Metadata-Version: 2.1
Name: cs.fileutils
Version: 20200318
Summary: convenience functions and classes for files and filenames/pathnames
Home-page: https://bitbucket.org/cameron_simpson/css/commits/all
Author: Cameron Simpson
Author-email: cs@cskk.id.au
License: GNU General Public License v3 or later (GPLv3+)
Description: *Latest release 20200318*:
        New findup(path,test) generator to walk up a file tree.
        
        Assorted convenience functions for files and filenames/pathnames.
        
        ## Function `abspath_from_file(path, from_file)`
        
        Return the absolute path of `path` with respect to `from_file`,
        as one might do for an include file.
        
        ## Class `BackedFile(ReadMixin)`
        
        A RawIOBase duck type
        which uses a backing file for initial data
        and writes new data to a front scratch file.
        
        ### Method `BackedFile.__init__(self, back_file, dirpath=None)`
        
        Initialise the BackedFile using `back_file` for the backing data.
        
        ## Class `BackedFile_TestMethods`
        
        Mixin for testing subclasses of BackedFile.
        Tests self.backed_fp.
        
        ## Function `compare(f1, f2, mode='rb')`
        
        Compare the contents of two file-like objects `f1` and `f2` for equality.
        
        If `f1` or `f2` is a string, open the named file using `mode`
        (default: "rb").
        
        ## Function `copy_data(fpin, fpout, nbytes, rsize=None)`
        
        Copy `nbytes` of data from `fpin` to `fpout`,
        return the number of bytes copied.
        
        Parameters:
        * `nbytes`: number of bytes to copy.
          If `None`, copy until EOF.
        * `rsize`: read size, default `DEFAULT_READSIZE`.
        
        ## Function `datafrom(arg, *a, **kw)`
        
        General purpose reader for files yielding data from `offset`.
        
        *WARNING*: this function might move the file pointer.
        
        Parameters:
        * `f`: the file from which to read data; if a string, the file
          is opened with mode="rb"; if an int, treated as an OS file
          descriptor; otherwise presumed to be a file-like object.
          If that object has a `.fileno()` method, treat that as an
          OS file descriptor and use it.
        * `offset`: starting offset for the data
        * `maxlength`: optional maximum amount of data to yield
        * `readsize`: read size, default DEFAULT_READSIZE.
        
        For file-like objects, the read1 method is used in preference
        to read if available. The file pointer is briefly moved during
        fetches.
        
        ## Function `datafrom_fd(fd, offset=None, readsize=None, aligned=True, maxlength=None)`
        
        General purpose reader for file descriptors yielding data from `offset`.
        This does not move the file descriptor position.
        
        Parameters:
        * `fd`: the file descriptor from which to read.
        * `offset`: the offset from which to read.
          If omitted, use the current file descriptor position.
        * `readsize`: the read size, default: `DEFAULT_READSIZE`
        * `aligned`: if true (the default), the first read is sized
          to align the new offset with a multiple of `readsize`.
        * `maxlength`: if specified yield no more than this many bytes of data.
        
        ## Function `file_based(*da, **dkw)`
        
        A decorator which caches a value obtained from a file.
        
        In addition to all the keyword arguments for `@cs.deco.cachedmethod`,
        this decorator also accepts the following arguments:
        * `attr_name`: the name for the associated attribute, used as
          the basis for the internal cache value attribute
        * `filename`: the filename to monitor.
          Default from the `._{attr_name}__filename attribute.
          This value will be passed to the method as the `filename` keyword
          parameter.
        * `poll_delay`: delay between file polls, default `DEFAULT_POLL_INTERVAL`.
        * `sig_func`: signature function used to encapsulate the relevant
          information about the file; default
          cs.filestate.FileState({filename}).
        
        If the decorated function raises OSError with errno == ENOENT,
        this returns None. Other exceptions are reraised.
        
        ## Function `file_data(fp, nbytes=None, rsize=None)`
        
        Read `nbytes` of data from `fp` and yield the chunks as read.
        
        Parameters:
        * `nbytes`: number of bytes to read; if None read until EOF.
        * `rsize`: read size, default DEFAULT_READSIZE.
        
        ## Function `file_property(*da, **dkw)`
        
        A property whose value reloads if a file changes.
        
        ## Function `files_property(func)`
        
        A property whose value reloads if any of a list of files changes.
        
        Note: this is just the default mode for `make_files_property`.
        
        `func` accepts the file path and returns the new value.
        The underlying attribute name is '_' + func.__name__,
        the default from make_files_property().
        The attribute {attr_name}_lock controls access to the property.
        The attributes {attr_name}_filestates and {attr_name}_paths track the
        associated file states.
        The attribute {attr_name}_lastpoll tracks the last poll time.
        
        The decorated function is passed the current list of files
        and returns the new list of files and the associated value.
        One example use would be a configuration file with recurive
        include operations; the inner function would parse the first
        file in the list, and the parse would accumulate this filename
        and those of any included files so that they can be monitored,
        triggering a fresh parse if one changes.
        
        Example:
        
            class C(object):
              def __init__(self):
                self._foo_path = '.foorc'
              @files_property
              def foo(self,paths):
                new_paths, result = parse(paths[0])
                return new_paths, result
        
        The load function is called on the first access and on every
        access thereafter where an associated file's `FileState` has
        changed and the time since the last successful load exceeds
        the poll_rate (1s). An attempt at avoiding races is made by
        ignoring reloads that raise exceptions and ignoring reloads
        where files that were stat()ed during the change check have
        changed state after the load.
        
        ## Function `findup(path, test, first=False)`
        
        Test the pathname `abspath(path)` and each of its ancestors
        against the callable `test`,
        yielding paths satisfying the test.
        
        If `first` is true (default `False`)
        this function always yields exactly one value,
        either the first path satisfying the test or `None`.
        This mode supports a use such as:
        
            matched_path = next(findup(path, test, first=True))
            # post condition: matched_path will be `None` on no match
            # otherwise the first matching path
        
        ## Function `lines_of(fp, partials=None)`
        
        Generator yielding lines from a file until EOF.
        Intended for file-like objects that lack a line iteration API.
        
        ## Function `lockfile(path, ext=None, poll_interval=None, timeout=None, runstate=None)`
        
        A context manager which takes and holds a lock file.
        
        Parameters:
        * `path`: the base associated with the lock file.
        * `ext`: the extension to the base used to construct the lock file name.
          Default: ".lock"
        * `timeout`: maximum time to wait before failing.
          Default: `None` (wait forever).
        * `poll_interval`: polling frequency when timeout is not 0.
        * `runstate`: optional RunState duck instance supporting cancellation.
        
        ## Function `longpath(path, environ=None, prefixes=None)`
        
        Return `path` with prefixes and environment variables substituted.
        The converse of shortpath().
        
        ## Function `make_files_property(attr_name=None, unset_object=None, poll_rate=1.0)`
        
        Construct a decorator that watches multiple associated files.
        
        Parameters:
        * `attr_name`: the underlying attribute, default: `'_'+func.__name__`
        * `unset_object`: the sentinel value for "uninitialised", default: `None`
        * `poll_rate`: how often in seconds to poll the file for changes,
          default from `DEFAULT_POLL_INTERVAL`: `1.0`
        
        The attribute {attr_name}_lock controls access to the property.
        The attributes {attr_name}_filestates and {attr_name}_paths track the
        associated files' state.
        The attribute {attr_name}_lastpoll tracks the last poll time.
        
        The decorated function is passed the current list of files
        and returns the new list of files and the associated value.
        
        One example use would be a configuration file with recursive
        include operations; the inner function would parse the first
        file in the list, and the parse would accumulate this filename
        and those of any included files so that they can be monitored,
        triggering a fresh parse if one changes.
        
        Example:
        
            class C(object):
              def __init__(self):
                self._foo_path = '.foorc'
              @files_property
              def foo(self,paths):
                new_paths, result = parse(paths[0])
                return new_paths, result
        
        The load function is called on the first access and on every
        access thereafter where an associated file's `FileState` has
        changed and the time since the last successful load exceeds
        the `poll_rate`.
        
        An attempt at avoiding races is made by
        ignoring reloads that raise exceptions and ignoring reloads
        where files that were `os.stat`()ed during the change check have
        changed state after the load.
        
        ## Function `makelockfile(path, ext=None, poll_interval=None, timeout=None, runstate=None)`
        
        Create a lockfile and return its path.
        
        The lockfile can be removed with os.remove.
        This is the core functionality supporting the lockfile()
        context manager.
        
        Paramaters:
        * `path`: the base associated with the lock file,
          often the filesystem object whose access is being managed.
        * `ext`: the extension to the base used to construct the lockfile name.
          Default: ".lock"
        * `timeout`: maximum time to wait before failing.
          Default: `None` (wait forever).
          Note that zero is an accepted value
          and requires the lock to succeed on the first attempt.
        * `poll_interval`: polling frequency when timeout is not 0.
        * `runstate`: optional RunState duck instance supporting cancellation.
          Note that if a cancelled RunState is provided
          no attempt will be made to make the lockfile.
        
        ## Function `max_suffix(dirpath, pfx)`
        
        Compute the highest existing numeric suffix
        for names starting with the prefix `pfx`.
        
        This is generally used as a starting point for picking a new numeric suffix.
        
        ## Function `mkdirn(path, sep='')`
        
        Create a new directory named `path+sep+n`,
        where `n` exceeds any name already present.
        
        Parameters:
        * `path`: the basic directory path.
        * `sep`: a separator between `path` and n.
          Default: ""
        
        ## Class `NullFile`
        
        Writable file that discards its input.
        
        Note that this is _not_ an open of `os.devnull`;
        it just discards writes and is not the underlying file descriptor.
        
        ### Method `NullFile.__init__(self)`
        
        Initialise the file offset to 0.
        
        ## Class `Pathname(builtins.str)`
        
        Subclass of str presenting convenience properties useful for
        format strings related to file paths.
        
        ## Function `poll_file(path, old_state, reload_file, missing_ok=False)`
        
        Watch a file for modification by polling its state as obtained by FileState().
        Call reload_file(path) if the state changes.
        Return (new_state, reload_file(path)) if the file was modified and was
        unchanged (stable state) beofre and after the reload_file().
        Otherwise return (None, None).
        
        This may raise an OSError if the `path` cannot be os.stat()ed
        and of course for any exceptions that occur calling `reload_file`.
        
        If `missing_ok` is true then a failure to os.stat() which
        raises OSError with ENOENT will just return (None, None).
        
        ## Function `read_data(fp, nbytes, rsize=None)`
        
        Read `nbytes` of data from `fp`, return the data.
        
        Parameters:
        * `nbytes`: number of bytes to copy.
          If `None`, copy until EOF.
        * `rsize`: read size, default `DEFAULT_READSIZE`.
        
        ## Function `read_from(fp, rsize=None, tail_mode=False, tail_delay=None)`
        
        Generator to present text or data from an open file until EOF.
        
        Parameters:
        * `rsize`: read size, default: DEFAULT_READSIZE
        * `tail_mode`: if true, yield an empty chunk at EOF, allowing resumption
          if the file grows.
        
        ## Class `ReadMixin`
        
        Useful read methods to accomodate modes not necessarily available in a class.
        
        Note that this mixin presumes that the attribute `self._lock`
        is a threading.RLock like context manager.
        
        Classes using this mixin should consider overriding the default
        .datafrom method with something more efficient or direct.
        
        ## Function `rewrite(filepath, data, mode='w', backup_ext=None, do_rename=False, do_diff=None, empty_ok=False, overwrite_anyway=False)`
        
        Rewrite the file `filepath` with data from the file object `data`.
        
        Parameters:
        * `empty_ok`: if not true, raise ValueError if the new data are
          empty.
          Default: `False`.
        * `overwrite_anyway`: if true (default `False`),
          skip the content check and overwrite unconditionally.
        * `backup_ext`: if a nonempty string,
          take a backup of the original at `filepath + backup_ext`.
        * `do_diff`: if not None, call `do_diff(filepath, tempfile)`.
        * `do_rename`: if true (default False),
          rename the temp file to `filepath`
          after copying the permission bits.
          Otherwise (default), copy the tempfile to `filepath`.
        
        ## Function `rewrite_cmgr(pathname, mode='w', backup_ext=None, keep_backup=False, do_rename=False, do_diff=None, empty_ok=False, overwrite_anyway=False)`
        
        Rewrite a file, presented as a context manager.
        
        Parameters:
        * `mode`: file write mode, defaulting to "w" for text.
        * `backup_ext`: backup extension. `None` means no backup.
          An empty string generates an extension based on the current time.
        * `keep_backup`: keep the backup file even if everything works.
        * `do_rename`: rename the temporary file to the original to update.
        * `do_diff`: call `do_diff(pathname, tempfile)` before commiting.
        * `empty_ok`: do not consider empty output an error.
        * `overwrite_anyway`: do not update the original if the new
          data are identical.
        
        Example:
        
            with rewrite_cmgr(pathname, backup_ext='', keep_backup=True) as f:
               ... write new content to f ...
        
        ## Class `RWFileBlockCache`
        
        A scratch file for storing data.
        
        ### Method `RWFileBlockCache.__init__(self, pathname=None, dirpath=None, suffix=None, lock=None)`
        
        Initialise the file.
        
        Parameters:
        * `pathname`: path of file. If None, create a new file with
          tempfile.mkstemp using dir=`dirpath` and unlink that file once
          opened.
        * `dirpath`: location for the file if made by mkstemp as above.
        * `lock`: an object to use as a mutex, allowing sharing with
          some outer system. A Lock will be allocated if omitted.
        
        ## Function `saferename(oldpath, newpath)`
        
        Rename a path using os.rename(),
        but raise an exception if the target path already exists.
        Note: slightly racey.
        
        ## Function `seekable(fp)`
        
        Try to test if a filelike object is seekable.
        
        First try the `.seekable` method from `IOBase`, otherwise try
        getting a file descriptor from `fp.fileno` and `os.stat`()ing that,
        otherwise return `False`.
        
        ## Function `shortpath(path, environ=None, prefixes=None)`
        
        Return `path` with the first matching leading prefix replaced.
        
        Parameters:
        * `environ`: environment mapping if not os.environ
        * `prefixes`: iterable of (prefix, subst) to consider for replacement;
          each `prefix` is subject to environment variable
          substitution before consideration
          The default considers "$HOME/" for replacement by "~/".
        
        ## Class `Tee`
        
        An object with .write, .flush and .close methods
        which copies data to multiple output files.
        
        ### Method `Tee.__init__(self, *fps)`
        
        Initialise the Tee; any arguments are taken to be output file objects.
        
        ## Function `tee(fp, fp2)`
        
        Context manager duplicating .write and .flush from fp to fp2.
        
        ## Function `tmpdir()`
        
        Return the pathname of the default temporary directory for scratch data,
        $TMPDIR or '/tmp'.
        
        ## Function `tmpdirn(tmp=None)`
        
        Make a new temporary directory with a numeric suffix.
        
        ## Function `trysaferename(oldpath, newpath)`
        
        A saferename() that returns True on success, False on failure.
        
        
        
        # Release Log
        
        *Release 20200318*:
        New findup(path,test) generator to walk up a file tree.
        
        *Release 20191006*:
        Adjust import of cs.deco.cachedmethod.
        
        *Release 20190729*:
        datafrom_fd: make `offset` optional, defaulting to fd position at call.
        
        *Release 20190617*:
        @file_based: adjust use of @cached from cached(wrap0, **dkw) to cached(**dkw)(wrap0).
        
        *Release 20190101*:
        datafrom: add maxlength keyword arg, bugfix fd and f.fileno cases.
        
        *Release 20181109*:
        Various bugfixes for BackedFile.
        Use a file's .read1 method if available in some scenarios.
        makelockfile: accept am optional RunState control parameter, improve some behaviour.
        datafrom_fd: new optional maxlength parameter limiting the amount of data returned.
        datafrom_fd: by default, perform an initial read to align all subsequent reads with the readsize.
        drop fdreader, add datafrom(f, offset, readsize) accepting a file or a file descriptor, expose datafrom_fd.
        ReadMixin.datafrom now mandatory. Add ReadMixin.bufferfrom.
        Assorted other improvements, minor bugfixes, documentation improvements.
        
        *Release 20171231.1*:
        Trite DISTINFO fix, no semantic changes.
        
        *Release 20171231*:
        Update imports, bump DEFAULT_READSIZE from 8KiB to 128KiB.
        
        *Release 20170608*:
        Move lockfile and the SharedAppend* classes to cs.sharedfile.
        BackedFile internal changes.
        
        *Release 20160918*:
        BackedFile: redo implementation of .front_file to fix resource leak; add .__len__; add methods .spans, .front_spans and .back_spans to return information about front vs back data.
        seek: bugfix: seek should return the new file offset.
        BackedFile does not subclass RawIOBase, it just works like one.
        
        *Release 20160828*:
        Use "install_requires" instead of "requires" in DISTINFO.
        Rename maxFilenameSuffix to max_suffix.
        Pull in OpenSocket file-like socket wrapper from cs.venti.tcp.
        Update for cs.asynchron changes.
        ... then move cs.fileutils.OpenSocket into new module cs.socketutils.
        New Tee class, for copying output to multiple files.
        NullFile class which discards writes (==> no-op for Tee).
        New class SavingFile to accrue output and move to specified pathname when complete.
        Memory usage improvements.
        Polyfill non-threadsafe implementation of pread if os.pread does not exist.
        New function seekable() to probe a file for seekability.
        SharedAppendFile: provide new .open(filemode) context manager for allowing direct file output for external users.
        New function makelockfile() presenting the logic to create a lock file separately from the lockfile context manager.
        Assorted bugfixes and improvements.
        
        *Release 20150116*:
        Initial PyPI release.
Keywords: python2,python3
Platform: UNKNOWN
Classifier: Programming Language :: Python
Classifier: Programming Language :: Python :: 2
Classifier: Programming Language :: Python :: 3
Classifier: Development Status :: 4 - Beta
Classifier: Intended Audience :: Developers
Classifier: Operating System :: OS Independent
Classifier: Topic :: Software Development :: Libraries :: Python Modules
Classifier: License :: OSI Approved :: GNU General Public License v3 or later (GPLv3+)
Description-Content-Type: text/markdown
