Speed up matching of case-insensitive character sets

"""Benchmark: SRE(count) fast path for case-insensitive set repeats."""
import re
import pyperf

N = 100
MIXED   = ("aBcDeFgHiJkLmNoPqRsTuVwX" * N)[:N]
ALNUM   = ("aB3dE6gH9kLmN0pQrStUvWx1" * N)[:N]
WORD    = ("aB_dE_gH_kLmN_pQrStUvW_1" * N)[:N]
NODIGIT = ("aBcDeF gHiJkL!mNoPqR.sT?" * N)[:N]
BYTES   = MIXED.encode("latin1")

SCANS = [
    ("scan_alpha_uni",  re.compile(r"[a-z]+",    re.I),        MIXED),
    ("scan_alpha_asc",  re.compile(r"[a-z]+",    re.I | re.A), MIXED),
    ("scan_alnum_uni",  re.compile(r"[a-z0-9]+", re.I),        ALNUM),
    ("scan_word_uni",   re.compile(r"[a-z0-9_]+",re.I),        WORD),
    ("scan_neg_uni",    re.compile(r"[^0-9]+",   re.I),        NODIGIT),
    ("scan_vowels_uni", re.compile(r"[aeiou]+",  re.I),        "aAeEiIoOuU" * (N // 10)),
    ("scan_alpha_loc",  re.compile(rb"[a-z]+",   re.L | re.I), BYTES),
]
DOC = ("The Quick Brown Fox jumps over 12 Lazy Dogs near IP 10_0_0_1 and Node7. " * 50)
FINDS = [
    ("find_words_ci", re.compile(r"[a-z]+",           re.I), DOC),
    ("find_ident_ci", re.compile(r"[a-z_][a-z0-9_]*", re.I), DOC),
]

def make_scan(p, s):
    def run():
        assert p.match(s) is not None
    return run

runner = pyperf.Runner()
for name, p, s in SCANS:
    runner.bench_func(name, make_scan(p, s))
for name, p, s in FINDS:
    runner.bench_func(name, (lambda p, s: lambda: p.findall(s))(p, s))

Run under the unpatched and patched builds, then
python -m pyperf compare_to before.json after.json --table.