			s = append(s, whitespaces...)
+			whitespaces = whitespaces[:0]
+		}
+	}
+	// Eat the right quote.
+	skip(parser)
+	end_mark := parser.mark
+	// Create a token.
+	*token = yaml_token_t{
+		typ:        yaml_SCALAR_TOKEN,
+		start_mark: start_mark,
+		end_mark:   end_mark,
+		value:      s,
+		style:      yaml_SINGLE_QUOTED_SCALAR_STYLE,
+	}
+	if !single {
+		token.style = yaml_DOUBLE_QUOTED_SCALAR_STYLE
+	}
+	return true
+}
+// Scan a plain scalar.
+func yaml_parser_scan_plain_scalar(parser *yaml_parser_t, token *yaml_token_t) bool {
+	var s, leading_break, trailing_breaks, whitespaces []byte
+	var leading_blanks bool
+	var indent = parser.indent + 1
+	start_mark := parser.mark
+	end_mark := parser.mark
+	// Consume the content of the plain scalar.
+	for {
+		// Check for a document indicator.
+		if parser.unread < 4 && !yaml_parser_update_buffer(parser, 4) {
+			return false
+		}
+		if parser.mark.column == 0 &&
+			((parser.buffer[parser.buffer_pos+0] == '-' &&
+				parser.buffer[parser.buffer_pos+1] == '-' &&
+				parser.buffer[parser.buffer_pos+2] == '-') ||
+				(parser.buffer[parser.buffer_pos+0] == '.' &&
+					parser.buffer[parser.buffer_pos+1] == '.' &&
+					parser.buffer[parser.buffer_pos+2] == '.')) &&
+			is_blankz(parser.buffer, parser.buffer_pos+3) {
+			break
+		}
+		// Check for a comment.
+		if parser.buffer[parser.buffer_pos] == '#' {
+			break
+		}
+		// Consume non-blank characters.
+		for !is_blankz(parser.buffer, parser.buffer_pos) {
+			// Check for indicators that may end a plain scalar.
+			if (parser.buffer[parser.buffer_pos] == ':' && is_blankz(parser.buffer, parser.buffer_pos+1)) ||
+				(parser.flow_level > 0 &&
+					(parser.buffer[parser.buffer_pos] == ',' ||
+						parser.buffer[parser.buffer_pos] == '?' || parser.buffer[parser.buffer_pos] == '[' ||
+						parser.buffer[parser.buffer_pos] == ']' || parser.buffer[parser.buffer_pos] == '{' ||
+						parser.buffer[parser.buffer_pos] == '}')) {
+				break
+			}
+			// Check if we need to join whitespaces and breaks.
+			if leading_blanks || len(whitespaces) > 0 {
+				if leading_blanks {
+					// Do we need to fold line breaks?
+					if leading_break[0] == '\n' {
+						if len(trailing_breaks) == 0 {
+							s = append(s, ' ')
+						} else {
+							s = append(s, trailing_breaks...)
+						}
+					} else {
+						s = append(s, leading_break...)
+						s = append(s, trailing_breaks...)
+					}
+					trailing_breaks = trailing_breaks[:0]
+					leading_break = leading_break[:0]
+					leading_blanks = false
+				} else {
+					s = append(s, whitespaces...)
+					whitespaces = whitespaces[:0]
+				}
+			}
+			// Copy the character.
+			s = read(parser, s)
+			end_mark = parser.mark
+			if parser.unread < 2 && !yaml_parser_update_buffer(parser, 2) {
+				return false
+			}
+		}
+		// Is it the end?
+		if !(is_blank(parser.buffer, parser.buffer_pos) || is_break(parser.buffer, parser.buffer_pos)) {
+			break
+		}
+		// Consume blank characters.
+		if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+			return false
+		}
+		for is_blank(parser.buffer, parser.buffer_pos) || is_break(parser.buffer, parser.buffer_pos) {
+			if is_blank(parser.buffer, parser.buffer_pos) {
+				// Check for tab characters that abuse indentation.
+				if leading_blanks && parser.mark.column < indent && is_tab(parser.buffer, parser.buffer_pos) {
+					yaml_parser_set_scanner_error(parser, "while scanning a plain scalar",
+						start_mark, "found a tab character that violates indentation")
+					return false
+				}
+				// Consume a space or a tab character.
+				if !leading_blanks {
+					whitespaces = read(parser, whitespaces)
+				} else {
+					skip(parser)
+				}
+			} else {
+				if parser.unread < 2 && !yaml_parser_update_buffer(parser, 2) {
+					return false
+				}
+				// Check if it is a first line break.
+				if !leading_blanks {
+					whitespaces = whitespaces[:0]
+					leading_break = read_line(parser, leading_break)
+					leading_blanks = true
+				} else {
+					trailing_breaks = read_line(parser, trailing_breaks)
+				}
+			}
+			if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+				return false
+			}
+		}
+		// Check indentation level.
+		if parser.flow_level == 0 && parser.mark.column < indent {
+			break
+		}
+	}
+	// Create a token.
+	*token = yaml_token_t{
+		typ:        yaml_SCALAR_TOKEN,
+		start_mark: start_mark,
+		end_mark:   end_mark,
+		value:      s,
+		style:      yaml_PLAIN_SCALAR_STYLE,
+	}
+	// Note that we change the 'simple_key_allowed' flag.
+	if leading_blanks {
+		parser.simple_key_allowed = true
+	}
+	return true
+}

Mercurial > yakumo_izuru > aya

comparison vendor/gopkg.in/yaml.v2/scannerc.go @ 66:787b5ee0289d draft