"""Parent class and utility class for producing a scansion pattern for a line of Latin verse.
Some useful methods
* Perform a conservative i to j transformation
* Performs elisions
* Accents vowels by position
* Breaks the line into a list of syllables by calling a Syllabifier class which may be injected
into this classes constructor.
"""
import logging
import re
from typing import Any, Dict, List
import cltk.prosody.lat.string_utils as string_utils
from cltk.prosody.lat.metrical_validator import MetricalValidator
from cltk.prosody.lat.scansion_constants import ScansionConstants
from cltk.prosody.lat.scansion_formatter import ScansionFormatter
from cltk.prosody.lat.syllabifier import Syllabifier
from cltk.prosody.lat.verse import Verse
LOG = logging.getLogger(__name__)
LOG.addHandler(logging.NullHandler())
__author__ = ["Todd Cook <todd.g.cook@gmail.com>"]
__license__ = "MIT License"
[docs]class VerseScanner:
"""
The scansion symbols used can be configured by passing a suitable constants class to
the constructor.
"""
def __init__(
self, constants=ScansionConstants(), syllabifier=Syllabifier(), **kwargs
):
self.constants = constants
self.remove_punct_map = string_utils.remove_punctuation_dict()
self.punctuation_substitutions = string_utils.punctuation_for_spaces_dict()
self.metrical_validator = MetricalValidator(constants)
self.formatter = ScansionFormatter(constants)
self.syllabifier = syllabifier
self.inverted_amphibrach_re = re.compile(
r"{}\s*{}\s*{}".format(
self.constants.STRESSED,
self.constants.UNSTRESSED,
self.constants.STRESSED,
)
)
self.syllable_matcher = re.compile(
r"[{}]".format(
self.constants.VOWELS
+ self.constants.ACCENTED_VOWELS
+ self.constants.LIQUIDS
+ self.constants.MUTES
)
)
[docs] def accent_by_position(self, verse_line: str) -> str:
"""
Accent vowels according to the rules of scansion.
:param verse_line: a line of unaccented verse
:return: the same line with vowels accented by position
>>> print(VerseScanner().accent_by_position(
... "Arma virumque cano, Troiae qui primus ab oris").lstrip())
Ārma virūmque canō Trojae qui primus ab oris
"""
line = verse_line.translate(self.punctuation_substitutions)
line = self.transform_i_to_j(line)
marks = list(line)
# locate and save dipthong positions since we don't want them being accented
dipthong_positions = []
for dipth in self.constants.DIPTHONGS:
if dipth in line:
dipthong_positions.append(line.find(dipth))
# Vowels followed by 2 consonants
# The digraphs ch, ph, th, qu and sometimes gu and su count as single consonants.
# see http://people.virginia.edu/~jdk3t/epicintrog/scansion.htm
marks = string_utils.overwrite(
marks,
"[{}][{}][{}]".format(
self.constants.VOWELS,
self.constants.CONSONANTS,
self.constants.CONSONANTS_WO_H,
),
self.constants.STRESSED,
)
# one space (or more for 'dropped' punctuation may intervene)
marks = string_utils.overwrite(
marks,
r"[{}][{}]\s*[{}]".format(
self.constants.VOWELS,
self.constants.CONSONANTS,
self.constants.CONSONANTS_WO_H,
),
self.constants.STRESSED,
)
# ... if both consonants are in the next word, the vowel may be long
# .... but it could be short if the vowel is not on the thesis/emphatic part of the foot
# ... see Gildersleeve and Lodge p.446
marks = string_utils.overwrite(
marks,
r"[{}]\s*[{}][{}]".format(
self.constants.VOWELS,
self.constants.CONSONANTS,
self.constants.CONSONANTS_WO_H,
),
self.constants.STRESSED,
)
# x is considered as two letters
marks = string_utils.overwrite(
marks, "[{}][xX]".format(self.constants.VOWELS), self.constants.STRESSED
)
# z is considered as two letters
marks = string_utils.overwrite(
marks, r"[{}][zZ]".format(self.constants.VOWELS), self.constants.STRESSED
)
original_verse = list(line)
for idx, word in enumerate(original_verse):
if marks[idx] == self.constants.STRESSED:
original_verse[idx] = self.constants.VOWELS_TO_ACCENTS[
original_verse[idx]
]
# make sure dipthongs aren't accented
for idx in dipthong_positions:
if original_verse[idx + 1] in self.constants.ACCENTS_TO_VOWELS:
original_verse[idx + 1] = self.constants.ACCENTS_TO_VOWELS[
original_verse[idx + 1]
]
return "".join(original_verse)
[docs] def elide_all(self, line: str) -> str:
"""
Given a string of space separated syllables, erase with spaces the syllable portions
that would disappear according to the rules of elision.
:param line:
:return:
"""
marks = list(line.translate(self.remove_punct_map))
all_vowels = self.constants.VOWELS + self.constants.ACCENTED_VOWELS
tmp = "".join(marks)
# Elision rules are compound but not cummulative: we place all elision edits into a list
# of candidates, and then merge, taking the least of each section of the line.
candidates = [
tmp,
self.elide(
tmp,
r"[{}][{}]\s+[{}]".format(
self.constants.CONSONANTS, all_vowels, all_vowels
),
1,
1,
),
self.elide(
tmp,
r"[{}][{}]\s+[hH]".format(self.constants.CONSONANTS, all_vowels),
1,
1,
),
self.elide(tmp, r"[aāuū]m\s+[{}]".format(all_vowels), 2),
self.elide(tmp, r"ae\s+[{}]".format(all_vowels), 2),
self.elide(tmp, r"[{}]\s+[{}]".format(all_vowels, all_vowels), 1),
self.elide(tmp, r"[uū]m\s+h", 2),
]
results = string_utils.merge_elisions(candidates)
return results
[docs] def calc_offset(self, syllables_spaces: List[str]) -> Dict[int, int]:
"""
Calculate a dictionary of accent positions from a list of syllables with spaces.
:param syllables_spaces:
:return:
"""
line = string_utils.flatten(syllables_spaces)
mydict = {} # type: Dict[int, int]
# #defaultdict(int) #type: Dict[int, int]
for idx, syl in enumerate(syllables_spaces):
target_syllable = syllables_spaces[idx]
skip_qu = string_utils.starts_with_qu(target_syllable)
matches = list(self.syllable_matcher.finditer(target_syllable))
for position, possible in enumerate(matches):
if skip_qu:
skip_qu = False
continue
(start, end) = possible.span()
if (
target_syllable[start:end]
in self.constants.VOWELS + self.constants.ACCENTED_VOWELS
):
part = line[: len("".join(syllables_spaces[:idx]))]
offset = len(part) + start
if (
line[offset]
not in self.constants.VOWELS + self.constants.ACCENTED_VOWELS
):
LOG.error("Problem at line {} offset {}".format(line, offset))
mydict[idx] = offset
return mydict
[docs] def produce_scansion(
self, stresses: list, syllables_wspaces: List[str], offset_map: Dict[int, int]
) -> str:
"""
Create a scansion string that has stressed and unstressed syllable positions in locations
that correspond with the original texts syllable vowels.
:param stresses list of syllable positions
:param syllables_wspaces list of syllables with spaces escaped for punctuation or elision
:param offset_map dictionary of syllable positions, and an offset amount which is the
number of spaces to skip in the original line before inserting the accent.
"""
scansion = list(" " * len(string_utils.flatten(syllables_wspaces)))
unstresses = string_utils.get_unstresses(stresses, len(syllables_wspaces))
try:
for idx in unstresses:
location = offset_map.get(idx)
if location is not None:
scansion[location] = self.constants.UNSTRESSED
for idx in stresses:
location = offset_map.get(idx)
if location is not None:
scansion[location] = self.constants.STRESSED
except Exception as e:
LOG.error(
"problem with syllables; check syllabification {}, {}".format(
syllables_wspaces, e
)
)
return "".join(scansion)
[docs] def flag_dipthongs(self, syllables: List[str]) -> List[int]:
"""
Return a list of syllables that contain a dipthong
:param syllables:
:return:
"""
long_positions = []
for idx, syl in enumerate(syllables):
for dipthong in self.constants.DIPTHONGS:
if dipthong in syllables[idx]:
if not string_utils.starts_with_qu(syllables[idx]):
long_positions.append(idx)
return long_positions
[docs] def elide(self, line: str, regexp: str, quantity: int = 1, offset: int = 0) -> str:
"""
Erase a section of a line, matching on a regex, pushing in a quantity of blank spaces,
and jumping forward with an offset if necessary.
If the elided vowel was strong, the vowel merged with takes on the stress.
:param line:
:param regexp:
:param quantity:
:param offset:
:return:
>>> print(VerseScanner().elide("uvae avaritia", r"[e]\s*[a]"))
uv āvaritia
>>> print(VerseScanner().elide("mare avaritia", r"[e]\s*[a]"))
mar avaritia
"""
matcher = re.compile(regexp)
positions = matcher.finditer(line)
new_line = line
for match in positions:
(start, end) = match.span() # pylint: disable=unused-variable
if (start > 0) and new_line[
start - 1 : start + 1
] in self.constants.DIPTHONGS:
vowel_to_coerce = new_line[end - 1]
new_line = (
new_line[: (start - 1) + offset]
+ (" " * (quantity + 2))
+ self.constants.stress_accent_dict[vowel_to_coerce]
+ new_line[end:]
)
else:
new_line = (
new_line[: start + offset]
+ (" " * quantity)
+ new_line[start + quantity + offset :]
)
return new_line
[docs] def correct_invalid_start(self, scansion: str) -> str:
"""
If a hexameter, hendecasyllables, or pentameter scansion starts with spondee,
an unstressed syllable in the third position must actually be stressed,
so we will convert it: - - | U -> - - | -
:param scansion:
:return:
>>> print(VerseScanner().correct_invalid_start(
... " - - U U - - U U U U U U - -").strip())
- - - - - - U U U U U U - -
"""
mark_list = string_utils.mark_list(scansion)
raw_scansion = scansion.replace(" ", "")
if raw_scansion.startswith(self.constants.SPONDEE + self.constants.UNSTRESSED):
new_scansion = list(
self.constants.SPONDEE + self.constants.SPONDEE + raw_scansion[4:]
)
corrected = "".join(new_scansion)
new_sequence = list(" " * len(scansion))
for idx, car in enumerate(corrected):
new_sequence[mark_list[idx]] = car
return "".join(new_sequence)
return scansion
[docs] def correct_first_two_dactyls(self, scansion: str) -> str:
"""
If a hexameter or pentameter starts with spondee,
an unstressed syllable in the third position must actually be stressed,
so we will convert it: - - | U -> - - | -
And/or if the starting pattern is spondee + trochee + stressed, then the unstressed
trochee can be corrected: - - | - u | - -> - - | - -| -
:param scansion:
:return:
>>> print(VerseScanner().correct_first_two_dactyls(
... " - - U U - - U U U U U U - -")) # doctest: +NORMALIZE_WHITESPACE
- - - - - - U U U U U U - -
"""
mark_list = string_utils.mark_list(scansion)
new_line = self.correct_invalid_start(scansion)
raw_scansion = new_line.replace(" ", "")
if raw_scansion.startswith(
self.constants.SPONDEE + self.constants.TROCHEE + self.constants.STRESSED
):
new_scansion = list(
self.constants.SPONDEE
+ self.constants.SPONDEE
+ self.constants.STRESSED
+ raw_scansion[5:]
)
corrected = "".join(new_scansion)
new_sequence = list(" " * len(scansion))
for idx, car in enumerate(corrected):
new_sequence[mark_list[idx]] = car
return "".join(new_sequence)
return new_line
[docs] def assign_candidate(self, verse: Verse, candidate: str) -> Verse:
"""
Helper method; make sure that the verse object is properly packaged.
:param verse:
:param candidate:
:return:
"""
verse.scansion = candidate
verse.valid = True
verse.accented = self.formatter.merge_line_scansion(
verse.original, verse.scansion
)
return verse