importer.py revision 5522:e56c3d89be79 
1# Copyright (c) 2008 The Hewlett-Packard Development Company
2# All rights reserved.
3#
4# Redistribution and use in source and binary forms, with or without
5# modification, are permitted provided that the following conditions are
6# met: redistributions of source code must retain the above copyright
7# notice, this list of conditions and the following disclaimer;
8# redistributions in binary form must reproduce the above copyright
9# notice, this list of conditions and the following disclaimer in the
10# documentation and/or other materials provided with the distribution;
11# neither the name of the copyright holders nor the names of its
12# contributors may be used to endorse or promote products derived from
13# this software without specific prior written permission.
14#
15# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
18# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
19# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
20# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
21# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
25# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26#
27# Authors: Nathan Binkert
28
29# Simple importer that allows python to import data from a dict of
30# code objects.  The keys are the module path, and the items are the
31# filename and bytecode of the file.
32class CodeImporter(object):
33    def __init__(self):
34        self.modules = {}
35
36    def add_module(self, filename, modpath, code):
37        if modpath in self.modules:
38            raise AttributeError, "%s already found in importer"
39
40        self.modules[modpath] = (filename, code)
41
42    def find_module(self, fullname, path):
43        if fullname in self.modules:
44            return self
45
46        return None
47
48    def load_module(self, fullname):
49        # Because the importer is created and initialized in its own
50        # little sandbox (in init.cc), the globals that were available
51        # when the importer module was loaded and CodeImporter was
52        # defined are not available when load_module is actually
53        # called. Soooo, the imports must live here.
54        import imp
55        import os
56        import sys
57        mod = imp.new_module(fullname)
58        sys.modules[fullname] = mod
59
60        try:
61            mod.__loader__ = self
62            srcfile,code = self.modules[fullname]
63            if os.path.basename(srcfile) == '__init__.py':
64                mod.__path__ = fullname.split('.')
65            mod.__file__ = srcfile
66
67            exec code in mod.__dict__
68        except Exception:
69            del sys.modules[fullname]
70            raise
71
72        return mod
73
74# Create an importer and add it to the meta_path so future imports can
75# use it.  There's currently nothing in the importer, but calls to
76# add_module can be used to add code.
77import sys
78importer = CodeImporter()
79add_module = importer.add_module
80sys.meta_path.append(importer)
81