import itertools
import logging
import subprocess
import sys
import tempfile
import time
_log = logging.getLogger(__name__)
def call(cmd):
"""Executes `cmd` and swallow stderr iff returncode is 0."""
with tempfile.TemporaryFile(prefix='stderr') as capture:
try:
output = subprocess.check_output(cmd, stderr=capture)
except subprocess.CalledProcessError:
capture.seek(0)
sys.stderr.write(capture.read().decode('ascii', errors='replace'))
raise
return output.decode()
class Timer:
def __init__(self, section):
self.section = section
def __enter__(self):
_log.debug('>>> %s', self.section)
self.start = time.clock_gettime(time.CLOCK_MONOTONIC)
return self
def __exit__(self, *exc):
self.end = time.clock_gettime(time.CLOCK_MONOTONIC)
self.interval = self.end - self.start
_log.debug('<<< %s %.2fs', self.section, self.interval)
return False # re-raise
def components_lt(left, right):
"""Port from nix/src/libexpr/names.cc"""
try:
lnum = int(left)
except (ValueError):
lnum = None
try:
rnum = int(right)
except (ValueError):
rnum = None
if lnum is not None and rnum is not None:
return lnum < rnum
if left == '' and rnum is not None:
return True
if left == 'pre' and right != 'pre':
return True
if right == 'pre':
return False
if rnum is not None:
return True
if lnum is not None:
return False
return left < right
def category(char):
"""Classify `char` into: punctuation, digit, non-digit."""
if char in ('.', '-'):
return 0
if char in ('0', '1', '2', '3', '4', '5', '6', '7', '8', '9'):
return 1
return 2
def split_components(v):
"""Yield cohesive groups of digits or non-digits. Skip punctuation."""
start = 0
stop = len(v)
while start < stop:
cat0 = category(v[start])
i = start + 1
while i < stop and category(v[i]) == cat0:
i += 1
if cat0 != 0:
yield v[start:i]
start = i
def compare_versions(left, right):
"""Compare two versions with the same logic as `nix-env -u`.
Returns -1 if `left` is older than `right`, 1 if `left` is newer
than `right`, and 0 if both versions are considered equal.
See https://nixos.org/nix/manual/#ssec-version-comparisons for rules
and examples.
"""
if left == right:
return 0
for (lc, rc) in itertools.zip_longest(
split_components(left), split_components(right), fillvalue=''):
if lc == rc:
continue
if components_lt(lc, rc):
return -1
if components_lt(rc, lc):
return 1
return 0
def haskeys(d, *keys):
"""Returns True if all keys are present in a nested dict `d`."""
if len(keys) == 1:
return keys[0] in d
first = keys[0]
if first in d and isinstance(d[first], dict):
return haskeys(d[first], *keys[1:])
return False
