Adding upstream version 0.91.0.upstream/0.91.0upstream

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

1 files changed, 1797 insertions, 0 deletions

diff --git a/lib/ruyaml/emitter.py b/lib/ruyaml/emitter.py
new file mode 100644
index 0000000..d5fe1a1
--- /dev/null
+++ b/lib/ruyaml/emitter.py
@@ -0,0 +1,1797 @@
+# coding: utf-8
+
+# Emitter expects events obeying the following grammar:
+# stream ::= STREAM-START document* STREAM-END
+# document ::= DOCUMENT-START node DOCUMENT-END
+# node ::= SCALAR | sequence | mapping
+# sequence ::= SEQUENCE-START node* SEQUENCE-END
+# mapping ::= MAPPING-START (node node)* MAPPING-END
+
+import sys
+
+# fmt: off
+from ruyaml.compat import (  # NOQA
+    _F,
+    DBG_EVENT,
+    check_anchorname_char,
+    dbg,
+    nprint,
+    nprintf,
+)
+from ruyaml.error import YAMLError, YAMLStreamError
+from ruyaml.events import *  # NOQA
+
+# fmt: on
+
+if False:  # MYPY
+    from typing import Any, Dict, List, Optional, Text, Tuple, Union  # NOQA
+
+    from ruyaml.compat import StreamType  # NOQA
+
+__all__ = ['Emitter', 'EmitterError']
+
+
+class EmitterError(YAMLError):
+    pass
+
+
+class ScalarAnalysis:
+    def __init__(
+        self,
+        scalar,
+        empty,
+        multiline,
+        allow_flow_plain,
+        allow_block_plain,
+        allow_single_quoted,
+        allow_double_quoted,
+        allow_block,
+    ):
+        # type: (Any, Any, Any, bool, bool, bool, bool, bool) -> None
+        self.scalar = scalar
+        self.empty = empty
+        self.multiline = multiline
+        self.allow_flow_plain = allow_flow_plain
+        self.allow_block_plain = allow_block_plain
+        self.allow_single_quoted = allow_single_quoted
+        self.allow_double_quoted = allow_double_quoted
+        self.allow_block = allow_block
+
+
+class Indents:
+    # replacement for the list based stack of None/int
+    def __init__(self):
+        # type: () -> None
+        self.values = []  # type: List[Tuple[int, bool]]
+
+    def append(self, val, seq):
+        # type: (Any, Any) -> None
+        self.values.append((val, seq))
+
+    def pop(self):
+        # type: () -> Any
+        return self.values.pop()[0]
+
+    def last_seq(self):
+        # type: () -> bool
+        # return the seq(uence) value for the element added before the last one
+        # in increase_indent()
+        try:
+            return self.values[-2][1]
+        except IndexError:
+            return False
+
+    def seq_flow_align(self, seq_indent, column):
+        # type: (int, int) -> int
+        # extra spaces because of dash
+        if len(self.values) < 2 or not self.values[-1][1]:
+            return 0
+        # -1 for the dash
+        base = self.values[-1][0] if self.values[-1][0] is not None else 0
+        return base + seq_indent - column - 1
+
+    def __len__(self):
+        # type: () -> int
+        return len(self.values)
+
+
+class Emitter:
+    # fmt: off
+    DEFAULT_TAG_PREFIXES = {
+        '!': '!',
+        'tag:yaml.org,2002:': '!!',
+    }
+    # fmt: on
+
+    MAX_SIMPLE_KEY_LENGTH = 128
+
+    def __init__(
+        self,
+        stream,
+        canonical=None,
+        indent=None,
+        width=None,
+        allow_unicode=None,
+        line_break=None,
+        block_seq_indent=None,
+        top_level_colon_align=None,
+        prefix_colon=None,
+        brace_single_entry_mapping_in_flow_sequence=None,
+        dumper=None,
+    ):
+        # type: (StreamType, Any, Optional[int], Optional[int], Optional[bool], Any, Optional[int], Optional[bool], Any, Optional[bool], Any) -> None  # NOQA
+        self.dumper = dumper
+        if self.dumper is not None and getattr(self.dumper, '_emitter', None) is None:
+            self.dumper._emitter = self
+        self.stream = stream
+
+        # Encoding can be overriden by STREAM-START.
+        self.encoding = None  # type: Optional[Text]
+        self.allow_space_break = None
+
+        # Emitter is a state machine with a stack of states to handle nested
+        # structures.
+        self.states = []  # type: List[Any]
+        self.state = self.expect_stream_start  # type: Any
+
+        # Current event and the event queue.
+        self.events = []  # type: List[Any]
+        self.event = None  # type: Any
+
+        # The current indentation level and the stack of previous indents.
+        self.indents = Indents()
+        self.indent = None  # type: Optional[int]
+
+        # flow_context is an expanding/shrinking list consisting of '{' and '['
+        # for each unclosed flow context. If empty list that means block context
+        self.flow_context = []  # type: List[Text]
+
+        # Contexts.
+        self.root_context = False
+        self.sequence_context = False
+        self.mapping_context = False
+        self.simple_key_context = False
+
+        # Characteristics of the last emitted character:
+        #  - current position.
+        #  - is it a whitespace?
+        #  - is it an indention character
+        #    (indentation space, '-', '?', or ':')?
+        self.line = 0
+        self.column = 0
+        self.whitespace = True
+        self.indention = True
+        self.compact_seq_seq = True  # dash after dash
+        self.compact_seq_map = True  # key after dash
+        # self.compact_ms = False   # dash after key, only when excplicit key with ?
+        self.no_newline = None  # type: Optional[bool]  # set if directly after `- `
+
+        # Whether the document requires an explicit document end indicator
+        self.open_ended = False
+
+        # colon handling
+        self.colon = ':'
+        self.prefixed_colon = (
+            self.colon if prefix_colon is None else prefix_colon + self.colon
+        )
+        # single entry mappings in flow sequence
+        self.brace_single_entry_mapping_in_flow_sequence = (
+            brace_single_entry_mapping_in_flow_sequence  # NOQA
+        )
+
+        # Formatting details.
+        self.canonical = canonical
+        self.allow_unicode = allow_unicode
+        # set to False to get "\Uxxxxxxxx" for non-basic unicode like emojis
+        self.unicode_supplementary = sys.maxunicode > 0xFFFF
+        self.sequence_dash_offset = block_seq_indent if block_seq_indent else 0
+        self.top_level_colon_align = top_level_colon_align
+        self.best_sequence_indent = 2
+        self.requested_indent = indent  # specific for literal zero indent
+        if indent and 1 < indent < 10:
+            self.best_sequence_indent = indent
+        self.best_map_indent = self.best_sequence_indent
+        # if self.best_sequence_indent < self.sequence_dash_offset + 1:
+        #     self.best_sequence_indent = self.sequence_dash_offset + 1
+        self.best_width = 80
+        if width and width > self.best_sequence_indent * 2:
+            self.best_width = width
+        self.best_line_break = '\n'  # type: Any
+        if line_break in ['\r', '\n', '\r\n']:
+            self.best_line_break = line_break
+
+        # Tag prefixes.
+        self.tag_prefixes = None  # type: Any
+
+        # Prepared anchor and tag.
+        self.prepared_anchor = None  # type: Any
+        self.prepared_tag = None  # type: Any
+
+        # Scalar analysis and style.
+        self.analysis = None  # type: Any
+        self.style = None  # type: Any
+
+        self.scalar_after_indicator = True  # write a scalar on the same line as `---`
+
+        self.alt_null = 'null'
+
+    @property
+    def stream(self):
+        # type: () -> Any
+        try:
+            return self._stream
+        except AttributeError:
+            raise YAMLStreamError('output stream needs to specified')
+
+    @stream.setter
+    def stream(self, val):
+        # type: (Any) -> None
+        if val is None:
+            return
+        if not hasattr(val, 'write'):
+            raise YAMLStreamError('stream argument needs to have a write() method')
+        self._stream = val
+
+    @property
+    def serializer(self):
+        # type: () -> Any
+        try:
+            if hasattr(self.dumper, 'typ'):
+                return self.dumper.serializer  # type: ignore
+            return self.dumper._serializer  # type: ignore
+        except AttributeError:
+            return self  # cyaml
+
+    @property
+    def flow_level(self):
+        # type: () -> int
+        return len(self.flow_context)
+
+    def dispose(self):
+        # type: () -> None
+        # Reset the state attributes (to clear self-references)
+        self.states = []
+        self.state = None
+
+    def emit(self, event):
+        # type: (Any) -> None
+        if dbg(DBG_EVENT):
+            nprint(event)
+        self.events.append(event)
+        while not self.need_more_events():
+            self.event = self.events.pop(0)
+            self.state()
+            self.event = None
+
+    # In some cases, we wait for a few next events before emitting.
+
+    def need_more_events(self):
+        # type: () -> bool
+        if not self.events:
+            return True
+        event = self.events[0]
+        if isinstance(event, DocumentStartEvent):
+            return self.need_events(1)
+        elif isinstance(event, SequenceStartEvent):
+            return self.need_events(2)
+        elif isinstance(event, MappingStartEvent):
+            return self.need_events(3)
+        else:
+            return False
+
+    def need_events(self, count):
+        # type: (int) -> bool
+        level = 0
+        for event in self.events[1:]:
+            if isinstance(event, (DocumentStartEvent, CollectionStartEvent)):
+                level += 1
+            elif isinstance(event, (DocumentEndEvent, CollectionEndEvent)):
+                level -= 1
+            elif isinstance(event, StreamEndEvent):
+                level = -1
+            if level < 0:
+                return False
+        return len(self.events) < count + 1
+
+    def increase_indent(self, flow=False, sequence=None, indentless=False):
+        # type: (bool, Optional[bool], bool) -> None
+        self.indents.append(self.indent, sequence)
+        if self.indent is None:  # top level
+            if flow:
+                # self.indent = self.best_sequence_indent if self.indents.last_seq() else \
+                #              self.best_map_indent
+                # self.indent = self.best_sequence_indent
+                self.indent = self.requested_indent
+            else:
+                self.indent = 0
+        elif not indentless:
+            self.indent += (
+                self.best_sequence_indent
+                if self.indents.last_seq()
+                else self.best_map_indent
+            )
+            # if self.indents.last_seq():
+            #     if self.indent == 0: # top level block sequence
+            #         self.indent = self.best_sequence_indent - self.sequence_dash_offset
+            #     else:
+            #         self.indent += self.best_sequence_indent
+            # else:
+            #     self.indent += self.best_map_indent
+
+    # States.
+
+    # Stream handlers.
+
+    def expect_stream_start(self):
+        # type: () -> None
+        if isinstance(self.event, StreamStartEvent):
+            if self.event.encoding and not hasattr(self.stream, 'encoding'):
+                self.encoding = self.event.encoding
+            self.write_stream_start()
+            self.state = self.expect_first_document_start
+        else:
+            raise EmitterError(
+                _F(
+                    'expected StreamStartEvent, but got {self_event!s}',
+                    self_event=self.event,
+                )
+            )
+
+    def expect_nothing(self):
+        # type: () -> None
+        raise EmitterError(
+            _F('expected nothing, but got {self_event!s}', self_event=self.event)
+        )
+
+    # Document handlers.
+
+    def expect_first_document_start(self):
+        # type: () -> Any
+        return self.expect_document_start(first=True)
+
+    def expect_document_start(self, first=False):
+        # type: (bool) -> None
+        if isinstance(self.event, DocumentStartEvent):
+            if (self.event.version or self.event.tags) and self.open_ended:
+                self.write_indicator('...', True)
+                self.write_indent()
+            if self.event.version:
+                version_text = self.prepare_version(self.event.version)
+                self.write_version_directive(version_text)
+            self.tag_prefixes = self.DEFAULT_TAG_PREFIXES.copy()
+            if self.event.tags:
+                handles = sorted(self.event.tags.keys())
+                for handle in handles:
+                    prefix = self.event.tags[handle]
+                    self.tag_prefixes[prefix] = handle
+                    handle_text = self.prepare_tag_handle(handle)
+                    prefix_text = self.prepare_tag_prefix(prefix)
+                    self.write_tag_directive(handle_text, prefix_text)
+            implicit = (
+                first
+                and not self.event.explicit
+                and not self.canonical
+                and not self.event.version
+                and not self.event.tags
+                and not self.check_empty_document()
+            )
+            if not implicit:
+                self.write_indent()
+                self.write_indicator('---', True)
+                if self.canonical:
+                    self.write_indent()
+            self.state = self.expect_document_root
+        elif isinstance(self.event, StreamEndEvent):
+            if self.open_ended:
+                self.write_indicator('...', True)
+                self.write_indent()
+            self.write_stream_end()
+            self.state = self.expect_nothing
+        else:
+            raise EmitterError(
+                _F(
+                    'expected DocumentStartEvent, but got {self_event!s}',
+                    self_event=self.event,
+                )
+            )
+
+    def expect_document_end(self):
+        # type: () -> None
+        if isinstance(self.event, DocumentEndEvent):
+            self.write_indent()
+            if self.event.explicit:
+                self.write_indicator('...', True)
+                self.write_indent()
+            self.flush_stream()
+            self.state = self.expect_document_start
+        else:
+            raise EmitterError(
+                _F(
+                    'expected DocumentEndEvent, but got {self_event!s}',
+                    self_event=self.event,
+                )
+            )
+
+    def expect_document_root(self):
+        # type: () -> None
+        self.states.append(self.expect_document_end)
+        self.expect_node(root=True)
+
+    # Node handlers.
+
+    def expect_node(self, root=False, sequence=False, mapping=False, simple_key=False):
+        # type: (bool, bool, bool, bool) -> None
+        self.root_context = root
+        self.sequence_context = sequence  # not used in PyYAML
+        self.mapping_context = mapping
+        self.simple_key_context = simple_key
+        if isinstance(self.event, AliasEvent):
+            self.expect_alias()
+        elif isinstance(self.event, (ScalarEvent, CollectionStartEvent)):
+            if (
+                self.process_anchor('&')
+                and isinstance(self.event, ScalarEvent)
+                and self.sequence_context
+            ):
+                self.sequence_context = False
+            if (
+                root
+                and isinstance(self.event, ScalarEvent)
+                and not self.scalar_after_indicator
+            ):
+                self.write_indent()
+            self.process_tag()
+            if isinstance(self.event, ScalarEvent):
+                # nprint('@', self.indention, self.no_newline, self.column)
+                self.expect_scalar()
+            elif isinstance(self.event, SequenceStartEvent):
+                # nprint('@', self.indention, self.no_newline, self.column)
+                i2, n2 = self.indention, self.no_newline  # NOQA
+                if self.event.comment:
+                    if self.event.flow_style is False and self.event.comment:
+                        if self.write_post_comment(self.event):
+                            self.indention = False
+                            self.no_newline = True
+                    if self.write_pre_comment(self.event):
+                        self.indention = i2
+                        self.no_newline = not self.indention
+                if (
+                    self.flow_level
+                    or self.canonical
+                    or self.event.flow_style
+                    or self.check_empty_sequence()
+                ):
+                    self.expect_flow_sequence()
+                else:
+                    self.expect_block_sequence()
+            elif isinstance(self.event, MappingStartEvent):
+                if self.event.flow_style is False and self.event.comment:
+                    self.write_post_comment(self.event)
+                if self.event.comment and self.event.comment[1]:
+                    self.write_pre_comment(self.event)
+                if (
+                    self.flow_level
+                    or self.canonical
+                    or self.event.flow_style
+                    or self.check_empty_mapping()
+                ):
+                    self.expect_flow_mapping(single=self.event.nr_items == 1)
+                else:
+                    self.expect_block_mapping()
+        else:
+            raise EmitterError(
+                _F('expected NodeEvent, but got {self_event!s}', self_event=self.event)
+            )
+
+    def expect_alias(self):
+        # type: () -> None
+        if self.event.anchor is None:
+            raise EmitterError('anchor is not specified for alias')
+        self.process_anchor('*')
+        self.state = self.states.pop()
+
+    def expect_scalar(self):
+        # type: () -> None
+        self.increase_indent(flow=True)
+        self.process_scalar()
+        self.indent = self.indents.pop()
+        self.state = self.states.pop()
+
+    # Flow sequence handlers.
+
+    def expect_flow_sequence(self):
+        # type: () -> None
+        ind = self.indents.seq_flow_align(self.best_sequence_indent, self.column)
+        self.write_indicator(' ' * ind + '[', True, whitespace=True)
+        self.increase_indent(flow=True, sequence=True)
+        self.flow_context.append('[')
+        self.state = self.expect_first_flow_sequence_item
+
+    def expect_first_flow_sequence_item(self):
+        # type: () -> None
+        if isinstance(self.event, SequenceEndEvent):
+            self.indent = self.indents.pop()
+            popped = self.flow_context.pop()
+            assert popped == '['
+            self.write_indicator(']', False)
+            if self.event.comment and self.event.comment[0]:
+                # eol comment on empty flow sequence
+                self.write_post_comment(self.event)
+            elif self.flow_level == 0:
+                self.write_line_break()
+            self.state = self.states.pop()
+        else:
+            if self.canonical or self.column > self.best_width:
+                self.write_indent()
+            self.states.append(self.expect_flow_sequence_item)
+            self.expect_node(sequence=True)
+
+    def expect_flow_sequence_item(self):
+        # type: () -> None
+        if isinstance(self.event, SequenceEndEvent):
+            self.indent = self.indents.pop()
+            popped = self.flow_context.pop()
+            assert popped == '['
+            if self.canonical:
+                self.write_indicator(',', False)
+                self.write_indent()
+            self.write_indicator(']', False)
+            if self.event.comment and self.event.comment[0]:
+                # eol comment on flow sequence
+                self.write_post_comment(self.event)
+            else:
+                self.no_newline = False
+            self.state = self.states.pop()
+        else:
+            self.write_indicator(',', False)
+            if self.canonical or self.column > self.best_width:
+                self.write_indent()
+            self.states.append(self.expect_flow_sequence_item)
+            self.expect_node(sequence=True)
+
+    # Flow mapping handlers.
+
+    def expect_flow_mapping(self, single=False):
+        # type: (Optional[bool]) -> None
+        ind = self.indents.seq_flow_align(self.best_sequence_indent, self.column)
+        map_init = '{'
+        if (
+            single
+            and self.flow_level
+            and self.flow_context[-1] == '['
+            and not self.canonical
+            and not self.brace_single_entry_mapping_in_flow_sequence
+        ):
+            # single map item with flow context, no curly braces necessary
+            map_init = ''
+        self.write_indicator(' ' * ind + map_init, True, whitespace=True)
+        self.flow_context.append(map_init)
+        self.increase_indent(flow=True, sequence=False)
+        self.state = self.expect_first_flow_mapping_key
+
+    def expect_first_flow_mapping_key(self):
+        # type: () -> None
+        if isinstance(self.event, MappingEndEvent):
+            self.indent = self.indents.pop()
+            popped = self.flow_context.pop()
+            assert popped == '{'  # empty flow mapping
+            self.write_indicator('}', False)
+            if self.event.comment and self.event.comment[0]:
+                # eol comment on empty mapping
+                self.write_post_comment(self.event)
+            elif self.flow_level == 0:
+                self.write_line_break()
+            self.state = self.states.pop()
+        else:
+            if self.canonical or self.column > self.best_width:
+                self.write_indent()
+            if not self.canonical and self.check_simple_key():
+                self.states.append(self.expect_flow_mapping_simple_value)
+                self.expect_node(mapping=True, simple_key=True)
+            else:
+                self.write_indicator('?', True)
+                self.states.append(self.expect_flow_mapping_value)
+                self.expect_node(mapping=True)
+
+    def expect_flow_mapping_key(self):
+        # type: () -> None
+        if isinstance(self.event, MappingEndEvent):
+            # if self.event.comment and self.event.comment[1]:
+            #     self.write_pre_comment(self.event)
+            self.indent = self.indents.pop()
+            popped = self.flow_context.pop()
+            assert popped in ['{', '']
+            if self.canonical:
+                self.write_indicator(',', False)
+                self.write_indent()
+            if popped != '':
+                self.write_indicator('}', False)
+            if self.event.comment and self.event.comment[0]:
+                # eol comment on flow mapping, never reached on empty mappings
+                self.write_post_comment(self.event)
+            else:
+                self.no_newline = False
+            self.state = self.states.pop()
+        else:
+            self.write_indicator(',', False)
+            if self.canonical or self.column > self.best_width:
+                self.write_indent()
+            if not self.canonical and self.check_simple_key():
+                self.states.append(self.expect_flow_mapping_simple_value)
+                self.expect_node(mapping=True, simple_key=True)
+            else:
+                self.write_indicator('?', True)
+                self.states.append(self.expect_flow_mapping_value)
+                self.expect_node(mapping=True)
+
+    def expect_flow_mapping_simple_value(self):
+        # type: () -> None
+        self.write_indicator(self.prefixed_colon, False)
+        self.states.append(self.expect_flow_mapping_key)
+        self.expect_node(mapping=True)
+
+    def expect_flow_mapping_value(self):
+        # type: () -> None
+        if self.canonical or self.column > self.best_width:
+            self.write_indent()
+        self.write_indicator(self.prefixed_colon, True)
+        self.states.append(self.expect_flow_mapping_key)
+        self.expect_node(mapping=True)
+
+    # Block sequence handlers.
+
+    def expect_block_sequence(self):
+        # type: () -> None
+        if self.mapping_context:
+            indentless = not self.indention
+        else:
+            indentless = False
+            if not self.compact_seq_seq and self.column != 0:
+                self.write_line_break()
+        self.increase_indent(flow=False, sequence=True, indentless=indentless)
+        self.state = self.expect_first_block_sequence_item
+
+    def expect_first_block_sequence_item(self):
+        # type: () -> Any
+        return self.expect_block_sequence_item(first=True)
+
+    def expect_block_sequence_item(self, first=False):
+        # type: (bool) -> None
+        if not first and isinstance(self.event, SequenceEndEvent):
+            if self.event.comment and self.event.comment[1]:
+                # final comments on a block list e.g. empty line
+                self.write_pre_comment(self.event)
+            self.indent = self.indents.pop()
+            self.state = self.states.pop()
+            self.no_newline = False
+        else:
+            if self.event.comment and self.event.comment[1]:
+                self.write_pre_comment(self.event)
+            nonl = self.no_newline if self.column == 0 else False
+            self.write_indent()
+            ind = self.sequence_dash_offset  # if  len(self.indents) > 1 else 0
+            self.write_indicator(' ' * ind + '-', True, indention=True)
+            if nonl or self.sequence_dash_offset + 2 > self.best_sequence_indent:
+                self.no_newline = True
+            self.states.append(self.expect_block_sequence_item)
+            self.expect_node(sequence=True)
+
+    # Block mapping handlers.
+
+    def expect_block_mapping(self):
+        # type: () -> None
+        if not self.mapping_context and not (self.compact_seq_map or self.column == 0):
+            self.write_line_break()
+        self.increase_indent(flow=False, sequence=False)
+        self.state = self.expect_first_block_mapping_key
+
+    def expect_first_block_mapping_key(self):
+        # type: () -> None
+        return self.expect_block_mapping_key(first=True)
+
+    def expect_block_mapping_key(self, first=False):
+        # type: (Any) -> None
+        if not first and isinstance(self.event, MappingEndEvent):
+            if self.event.comment and self.event.comment[1]:
+                # final comments from a doc
+                self.write_pre_comment(self.event)
+            self.indent = self.indents.pop()
+            self.state = self.states.pop()
+        else:
+            if self.event.comment and self.event.comment[1]:
+                # final comments from a doc
+                self.write_pre_comment(self.event)
+            self.write_indent()
+            if self.check_simple_key():
+                if not isinstance(
+                    self.event, (SequenceStartEvent, MappingStartEvent)
+                ):  # sequence keys
+                    try:
+                        if self.event.style == '?':
+                            self.write_indicator('?', True, indention=True)
+                    except AttributeError:  # aliases have no style
+                        pass
+                self.states.append(self.expect_block_mapping_simple_value)
+                self.expect_node(mapping=True, simple_key=True)
+                # test on style for alias in !!set
+                if isinstance(self.event, AliasEvent) and not self.event.style == '?':
+                    self.stream.write(' ')
+            else:
+                self.write_indicator('?', True, indention=True)
+                self.states.append(self.expect_block_mapping_value)
+                self.expect_node(mapping=True)
+
+    def expect_block_mapping_simple_value(self):
+        # type: () -> None
+        if getattr(self.event, 'style', None) != '?':
+            # prefix = ''
+            if self.indent == 0 and self.top_level_colon_align is not None:
+                # write non-prefixed colon
+                c = ' ' * (self.top_level_colon_align - self.column) + self.colon
+            else:
+                c = self.prefixed_colon
+            self.write_indicator(c, False)
+        self.states.append(self.expect_block_mapping_key)
+        self.expect_node(mapping=True)
+
+    def expect_block_mapping_value(self):
+        # type: () -> None
+        self.write_indent()
+        self.write_indicator(self.prefixed_colon, True, indention=True)
+        self.states.append(self.expect_block_mapping_key)
+        self.expect_node(mapping=True)
+
+    # Checkers.
+
+    def check_empty_sequence(self):
+        # type: () -> bool
+        return (
+            isinstance(self.event, SequenceStartEvent)
+            and bool(self.events)
+            and isinstance(self.events[0], SequenceEndEvent)
+        )
+
+    def check_empty_mapping(self):
+        # type: () -> bool
+        return (
+            isinstance(self.event, MappingStartEvent)
+            and bool(self.events)
+            and isinstance(self.events[0], MappingEndEvent)
+        )
+
+    def check_empty_document(self):
+        # type: () -> bool
+        if not isinstance(self.event, DocumentStartEvent) or not self.events:
+            return False
+        event = self.events[0]
+        return (
+            isinstance(event, ScalarEvent)
+            and event.anchor is None
+            and event.tag is None
+            and event.implicit
+            and event.value == ""
+        )
+
+    def check_simple_key(self):
+        # type: () -> bool
+        length = 0
+        if isinstance(self.event, NodeEvent) and self.event.anchor is not None:
+            if self.prepared_anchor is None:
+                self.prepared_anchor = self.prepare_anchor(self.event.anchor)
+            length += len(self.prepared_anchor)
+        if (
+            isinstance(self.event, (ScalarEvent, CollectionStartEvent))
+            and self.event.tag is not None
+        ):
+            if self.prepared_tag is None:
+                self.prepared_tag = self.prepare_tag(self.event.tag)
+            length += len(self.prepared_tag)
+        if isinstance(self.event, ScalarEvent):
+            if self.analysis is None:
+                self.analysis = self.analyze_scalar(self.event.value)
+            length += len(self.analysis.scalar)
+        return length < self.MAX_SIMPLE_KEY_LENGTH and (
+            isinstance(self.event, AliasEvent)
+            or (
+                isinstance(self.event, SequenceStartEvent)
+                and self.event.flow_style is True
+            )
+            or (
+                isinstance(self.event, MappingStartEvent)
+                and self.event.flow_style is True
+            )
+            or (
+                isinstance(self.event, ScalarEvent)
+                # if there is an explicit style for an empty string, it is a simple key
+                and not (self.analysis.empty and self.style and self.style not in '\'"')
+                and not self.analysis.multiline
+            )
+            or self.check_empty_sequence()
+            or self.check_empty_mapping()
+        )
+
+    # Anchor, Tag, and Scalar processors.
+
+    def process_anchor(self, indicator):
+        # type: (Any) -> bool
+        if self.event.anchor is None:
+            self.prepared_anchor = None
+            return False
+        if self.prepared_anchor is None:
+            self.prepared_anchor = self.prepare_anchor(self.event.anchor)
+        if self.prepared_anchor:
+            self.write_indicator(indicator + self.prepared_anchor, True)
+            # issue 288
+            self.no_newline = False
+        self.prepared_anchor = None
+        return True
+
+    def process_tag(self):
+        # type: () -> None
+        tag = self.event.tag
+        if isinstance(self.event, ScalarEvent):
+            if self.style is None:
+                self.style = self.choose_scalar_style()
+                if (
+                    self.event.value == ''
+                    and self.style == "'"
+                    and tag == 'tag:yaml.org,2002:null'
+                    and self.alt_null is not None
+                ):
+                    self.event.value = self.alt_null
+                    self.analysis = None
+                    self.style = self.choose_scalar_style()
+            if (not self.canonical or tag is None) and (
+                (self.style == "" and self.event.implicit[0])
+                or (self.style != "" and self.event.implicit[1])
+            ):
+                self.prepared_tag = None
+                return
+            if self.event.implicit[0] and tag is None:
+                tag = '!'
+                self.prepared_tag = None
+        else:
+            if (not self.canonical or tag is None) and self.event.implicit:
+                self.prepared_tag = None
+                return
+        if tag is None:
+            raise EmitterError('tag is not specified')
+        if self.prepared_tag is None:
+            self.prepared_tag = self.prepare_tag(tag)
+        if self.prepared_tag:
+            self.write_indicator(self.prepared_tag, True)
+            if (
+                self.sequence_context
+                and not self.flow_level
+                and isinstance(self.event, ScalarEvent)
+            ):
+                self.no_newline = True
+        self.prepared_tag = None
+
+    def choose_scalar_style(self):
+        # type: () -> Any
+        if self.analysis is None:
+            self.analysis = self.analyze_scalar(self.event.value)
+        if self.event.style == '"' or self.canonical:
+            return '"'
+        if (not self.event.style or self.event.style == '?') and (
+            self.event.implicit[0] or not self.event.implicit[2]
+        ):
+            if not (
+                self.simple_key_context
+                and (self.analysis.empty or self.analysis.multiline)
+            ) and (
+                self.flow_level
+                and self.analysis.allow_flow_plain
+                or (not self.flow_level and self.analysis.allow_block_plain)
+            ):
+                return ""
+        self.analysis.allow_block = True
+        if self.event.style and self.event.style in '|>':
+            if (
+                not self.flow_level
+                and not self.simple_key_context
+                and self.analysis.allow_block
+            ):
+                return self.event.style
+        if not self.event.style and self.analysis.allow_double_quoted:
+            if "'" in self.event.value or '\n' in self.event.value:
+                return '"'
+        if not self.event.style or self.event.style == "'":
+            if self.analysis.allow_single_quoted and not (
+                self.simple_key_context and self.analysis.multiline
+            ):
+                return "'"
+        return '"'
+
+    def process_scalar(self):
+        # type: () -> None
+        if self.analysis is None:
+            self.analysis = self.analyze_scalar(self.event.value)
+        if self.style is None:
+            self.style = self.choose_scalar_style()
+        split = not self.simple_key_context
+        # if self.analysis.multiline and split    \
+        #         and (not self.style or self.style in '\'\"'):
+        #     self.write_indent()
+        # nprint('xx', self.sequence_context, self.flow_level)
+        if self.sequence_context and not self.flow_level:
+            self.write_indent()
+        if self.style == '"':
+            self.write_double_quoted(self.analysis.scalar, split)
+        elif self.style == "'":
+            self.write_single_quoted(self.analysis.scalar, split)
+        elif self.style == '>':
+            self.write_folded(self.analysis.scalar)
+            if (
+                self.event.comment
+                and self.indent is not None
+                and self.event.comment[0]
+                and self.event.comment[0].column >= self.indent
+            ):
+                # comment following a folded scalar must dedent (issue 376)
+                self.event.comment[0].column = self.indent - 1  # type: ignore
+        elif self.style == '|':
+            # self.write_literal(self.analysis.scalar, self.event.comment)
+            try:
+                cmx = self.event.comment[1][0]
+            except (IndexError, TypeError):
+                cmx = ""
+            self.write_literal(self.analysis.scalar, cmx)
+            if (
+                self.event.comment
+                and self.indent is not None
+                and self.event.comment[0]
+                and self.event.comment[0].column >= self.indent
+            ):
+                # comment following a literal scalar must dedent (issue 376)
+                self.event.comment[0].column = self.indent - 1  # type: ignore
+        else:
+            self.write_plain(self.analysis.scalar, split)
+        self.analysis = None
+        self.style = None
+        if self.event.comment:
+            self.write_post_comment(self.event)
+
+    # Analyzers.
+
+    def prepare_version(self, version):
+        # type: (Any) -> Any
+        major, minor = version
+        if major != 1:
+            raise EmitterError(
+                _F(
+                    'unsupported YAML version: {major:d}.{minor:d}',
+                    major=major,
+                    minor=minor,
+                )
+            )
+        return _F('{major:d}.{minor:d}', major=major, minor=minor)
+
+    def prepare_tag_handle(self, handle):
+        # type: (Any) -> Any
+        if not handle:
+            raise EmitterError('tag handle must not be empty')
+        if handle[0] != '!' or handle[-1] != '!':
+            raise EmitterError(
+                _F("tag handle must start and end with '!': {handle!r}", handle=handle)
+            )
+        for ch in handle[1:-1]:
+            if not (
+                '0' <= ch <= '9' or 'A' <= ch <= 'Z' or 'a' <= ch <= 'z' or ch in '-_'
+            ):
+                raise EmitterError(
+                    _F(
+                        'invalid character {ch!r} in the tag handle: {handle!r}',
+                        ch=ch,
+                        handle=handle,
+                    )
+                )
+        return handle
+
+    def prepare_tag_prefix(self, prefix):
+        # type: (Any) -> Any
+        if not prefix:
+            raise EmitterError('tag prefix must not be empty')
+        chunks = []  # type: List[Any]
+        start = end = 0
+        if prefix[0] == '!':
+            end = 1
+        ch_set = "-;/?:@&=+$,_.~*'()[]"
+        if self.dumper:
+            version = getattr(self.dumper, 'version', (1, 2))
+            if version is None or version >= (1, 2):
+                ch_set += '#'
+        while end < len(prefix):
+            ch = prefix[end]
+            if '0' <= ch <= '9' or 'A' <= ch <= 'Z' or 'a' <= ch <= 'z' or ch in ch_set:
+                end += 1
+            else:
+                if start < end:
+                    chunks.append(prefix[start:end])
+                start = end = end + 1
+                data = ch
+                for ch in data:
+                    chunks.append(_F('%{ord_ch:02X}', ord_ch=ord(ch)))
+        if start < end:
+            chunks.append(prefix[start:end])
+        return "".join(chunks)
+
+    def prepare_tag(self, tag):
+        # type: (Any) -> Any
+        if not tag:
+            raise EmitterError('tag must not be empty')
+        if tag == '!':
+            return tag
+        handle = None
+        suffix = tag
+        prefixes = sorted(self.tag_prefixes.keys())
+        for prefix in prefixes:
+            if tag.startswith(prefix) and (prefix == '!' or len(prefix) < len(tag)):
+                handle = self.tag_prefixes[prefix]
+                suffix = tag[len(prefix) :]
+        chunks = []  # type: List[Any]
+        start = end = 0
+        ch_set = "-;/?:@&=+$,_.~*'()[]"
+        if self.dumper:
+            version = getattr(self.dumper, 'version', (1, 2))
+            if version is None or version >= (1, 2):
+                ch_set += '#'
+        while end < len(suffix):
+            ch = suffix[end]
+            if (
+                '0' <= ch <= '9'
+                or 'A' <= ch <= 'Z'
+                or 'a' <= ch <= 'z'
+                or ch in ch_set
+                or (ch == '!' and handle != '!')
+            ):
+                end += 1
+            else:
+                if start < end:
+                    chunks.append(suffix[start:end])
+                start = end = end + 1
+                data = ch
+                for ch in data:
+                    chunks.append(_F('%{ord_ch:02X}', ord_ch=ord(ch)))
+        if start < end:
+            chunks.append(suffix[start:end])
+        suffix_text = "".join(chunks)
+        if handle:
+            return _F(
+                '{handle!s}{suffix_text!s}', handle=handle, suffix_text=suffix_text
+            )
+        else:
+            return _F('!<{suffix_text!s}>', suffix_text=suffix_text)
+
+    def prepare_anchor(self, anchor):
+        # type: (Any) -> Any
+        if not anchor:
+            raise EmitterError('anchor must not be empty')
+        for ch in anchor:
+            if not check_anchorname_char(ch):
+                raise EmitterError(
+                    _F(
+                        'invalid character {ch!r} in the anchor: {anchor!r}',
+                        ch=ch,
+                        anchor=anchor,
+                    )
+                )
+        return anchor
+
+    def analyze_scalar(self, scalar):
+        # type: (Any) -> Any
+        # Empty scalar is a special case.
+        if not scalar:
+            return ScalarAnalysis(
+                scalar=scalar,
+                empty=True,
+                multiline=False,
+                allow_flow_plain=False,
+                allow_block_plain=True,
+                allow_single_quoted=True,
+                allow_double_quoted=True,
+                allow_block=False,
+            )
+
+        # Indicators and special characters.
+        block_indicators = False
+        flow_indicators = False
+        line_breaks = False
+        special_characters = False
+
+        # Important whitespace combinations.
+        leading_space = False
+        leading_break = False
+        trailing_space = False
+        trailing_break = False
+        break_space = False
+        space_break = False
+
+        # Check document indicators.
+        if scalar.startswith('---') or scalar.startswith('...'):
+            block_indicators = True
+            flow_indicators = True
+
+        # First character or preceded by a whitespace.
+        preceeded_by_whitespace = True
+
+        # Last character or followed by a whitespace.
+        followed_by_whitespace = (
+            len(scalar) == 1 or scalar[1] in '\0 \t\r\n\x85\u2028\u2029'
+        )
+
+        # The previous character is a space.
+        previous_space = False
+
+        # The previous character is a break.
+        previous_break = False
+
+        index = 0
+        while index < len(scalar):
+            ch = scalar[index]
+
+            # Check for indicators.
+            if index == 0:
+                # Leading indicators are special characters.
+                if ch in '#,[]{}&*!|>\'"%@`':
+                    flow_indicators = True
+                    block_indicators = True
+                if ch in '?:':  # ToDo
+                    if self.serializer.use_version == (1, 1):
+                        flow_indicators = True
+                    elif len(scalar) == 1:  # single character
+                        flow_indicators = True
+                    if followed_by_whitespace:
+                        block_indicators = True
+                if ch == '-' and followed_by_whitespace:
+                    flow_indicators = True
+                    block_indicators = True
+            else:
+                # Some indicators cannot appear within a scalar as well.
+                if ch in ',[]{}':  # http://yaml.org/spec/1.2/spec.html#id2788859
+                    flow_indicators = True
+                if ch == '?' and self.serializer.use_version == (1, 1):
+                    flow_indicators = True
+                if ch == ':':
+                    if followed_by_whitespace:
+                        flow_indicators = True
+                        block_indicators = True
+                if ch == '#' and preceeded_by_whitespace:
+                    flow_indicators = True
+                    block_indicators = True
+
+            # Check for line breaks, special, and unicode characters.
+            if ch in '\n\x85\u2028\u2029':
+                line_breaks = True
+            if not (ch == '\n' or '\x20' <= ch <= '\x7E'):
+                if (
+                    ch == '\x85'
+                    or '\xA0' <= ch <= '\uD7FF'
+                    or '\uE000' <= ch <= '\uFFFD'
+                    or (
+                        self.unicode_supplementary
+                        and ('\U00010000' <= ch <= '\U0010FFFF')
+                    )
+                ) and ch != '\uFEFF':
+                    # unicode_characters = True
+                    if not self.allow_unicode:
+                        special_characters = True
+                else:
+                    special_characters = True
+
+            # Detect important whitespace combinations.
+            if ch == ' ':
+                if index == 0:
+                    leading_space = True
+                if index == len(scalar) - 1:
+                    trailing_space = True
+                if previous_break:
+                    break_space = True
+                previous_space = True
+                previous_break = False
+            elif ch in '\n\x85\u2028\u2029':
+                if index == 0:
+                    leading_break = True
+                if index == len(scalar) - 1:
+                    trailing_break = True
+                if previous_space:
+                    space_break = True
+                previous_space = False
+                previous_break = True
+            else:
+                previous_space = False
+                previous_break = False
+
+            # Prepare for the next character.
+            index += 1
+            preceeded_by_whitespace = ch in '\0 \t\r\n\x85\u2028\u2029'
+            followed_by_whitespace = (
+                index + 1 >= len(scalar)
+                or scalar[index + 1] in '\0 \t\r\n\x85\u2028\u2029'
+            )
+
+        # Let's decide what styles are allowed.
+        allow_flow_plain = True
+        allow_block_plain = True
+        allow_single_quoted = True
+        allow_double_quoted = True
+        allow_block = True
+
+        # Leading and trailing whitespaces are bad for plain scalars.
+        if leading_space or leading_break or trailing_space or trailing_break:
+            allow_flow_plain = allow_block_plain = False
+
+        # We do not permit trailing spaces for block scalars.
+        if trailing_space:
+            allow_block = False
+
+        # Spaces at the beginning of a new line are only acceptable for block
+        # scalars.
+        if break_space:
+            allow_flow_plain = allow_block_plain = allow_single_quoted = False
+
+        # Spaces followed by breaks, as well as special character are only
+        # allowed for double quoted scalars.
+        if special_characters:
+            allow_flow_plain = (
+                allow_block_plain
+            ) = allow_single_quoted = allow_block = False
+        elif space_break:
+            allow_flow_plain = allow_block_plain = allow_single_quoted = False
+            if not self.allow_space_break:
+                allow_block = False
+
+        # Although the plain scalar writer supports breaks, we never emit
+        # multiline plain scalars.
+        if line_breaks:
+            allow_flow_plain = allow_block_plain = False
+
+        # Flow indicators are forbidden for flow plain scalars.
+        if flow_indicators:
+            allow_flow_plain = False
+
+        # Block indicators are forbidden for block plain scalars.
+        if block_indicators:
+            allow_block_plain = False
+
+        return ScalarAnalysis(
+            scalar=scalar,
+            empty=False,
+            multiline=line_breaks,
+            allow_flow_plain=allow_flow_plain,
+            allow_block_plain=allow_block_plain,
+            allow_single_quoted=allow_single_quoted,
+            allow_double_quoted=allow_double_quoted,
+            allow_block=allow_block,
+        )
+
+    # Writers.
+
+    def flush_stream(self):
+        # type: () -> None
+        if hasattr(self.stream, 'flush'):
+            self.stream.flush()
+
+    def write_stream_start(self):
+        # type: () -> None
+        # Write BOM if needed.
+        if self.encoding and self.encoding.startswith('utf-16'):
+            self.stream.write('\uFEFF'.encode(self.encoding))
+
+    def write_stream_end(self):
+        # type: () -> None
+        self.flush_stream()
+
+    def write_indicator(
+        self, indicator, need_whitespace, whitespace=False, indention=False
+    ):
+        # type: (Any, Any, bool, bool) -> None
+        if self.whitespace or not need_whitespace:
+            data = indicator
+        else:
+            data = ' ' + indicator
+        self.whitespace = whitespace
+        self.indention = self.indention and indention
+        self.column += len(data)
+        self.open_ended = False
+        if bool(self.encoding):
+            data = data.encode(self.encoding)
+        self.stream.write(data)
+
+    def write_indent(self):
+        # type: () -> None
+        indent = self.indent or 0
+        if (
+            not self.indention
+            or self.column > indent
+            or (self.column == indent and not self.whitespace)
+        ):
+            if bool(self.no_newline):
+                self.no_newline = False
+            else:
+                self.write_line_break()
+        if self.column < indent:
+            self.whitespace = True
+            data = ' ' * (indent - self.column)
+            self.column = indent
+            if self.encoding:
+                data = data.encode(self.encoding)  # type: ignore
+            self.stream.write(data)
+
+    def write_line_break(self, data=None):
+        # type: (Any) -> None
+        if data is None:
+            data = self.best_line_break
+        self.whitespace = True
+        self.indention = True
+        self.line += 1
+        self.column = 0
+        if bool(self.encoding):
+            data = data.encode(self.encoding)
+        self.stream.write(data)
+
+    def write_version_directive(self, version_text):
+        # type: (Any) -> None
+        data = _F('%YAML {version_text!s}', version_text=version_text)
+        if self.encoding:
+            data = data.encode(self.encoding)  # type: ignore
+        self.stream.write(data)
+        self.write_line_break()
+
+    def write_tag_directive(self, handle_text, prefix_text):
+        # type: (Any, Any) -> None
+        data = _F(
+            '%TAG {handle_text!s} {prefix_text!s}',
+            handle_text=handle_text,
+            prefix_text=prefix_text,
+        )
+        if self.encoding:
+            data = data.encode(self.encoding)  # type: ignore
+        self.stream.write(data)
+        self.write_line_break()
+
+    # Scalar streams.
+
+    def write_single_quoted(self, text, split=True):
+        # type: (Any, Any) -> None
+        if self.root_context:
+            if self.requested_indent is not None:
+                self.write_line_break()
+                if self.requested_indent != 0:
+                    self.write_indent()
+        self.write_indicator("'", True)
+        spaces = False
+        breaks = False
+        start = end = 0
+        while end <= len(text):
+            ch = None
+            if end < len(text):
+                ch = text[end]
+            if spaces:
+                if ch is None or ch != ' ':
+                    if (
+                        start + 1 == end
+                        and self.column > self.best_width
+                        and split
+                        and start != 0
+                        and end != len(text)
+                    ):
+                        self.write_indent()
+                    else:
+                        data = text[start:end]
+                        self.column += len(data)
+                        if bool(self.encoding):
+                            data = data.encode(self.encoding)
+                        self.stream.write(data)
+                    start = end
+            elif breaks:
+                if ch is None or ch not in '\n\x85\u2028\u2029':
+                    if text[start] == '\n':
+                        self.write_line_break()
+                    for br in text[start:end]:
+                        if br == '\n':
+                            self.write_line_break()
+                        else:
+                            self.write_line_break(br)
+                    self.write_indent()
+                    start = end
+            else:
+                if ch is None or ch in ' \n\x85\u2028\u2029' or ch == "'":
+                    if start < end:
+                        data = text[start:end]
+                        self.column += len(data)
+                        if bool(self.encoding):
+                            data = data.encode(self.encoding)
+                        self.stream.write(data)
+                        start = end
+            if ch == "'":
+                data = "''"
+                self.column += 2
+                if bool(self.encoding):
+                    data = data.encode(self.encoding)
+                self.stream.write(data)
+                start = end + 1
+            if ch is not None:
+                spaces = ch == ' '
+                breaks = ch in '\n\x85\u2028\u2029'
+            end += 1
+        self.write_indicator("'", False)
+
+    ESCAPE_REPLACEMENTS = {
+        '\0': '0',
+        '\x07': 'a',
+        '\x08': 'b',
+        '\x09': 't',
+        '\x0A': 'n',
+        '\x0B': 'v',
+        '\x0C': 'f',
+        '\x0D': 'r',
+        '\x1B': 'e',
+        '"': '"',
+        '\\': '\\',
+        '\x85': 'N',
+        '\xA0': '_',
+        '\u2028': 'L',
+        '\u2029': 'P',
+    }
+
+    def write_double_quoted(self, text, split=True):
+        # type: (Any, Any) -> None
+        if self.root_context:
+            if self.requested_indent is not None:
+                self.write_line_break()
+                if self.requested_indent != 0:
+                    self.write_indent()
+        self.write_indicator('"', True)
+        start = end = 0
+        while end <= len(text):
+            ch = None
+            if end < len(text):
+                ch = text[end]
+            if (
+                ch is None
+                or ch in '"\\\x85\u2028\u2029\uFEFF'
+                or not (
+                    '\x20' <= ch <= '\x7E'
+                    or (
+                        self.allow_unicode
+                        and ('\xA0' <= ch <= '\uD7FF' or '\uE000' <= ch <= '\uFFFD')
+                    )
+                )
+            ):
+                if start < end:
+                    data = text[start:end]
+                    self.column += len(data)
+                    if bool(self.encoding):
+                        data = data.encode(self.encoding)
+                    self.stream.write(data)
+                    start = end
+                if ch is not None:
+                    if ch in self.ESCAPE_REPLACEMENTS:
+                        data = '\\' + self.ESCAPE_REPLACEMENTS[ch]
+                    elif ch <= '\xFF':
+                        data = _F('\\x{ord_ch:02X}', ord_ch=ord(ch))
+                    elif ch <= '\uFFFF':
+                        data = _F('\\u{ord_ch:04X}', ord_ch=ord(ch))
+                    else:
+                        data = _F('\\U{ord_ch:08X}', ord_ch=ord(ch))
+                    self.column += len(data)
+                    if bool(self.encoding):
+                        data = data.encode(self.encoding)
+                    self.stream.write(data)
+                    start = end + 1
+            if (
+                0 < end < len(text) - 1
+                and (ch == ' ' or start >= end)
+                and self.column + (end - start) > self.best_width
+                and split
+            ):
+                data = text[start:end] + '\\'
+                if start < end:
+                    start = end
+                self.column += len(data)
+                if bool(self.encoding):
+                    data = data.encode(self.encoding)
+                self.stream.write(data)
+                self.write_indent()
+                self.whitespace = False
+                self.indention = False
+                if text[start] == ' ':
+                    data = '\\'
+                    self.column += len(data)
+                    if bool(self.encoding):
+                        data = data.encode(self.encoding)
+                    self.stream.write(data)
+            end += 1
+        self.write_indicator('"', False)
+
+    def determine_block_hints(self, text):
+        # type: (Any) -> Any
+        indent = 0
+        indicator = ''
+        hints = ''
+        if text:
+            if text[0] in ' \n\x85\u2028\u2029':
+                indent = self.best_sequence_indent
+                hints += str(indent)
+            elif self.root_context:
+                for end in ['\n---', '\n...']:
+                    pos = 0
+                    while True:
+                        pos = text.find(end, pos)
+                        if pos == -1:
+                            break
+                        try:
+                            if text[pos + 4] in ' \r\n':
+                                break
+                        except IndexError:
+                            pass
+                        pos += 1
+                    if pos > -1:
+                        break
+                if pos > 0:
+                    indent = self.best_sequence_indent
+            if text[-1] not in '\n\x85\u2028\u2029':
+                indicator = '-'
+            elif len(text) == 1 or text[-2] in '\n\x85\u2028\u2029':
+                indicator = '+'
+        hints += indicator
+        return hints, indent, indicator
+
+    def write_folded(self, text):
+        # type: (Any) -> None
+        hints, _indent, _indicator = self.determine_block_hints(text)
+        self.write_indicator('>' + hints, True)
+        if _indicator == '+':
+            self.open_ended = True
+        self.write_line_break()
+        leading_space = True
+        spaces = False
+        breaks = True
+        start = end = 0
+        while end <= len(text):
+            ch = None
+            if end < len(text):
+                ch = text[end]
+            if breaks:
+                if ch is None or ch not in '\n\x85\u2028\u2029\a':
+                    if (
+                        not leading_space
+                        and ch is not None
+                        and ch != ' '
+                        and text[start] == '\n'
+                    ):
+                        self.write_line_break()
+                    leading_space = ch == ' '
+                    for br in text[start:end]:
+                        if br == '\n':
+                            self.write_line_break()
+                        else:
+                            self.write_line_break(br)
+                    if ch is not None:
+                        self.write_indent()
+                    start = end
+            elif spaces:
+                if ch != ' ':
+                    if start + 1 == end and self.column > self.best_width:
+                        self.write_indent()
+                    else:
+                        data = text[start:end]
+                        self.column += len(data)
+                        if bool(self.encoding):
+                            data = data.encode(self.encoding)
+                        self.stream.write(data)
+                    start = end
+            else:
+                if ch is None or ch in ' \n\x85\u2028\u2029\a':
+                    data = text[start:end]
+                    self.column += len(data)
+                    if bool(self.encoding):
+                        data = data.encode(self.encoding)
+                    self.stream.write(data)
+                    if ch == '\a':
+                        if end < (len(text) - 1) and not text[end + 2].isspace():
+                            self.write_line_break()
+                            self.write_indent()
+                            end += 2  # \a and the space that is inserted on the fold
+                        else:
+                            raise EmitterError(
+                                'unexcpected fold indicator \\a before space'
+                            )
+                    if ch is None:
+                        self.write_line_break()
+                    start = end
+            if ch is not None:
+                breaks = ch in '\n\x85\u2028\u2029'
+                spaces = ch == ' '
+            end += 1
+
+    def write_literal(self, text, comment=None):
+        # type: (Any, Any) -> None
+        hints, _indent, _indicator = self.determine_block_hints(text)
+        # if comment is not None:
+        #    try:
+        #        hints += comment[1][0]
+        #    except (TypeError, IndexError) as e:
+        #        pass
+        if not isinstance(comment, str):
+            comment = ''
+        self.write_indicator('|' + hints + comment, True)
+        # try:
+        #    nprintf('selfev', comment)
+        #    cmx = comment[1][0]
+        #    if cmx:
+        #        self.stream.write(cmx)
+        # except (TypeError, IndexError) as e:
+        #    pass
+        if _indicator == '+':
+            self.open_ended = True
+        self.write_line_break()
+        breaks = True
+        start = end = 0
+        while end <= len(text):
+            ch = None
+            if end < len(text):
+                ch = text[end]
+            if breaks:
+                if ch is None or ch not in '\n\x85\u2028\u2029':
+                    for br in text[start:end]:
+                        if br == '\n':
+                            self.write_line_break()
+                        else:
+                            self.write_line_break(br)
+                    if ch is not None:
+                        if self.root_context:
+                            idnx = self.indent if self.indent is not None else 0
+                            self.stream.write(' ' * (_indent + idnx))
+                        else:
+                            self.write_indent()
+                    start = end
+            else:
+                if ch is None or ch in '\n\x85\u2028\u2029':
+                    data = text[start:end]
+                    if bool(self.encoding):
+                        data = data.encode(self.encoding)
+                    self.stream.write(data)
+                    if ch is None:
+                        self.write_line_break()
+                    start = end
+            if ch is not None:
+                breaks = ch in '\n\x85\u2028\u2029'
+            end += 1
+
+    def write_plain(self, text, split=True):
+        # type: (Any, Any) -> None
+        if self.root_context:
+            if self.requested_indent is not None:
+                self.write_line_break()
+                if self.requested_indent != 0:
+                    self.write_indent()
+            else:
+                self.open_ended = True
+        if not text:
+            return
+        if not self.whitespace:
+            data = ' '
+            self.column += len(data)
+            if self.encoding:
+                data = data.encode(self.encoding)  # type: ignore
+            self.stream.write(data)
+        self.whitespace = False
+        self.indention = False
+        spaces = False
+        breaks = False
+        start = end = 0
+        while end <= len(text):
+            ch = None
+            if end < len(text):
+                ch = text[end]
+            if spaces:
+                if ch != ' ':
+                    if start + 1 == end and self.column > self.best_width and split:
+                        self.write_indent()
+                        self.whitespace = False
+                        self.indention = False
+                    else:
+                        data = text[start:end]
+                        self.column += len(data)
+                        if self.encoding:
+                            data = data.encode(self.encoding)  # type: ignore
+                        self.stream.write(data)
+                    start = end
+            elif breaks:
+                if ch not in '\n\x85\u2028\u2029':  # type: ignore
+                    if text[start] == '\n':
+                        self.write_line_break()
+                    for br in text[start:end]:
+                        if br == '\n':
+                            self.write_line_break()
+                        else:
+                            self.write_line_break(br)
+                    self.write_indent()
+                    self.whitespace = False
+                    self.indention = False
+                    start = end
+            else:
+                if ch is None or ch in ' \n\x85\u2028\u2029':
+                    data = text[start:end]
+                    self.column += len(data)
+                    if self.encoding:
+                        data = data.encode(self.encoding)  # type: ignore
+                    try:
+                        self.stream.write(data)
+                    except:  # NOQA
+                        sys.stdout.write(repr(data) + '\n')
+                        raise
+                    start = end
+            if ch is not None:
+                spaces = ch == ' '
+                breaks = ch in '\n\x85\u2028\u2029'
+            end += 1
+
+    def write_comment(self, comment, pre=False):
+        # type: (Any, bool) -> None
+        value = comment.value
+        # nprintf('{:02d} {:02d} {!r}'.format(self.column, comment.start_mark.column, value))
+        if not pre and value[-1] == '\n':
+            value = value[:-1]
+        try:
+            # get original column position
+            col = comment.start_mark.column
+            if comment.value and comment.value.startswith('\n'):
+                # never inject extra spaces if the comment starts with a newline
+                # and not a real comment (e.g. if you have an empty line following a key-value
+                col = self.column
+            elif col < self.column + 1:
+                ValueError
+        except ValueError:
+            col = self.column + 1
+        # nprint('post_comment', self.line, self.column, value)
+        try:
+            # at least one space if the current column >= the start column of the comment
+            # but not at the start of a line
+            nr_spaces = col - self.column
+            if self.column and value.strip() and nr_spaces < 1 and value[0] != '\n':
+                nr_spaces = 1
+            value = ' ' * nr_spaces + value
+            try:
+                if bool(self.encoding):
+                    value = value.encode(self.encoding)
+            except UnicodeDecodeError:
+                pass
+            self.stream.write(value)
+        except TypeError:
+            raise
+        if not pre:
+            self.write_line_break()
+
+    def write_pre_comment(self, event):
+        # type: (Any) -> bool
+        comments = event.comment[1]
+        if comments is None:
+            return False
+        try:
+            start_events = (MappingStartEvent, SequenceStartEvent)
+            for comment in comments:
+                if isinstance(event, start_events) and getattr(
+                    comment, 'pre_done', None
+                ):
+                    continue
+                if self.column != 0:
+                    self.write_line_break()
+                self.write_comment(comment, pre=True)
+                if isinstance(event, start_events):
+                    comment.pre_done = True
+        except TypeError:
+            sys.stdout.write('eventtt {} {}'.format(type(event), event))
+            raise
+        return True
+
+    def write_post_comment(self, event):
+        # type: (Any) -> bool
+        if self.event.comment[0] is None:
+            return False
+        comment = event.comment[0]
+        self.write_comment(comment)
+        return True