mdwsetup.py: Use `with open(...) as f' instead of `try'/`finally'.

[cfd] / mdwsetup.py

### -*-python-*-
###
### Utility module for Python build systems
###
### (c) 2009 Straylight/Edgeware
###

###----- Licensing notice ---------------------------------------------------
###
### This file is part of the Common Files Distribution (`common')
###
### `Common' is free software; you can redistribute it and/or modify
### it under the terms of the GNU General Public License as published by
### the Free Software Foundation; either version 2 of the License, or
### (at your option) any later version.
###
### `Common' 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 `common'; if not, write to the Free Software Foundation,
### Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

from __future__ import with_statement

import sys as SYS
import os as OS
import re as RE
import subprocess as SUB

import distutils.core as DC

###--------------------------------------------------------------------------
### Random utilities.

def uniquify(seq):
  """
  Return a list of the elements of SEQ, with duplicates removed.

  Only the first occurrence (according to `==') is left.
  """
  seen = {}
  out = []
  for item in seq:
    if item not in seen:
      seen[item] = True
      out.append(item)
  return out

###--------------------------------------------------------------------------
### Subprocess hacking.

class SubprocessFailure (Exception):
  def __init__(me, file, rc):
    me.args = (file, rc)
    me.file = file
    me.rc = rc
  def __str__(me):
    if WIFEXITED(me.rc):
      return '%s failed (rc = %d)' % (me.file, WEXITSTATUS(me.rc))
    elif WIFSIGNALED(me.rc):
      return '%s died (signal %d)' % (me.file, WTERMSIG(me.rc))
    else:
      return '%s died inexplicably' % (me.file)

def progoutput(command):
  """
  Run the shell COMMAND and return its standard output.

  The COMMAND must produce exactly one line of output, and must exit with
  status zero.
  """
  kid = SUB.Popen(command, stdout = SUB.PIPE)
  out = kid.stdout.readline()
  junk = kid.stdout.read()
  if junk != '':
    raise ValueError, \
          "Child process `%s' produced unspected output %r" % (command, junk)
  rc = kid.wait()
  if rc != 0:
    raise SubprocessFailure, (command, rc)
  return out.rstrip('\n')

###--------------------------------------------------------------------------
### External library packages.

INCLUDEDIRS = []
LIBDIRS = []
LIBS = []

def pkg_config(pkg, version):
  """
  Find the external package PKG and store the necessary compiler flags.

  The include-directory names are stored in INCLUDEDIRS; the
  library-directory names are in LIBDIRS; and the library names themselves
  are in LIBS.
  """
  spec = '%s >= %s' % (pkg, version)
  def weird(what, word):
    raise ValueError, \
          "Unexpected `%s' item `%s' from package `%s'" % (what, word, pkg)
  for word in progoutput(['pkg-config', '--cflags', spec]).split():
    if word.startswith('-I'):
      INCLUDEDIRS.append(word[2:])
    else:
      weird('--cflags', word)
  for word in progoutput(['pkg-config', '--libs', spec]).split():
    if word.startswith('-L'):
      LIBDIRS.append(word[2:])
    elif word.startswith('-l'):
      LIBS.append(word[2:])
    else:
      weird('--libs', word)

###--------------------------------------------------------------------------
### Substituting variables in files.

def needs_update_p(target, sources):
  """
  Returns whether TARGET is out of date relative to its SOURCES.

  If TARGET exists and was modified more recentently than any of its SOURCES
  then it doesn't need updating.
  """
  if not OS.path.exists(target):
    return True
  t_target = OS.stat(target).st_mtime
  for source in sources:
    if OS.stat(source).st_mtime >= t_target:
      return True
  return False

RX_SUBST = RE.compile(r'\%(\w+)\%')
def derive(target, source, substmap):
  """
  Derive TARGET from SOURCE by making simple substitutions.

  The SOURCE may contain markers %FOO%; these are replaced by SUBSTMAP['FOO']
  in the TARGET file.
  """
  if not needs_update_p(target, [source]):
    return False
  print "making `%s' from `%s'" % (target, source)
  temp = target + '.new'
  with open(temp, 'w') as ft:
    with open(source, 'r') as fs:
      for line in fs:
        ft.write(RX_SUBST.sub((lambda m: substmap[m.group(1)]), line))
  OS.rename(temp, target)

def generate(target, source = None):
  """
  Generate TARGET by running the SOURCE Python script.

  If SOURCE is omitted, replace the extension of TARGET by `.py'.
  """
  if source is None:
    source = OS.path.splitext(target)[0] + '.py'
  if not needs_update_p(target, [source]):
    return
  print "making `%s' using `%s'" % (target, source)
  temp = target + '.new'
  with open(temp, 'w') as ft:
    rc = SUB.call([SYS.executable, source], stdout = ft)
  if rc != 0:
    raise SubprocessFailure, (source, rc)
  OS.rename(temp, target)

###--------------------------------------------------------------------------
### Discovering version numbers.

def auto_version(writep = True):
  """
  Returns the package version number.

  As a side-effect, if WRITEP is true, then write the version number to the
  RELEASE file so that it gets included in distributions.
  """
  version = progoutput(['./auto-version'])
  if writep:
    with open('RELEASE.new', 'w') as ft: ft.write('%s\n' % version)
    OS.rename('RELEASE.new', 'RELEASE')
  return version

###----- That's all, folks --------------------------------------------------