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Replace re.sub by the faster str.translate. #23295

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Merged
merged 1 commit into from
Jun 21, 2022
Merged

Replace re.sub by the faster str.translate. #23295

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46 changes: 17 additions & 29 deletions lib/matplotlib/backends/backend_pdf.py
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Original file line number Diff line number Diff line change
Expand Up @@ -13,7 +13,6 @@
import logging
import math
import os
import re
import string
import struct
import sys
Expand Down Expand Up @@ -119,25 +118,6 @@ def _fill(strings, linelen=75):
result.append(b' '.join(strings[lasti:]))
return b'\n'.join(result)

# PDF strings are supposed to be able to include any eight-bit data,
# except that unbalanced parens and backslashes must be escaped by a
# backslash. However, sf bug #2708559 shows that the carriage return
# character may get read as a newline; these characters correspond to
# \gamma and \Omega in TeX's math font encoding. Escaping them fixes
# the bug.
_string_escape_regex = re.compile(br'([\\()\r\n])')


def _string_escape(match):
m = match.group(0)
if m in br'\()':
return b'\\' + m
elif m == b'\n':
return br'\n'
elif m == b'\r':
return br'\r'
assert False


def _create_pdf_info_dict(backend, metadata):
"""
Expand Down Expand Up @@ -267,6 +247,15 @@ def _get_link_annotation(gc, x, y, width, height):
return link_annotation


# PDF strings are supposed to be able to include any eight-bit data, except
# that unbalanced parens and backslashes must be escaped by a backslash.
# However, sf bug #2708559 shows that the carriage return character may get
# read as a newline; these characters correspond to \gamma and \Omega in TeX's
# math font encoding. Escaping them fixes the bug.
_str_escapes = str.maketrans({
'\\': '\\\\', '(': '\\(', ')': '\\)', '\n': '\\n', '\r': '\\r'})


def pdfRepr(obj):
"""Map Python objects to PDF syntax."""

Expand All @@ -292,22 +281,21 @@ def pdfRepr(obj):
elif isinstance(obj, (int, np.integer)):
return b"%d" % obj

# Unicode strings are encoded in UTF-16BE with byte-order mark.
# Non-ASCII Unicode strings are encoded in UTF-16BE with byte-order mark.
elif isinstance(obj, str):
try:
# But maybe it's really ASCII?
s = obj.encode('ASCII')
return pdfRepr(s)
except UnicodeEncodeError:
s = codecs.BOM_UTF16_BE + obj.encode('UTF-16BE')
return pdfRepr(s)
return pdfRepr(obj.encode('ascii') if obj.isascii()
else codecs.BOM_UTF16_BE + obj.encode('UTF-16BE'))

# Strings are written in parentheses, with backslashes and parens
# escaped. Actually balanced parens are allowed, but it is
# simpler to escape them all. TODO: cut long strings into lines;
# I believe there is some maximum line length in PDF.
# Despite the extra decode/encode, translate is faster than regex.
elif isinstance(obj, bytes):
return b'(' + _string_escape_regex.sub(_string_escape, obj) + b')'
return (
b'(' +
obj.decode('latin-1').translate(_str_escapes).encode('latin-1')
+ b')')

# Dictionaries. The keys must be PDF names, so if we find strings
# there, we make Name objects from them. The values may be
Expand Down