Merge branch 'cb/maint-orphan-merge-noclobber'
[git/kirr.git] / git_remote_helpers / util.py
blobdce83e60660825ba115c503ce0776955d90c1a44
1 #!/usr/bin/env python
3 """Misc. useful functionality used by the rest of this package.
5 This module provides common functionality used by the other modules in
6 this package.
8 """
10 import sys
11 import os
12 import subprocess
15 # Whether or not to show debug messages
16 DEBUG = False
18 def notify(msg, *args):
19 """Print a message to stderr."""
20 print >> sys.stderr, msg % args
22 def debug (msg, *args):
23 """Print a debug message to stderr when DEBUG is enabled."""
24 if DEBUG:
25 print >> sys.stderr, msg % args
27 def error (msg, *args):
28 """Print an error message to stderr."""
29 print >> sys.stderr, "ERROR:", msg % args
31 def warn(msg, *args):
32 """Print a warning message to stderr."""
33 print >> sys.stderr, "warning:", msg % args
35 def die (msg, *args):
36 """Print as error message to stderr and exit the program."""
37 error(msg, *args)
38 sys.exit(1)
41 class ProgressIndicator(object):
43 """Simple progress indicator.
45 Displayed as a spinning character by default, but can be customized
46 by passing custom messages that overrides the spinning character.
48 """
50 States = ("|", "/", "-", "\\")
52 def __init__ (self, prefix = "", f = sys.stdout):
53 """Create a new ProgressIndicator, bound to the given file object."""
54 self.n = 0 # Simple progress counter
55 self.f = f # Progress is written to this file object
56 self.prev_len = 0 # Length of previous msg (to be overwritten)
57 self.prefix = prefix # Prefix prepended to each progress message
58 self.prefix_lens = [] # Stack of prefix string lengths
60 def pushprefix (self, prefix):
61 """Append the given prefix onto the prefix stack."""
62 self.prefix_lens.append(len(self.prefix))
63 self.prefix += prefix
65 def popprefix (self):
66 """Remove the last prefix from the prefix stack."""
67 prev_len = self.prefix_lens.pop()
68 self.prefix = self.prefix[:prev_len]
70 def __call__ (self, msg = None, lf = False):
71 """Indicate progress, possibly with a custom message."""
72 if msg is None:
73 msg = self.States[self.n % len(self.States)]
74 msg = self.prefix + msg
75 print >> self.f, "\r%-*s" % (self.prev_len, msg),
76 self.prev_len = len(msg.expandtabs())
77 if lf:
78 print >> self.f
79 self.prev_len = 0
80 self.n += 1
82 def finish (self, msg = "done", noprefix = False):
83 """Finalize progress indication with the given message."""
84 if noprefix:
85 self.prefix = ""
86 self(msg, True)
89 def start_command (args, cwd = None, shell = False, add_env = None,
90 stdin = subprocess.PIPE, stdout = subprocess.PIPE,
91 stderr = subprocess.PIPE):
92 """Start the given command, and return a subprocess object.
94 This provides a simpler interface to the subprocess module.
96 """
97 env = None
98 if add_env is not None:
99 env = os.environ.copy()
100 env.update(add_env)
101 return subprocess.Popen(args, bufsize = 1, stdin = stdin, stdout = stdout,
102 stderr = stderr, cwd = cwd, shell = shell,
103 env = env, universal_newlines = True)
106 def run_command (args, cwd = None, shell = False, add_env = None,
107 flag_error = True):
108 """Run the given command to completion, and return its results.
110 This provides a simpler interface to the subprocess module.
112 The results are formatted as a 3-tuple: (exit_code, output, errors)
114 If flag_error is enabled, Error messages will be produced if the
115 subprocess terminated with a non-zero exit code and/or stderr
116 output.
118 The other arguments are passed on to start_command().
121 process = start_command(args, cwd, shell, add_env)
122 (output, errors) = process.communicate()
123 exit_code = process.returncode
124 if flag_error and errors:
125 error("'%s' returned errors:\n---\n%s---", " ".join(args), errors)
126 if flag_error and exit_code:
127 error("'%s' returned exit code %i", " ".join(args), exit_code)
128 return (exit_code, output, errors)
131 def file_reader_method (missing_ok = False):
132 """Decorator for simplifying reading of files.
134 If missing_ok is True, a failure to open a file for reading will
135 not raise the usual IOError, but instead the wrapped method will be
136 called with f == None. The method must in this case properly
137 handle f == None.
140 def _wrap (method):
141 """Teach given method to handle both filenames and file objects.
143 The given method must take a file object as its second argument
144 (the first argument being 'self', of course). This decorator
145 will take a filename given as the second argument and promote
146 it to a file object.
149 def _wrapped_method (self, filename, *args, **kwargs):
150 if isinstance(filename, file):
151 f = filename
152 else:
153 try:
154 f = open(filename, 'r')
155 except IOError:
156 if missing_ok:
157 f = None
158 else:
159 raise
160 try:
161 return method(self, f, *args, **kwargs)
162 finally:
163 if not isinstance(filename, file) and f:
164 f.close()
165 return _wrapped_method
166 return _wrap
169 def file_writer_method (method):
170 """Decorator for simplifying writing of files.
172 Enables the given method to handle both filenames and file objects.
174 The given method must take a file object as its second argument
175 (the first argument being 'self', of course). This decorator will
176 take a filename given as the second argument and promote it to a
177 file object.
180 def _new_method (self, filename, *args, **kwargs):
181 if isinstance(filename, file):
182 f = filename
183 else:
184 # Make sure the containing directory exists
185 parent_dir = os.path.dirname(filename)
186 if not os.path.isdir(parent_dir):
187 os.makedirs(parent_dir)
188 f = open(filename, 'w')
189 try:
190 return method(self, f, *args, **kwargs)
191 finally:
192 if not isinstance(filename, file):
193 f.close()
194 return _new_method