scannerc.go

		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 simple_key.possible {
		// 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

		// 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
	}