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Source code for xsdata.formats.dataclass.parsers.xml

from dataclasses import dataclass
from dataclasses import field
from typing import Any
from typing import Dict
from typing import List
from typing import Optional
from typing import Type

from xsdata.formats.dataclass.parsers.bases import NodeParser
from xsdata.formats.dataclass.parsers.bases import Parsed
from xsdata.formats.dataclass.parsers.handlers import default_handler
from xsdata.formats.dataclass.parsers.mixins import XmlHandler
from xsdata.formats.dataclass.parsers.mixins import XmlNode
from xsdata.models.enums import EventType
from xsdata.utils.namespaces import local_name
from xsdata.utils.text import snake_case


@dataclass
class XmlParser(NodeParser):
    """
    Default Xml parser for dataclasses.

    :param config: Parser configuration
    :param context: Model context provider
    :param handler: Override default XmlHandler
    :ivar ms_map: The prefix-URI map generated during parsing
    """

    handler: Type[XmlHandler] = field(default=default_handler())


@dataclass
class UserXmlParser(NodeParser):
    """
    User Xml parser for dataclasses with hooks for emitting events to alter the
    behavior when an elements starts or ends.

    :param config: Parser configuration
    :param context: Model context provider
    :param handler: Override default XmlHandler
    :ivar ms_map: The prefix-URI map generated during parsing
    :ivar emit_cache: Qname to event name cache
    """

    handler: Type[XmlHandler] = field(default=default_handler())
    emit_cache: Dict = field(init=False, default_factory=dict)

    def start(
        self,
        clazz: Optional[Type],
        queue: List[XmlNode],
        objects: List[Parsed],
        qname: str,
        attrs: Dict,
        ns_map: Dict,
    ):
        super().start(clazz, queue, objects, qname, attrs, ns_map)
        self.emit_event(EventType.START, qname, attrs=attrs)

    def end(
        self,
        queue: List[XmlNode],
        objects: List[Parsed],
        qname: str,
        text: Optional[str],
        tail: Optional[str],
    ) -> bool:
        result = super().end(queue, objects, qname, text, tail)
        if result:
            self.emit_event(EventType.END, qname, obj=objects[-1][1])
        return result

    def emit_event(self, event: str, name: str, **kwargs: Any):
        """
        Propagate event to subclasses.

        Match event and name to a subclass method and trigger it with
        any input keyword arguments.

        Example::

            event=start, name={urn}bookTitle -> start_booking_title(**kwargs)

        :param event: Event type start|end
        :param name: Element qualified name
        :param kwargs: Event keyword arguments
        """

        key = (event, name)
        if key not in self.emit_cache:
            method_name = f"{event}_{snake_case(local_name(name))}"
            self.emit_cache[key] = getattr(self, method_name, None)

        method = self.emit_cache[key]
        if method:
            method(**kwargs)