cola/utils.py

   1 """Miscellaneous utility functions"""
   2 import copy
   3 import os
   4 import random
   5 import re
   6 import shlex
   7 import sys
   8 import tempfile
   9 import time
  10 import traceback
  11
  12 from . import core
  13 from . import compat
  14
  15 random.seed(hash(time.time()))
  16
  17
  18 def asint(obj, default=0):
  19     """Make any value into an int, even if the cast fails"""
  20     try:
  21         value = int(obj)
  22     except (TypeError, ValueError):
  23         value = default
  24     return value
  25
  26
  27 def clamp(value, low, high):
  28     """Clamp a value to the specified range"""
  29     return min(high, max(low, value))
  30
  31
  32 def epoch_millis():
  33     return int(time.time() * 1000)
  34
  35
  36 def add_parents(paths):
  37     """Iterate over each item in the set and add its parent directories."""
  38     all_paths = set()
  39     for path in paths:
  40         while '//' in path:
  41             path = path.replace('//', '/')
  42         all_paths.add(path)
  43         if '/' in path:
  44             parent_dir = dirname(path)
  45             while parent_dir:
  46                 all_paths.add(parent_dir)
  47                 parent_dir = dirname(parent_dir)
  48     return all_paths
  49
  50
  51 def format_exception(exc):
  52     """Format an exception object for display"""
  53     exc_type, exc_value, exc_tb = sys.exc_info()
  54     details = traceback.format_exception(exc_type, exc_value, exc_tb)
  55     details = '\n'.join(map(core.decode, details))
  56     if hasattr(exc, 'msg'):
  57         msg = exc.msg
  58     else:
  59         msg = core.decode(repr(exc))
  60     return (msg, details)
  61
  62
  63 def sublist(values, remove):
  64     """Subtracts list b from list a and returns the resulting list."""
  65     # conceptually, c = a - b
  66     result = []
  67     for item in values:
  68         if item not in remove:
  69             result.append(item)
  70     return result
  71
  72
  73 __grep_cache = {}
  74
  75
  76 def grep(pattern, items, squash=True):
  77     """Greps a list for items that match a pattern
  78
  79     :param squash: If only one item matches, return just that item
  80     :returns: List of matching items
  81
  82     """
  83     isdict = isinstance(items, dict)
  84     if pattern in __grep_cache:
  85         regex = __grep_cache[pattern]
  86     else:
  87         regex = __grep_cache[pattern] = re.compile(pattern)
  88     matched = []
  89     matchdict = {}
  90     for item in items:
  91         match = regex.match(item)
  92         if not match:
  93             continue
  94         groups = match.groups()
  95         if not groups:
  96             subitems = match.group(0)
  97         else:
  98             if len(groups) == 1:
  99                 subitems = groups[0]
 100             else:
 101                 subitems = list(groups)
 102         if isdict:
 103             matchdict[item] = items[item]
 104         else:
 105             matched.append(subitems)
 106
 107     if isdict:
 108         result = matchdict
 109     elif squash and len(matched) == 1:
 110         result = matched[0]
 111     else:
 112         result = matched
 113
 114     return result
 115
 116
 117 def basename(path):
 118     """
 119     An os.path.basename() implementation that always uses '/'
 120
 121     Avoid os.path.basename because git's output always
 122     uses '/' regardless of platform.
 123
 124     """
 125     return path.rsplit('/', 1)[-1]
 126
 127
 128 def strip_one(path):
 129     """Strip one level of directory"""
 130     return path.strip('/').split('/', 1)[-1]
 131
 132
 133 def dirname(path, current_dir=''):
 134     """
 135     An os.path.dirname() implementation that always uses '/'
 136
 137     Avoid os.path.dirname because git's output always
 138     uses '/' regardless of platform.
 139
 140     """
 141     while '//' in path:
 142         path = path.replace('//', '/')
 143     path_dirname = path.rsplit('/', 1)[0]
 144     if path_dirname == path:
 145         return current_dir
 146     return path.rsplit('/', 1)[0]
 147
 148
 149 def splitpath(path):
 150     """Split paths using '/' regardless of platform"""
 151     return path.split('/')
 152
 153
 154 def split(name):
 155     """Split a path-like name. Returns tuple "(head, tail)" where "tail" is
 156     everything after the final slash. The "head" may be empty.
 157
 158     This is the same as os.path.split() but only uses '/' as the delimiter.
 159
 160     >>> split('a/b/c')
 161     ('a/b', 'c')
 162
 163     >>> split('xyz')
 164     ('', 'xyz')
 165
 166     """
 167     return (dirname(name), basename(name))
 168
 169
 170 def join(*paths):
 171     """Join paths using '/' regardless of platform
 172
 173     >>> join('a', 'b', 'c')
 174     'a/b/c'
 175
 176     """
 177     return '/'.join(paths)
 178
 179
 180 def normalize_slash(value):
 181     """Strip and normalize slashes in a string
 182
 183     >>> normalize_slash('///Meow///Cat///')
 184     'Meow/Cat'
 185
 186     """
 187     value = value.strip('/')
 188     new_value = value.replace('//', '/')
 189     while new_value != value:
 190         value = new_value
 191         new_value = value.replace('//', '/')
 192     return value
 193
 194
 195 def pathjoin(paths):
 196     """Join a list of paths using '/' regardless of platform
 197
 198     >>> pathjoin(['a', 'b', 'c'])
 199     'a/b/c'
 200
 201     """
 202     return join(*paths)
 203
 204
 205 def pathset(path):
 206     """Return all of the path components for the specified path
 207
 208     >>> pathset('foo/bar/baz') == ['foo', 'foo/bar', 'foo/bar/baz']
 209     True
 210
 211     """
 212     result = []
 213     parts = splitpath(path)
 214     prefix = ''
 215     for part in parts:
 216         result.append(prefix + part)
 217         prefix += part + '/'
 218
 219     return result
 220
 221
 222 def select_directory(paths):
 223     """Return the first directory in a list of paths"""
 224     if not paths:
 225         return core.getcwd()
 226
 227     for path in paths:
 228         if core.isdir(path):
 229             return path
 230
 231     return os.path.dirname(paths[0]) or core.getcwd()
 232
 233
 234 def strip_prefix(prefix, string):
 235     """Return string, without the prefix. Blow up if string doesn't
 236     start with prefix."""
 237     assert string.startswith(prefix)
 238     return string[len(prefix) :]
 239
 240
 241 def tablength(word, tabwidth):
 242     """Return length of a word taking tabs into account
 243
 244     >>> tablength("\\t\\t\\t\\tX", 8)
 245     33
 246
 247     """
 248     return len(word.replace('\t', '')) + word.count('\t') * tabwidth
 249
 250
 251 def _shell_split_py2(value):
 252     """Python2 requires bytes inputs to shlex.split().  Returns [unicode]"""
 253     try:
 254         result = shlex.split(core.encode(value))
 255     except ValueError:
 256         result = core.encode(value).strip().split()
 257     # Decode to unicode strings
 258     return [core.decode(arg) for arg in result]
 259
 260
 261 def _shell_split_py3(value):
 262     """Python3 requires unicode inputs to shlex.split().  Converts to unicode"""
 263     try:
 264         result = shlex.split(value)
 265     except ValueError:
 266         result = core.decode(value).strip().split()
 267     # Already unicode
 268     return result
 269
 270
 271 def shell_split(value):
 272     if compat.PY2:
 273         # Encode before calling split()
 274         values = _shell_split_py2(value)
 275     else:
 276         # Python3 does not need the encode/decode dance
 277         values = _shell_split_py3(value)
 278     return values
 279
 280
 281 def tmp_filename(label, suffix=''):
 282     label = 'git-cola-' + label.replace('/', '-').replace('\\', '-')
 283     with tempfile.NamedTemporaryFile(
 284         prefix=label + '-', suffix=suffix, delete=False
 285     ) as handle:
 286         return handle.name
 287
 288
 289 def is_linux():
 290     """Is this a linux machine?"""
 291     return sys.platform.startswith('linux')
 292
 293
 294 def is_debian():
 295     """Is it debian?"""
 296     return os.path.exists('/usr/bin/apt-get')
 297
 298
 299 def is_darwin():
 300     """Return True on OSX."""
 301     return sys.platform == 'darwin'
 302
 303
 304 def is_win32():
 305     """Return True on win32"""
 306     return sys.platform in {'win32', 'cygwin'}
 307
 308
 309 def launch_default_app(paths):
 310     """Execute the default application on the specified paths"""
 311     if is_win32():
 312         for path in paths:
 313             if hasattr(os, 'startfile'):
 314                 os.startfile(path)  # pylint: disable=no-member
 315         return
 316
 317     if is_darwin():
 318         launcher = 'open'
 319     else:
 320         launcher = 'xdg-open'
 321
 322     core.fork([launcher] + paths)
 323
 324
 325 def expandpath(path):
 326     """Expand ~user/ and environment $variables"""
 327     path = os.path.expandvars(path)
 328     if path.startswith('~'):
 329         path = os.path.expanduser(path)
 330     return path
 331
 332
 333 class Group:
 334     """Operate on a collection of objects as a single unit"""
 335
 336     def __init__(self, *members):
 337         self._members = members
 338
 339     def __getattr__(self, name):
 340         """Return a function that relays calls to the group"""
 341
 342         def relay(*args, **kwargs):
 343             for member in self._members:
 344                 method = getattr(member, name)
 345                 method(*args, **kwargs)
 346
 347         setattr(self, name, relay)
 348         return relay
 349
 350
 351 class Proxy:
 352     """Wrap an object and override attributes"""
 353
 354     def __init__(self, obj, **overrides):
 355         self._obj = obj
 356         for k, v in overrides.items():
 357             setattr(self, k, v)
 358
 359     def __getattr__(self, name):
 360         return getattr(self._obj, name)
 361
 362
 363 def slice_func(input_items, map_func):
 364     """Slice input_items and call `map_func` over every slice
 365
 366     This exists because of "errno: Argument list too long"
 367
 368     """
 369     # This comment appeared near the top of include/linux/binfmts.h
 370     # in the Linux source tree:
 371     #
 372     # /*
 373     #  * MAX_ARG_PAGES defines the number of pages allocated for arguments
 374     #  * and envelope for the new program. 32 should suffice, this gives
 375     #  * a maximum env+arg of 128kB w/4KB pages!
 376     #  */
 377     # #define MAX_ARG_PAGES 32
 378     #
 379     # 'size' is a heuristic to keep things highly performant by minimizing
 380     # the number of slices.  If we wanted it to run as few commands as
 381     # possible we could call "getconf ARG_MAX" and make a better guess,
 382     # but it's probably not worth the complexity (and the extra call to
 383     # getconf that we can't do on Windows anyways).
 384     #
 385     # In my testing, getconf ARG_MAX on Mac OS X Mountain Lion reported
 386     # 262144 and Debian/Linux-x86_64 reported 2097152.
 387     #
 388     # The hard-coded max_arg_len value is safely below both of these
 389     # real-world values.
 390
 391     # 4K pages x 32 MAX_ARG_PAGES
 392     max_arg_len = (32 * 4096) // 4  # allow plenty of space for the environment
 393     max_filename_len = 256
 394     size = max_arg_len // max_filename_len
 395
 396     status = 0
 397     outs = []
 398     errs = []
 399
 400     items = copy.copy(input_items)
 401     while items:
 402         stat, out, err = map_func(items[:size])
 403         if stat < 0:
 404             status = min(stat, status)
 405         else:
 406             status = max(stat, status)
 407         outs.append(out)
 408         errs.append(err)
 409         items = items[size:]
 410
 411     return (status, '\n'.join(outs), '\n'.join(errs))
 412
 413
 414 class Sequence:
 415     def __init__(self, sequence):
 416         self.sequence = sequence
 417
 418     def index(self, item, default=-1):
 419         try:
 420             idx = self.sequence.index(item)
 421         except ValueError:
 422             idx = default
 423         return idx
 424
 425     def __getitem__(self, idx):
 426         return self.sequence[idx]
 427
 428
 429 def catch_runtime_error(func, *args, **kwargs):
 430     """Run the function safely.
 431
 432     Catch RuntimeError to avoid tracebacks during application shutdown.
 433
 434     """
 435     # Signals and callbacks can sometimes get triggered during application shutdown.
 436     # This can happen when exiting while background tasks are still processing.
 437     # Guard against this by making this operation a no-op.
 438     try:
 439         valid = True
 440         result = func(*args, **kwargs)
 441     except RuntimeError:
 442         valid = False
 443         result = None
 444     return (valid, result)