Add jaraco.context==4.1.1

[skip ci]

lib/jaraco/context.py

@@ -0,0 +1,213 @@
+import os
+import subprocess
+import contextlib
+import functools
+import tempfile
+import shutil
+import operator
+
+
+@contextlib.contextmanager
+def pushd(dir):
+    orig = os.getcwd()
+    os.chdir(dir)
+    try:
+        yield dir
+    finally:
+        os.chdir(orig)
+
+
+@contextlib.contextmanager
+def tarball_context(url, target_dir=None, runner=None, pushd=pushd):
+    """
+    Get a tarball, extract it, change to that directory, yield, then
+    clean up.
+    `runner` is the function to invoke commands.
+    `pushd` is a context manager for changing the directory.
+    """
+    if target_dir is None:
+        target_dir = os.path.basename(url).replace('.tar.gz', '').replace('.tgz', '')
+    if runner is None:
+        runner = functools.partial(subprocess.check_call, shell=True)
+    # In the tar command, use --strip-components=1 to strip the first path and
+    #  then
+    #  use -C to cause the files to be extracted to {target_dir}. This ensures
+    #  that we always know where the files were extracted.
+    runner('mkdir {target_dir}'.format(**vars()))
+    try:
+        getter = 'wget {url} -O -'
+        extract = 'tar x{compression} --strip-components=1 -C {target_dir}'
+        cmd = ' | '.join((getter, extract))
+        runner(cmd.format(compression=infer_compression(url), **vars()))
+        with pushd(target_dir):
+            yield target_dir
+    finally:
+        runner('rm -Rf {target_dir}'.format(**vars()))
+
+
+def infer_compression(url):
+    """
+    Given a URL or filename, infer the compression code for tar.
+    """
+    # cheat and just assume it's the last two characters
+    compression_indicator = url[-2:]
+    mapping = dict(gz='z', bz='j', xz='J')
+    # Assume 'z' (gzip) if no match
+    return mapping.get(compression_indicator, 'z')
+
+
+@contextlib.contextmanager
+def temp_dir(remover=shutil.rmtree):
+    """
+    Create a temporary directory context. Pass a custom remover
+    to override the removal behavior.
+    """
+    temp_dir = tempfile.mkdtemp()
+    try:
+        yield temp_dir
+    finally:
+        remover(temp_dir)
+
+
+@contextlib.contextmanager
+def repo_context(url, branch=None, quiet=True, dest_ctx=temp_dir):
+    """
+    Check out the repo indicated by url.
+
+    If dest_ctx is supplied, it should be a context manager
+    to yield the target directory for the check out.
+    """
+    exe = 'git' if 'git' in url else 'hg'
+    with dest_ctx() as repo_dir:
+        cmd = [exe, 'clone', url, repo_dir]
+        if branch:
+            cmd.extend(['--branch', branch])
+        devnull = open(os.path.devnull, 'w')
+        stdout = devnull if quiet else None
+        subprocess.check_call(cmd, stdout=stdout)
+        yield repo_dir
+
+
+@contextlib.contextmanager
+def null():
+    yield
+
+
+class ExceptionTrap:
+    """
+    A context manager that will catch certain exceptions and provide an
+    indication they occurred.
+
+    >>> with ExceptionTrap() as trap:
+    ...     raise Exception()
+    >>> bool(trap)
+    True
+
+    >>> with ExceptionTrap() as trap:
+    ...     pass
+    >>> bool(trap)
+    False
+
+    >>> with ExceptionTrap(ValueError) as trap:
+    ...     raise ValueError("1 + 1 is not 3")
+    >>> bool(trap)
+    True
+
+    >>> with ExceptionTrap(ValueError) as trap:
+    ...     raise Exception()
+    Traceback (most recent call last):
+    ...
+    Exception
+
+    >>> bool(trap)
+    False
+    """
+
+    exc_info = None, None, None
+
+    def __init__(self, exceptions=(Exception,)):
+        self.exceptions = exceptions
+
+    def __enter__(self):
+        return self
+
+    @property
+    def type(self):
+        return self.exc_info[0]
+
+    @property
+    def value(self):
+        return self.exc_info[1]
+
+    @property
+    def tb(self):
+        return self.exc_info[2]
+
+    def __exit__(self, *exc_info):
+        type = exc_info[0]
+        matches = type and issubclass(type, self.exceptions)
+        if matches:
+            self.exc_info = exc_info
+        return matches
+
+    def __bool__(self):
+        return bool(self.type)
+
+    def raises(self, func, *, _test=bool):
+        """
+        Wrap func and replace the result with the truth
+        value of the trap (True if an exception occurred).
+
+        First, give the decorator an alias to support Python 3.8
+        Syntax.
+
+        >>> raises = ExceptionTrap(ValueError).raises
+
+        Now decorate a function that always fails.
+
+        >>> @raises
+        ... def fail():
+        ...     raise ValueError('failed')
+        >>> fail()
+        True
+        """
+
+        @functools.wraps(func)
+        def wrapper(*args, **kwargs):
+            with ExceptionTrap(self.exceptions) as trap:
+                func(*args, **kwargs)
+            return _test(trap)
+
+        return wrapper
+
+    def passes(self, func):
+        """
+        Wrap func and replace the result with the truth
+        value of the trap (True if no exception).
+
+        First, give the decorator an alias to support Python 3.8
+        Syntax.
+
+        >>> passes = ExceptionTrap(ValueError).passes
+
+        Now decorate a function that always fails.
+
+        >>> @passes
+        ... def fail():
+        ...     raise ValueError('failed')
+
+        >>> fail()
+        False
+        """
+        return self.raises(func, _test=operator.not_)
+
+
+class suppress(contextlib.suppress, contextlib.ContextDecorator):
+    """
+    A version of contextlib.suppress with decorator support.
+
+    >>> @suppress(KeyError)
+    ... def key_error():
+    ...     {}['']
+    >>> key_error()
+    """