Mercurial > public > mercurial-scm > hg
comparison mercurial/utils/stringutil.py @ 49030:75794847ef62
stringutil: try to avoid running `splitlines()` only to get first line
It's wasteful to call `splitlines()` and only get the first line from
it. However, Python doesn't seem to provide a built-in way of doing
just one split based on the set of bytes used by `splitlines()`. As a
workaround, we do an initial split on just LF and then call
`splitlines()` on the result. Thanks to Joerg for this suggestion. I
didn't bother to also split on CR, so users with old Mac editors (or
repos created by such editors) will not get this performance
improvement.
Differential Revision: https://phab.mercurial-scm.org/D12413
| author | Martin von Zweigbergk <martinvonz@google.com> |
|---|---|
| date | Fri, 25 Mar 2022 08:33:03 -0700 |
| parents | 51aed118f9dc |
| children | d44e3c45f0e4 |
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| 49029:eb8aed493a56 | 49030:75794847ef62 |
|---|---|
| 685 return _correctauthorformat.match(author) is not None | 685 return _correctauthorformat.match(author) is not None |
| 686 | 686 |
| 687 | 687 |
| 688 def firstline(text): | 688 def firstline(text): |
| 689 """Return the first line of the input""" | 689 """Return the first line of the input""" |
| 690 # Try to avoid running splitlines() on the whole string | |
| 691 i = text.find(b'\n') | |
| 692 if i != -1: | |
| 693 text = text[:i] | |
| 690 try: | 694 try: |
| 691 return text.splitlines()[0] | 695 return text.splitlines()[0] |
| 692 except IndexError: | 696 except IndexError: |
| 693 return b'' | 697 return b'' |
| 694 | 698 |