➡️ dinglehopper: Move ExtractedText to its own file
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import enum
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import re
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import unicodedata
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from contextlib import suppress
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from itertools import repeat
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from typing import Optional
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import attr
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from .substitute_equivalences import substitute_equivalences
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class Normalization(enum.Enum):
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NFC = 1
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NFC_MUFI = 2 # TODO
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NFC_SBB = 3
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def normalize(text, normalization):
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if normalization == Normalization.NFC:
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return unicodedata.normalize('NFC', text)
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if normalization == Normalization.NFC_MUFI:
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raise NotImplementedError()
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if normalization == Normalization.NFC_SBB:
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return substitute_equivalences(text)
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else:
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raise ValueError()
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# XXX hack
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def normalize_sbb(t):
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return normalize(t, Normalization.NFC_SBB)
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@attr.s(frozen=True)
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class ExtractedText:
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"""
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Extracted text
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Objects of this class are guaranteed to be a. always in their normalization and
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b. in NFC.
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"""
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segment_id = attr.ib(type=Optional[str])
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@segment_id.validator
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def check(self, _, value):
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if value is None:
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return
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if not re.match(r'[\w\d_-]+', value):
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raise ValueError('Malformed segment id "{}"'.format(value))
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# An object contains either
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# a. _text itself
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# b. or segments (ExtractedText) and a joiner
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segments = attr.ib(type=Optional[list], converter=attr.converters.optional(list))
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joiner = attr.ib(type=Optional[str])
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_text = attr.ib(type=Optional[str])
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@segments.validator
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def check(self, _, value):
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if value is not None and self._text is not None:
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raise ValueError("Can't have both segments and text")
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@_text.validator
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def check(self, _, value):
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if value is not None and self.segments is not None:
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raise ValueError("Can't have both segments and text")
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if value is not None and unicodedata.normalize('NFC', value) != value:
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raise ValueError('String "{}" is not in NFC.'.format(value))
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if value is not None and normalize(value, self.normalization) != value:
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raise ValueError('String "{}" is not normalized.'.format(value))
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normalization = attr.ib(converter=Normalization, default=Normalization.NFC_SBB)
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@property
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def text(self):
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if self._text is not None:
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if self._text == '':
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return None
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else:
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return self._text
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else:
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return self.joiner.join(s.text for s in self.segments)
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_segment_id_for_pos = None
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def segment_id_for_pos(self, pos):
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# Calculate segment ids once, on the first call
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if not self._segment_id_for_pos:
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segment_id_for_pos = []
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for s in self.segments:
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segment_id_for_pos.extend(repeat(s.segment_id, len(s.text)))
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segment_id_for_pos.extend(repeat(None, len(self.joiner)))
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segment_id_for_pos = segment_id_for_pos[:-len(self.joiner)]
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# This is frozen, so we have to jump through the hoop:
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object.__setattr__(self, '_segment_id_for_pos', segment_id_for_pos)
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assert self._segment_id_for_pos
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return self._segment_id_for_pos[pos]
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@classmethod
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def from_text_segment(cls, text_segment, nsmap):
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"""Build an ExtractedText from a PAGE content text element"""
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segment_id = text_segment.attrib['id']
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segment_text = None
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with suppress(AttributeError):
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segment_text = text_segment.find('./page:TextEquiv/page:Unicode', namespaces=nsmap).text
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segment_text = segment_text or ''
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segment_text = normalize_sbb(segment_text) # FIXME hardcoded SBB normalization
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segment_text = segment_text or ''
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return cls(segment_id, None, None, segment_text)
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@classmethod
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def from_str(cls, text, normalization=Normalization.NFC_SBB):
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normalized_text = normalize(text, normalization)
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return cls(None, None, None, normalized_text, normalization=normalization)
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