serializer.py

# coding: utf-8

from ruamel.yaml.error import YAMLError
from ruamel.yaml.compat import nprint, DBG_NODE, dbg, nprintf  # NOQA
from ruamel.yaml.util import RegExp

from ruamel.yaml.events import (
    StreamStartEvent,
    StreamEndEvent,
    MappingStartEvent,
    MappingEndEvent,
    SequenceStartEvent,
    SequenceEndEvent,
    AliasEvent,
    ScalarEvent,
    DocumentStartEvent,
    DocumentEndEvent,
)
from ruamel.yaml.nodes import MappingNode, ScalarNode, SequenceNode

from typing import Any, Dict, Union, Text, Optional  # NOQA
from ruamel.yaml.compat import VersionType  # NOQA

__all__ = ['Serializer', 'SerializerError']


class SerializerError(YAMLError):
    pass


class Serializer:

    # 'id' and 3+ numbers, but not 000
    ANCHOR_TEMPLATE = 'id{:03d}'
    ANCHOR_RE = RegExp('id(?!000$)\\d{3,}')

    def __init__(
        self,
        encoding: Any = None,
        explicit_start: Optional[bool] = None,
        explicit_end: Optional[bool] = None,
        version: Optional[VersionType] = None,
        tags: Any = None,
        dumper: Any = None,
    ) -> None:
        # NOQA
        self.dumper = dumper
        if self.dumper is not None:
            self.dumper._serializer = self
        self.use_encoding = encoding
        self.use_explicit_start = explicit_start
        self.use_explicit_end = explicit_end
        if isinstance(version, str):
            self.use_version = tuple(map(int, version.split('.')))
        else:
            self.use_version = version  # type: ignore
        self.use_tags = tags
        self.serialized_nodes: Dict[Any, Any] = {}
        self.anchors: Dict[Any, Any] = {}
        self.last_anchor_id = 0
        self.closed: Optional[bool] = None
        self._templated_id = None

    @property
    def emitter(self) -> Any:
        if hasattr(self.dumper, 'typ'):
            return self.dumper.emitter
        return self.dumper._emitter

    @property
    def resolver(self) -> Any:
        if hasattr(self.dumper, 'typ'):
            self.dumper.resolver
        return self.dumper._resolver

    def open(self) -> None:
        if self.closed is None:
            self.emitter.emit(StreamStartEvent(encoding=self.use_encoding))
            self.closed = False
        elif self.closed:
            raise SerializerError('serializer is closed')
        else:
            raise SerializerError('serializer is already opened')

    def close(self) -> None:
        if self.closed is None:
            raise SerializerError('serializer is not opened')
        elif not self.closed:
            self.emitter.emit(StreamEndEvent())
            self.closed = True

    # def __del__(self):
    #     self.close()

    def serialize(self, node: Any) -> None:
        if dbg(DBG_NODE):
            nprint('Serializing nodes')
            node.dump()
        if self.closed is None:
            raise SerializerError('serializer is not opened')
        elif self.closed:
            raise SerializerError('serializer is closed')
        self.emitter.emit(
            DocumentStartEvent(
                explicit=self.use_explicit_start, version=self.use_version, tags=self.use_tags,
            ),
        )
        self.anchor_node(node)
        self.serialize_node(node, None, None)
        self.emitter.emit(DocumentEndEvent(explicit=self.use_explicit_end))
        self.serialized_nodes = {}
        self.anchors = {}
        self.last_anchor_id = 0

    def anchor_node(self, node: Any) -> None:
        if node in self.anchors:
            if self.anchors[node] is None:
                self.anchors[node] = self.generate_anchor(node)
        else:
            anchor = None
            try:
                if node.anchor.always_dump:
                    anchor = node.anchor.value
            except:  # NOQA
                pass
            self.anchors[node] = anchor
            if isinstance(node, SequenceNode):
                for item in node.value:
                    self.anchor_node(item)
            elif isinstance(node, MappingNode):
                for key, value in node.value:
                    self.anchor_node(key)
                    self.anchor_node(value)

    def generate_anchor(self, node: Any) -> Any:
        try:
            anchor = node.anchor.value
        except:  # NOQA
            anchor = None
        if anchor is None:
            self.last_anchor_id += 1
            return self.ANCHOR_TEMPLATE.format(self.last_anchor_id)
        return anchor

    def serialize_node(self, node: Any, parent: Any, index: Any) -> None:
        alias = self.anchors[node]
        if node in self.serialized_nodes:
            node_style = getattr(node, 'style', None)
            if node_style != '?':
                node_style = None
            self.emitter.emit(AliasEvent(alias, style=node_style))
        else:
            self.serialized_nodes[node] = True
            self.resolver.descend_resolver(parent, index)
            if isinstance(node, ScalarNode):
                # here check if the node.tag equals the one that would result from parsing
                # if not equal quoting is necessary for strings
                detected_tag = self.resolver.resolve(ScalarNode, node.value, (True, False))
                default_tag = self.resolver.resolve(ScalarNode, node.value, (False, True))
                implicit = (
                    (node.ctag == detected_tag),
                    (node.ctag == default_tag),
                    node.tag.startswith('tag:yaml.org,2002:'),  # type: ignore
                )
                self.emitter.emit(
                    ScalarEvent(
                        alias,
                        node.ctag,
                        implicit,
                        node.value,
                        style=node.style,
                        comment=node.comment,
                    ),
                )
            elif isinstance(node, SequenceNode):
                implicit = node.ctag == self.resolver.resolve(SequenceNode, node.value, True)
                comment = node.comment
                end_comment = None
                seq_comment = None
                if node.flow_style is True:
                    if comment:  # eol comment on flow style sequence
                        seq_comment = comment[0]
                        # comment[0] = None
                if comment and len(comment) > 2:
                    end_comment = comment[2]
                else:
                    end_comment = None
                self.emitter.emit(
                    SequenceStartEvent(
                        alias,
                        node.ctag,
                        implicit,
                        flow_style=node.flow_style,
                        comment=node.comment,
                    ),
                )
                index = 0
                for item in node.value:
                    self.serialize_node(item, node, index)
                    index += 1
                self.emitter.emit(SequenceEndEvent(comment=[seq_comment, end_comment]))
            elif isinstance(node, MappingNode):
                implicit = node.ctag == self.resolver.resolve(MappingNode, node.value, True)
                comment = node.comment
                end_comment = None
                map_comment = None
                if node.flow_style is True:
                    if comment:  # eol comment on flow style sequence
                        map_comment = comment[0]
                        # comment[0] = None
                if comment and len(comment) > 2:
                    end_comment = comment[2]
                self.emitter.emit(
                    MappingStartEvent(
                        alias,
                        node.ctag,
                        implicit,
                        flow_style=node.flow_style,
                        comment=node.comment,
                        nr_items=len(node.value),
                    ),
                )
                for key, value in node.value:
                    self.serialize_node(key, node, None)
                    self.serialize_node(value, node, key)
                self.emitter.emit(MappingEndEvent(comment=[map_comment, end_comment]))
            self.resolver.ascend_resolver()


def templated_id(s: Text) -> Any:
    return Serializer.ANCHOR_RE.match(s)