PERF: Cython version of Python _TIMEPAT regexp in parsing.pyx
State: closed

- [x] closes #N/A
- [ ] tests added / passed
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

`asv continuous -f 1.05 origin/master HEAD -b ^io.csv.ReadCSVParseSpecialDate -a warmup_time=2 -a sample_time=2`:

master | patch | ratio | test_name
-|-|-|-
276±1ms|          262±2ms|     0.95|  io.csv.ReadCSVParseSpecialDate.time_read_special_date('hm')
16.6±0.2ms|      14.2±0.08ms|     0.85|  io.csv.ReadCSVParseSpecialDate.time_read_special_date('mdY')
42.7±0.9ms|       35.0±0.2ms |    0.82|  io.csv.ReadCSVParseSpecialDate.time_read_special_date('mY')


Labels:
name: Datetime
description: Datetime data dtype
name: Performance
description: Memory or execution speed performance

Comments:
# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/26204?src=pr&el=h1) Report
> Merging [#26204](https://codecov.io/gh/pandas-dev/pandas/pull/26204?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/d74901b1a114d70244fb919e8de630fb53481b00?src=pr&el=desc) will **decrease** coverage by `<.01%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/26204/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/26204?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #26204      +/-   ##
==========================================
- Coverage   91.98%   91.98%   -0.01%     
==========================================
  Files         175      175              
  Lines       52372    52372              
==========================================
- Hits        48176    48173       -3     
- Misses       4196     4199       +3
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.53% <ø> (ø)` | :arrow_up: |
| #single | `40.7% <ø> (-0.16%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/26204?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/io/gbq.py](https://codecov.io/gh/pandas-dev/pandas/pull/26204/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2dicS5weQ==) | `78.94% <0%> (-10.53%)` | :arrow_down: |
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/26204/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `96.9% <0%> (-0.12%)` | :arrow_down: |
| [pandas/util/testing.py](https://codecov.io/gh/pandas-dev/pandas/pull/26204/diff?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvdGVzdGluZy5weQ==) | `90.71% <0%> (+0.1%)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/26204?src=pr&el=continue).
> **Legend** - [Click here to learn more](https://docs.codecov.io/docs/codecov-delta)
> `Δ = absolute <relative> (impact)`, `ø = not affected`, `? = missing data`
> Powered by [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/26204?src=pr&el=footer). Last update [d74901b...8f26757](https://codecov.io/gh/pandas-dev/pandas/pull/26204?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).

# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/26204?src=pr&el=h1) Report
> Merging [#26204](https://codecov.io/gh/pandas-dev/pandas/pull/26204?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/d41c1da192ef935c2931d2bb1bf8547c9435a012?src=pr&el=desc) will **decrease** coverage by `<.01%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/26204/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/26204?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #26204      +/-   ##
==========================================
- Coverage   91.98%   91.98%   -0.01%     
==========================================
  Files         175      175              
  Lines       52372    52372              
==========================================
- Hits        48176    48172       -4     
- Misses       4196     4200       +4
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.53% <ø> (ø)` | :arrow_up: |
| #single | `40.7% <ø> (-0.15%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/26204?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/io/gbq.py](https://codecov.io/gh/pandas-dev/pandas/pull/26204/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2dicS5weQ==) | `78.94% <0%> (-10.53%)` | :arrow_down: |
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/26204/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `96.9% <0%> (-0.12%)` | :arrow_down: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/26204?src=pr&el=continue).
> **Legend** - [Click here to learn more](https://docs.codecov.io/docs/codecov-delta)
> `Δ = absolute <relative> (impact)`, `ø = not affected`, `? = missing data`
> Powered by [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/26204?src=pr&el=footer). Last update [d41c1da...464380f](https://codecov.io/gh/pandas-dev/pandas/pull/26204?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).

Note to reviewers - current failures seem to be introduced by #26200
also merge master; ci has been fixed
> also merge master; ci has been fixed

I've rebased instead, I personally find rebased history cleaner than merged.
> I've rebased instead, I personally find rebased history cleaner than merged.

I agree :-D

we use merge master as its somwhat friendlier to new users, in any event everything is squashed on merge anyways (so the commit history is only relevant to you)
@jreback pinging on green
thanks @anmyachev