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Provides a _paths_from_path_patterns that will generate a list of paths from a list of path patterns. A "path pattern" can include glob chars. By default it generates a recursive listing of file paths, but: recursion can be turned off, file and/or dir paths can be listed. It supports a list of glob exclusions or inclusions.

This function makes it easy to implement typical "-r|--recursive" and "-x|--exclude" options for command-line scripts that work on given file paths. See example usages below.

Note: I use a leading _ on function names because my typical usage of my recipes is as re-usable internal functions in Python modules.

Python, 259 lines
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def _should_include_path(path, includes, excludes):
    """Return True iff the given path should be included."""
    from os.path import basename
    from fnmatch import fnmatch

    base = basename(path)
    if includes:
        for include in includes:
            if fnmatch(base, include):
                try:
                    log.debug("include `%s' (matches `%s')", path, include)
                except (NameError, AttributeError):
                    pass
                break
        else:
            try:
                log.debug("exclude `%s' (matches no includes)", path)
            except (NameError, AttributeError):
                pass
            return False
    for exclude in excludes:
        if fnmatch(base, exclude):
            try:
                log.debug("exclude `%s' (matches `%s')", path, exclude)
            except (NameError, AttributeError):
                pass
            return False
    return True

def _walk(top, topdown=True, onerror=None, follow_symlinks=False):
    """A version of `os.walk()` with a couple differences regarding symlinks.
    
    1. follow_symlinks=False (the default): A symlink to a dir is
       returned as a *non*-dir. In `os.walk()`, a symlink to a dir is
       returned in the *dirs* list, but it is not recursed into.
    2. follow_symlinks=True: A symlink to a dir is returned in the
       *dirs* list (as with `os.walk()`) but it *is conditionally*
       recursed into (unlike `os.walk()`).
       
       A symlinked dir is only recursed into if it is to a deeper dir
       within the same tree. This is my understanding of how `find -L
       DIR` works.
    """
    import os
    from os.path import join, isdir, islink, abspath

    # We may not have read permission for top, in which case we can't
    # get a list of the files the directory contains.  os.path.walk
    # always suppressed the exception then, rather than blow up for a
    # minor reason when (say) a thousand readable directories are still
    # left to visit.  That logic is copied here.
    try:
        names = os.listdir(top)
    except OSError, err:
        if onerror is not None:
            onerror(err)
        return

    dirs, nondirs = [], []
    if follow_symlinks:
        for name in names:
            if isdir(join(top, name)):
                dirs.append(name)
            else:
                nondirs.append(name)
    else:
        for name in names:
            path = join(top, name)
            if islink(path):
                nondirs.append(name)
            elif isdir(path):
                dirs.append(name)
            else:
                nondirs.append(name)

    if topdown:
        yield top, dirs, nondirs
    for name in dirs:
        path = join(top, name)
        if follow_symlinks and islink(path):
            # Only walk this path if it links deeper in the same tree.
            top_abs = abspath(top)
            link_abs = abspath(join(top, os.readlink(path)))
            if not link_abs.startswith(top_abs + os.sep):
                continue
        for x in _walk(path, topdown, onerror, follow_symlinks=follow_symlinks):
            yield x
    if not topdown:
        yield top, dirs, nondirs

_NOT_SPECIFIED = ("NOT", "SPECIFIED")
def _paths_from_path_patterns(path_patterns, files=True, dirs="never",
                              recursive=True, includes=None, excludes=None,
                              skip_dupe_dirs=False,
                              follow_symlinks=False,
                              on_error=_NOT_SPECIFIED):
    """_paths_from_path_patterns([<path-patterns>, ...]) -> file paths

    Generate a list of paths (files and/or dirs) represented by the given path
    patterns.

        "path_patterns" is a list of paths optionally using the '*', '?' and
            '[seq]' glob patterns.
        "files" is boolean (default True) indicating if file paths
            should be yielded
        "dirs" is string indicating under what conditions dirs are
            yielded. It must be one of:
              never             (default) never yield dirs
              always            yield all dirs matching given patterns
              if-not-recursive  only yield dirs for invocations when
                                recursive=False
            See use cases below for more details.
        "recursive" is boolean (default True) indicating if paths should
            be recursively yielded under given dirs.
        "includes" is a list of file patterns to include in recursive
            searches.
        "excludes" is a list of file and dir patterns to exclude.
            (Note: This is slightly different than GNU grep's --exclude
            option which only excludes *files*.  I.e. you cannot exclude
            a ".svn" dir.)
        "skip_dupe_dirs" can be set True to watch for and skip
            descending into a dir that has already been yielded. Note
            that this currently does not dereference symlinks.
        "follow_symlinks" is a boolean indicating whether to follow
            symlinks (default False). To guard against infinite loops
            with circular dir symlinks, only dir symlinks to *deeper*
            dirs are followed.
        "on_error" is an error callback called when a given path pattern
            matches nothing:
                on_error(PATH_PATTERN)
            If not specified, the default is look for a "log" global and
            call:
                log.error("`%s': No such file or directory")
            Specify None to do nothing.

    Typically this is useful for a command-line tool that takes a list
    of paths as arguments. (For Unix-heads: the shell on Windows does
    NOT expand glob chars, that is left to the app.)

    Use case #1: like `grep -r`
      {files=True, dirs='never', recursive=(if '-r' in opts)}
        script FILE     # yield FILE, else call on_error(FILE)
        script DIR      # yield nothing
        script PATH*    # yield all files matching PATH*; if none,
                        # call on_error(PATH*) callback
        script -r DIR   # yield files (not dirs) recursively under DIR
        script -r PATH* # yield files matching PATH* and files recursively
                        # under dirs matching PATH*; if none, call
                        # on_error(PATH*) callback

    Use case #2: like `file -r` (if it had a recursive option)
      {files=True, dirs='if-not-recursive', recursive=(if '-r' in opts)}
        script FILE     # yield FILE, else call on_error(FILE)
        script DIR      # yield DIR, else call on_error(DIR)
        script PATH*    # yield all files and dirs matching PATH*; if none,
                        # call on_error(PATH*) callback
        script -r DIR   # yield files (not dirs) recursively under DIR
        script -r PATH* # yield files matching PATH* and files recursively
                        # under dirs matching PATH*; if none, call
                        # on_error(PATH*) callback

    Use case #3: kind of like `find .`
      {files=True, dirs='always', recursive=(if '-r' in opts)}
        script FILE     # yield FILE, else call on_error(FILE)
        script DIR      # yield DIR, else call on_error(DIR)
        script PATH*    # yield all files and dirs matching PATH*; if none,
                        # call on_error(PATH*) callback
        script -r DIR   # yield files and dirs recursively under DIR
                        # (including DIR)
        script -r PATH* # yield files and dirs matching PATH* and recursively
                        # under dirs; if none, call on_error(PATH*)
                        # callback
    """
    from os.path import basename, exists, isdir, join, normpath, abspath, \
                        lexists, islink, realpath
    from glob import glob

    assert not isinstance(path_patterns, basestring), \
        "'path_patterns' must be a sequence, not a string: %r" % path_patterns
    if includes is None: includes = []
    if excludes is None: excludes = []
    GLOB_CHARS = '*?['

    if skip_dupe_dirs:
        searched_dirs = set()

    for path_pattern in path_patterns:
        # Determine the set of paths matching this path_pattern.
        for glob_char in GLOB_CHARS:
            if glob_char in path_pattern:
                paths = glob(path_pattern)
                break
        else:
            if follow_symlinks:
                paths = exists(path_pattern) and [path_pattern] or []
            else:
                paths = lexists(path_pattern) and [path_pattern] or []
        if not paths:
            if on_error is None:
                pass
            elif on_error is _NOT_SPECIFIED:
                try:
                    log.error("`%s': No such file or directory", path_pattern)
                except (NameError, AttributeError):
                    pass
            else:
                on_error(path_pattern)

        for path in paths:
            if (follow_symlinks or not islink(path)) and isdir(path):
                if skip_dupe_dirs:
                    canon_path = normpath(abspath(path))
                    if follow_symlinks:
                        canon_path = realpath(canon_path)
                    if canon_path in searched_dirs:
                        continue
                    else:
                        searched_dirs.add(canon_path)

                # 'includes' SHOULD affect whether a dir is yielded.
                if (dirs == "always"
                    or (dirs == "if-not-recursive" and not recursive)
                   ) and _should_include_path(path, includes, excludes):
                    yield path

                # However, if recursive, 'includes' should NOT affect
                # whether a dir is recursed into. Otherwise you could
                # not:
                #   script -r --include="*.py" DIR
                if recursive and _should_include_path(path, [], excludes):
                    for dirpath, dirnames, filenames in _walk(path, 
                            follow_symlinks=follow_symlinks):
                        dir_indeces_to_remove = []
                        for i, dirname in enumerate(dirnames):
                            d = join(dirpath, dirname)
                            if skip_dupe_dirs:
                                canon_d = normpath(abspath(d))
                                if follow_symlinks:
                                    canon_d = realpath(canon_d)
                                if canon_d in searched_dirs:
                                    dir_indeces_to_remove.append(i)
                                    continue
                                else:
                                    searched_dirs.add(canon_d)
                            if dirs == "always" \
                               and _should_include_path(d, includes, excludes):
                                yield d
                            if not _should_include_path(d, [], excludes):
                                dir_indeces_to_remove.append(i)
                        for i in reversed(dir_indeces_to_remove):
                            del dirnames[i]
                        if files:
                            for filename in sorted(filenames):
                                f = join(dirpath, filename)
                                if _should_include_path(f, includes, excludes):
                                    yield f

            elif files and _should_include_path(path, includes, excludes):
                yield path
Example usages

Boring basic glob equivalent:

>>> for path in _paths_from_path_patterns(["/Users/trentm/src/python/Python/*.c"]): print path 
/Users/trentm/src/python/Python/_warnings.c
/Users/trentm/src/python/Python/asdl.c
/Users/trentm/src/python/Python/ast.c
...

Recursively all files under a given dir:

>>> for path in _paths_from_path_patterns(["/Users/trentm/src/python/Lib"]): print path
/Users/trentm/src/python/Lib/BaseHTTPServer.py
/Users/trentm/src/python/Lib/Bastion.py
/Users/trentm/src/python/Lib/Bastion.pyc
...
/Users/trentm/src/python/Lib/.svn/dir-prop-base
/Users/trentm/src/python/Lib/.svn/entries
/Users/trentm/src/python/Lib/.svn/prop-base/BaseHTTPServer.py.svn-base
/Users/trentm/src/python/Lib/.svn/prop-base/Bastion.py.svn-base
...
/Users/trentm/src/python/Lib/compiler/__init__.py
/Users/trentm/src/python/Lib/compiler/ast.py
...

Skip ".svn" dirs and "*.pyc" files using excludes argument:

>>> for path in _paths_from_path_patterns(["/Users/trentm/src/python/Lib"], excludes=[".svn", "*.pyc"]): print path
/Users/trentm/src/python/Lib/BaseHTTPServer.py
/Users/trentm/src/python/Lib/Bastion.py
...
/Users/trentm/src/python/Lib/compiler/__init__.py
/Users/trentm/src/python/Lib/compiler/ast.py
...
/Users/trentm/src/python/Lib/test/zipdir.zip
...

Include only specific file patterns with the includes argument:

>>> for path in _paths_from_path_patterns(["/Users/trentm/src/python/Lib"], excludes=[".svn"], includes=["*.py"]): print path
/Users/trentm/src/python/Lib/BaseHTTPServer.py
/Users/trentm/src/python/Lib/Bastion.py
...
/Users/trentm/src/python/Lib/compiler/__init__.py
/Users/trentm/src/python/Lib/compiler/ast.py
...
Other options
  • Use dirs="always" to generate directory paths as well a la GNU find.
  • Use dirs="if-not-recursive" to generate directory paths a la file -r.
  • Use on_error to control error handling of individual paths.
  • Use follow_symlinks to handle symlinks.

2 comments

Trent Mick 11 years, 5 months ago  # | flag

r3: allow excludes and includes args to be None without blowing up

Andrea Crotti 10 years ago  # | flag

The complexity of the functions is way higher what it should be imho, suggest splitting in many more testable and understandable functions..

Created by Trent Mick on Tue, 18 May 2010 (MIT)
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