Initial commit

venv/lib/python3.10/site-packages/matplotlib/_fontconfig_pattern.py

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+"""
+A module for parsing and generating `fontconfig patterns`_.
+
+.. _fontconfig patterns:
+   https://www.freedesktop.org/software/fontconfig/fontconfig-user.html
+"""
+
+# This class logically belongs in `matplotlib.font_manager`, but placing it
+# there would have created cyclical dependency problems, because it also needs
+# to be available from `matplotlib.rcsetup` (for parsing matplotlibrc files).
+
+from functools import lru_cache, partial
+import re
+
+from pyparsing import (
+    Group, Optional, ParseException, Regex, StringEnd, Suppress, ZeroOrMore, one_of)
+
+
+_family_punc = r'\\\-:,'
+_family_unescape = partial(re.compile(r'\\(?=[%s])' % _family_punc).sub, '')
+_family_escape = partial(re.compile(r'(?=[%s])' % _family_punc).sub, r'\\')
+_value_punc = r'\\=_:,'
+_value_unescape = partial(re.compile(r'\\(?=[%s])' % _value_punc).sub, '')
+_value_escape = partial(re.compile(r'(?=[%s])' % _value_punc).sub, r'\\')
+
+
+_CONSTANTS = {
+    'thin':           ('weight', 'light'),
+    'extralight':     ('weight', 'light'),
+    'ultralight':     ('weight', 'light'),
+    'light':          ('weight', 'light'),
+    'book':           ('weight', 'book'),
+    'regular':        ('weight', 'regular'),
+    'normal':         ('weight', 'normal'),
+    'medium':         ('weight', 'medium'),
+    'demibold':       ('weight', 'demibold'),
+    'semibold':       ('weight', 'semibold'),
+    'bold':           ('weight', 'bold'),
+    'extrabold':      ('weight', 'extra bold'),
+    'black':          ('weight', 'black'),
+    'heavy':          ('weight', 'heavy'),
+    'roman':          ('slant', 'normal'),
+    'italic':         ('slant', 'italic'),
+    'oblique':        ('slant', 'oblique'),
+    'ultracondensed': ('width', 'ultra-condensed'),
+    'extracondensed': ('width', 'extra-condensed'),
+    'condensed':      ('width', 'condensed'),
+    'semicondensed':  ('width', 'semi-condensed'),
+    'expanded':       ('width', 'expanded'),
+    'extraexpanded':  ('width', 'extra-expanded'),
+    'ultraexpanded':  ('width', 'ultra-expanded'),
+}
+
+
+@lru_cache  # The parser instance is a singleton.
+def _make_fontconfig_parser():
+    def comma_separated(elem):
+        return elem + ZeroOrMore(Suppress(",") + elem)
+
+    family = Regex(fr"([^{_family_punc}]|(\\[{_family_punc}]))*")
+    size = Regex(r"([0-9]+\.?[0-9]*|\.[0-9]+)")
+    name = Regex(r"[a-z]+")
+    value = Regex(fr"([^{_value_punc}]|(\\[{_value_punc}]))*")
+    prop = Group((name + Suppress("=") + comma_separated(value)) | one_of(_CONSTANTS))
+    return (
+        Optional(comma_separated(family)("families"))
+        + Optional("-" + comma_separated(size)("sizes"))
+        + ZeroOrMore(":" + prop("properties*"))
+        + StringEnd()
+    )
+
+
+# `parse_fontconfig_pattern` is a bottleneck during the tests because it is
+# repeatedly called when the rcParams are reset (to validate the default
+# fonts).  In practice, the cache size doesn't grow beyond a few dozen entries
+# during the test suite.
+@lru_cache
+def parse_fontconfig_pattern(pattern):
+    """
+    Parse a fontconfig *pattern* into a dict that can initialize a
+    `.font_manager.FontProperties` object.
+    """
+    parser = _make_fontconfig_parser()
+    try:
+        parse = parser.parse_string(pattern)
+    except ParseException as err:
+        # explain becomes a plain method on pyparsing 3 (err.explain(0)).
+        raise ValueError("\n" + ParseException.explain(err, 0)) from None
+    parser.reset_cache()
+    props = {}
+    if "families" in parse:
+        props["family"] = [*map(_family_unescape, parse["families"])]
+    if "sizes" in parse:
+        props["size"] = [*parse["sizes"]]
+    for prop in parse.get("properties", []):
+        if len(prop) == 1:
+            prop = _CONSTANTS[prop[0]]
+        k, *v = prop
+        props.setdefault(k, []).extend(map(_value_unescape, v))
+    return props
+
+
+def generate_fontconfig_pattern(d):
+    """Convert a `.FontProperties` to a fontconfig pattern string."""
+    kvs = [(k, getattr(d, f"get_{k}")())
+           for k in ["style", "variant", "weight", "stretch", "file", "size"]]
+    # Families is given first without a leading keyword.  Other entries (which
+    # are necessarily scalar) are given as key=value, skipping Nones.
+    return (",".join(_family_escape(f) for f in d.get_family())
+            + "".join(f":{k}={_value_escape(str(v))}"
+                      for k, v in kvs if v is not None))