stgit/utils.py

"""Common utility functions
"""

import errno, os, os.path

__copyright__ = """
Copyright (C) 2005, Catalin Marinas <catalin.marinas@gmail.com>

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License version 2 as
published by the Free Software Foundation.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
"""

def mkdir_file(filename, mode):
    """Opens filename with the given mode, creating the directory it's
    in if it doesn't already exist."""
    create_dirs(os.path.dirname(filename))
    return file(filename, mode)

def read_string(filename, multiline = False):
    """Reads the first line from a file
    """
    f = file(filename, 'r')
    if multiline:
        result = f.read()
    else:
        result = f.readline().strip()
    f.close()
    return result

def write_string(filename, line, multiline = False):
    """Writes 'line' to file and truncates it
    """
    f = mkdir_file(filename, 'w+')
    if multiline:
        f.write(line)
    else:
        print >> f, line
    f.close()

def append_strings(filename, lines):
    """Appends 'lines' sequence to file
    """
    f = mkdir_file(filename, 'a+')
    for line in lines:
        print >> f, line
    f.close()

def append_string(filename, line):
    """Appends 'line' to file
    """
    f = mkdir_file(filename, 'a+')
    print >> f, line
    f.close()

def insert_string(filename, line):
    """Inserts 'line' at the beginning of the file
    """
    f = mkdir_file(filename, 'r+')
    lines = f.readlines()
    f.seek(0); f.truncate()
    print >> f, line
    f.writelines(lines)
    f.close()

def create_empty_file(name):
    """Creates an empty file
    """
    mkdir_file(name, 'w+').close()

def list_files_and_dirs(path):
    """Return the sets of filenames and directory names in a
    directory."""
    files, dirs = [], []
    for fd in os.listdir(path):
        full_fd = os.path.join(path, fd)
        if os.path.isfile(full_fd):
            files.append(fd)
        elif os.path.isdir(full_fd):
            dirs.append(fd)
    return files, dirs

def walk_tree(basedir):
    """Starting in the given directory, iterate through all its
    subdirectories. For each subdirectory, yield the name of the
    subdirectory (relative to the base directory), the list of
    filenames in the subdirectory, and the list of directory names in
    the subdirectory."""
    subdirs = ['']
    while subdirs:
        subdir = subdirs.pop()
        files, dirs = list_files_and_dirs(os.path.join(basedir, subdir))
        for d in dirs:
            subdirs.append(os.path.join(subdir, d))
        yield subdir, files, dirs

def strip_prefix(prefix, string):
    """Return string, without the prefix. Blow up if string doesn't
    start with prefix."""
    assert string.startswith(prefix)
    return string[len(prefix):]

def strip_suffix(suffix, string):
    """Return string, without the suffix. Blow up if string doesn't
    end with suffix."""
    assert string.endswith(suffix)
    return string[:-len(suffix)]

def remove_dirs(basedir, dirs):
    """Starting at join(basedir, dirs), remove the directory if empty,
    and try the same with its parent, until we find a nonempty
    directory or reach basedir."""
    path = dirs
    while path:
        try:
            os.rmdir(os.path.join(basedir, path))
        except OSError:
            return # can't remove nonempty directory
        path = os.path.dirname(path)

def remove_file_and_dirs(basedir, file):
    """Remove join(basedir, file), and then remove the directory it
    was in if empty, and try the same with its parent, until we find a
    nonempty directory or reach basedir."""
    os.remove(os.path.join(basedir, file))
    remove_dirs(basedir, os.path.dirname(file))

def create_dirs(directory):
    """Create the given directory, if the path doesn't already exist."""
    if directory and not os.path.isdir(directory):
        create_dirs(os.path.dirname(directory))
        try:
            os.mkdir(directory)
        except OSError, e:
            if e.errno != errno.EEXIST:
                raise e

def rename(basedir, file1, file2):
    """Rename join(basedir, file1) to join(basedir, file2), not
    leaving any empty directories behind and creating any directories
    necessary."""
    full_file2 = os.path.join(basedir, file2)
    create_dirs(os.path.dirname(full_file2))
    os.rename(os.path.join(basedir, file1), full_file2)
    remove_dirs(basedir, os.path.dirname(file1))