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Differential D4364

match: document that visitchildrenset might return files
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Authored by spectral on Aug 24 2018, 1:19 AM.

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rHG27946fca8a05: match: document that visitchildrenset might return files
Summary

At least when using includematcher, and probably most matchers, we do not know
if a/b/f refers to a file 'f' in a/b, or a subdirectory 'f' in a/b, so most
matchers will return {'f'} for visitchildrenset('a/b'). Arguably, all matchers
could/should - for exactmatcher, we know that 'f' is a file, but there's no
reason to return 'this' for visitchildrenset('a/b') causing code to investigate
'a/b/x', for example.

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rHG Mercurial
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Changeset List

PathPackages
Mmercurial/dirstate.py (13 lines)
Mmercurial/match.py (17 lines)

Diff 10559

mercurial/dirstate.py

entries = listdir(join(nd), stat=True, skip=skip) entries = listdir(join(nd), stat=True, skip=skip)
except OSError as inst: except OSError as inst:
if inst.errno in (errno.EACCES, errno.ENOENT): if inst.errno in (errno.EACCES, errno.ENOENT):
match.bad(self.pathto(nd), match.bad(self.pathto(nd),
encoding.strtolocal(inst.strerror)) encoding.strtolocal(inst.strerror))
continue continue
raise raise
for f, kind, st in entries: for f, kind, st in entries:
# If we needed to inspect any files, visitentries would have # Some matchers may return files in the visitentries set,
# been 'this' or 'all', and we would have set it to None # instead of 'this', if the matcher explicitly mentions them
# above. If we have visitentries populated here, we don't # and is not an exactmatcher. This is acceptable; we do not
# care about any files in this directory, so no need to # make any hard assumptions about file-or-directory below
# check the type of `f`. # based on the presence of `f` in visitentries. If
# visitchildrenset returned a set, we can always skip the
# entries *not* in the set it provided regardless of whether
# they're actually a file or a directory.
if visitentries and f not in visitentries: if visitentries and f not in visitentries:
continue continue
if normalizefile: if normalizefile:
# even though f might be a directory, we're only # even though f might be a directory, we're only
# interested in comparing it to files currently in the # interested in comparing it to files currently in the
# dmap -- therefore normalizefile is enough # dmap -- therefore normalizefile is enough
nf = normalizefile(nd and (nd + "/" + f) or f, True, nf = normalizefile(nd and (nd + "/" + f) or f, True,
True) True)

mercurial/match.py

This function is very similar to 'visitdir', and the following mapping This function is very similar to 'visitdir', and the following mapping
can be applied: can be applied:
visitdir | visitchildrenlist visitdir | visitchildrenlist
----------+------------------- ----------+-------------------
False | set() False | set()
'all' | 'all' 'all' | 'all'
True | 'this' OR non-empty set of subdirs to visit True | 'this' OR non-empty set of subdirs -or files- to visit
Example: Example:
Assume matchers ['path:foo/bar', 'rootfilesin:qux'], we would return Assume matchers ['path:foo/bar', 'rootfilesin:qux'], we would return
the following values (assuming the implementation of visitchildrenset the following values (assuming the implementation of visitchildrenset
is capable of recognizing this; some implementations are not). is capable of recognizing this; some implementations are not).
'.' -> {'foo', 'qux'} '.' -> {'foo', 'qux'}
'baz' -> set() 'baz' -> set()
'foo' -> {'bar'} 'foo' -> {'bar'}
# Ideally this would be 'all', but since the prefix nature of matchers # Ideally this would be 'all', but since the prefix nature of matchers
# is applied to the entire matcher, we have to downgrade to this # is applied to the entire matcher, we have to downgrade this to
# 'this' due to the non-prefix 'rootfilesin'-kind matcher. # 'this' due to the non-prefix 'rootfilesin'-kind matcher being mixed
# in.
'foo/bar' -> 'this' 'foo/bar' -> 'this'
'qux' -> 'this' 'qux' -> 'this'
Important:
Most matchers do not know if they're representing files or
directories. They see ['path:dir/f'] and don't know whether 'f' is a
file or a directory, so visitchildrenset('dir') for most matchers will
return {'f'}, but if the matcher knows it's a file (like exactmatcher
does), it may return 'this'. Do not rely on the return being a set
indicating that there are no files in this dir to investigate (or
equivalently that if there are files to investigate in 'dir' that it
will always return 'this').
''' '''
return 'this' return 'this'
def always(self): def always(self):
'''Matcher will match everything and .files() will be empty -- '''Matcher will match everything and .files() will be empty --
optimization might be possible.''' optimization might be possible.'''
return False return False