diff env/lib/python3.7/site-packages/yaml/emitter.py @ 5:9b1c78e6ba9c draft default tip

"planemo upload commit 6c0a8142489327ece472c84e558c47da711a9142"

--- a/env/lib/python3.7/site-packages/yaml/emitter.py	Thu May 14 16:47:39 2020 -0400
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,1137 +0,0 @@
-
-# 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
-
-__all__ = ['Emitter', 'EmitterError']
-
-from .error import YAMLError
-from .events import *
-
-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):
-        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 Emitter:
-
-    DEFAULT_TAG_PREFIXES = {
-        '!' : '!',
-        'tag:yaml.org,2002:' : '!!',
-    }
-
-    def __init__(self, stream, canonical=None, indent=None, width=None,
-            allow_unicode=None, line_break=None):
-
-        # The stream should have the methods `write` and possibly `flush`.
-        self.stream = stream
-
-        # Encoding can be overridden by STREAM-START.
-        self.encoding = None
-
-        # Emitter is a state machine with a stack of states to handle nested
-        # structures.
-        self.states = []
-        self.state = self.expect_stream_start
-
-        # Current event and the event queue.
-        self.events = []
-        self.event = None
-
-        # The current indentation level and the stack of previous indents.
-        self.indents = []
-        self.indent = None
-
-        # Flow level.
-        self.flow_level = 0
-
-        # 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
-
-        # Whether the document requires an explicit document indicator
-        self.open_ended = False
-
-        # Formatting details.
-        self.canonical = canonical
-        self.allow_unicode = allow_unicode
-        self.best_indent = 2
-        if indent and 1 < indent < 10:
-            self.best_indent = indent
-        self.best_width = 80
-        if width and width > self.best_indent*2:
-            self.best_width = width
-        self.best_line_break = '\n'
-        if line_break in ['\r', '\n', '\r\n']:
-            self.best_line_break = line_break
-
-        # Tag prefixes.
-        self.tag_prefixes = None
-
-        # Prepared anchor and tag.
-        self.prepared_anchor = None
-        self.prepared_tag = None
-
-        # Scalar analysis and style.
-        self.analysis = None
-        self.style = None
-
-    def dispose(self):
-        # Reset the state attributes (to clear self-references)
-        self.states = []
-        self.state = None
-
-    def emit(self, 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):
-        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):
-        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, indentless=False):
-        self.indents.append(self.indent)
-        if self.indent is None:
-            if flow:
-                self.indent = self.best_indent
-            else:
-                self.indent = 0
-        elif not indentless:
-            self.indent += self.best_indent
-
-    # States.
-
-    # Stream handlers.
-
-    def expect_stream_start(self):
-        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("expected StreamStartEvent, but got %s"
-                    % self.event)
-
-    def expect_nothing(self):
-        raise EmitterError("expected nothing, but got %s" % self.event)
-
-    # Document handlers.
-
-    def expect_first_document_start(self):
-        return self.expect_document_start(first=True)
-
-    def expect_document_start(self, first=False):
-        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("expected DocumentStartEvent, but got %s"
-                    % self.event)
-
-    def expect_document_end(self):
-        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("expected DocumentEndEvent, but got %s"
-                    % self.event)
-
-    def expect_document_root(self):
-        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):
-        self.root_context = root
-        self.sequence_context = sequence
-        self.mapping_context = mapping
-        self.simple_key_context = simple_key
-        if isinstance(self.event, AliasEvent):
-            self.expect_alias()
-        elif isinstance(self.event, (ScalarEvent, CollectionStartEvent)):
-            self.process_anchor('&')
-            self.process_tag()
-            if isinstance(self.event, ScalarEvent):
-                self.expect_scalar()
-            elif isinstance(self.event, SequenceStartEvent):
-                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.flow_level or self.canonical or self.event.flow_style   \
-                        or self.check_empty_mapping():
-                    self.expect_flow_mapping()
-                else:
-                    self.expect_block_mapping()
-        else:
-            raise EmitterError("expected NodeEvent, but got %s" % self.event)
-
-    def expect_alias(self):
-        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):
-        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):
-        self.write_indicator('[', True, whitespace=True)
-        self.flow_level += 1
-        self.increase_indent(flow=True)
-        self.state = self.expect_first_flow_sequence_item
-
-    def expect_first_flow_sequence_item(self):
-        if isinstance(self.event, SequenceEndEvent):
-            self.indent = self.indents.pop()
-            self.flow_level -= 1
-            self.write_indicator(']', False)
-            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):
-        if isinstance(self.event, SequenceEndEvent):
-            self.indent = self.indents.pop()
-            self.flow_level -= 1
-            if self.canonical:
-                self.write_indicator(',', False)
-                self.write_indent()
-            self.write_indicator(']', 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):
-        self.write_indicator('{', True, whitespace=True)
-        self.flow_level += 1
-        self.increase_indent(flow=True)
-        self.state = self.expect_first_flow_mapping_key
-
-    def expect_first_flow_mapping_key(self):
-        if isinstance(self.event, MappingEndEvent):
-            self.indent = self.indents.pop()
-            self.flow_level -= 1
-            self.write_indicator('}', False)
-            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):
-        if isinstance(self.event, MappingEndEvent):
-            self.indent = self.indents.pop()
-            self.flow_level -= 1
-            if self.canonical:
-                self.write_indicator(',', False)
-                self.write_indent()
-            self.write_indicator('}', 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):
-        self.write_indicator(':', False)
-        self.states.append(self.expect_flow_mapping_key)
-        self.expect_node(mapping=True)
-
-    def expect_flow_mapping_value(self):
-        if self.canonical or self.column > self.best_width:
-            self.write_indent()
-        self.write_indicator(':', True)
-        self.states.append(self.expect_flow_mapping_key)
-        self.expect_node(mapping=True)
-
-    # Block sequence handlers.
-
-    def expect_block_sequence(self):
-        indentless = (self.mapping_context and not self.indention)
-        self.increase_indent(flow=False, indentless=indentless)
-        self.state = self.expect_first_block_sequence_item
-
-    def expect_first_block_sequence_item(self):
-        return self.expect_block_sequence_item(first=True)
-
-    def expect_block_sequence_item(self, first=False):
-        if not first and isinstance(self.event, SequenceEndEvent):
-            self.indent = self.indents.pop()
-            self.state = self.states.pop()
-        else:
-            self.write_indent()
-            self.write_indicator('-', True, indention=True)
-            self.states.append(self.expect_block_sequence_item)
-            self.expect_node(sequence=True)
-
-    # Block mapping handlers.
-
-    def expect_block_mapping(self):
-        self.increase_indent(flow=False)
-        self.state = self.expect_first_block_mapping_key
-
-    def expect_first_block_mapping_key(self):
-        return self.expect_block_mapping_key(first=True)
-
-    def expect_block_mapping_key(self, first=False):
-        if not first and isinstance(self.event, MappingEndEvent):
-            self.indent = self.indents.pop()
-            self.state = self.states.pop()
-        else:
-            self.write_indent()
-            if self.check_simple_key():
-                self.states.append(self.expect_block_mapping_simple_value)
-                self.expect_node(mapping=True, simple_key=True)
-            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):
-        self.write_indicator(':', False)
-        self.states.append(self.expect_block_mapping_key)
-        self.expect_node(mapping=True)
-
-    def expect_block_mapping_value(self):
-        self.write_indent()
-        self.write_indicator(':', True, indention=True)
-        self.states.append(self.expect_block_mapping_key)
-        self.expect_node(mapping=True)
-
-    # Checkers.
-
-    def check_empty_sequence(self):
-        return (isinstance(self.event, SequenceStartEvent) and self.events
-                and isinstance(self.events[0], SequenceEndEvent))
-
-    def check_empty_mapping(self):
-        return (isinstance(self.event, MappingStartEvent) and self.events
-                and isinstance(self.events[0], MappingEndEvent))
-
-    def check_empty_document(self):
-        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):
-        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 < 128 and (isinstance(self.event, AliasEvent)
-            or (isinstance(self.event, ScalarEvent)
-                    and not self.analysis.empty 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):
-        if self.event.anchor is None:
-            self.prepared_anchor = None
-            return
-        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)
-        self.prepared_anchor = None
-
-    def process_tag(self):
-        tag = self.event.tag
-        if isinstance(self.event, ScalarEvent):
-            if self.style is 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)
-        self.prepared_tag = None
-
-    def choose_scalar_style(self):
-        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 and self.event.implicit[0]:
-            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 ''
-        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 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):
-        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()
-        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)
-        elif self.style == '|':
-            self.write_literal(self.analysis.scalar)
-        else:
-            self.write_plain(self.analysis.scalar, split)
-        self.analysis = None
-        self.style = None
-
-    # Analyzers.
-
-    def prepare_version(self, version):
-        major, minor = version
-        if major != 1:
-            raise EmitterError("unsupported YAML version: %d.%d" % (major, minor))
-        return '%d.%d' % (major, minor)
-
-    def prepare_tag_handle(self, handle):
-        if not handle:
-            raise EmitterError("tag handle must not be empty")
-        if handle[0] != '!' or handle[-1] != '!':
-            raise EmitterError("tag handle must start and end with '!': %r" % 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("invalid character %r in the tag handle: %r"
-                        % (ch, handle))
-        return handle
-
-    def prepare_tag_prefix(self, prefix):
-        if not prefix:
-            raise EmitterError("tag prefix must not be empty")
-        chunks = []
-        start = end = 0
-        if prefix[0] == '!':
-            end = 1
-        while end < len(prefix):
-            ch = prefix[end]
-            if '0' <= ch <= '9' or 'A' <= ch <= 'Z' or 'a' <= ch <= 'z' \
-                    or ch in '-;/?!:@&=+$,_.~*\'()[]':
-                end += 1
-            else:
-                if start < end:
-                    chunks.append(prefix[start:end])
-                start = end = end+1
-                data = ch.encode('utf-8')
-                for ch in data:
-                    chunks.append('%%%02X' % ord(ch))
-        if start < end:
-            chunks.append(prefix[start:end])
-        return ''.join(chunks)
-
-    def prepare_tag(self, tag):
-        if not tag:
-            raise EmitterError("tag must not be empty")
-        if tag == '!':
-            return tag
-        handle = None
-        suffix = tag
-        prefixes = sorted(self.tag_prefixes.keys())
-        for prefix in prefixes:
-            if tag.startswith(prefix)   \
-                    and (prefix == '!' or len(prefix) < len(tag)):
-                handle = self.tag_prefixes[prefix]
-                suffix = tag[len(prefix):]
-        chunks = []
-        start = end = 0
-        while end < len(suffix):
-            ch = suffix[end]
-            if '0' <= ch <= '9' or 'A' <= ch <= 'Z' or 'a' <= ch <= 'z' \
-                    or ch in '-;/?:@&=+$,_.~*\'()[]'   \
-                    or (ch == '!' and handle != '!'):
-                end += 1
-            else:
-                if start < end:
-                    chunks.append(suffix[start:end])
-                start = end = end+1
-                data = ch.encode('utf-8')
-                for ch in data:
-                    chunks.append('%%%02X' % ch)
-        if start < end:
-            chunks.append(suffix[start:end])
-        suffix_text = ''.join(chunks)
-        if handle:
-            return '%s%s' % (handle, suffix_text)
-        else:
-            return '!<%s>' % suffix_text
-
-    def prepare_anchor(self, anchor):
-        if not anchor:
-            raise EmitterError("anchor must not be empty")
-        for ch in anchor:
-            if not ('0' <= ch <= '9' or 'A' <= ch <= 'Z' or 'a' <= ch <= 'z'    \
-                    or ch in '-_'):
-                raise EmitterError("invalid character %r in the anchor: %r"
-                        % (ch, anchor))
-        return anchor
-
-    def analyze_scalar(self, scalar):
-
-        # 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.
-        preceded_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 '?:':
-                    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 ',?[]{}':
-                    flow_indicators = True
-                if ch == ':':
-                    flow_indicators = True
-                    if followed_by_whitespace:
-                        block_indicators = True
-                if ch == '#' and preceded_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 '\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
-            preceded_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 space_break or special_characters:
-            allow_flow_plain = allow_block_plain =  \
-            allow_single_quoted = 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):
-        if hasattr(self.stream, 'flush'):
-            self.stream.flush()
-
-    def write_stream_start(self):
-        # 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):
-        self.flush_stream()
-
-    def write_indicator(self, indicator, need_whitespace,
-            whitespace=False, indention=False):
-        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 self.encoding:
-            data = data.encode(self.encoding)
-        self.stream.write(data)
-
-    def write_indent(self):
-        indent = self.indent or 0
-        if not self.indention or self.column > indent   \
-                or (self.column == indent and not self.whitespace):
-            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)
-            self.stream.write(data)
-
-    def write_line_break(self, data=None):
-        if data is None:
-            data = self.best_line_break
-        self.whitespace = True
-        self.indention = True
-        self.line += 1
-        self.column = 0
-        if self.encoding:
-            data = data.encode(self.encoding)
-        self.stream.write(data)
-
-    def write_version_directive(self, version_text):
-        data = '%%YAML %s' % version_text
-        if self.encoding:
-            data = data.encode(self.encoding)
-        self.stream.write(data)
-        self.write_line_break()
-
-    def write_tag_directive(self, handle_text, prefix_text):
-        data = '%%TAG %s %s' % (handle_text, prefix_text)
-        if self.encoding:
-            data = data.encode(self.encoding)
-        self.stream.write(data)
-        self.write_line_break()
-
-    # Scalar streams.
-
-    def write_single_quoted(self, text, split=True):
-        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 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 self.encoding:
-                            data = data.encode(self.encoding)
-                        self.stream.write(data)
-                        start = end
-            if ch == '\'':
-                data = '\'\''
-                self.column += 2
-                if 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):
-        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 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 = '\\x%02X' % ord(ch)
-                    elif ch <= '\uFFFF':
-                        data = '\\u%04X' % ord(ch)
-                    else:
-                        data = '\\U%08X' % ord(ch)
-                    self.column += len(data)
-                    if 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 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 self.encoding:
-                        data = data.encode(self.encoding)
-                    self.stream.write(data)
-            end += 1
-        self.write_indicator('"', False)
-
-    def determine_block_hints(self, text):
-        hints = ''
-        if text:
-            if text[0] in ' \n\x85\u2028\u2029':
-                hints += str(self.best_indent)
-            if text[-1] not in '\n\x85\u2028\u2029':
-                hints += '-'
-            elif len(text) == 1 or text[-2] in '\n\x85\u2028\u2029':
-                hints += '+'
-        return hints
-
-    def write_folded(self, text):
-        hints = self.determine_block_hints(text)
-        self.write_indicator('>'+hints, True)
-        if hints[-1:] == '+':
-            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':
-                    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 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':
-                    data = text[start:end]
-                    self.column += len(data)
-                    if 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')
-                spaces = (ch == ' ')
-            end += 1
-
-    def write_literal(self, text):
-        hints = self.determine_block_hints(text)
-        self.write_indicator('|'+hints, True)
-        if hints[-1:] == '+':
-            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:
-                        self.write_indent()
-                    start = end
-            else:
-                if ch is None or ch in '\n\x85\u2028\u2029':
-                    data = text[start:end]
-                    if 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):
-        if self.root_context:
-            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)
-            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)
-                        self.stream.write(data)
-                    start = end
-            elif breaks:
-                if 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()
-                    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)
-                    self.stream.write(data)
-                    start = end
-            if ch is not None:
-                spaces = (ch == ' ')
-                breaks = (ch in '\n\x85\u2028\u2029')
-            end += 1