extendedtags.py

# Created: 30.04.2011
# Copyright (c) 2011-2019, Manfred Moitzi
# License: MIT License
"""
Extended Tags
-------------

Represents the extended DXF tag structure introduced with DXF R13.

"""
from typing import TYPE_CHECKING, Iterable, Optional, List
from itertools import chain
import logging
from .types import tuples_to_tags
from .tags import Tags, DXFTag, NONE_TAG
from .const import DXFStructureError, DXFValueError, DXFKeyError
from .types import APP_DATA_MARKER, SUBCLASS_MARKER, XDATA_MARKER, EMBEDDED_OBJ_MARKER, EMBEDDED_OBJ_STR
from .types import is_app_data_marker, is_embedded_object_marker
from .tagger import internal_tag_compiler

logger = logging.getLogger('ezdxf')

if TYPE_CHECKING:
    from ezdxf.eztypes import IterableTags


class ExtendedTags:
    """
    Manages DXF tags located in sub structures:

        - Subclasses
        - AppData
        - Extended Data (XDATA)
        - Embedded objects

    Args:
        tags: iterable of :class:`~ezdxf.lldxf.types.DXFTag`
        legacy: flag for DXF R12 tags

    """
    __slots__ = ('subclasses', 'appdata', 'xdata', 'embedded_objects')

    def __init__(self, tags: Iterable[DXFTag] = None, legacy=False):
        if isinstance(tags, str):
            raise DXFValueError("use ExtendedTags.from_text() to create tags from a string.")

        self.appdata = list()  # type: List[Tags] # code == 102, keys are "{<arbitrary name>", values are Tags()
        self.subclasses = list()  # type: List[Tags] # code == 100, keys are "subclassname", values are Tags()
        self.xdata = list()  # type: List[Tags] # code >= 1000, keys are "APPNAME", values are Tags()

        # store embedded objects as list, but embedded objects are rare, so storing an empty list for every DXF entity
        # is waste of memory
        self.embedded_objects = None  # type: Optional[List[Tags]]
        if tags is not None:
            self._setup(tags)
            if legacy:
                self.legacy_repair()

    def legacy_repair(self):
        """ Legacy (DXF R12) tags handling and repair. """
        self.flatten_subclasses()
        # ... and we can do some checks:
        # I think DXF R12 does not support (102, '{APPID') ... structures
        if len(self.appdata):
            # just a debug message, do not delete appdata, this would corrupt the data structure
            self.debug('Found application defined entity data in DXF R12.')

        # that is really unlikely, but...
        if self.embedded_objects is not None:
            # removing embedded objects does not corrupt data structure
            self.embedded_objects = None
            self.debug('Found embedded object in DXF R12.')

    def flatten_subclasses(self):
        """ Flatten subclasses in legacy mode (DXF R12).

        There exists DXF R12 with subclass markers, technical incorrect but works if reader ignore subclass marker tags,
        unfortunately ezdxf, tries to use this subclass markers and therefore R12 parsing by ezdxf does not work without
        removing this subclass markers.

        This method removes the subclass markers and flattens all subclasses into :attr:`ExtendedTags.noclass`.

        """
        if len(self.subclasses) < 2:
            return
        noclass = self.noclass
        for subclass in self.subclasses[1:]:
            noclass.extend(subclass[1:])  # exclude first tag (100, subclass marker)
        self.subclasses = [noclass]
        self.debug('Removed subclass marker from entity, invalid for R12.')

    def debug(self, msg: str) -> None:
        try:
            handle = '(#{})'.format(self.get_handle())
        except DXFValueError:
            handle = ''
        msg += ' <{}{}>'.format(self.dxftype(), handle)
        logger.debug(msg)

    def __copy__(self) -> 'ExtendedTags':
        """
        Shallow copy - linked entities are not duplicated!

        :class:`ExtendedTags` knows nothing about the entity database, and has no access to, so it is not possible for
        :class:`ExtendedTags` to do a deep copy, by also copying linked entities (VERTEX, ATTRIB, SEQEND).
        To do a deep copy, go one layer up and use :meth:`DXFEntity.copy`.

        """

        def copy(tag_lists):
            return [tags.clone() for tags in tag_lists]

        clone = self.__class__()
        clone.appdata = copy(self.appdata)
        clone.subclasses = copy(self.subclasses)
        clone.xdata = copy(self.xdata)
        if self.embedded_objects is not None:
            clone.embedded_objects = copy(self.embedded_objects)
        return clone

    clone = __copy__

    def __getitem__(self, index) -> Tags:
        return self.noclass[index]

    @property
    def noclass(self) -> Tags:
        """ Property to access :code:`self.subclasses[0]`. """
        return self.subclasses[0]

    def get_handle(self) -> str:
        return self.noclass.get_handle()

    def dxftype(self) -> str:
        return self.noclass[0].value

    def replace_handle(self, handle: str) -> None:
        self.noclass.replace_handle(handle)

    def _setup(self, iterable: Iterable[DXFTag]) -> None:
        tagstream = iter(iterable)

        def is_end_of_class(tag):
            # fast path
            if tag.code not in {SUBCLASS_MARKER, EMBEDDED_OBJ_MARKER, XDATA_MARKER}:
                return False
            else:
                # really an embedded object
                if tag.code == EMBEDDED_OBJ_MARKER and tag.value != EMBEDDED_OBJ_STR:
                    return False
                else:
                    return True

        def collect_base_class() -> DXFTag:
            """
            The base class contains AppData, but not XDATA, ends with
            SUBCLASS_MARKER, XDATA_MARKER or EMBEDDED_OBJ_MARKER.

            """
            # All subclasses begin with (100, subclass name)
            # EXCEPT DIMASSOC has one subclass starting with: (1, AcDbOsnapPointRef). Well done, Autodesk!
            # This special subclass is ignored by ezdxf, content is included in the preceding subclass: (100, AcDbDimAssoc)
            #
            # TEXT contains 2x the (100, AcDbText). Also well done, Autodesk! Therefore it is not possible to use an
            # (ordered) dict where subclass name is key, but usual use case is access by index.

            data = Tags()
            try:
                while True:
                    tag = next(tagstream)
                    if is_app_data_marker(tag):
                        app_data_pos = len(self.appdata)
                        data.append(DXFTag(tag.code, app_data_pos))
                        collect_app_data(tag)
                    elif is_end_of_class(tag):
                        self.subclasses.append(data)
                        return tag
                    else:
                        data.append(tag)
            except StopIteration:
                pass
            self.subclasses.append(data)
            return NONE_TAG

        def collect_subclass(starttag: DXFTag) -> DXFTag:
            """
            A subclass does NOT contain AppData or XDATA, and ends with ``SUBCLASS_MARKER``, ``XDATA_MARKER`` or
            ``EMBEDDED_OBJ_MARKER``.

            """
            # All subclasses begin with (100, subclass name)
            # EXCEPT DIMASSOC has one subclass starting with: (1, AcDbOsnapPointRef). Well done, Autodesk!
            # This special subclass is ignored by ezdxf, content is included in the preceding subclass: (100, AcDbDimAssoc)
            #
            # TEXT contains 2x the (100, AcDbText). Also well done, Autodesk! Therefore it is not possible to use an
            # (ordered) dict where subclass name is key, but usual use case is access by index.

            data = Tags([starttag])
            try:
                while True:
                    tag = next(tagstream)
                    # removed app data collection in subclasses
                    # if it later turns out that app data exists in subclasses, then reuse collect_base_class() which
                    # is the original collect_subclass() method
                    if is_end_of_class(tag):
                        self.subclasses.append(data)
                        return tag
                    else:
                        data.append(tag)
            except StopIteration:
                pass
            self.subclasses.append(data)
            return NONE_TAG

        def collect_app_data(starttag: DXFTag) -> None:
            """
            AppData can't contain XDATA or subclasses.

            I guess AppData can only appear in the first subclass (unnamed)

            """
            data = Tags([starttag])
            closing_strings = ('}', starttag.value[1:] + '}')  # alternative closing tag 'APPID}'
            while True:
                try:
                    tag = next(tagstream)
                except StopIteration:
                    raise DXFStructureError("Missing closing (102, '}') tag for appdata structure.")
                data.append(tag)
                if (tag.code == APP_DATA_MARKER) and (tag.value in closing_strings):
                    break
                    # every other (102, ) tag is treated as usual tag
            self.appdata.append(data)

        def collect_xdata(starttag: DXFTag) -> DXFTag:
            """
            XDATA is always at the end of the entity and can not contain AppData or subclasses.

            NEW: 09.08.2018

            Since AutoCAD 2018, DXF entities can contain embedded objects, this objects appear at the end of an entity,
            after XDATA (if XDATA exists).

            EDIT: 07.03.2019

            It seem that embedded object replaced XDATA e.g. MTEXT, and I expect, if both are present, XDATA will
            follow embedded object

            """
            data = Tags([starttag])
            try:
                while True:
                    tag = next(tagstream)
                    if tag.code == XDATA_MARKER:
                        self.xdata.append(data)
                        return tag
                    else:
                        data.append(tag)
            except StopIteration:
                pass
            self.xdata.append(data)
            return NONE_TAG

        def collect_embedded_object(starttag: DXFTag) -> DXFTag:
            """
            Since AutoCAD 2018, DXF entities can contain embedded objects, this objects appear at the end of an entity,
            also after XDATA, and start with the (101, 'Embedded Object') tag.

            All embedded object data is collected in a simple Tags() object, no subclass app data or XDATA processing is
            done. ezdxf does not use or modify the embedded object data, the data is just stored and written out as it
            is.

            self.embedded_objects = [1. embedded object as Tags(), 2. embedded object as Tags(), ...]

            """
            if self.embedded_objects is None:
                self.embedded_objects = list()
            data = Tags([starttag])
            try:
                while True:
                    tag = next(tagstream)
                    if is_embedded_object_marker(tag) or tag.code == XDATA_MARKER:
                        # another embedded object found, don't know if an DXF entity can contain more than one embedded
                        # objects
                        self.embedded_objects.append(data)
                        return tag
                    else:
                        data.append(tag)
            except StopIteration:
                pass
            self.embedded_objects.append(data)
            return NONE_TAG

        tag = collect_base_class()  # preceding tags without a subclass
        while tag.code == SUBCLASS_MARKER:
            tag = collect_subclass(tag)

        while is_embedded_object_marker(tag):
            tag = collect_embedded_object(tag)

        # I expect that XDATA and embedded objects do not appear in an entity at the same time,
        # but if so I expect XDATA appear after an embedded object
        while tag.code == XDATA_MARKER:
            tag = collect_xdata(tag)

        if tag is not NONE_TAG:
            raise DXFStructureError("Unexpected tag '%r' at end of entity." % tag)

    def __iter__(self) -> Iterable[DXFTag]:
        for subclass in self.subclasses:
            for tag in subclass:
                if tag.code == APP_DATA_MARKER and isinstance(tag.value, int):
                    yield from self.appdata[tag.value]
                else:
                    yield tag

        yield from chain.from_iterable(self.xdata)

        if self.embedded_objects is not None:
            yield from chain.from_iterable(self.embedded_objects)

    def get_subclass(self, name: str, pos: int = 0) -> Tags:
        for index, subclass in enumerate(self.subclasses):
            try:
                if (index >= pos) and (subclass[0].value == name):
                    return subclass
            except IndexError:
                pass  # subclass[0]: ignore empty subclasses

        raise DXFKeyError("Subclass '%s' does not exist." % name)

    def has_xdata(self, appid: str) -> bool:
        return any(xdata[0].value == appid for xdata in self.xdata)

    def get_xdata(self, appid: str) -> Tags:
        for xdata in self.xdata:
            if xdata[0].value == appid:
                return xdata
        raise DXFValueError("No extended data for APPID '%s'" % appid)

    def set_xdata(self, appid: str, tags: 'IterableTags') -> None:
        xdata = self.get_xdata(appid)
        xdata[1:] = tuples_to_tags(tags)

    def new_xdata(self, appid: str, tags: 'IterableTags' = None) -> Tags:
        """
        Append a new XDATA block.

        Assumes that no XDATA block with the same `appid` already exists::

            try:
                xdata = tags.get_xdata('EZDXF')
            except ValueError:
                xdata = tags.new_xdata('EZDXF')
        """
        xtags = Tags([DXFTag(XDATA_MARKER, appid)])
        if tags is not None:
            xtags.extend(tuples_to_tags(tags))
        self.xdata.append(xtags)
        return xtags

    def has_app_data(self, appid: str) -> bool:
        return any(appdata[0].value == appid for appdata in self.appdata)

    def get_app_data(self, appid: str) -> Tags:
        """
        Get AppData including first and last marker tag.

        """
        for appdata in self.appdata:
            if appdata[0].value == appid:
                return appdata
        raise DXFValueError("Application defined group '%s' does not exist." % appid)

    def get_app_data_content(self, appid: str) -> Tags:
        """
        Get AppData without first and last marker tag.

        """
        return Tags(self.get_app_data(appid)[1:-1])

    def set_app_data_content(self, appid: str, tags: 'IterableTags') -> None:
        app_data = self.get_app_data(appid)
        app_data[1:-1] = tuples_to_tags(tags)

    def new_app_data(self, appid: str, tags: 'IterableTags' = None, subclass_name: str = None) -> Tags:
        """
        Append a new AppData block to subclass `subclass_name`.

        Assumes that no app data block with the same `appid` already exist::

            try:
                app_data = tags.get_app_data('{ACAD_REACTORS', tags)
            except ValueError:
                app_data = tags.new_app_data('{ACAD_REACTORS', tags)

        """
        if not appid.startswith('{'):
            raise DXFValueError("App data id has to start with '{'.")

        app_tags = Tags([
            DXFTag(APP_DATA_MARKER, appid),
            DXFTag(APP_DATA_MARKER, '}'),
        ])
        if tags is not None:
            app_tags[1:1] = tuples_to_tags(tags)

        if subclass_name is None:
            subclass = self.noclass
        else:
            subclass = self.get_subclass(subclass_name, 1)  # raises KeyError, if not exists
        app_data_pos = len(self.appdata)
        subclass.append(DXFTag(APP_DATA_MARKER, app_data_pos))
        self.appdata.append(app_tags)
        return app_tags

    @classmethod
    def from_text(cls, text: str, legacy=False) -> 'ExtendedTags':
        return cls(internal_tag_compiler(text), legacy=legacy)