source: sasview/register.py @ 89590cd

ESS_GUIESS_GUI_DocsESS_GUI_batch_fittingESS_GUI_bumps_abstractionESS_GUI_iss1116ESS_GUI_iss879ESS_GUI_iss959ESS_GUI_openclESS_GUI_orderingESS_GUI_sync_sascalccostrafo411magnetic_scattrelease-4.1.1release-4.1.2release-4.2.2release_4.0.1ticket-1009ticket-1094-headlessticket-1242-2d-resolutionticket-1243ticket-1249ticket885unittest-saveload
Last change on this file since 89590cd was ee5479d8, checked in by Gervaise Alina <gervyh@…>, 16 years ago
  • Property mode set to 100644
File size: 3.8 KB
Line 
1# This program is public domain
2"""
3File extension registry.
4
5This provides routines for opening files based on extension,
6and registers the built-in file extensions.
7"""
8import logging
9import os.path
10
11class ExtensionRegistry(object):
12    """
13    Associate a file loader with an extension.
14
15    Note that there may be multiple loaders for the same extension.
16
17    Example:
18
19    registry = ExtensionRegistry()
20
21    # Add an association by setting an element
22    registry['.zip'] = unzip
23
24    # Multiple extensions for one loader
25    registry['.tgz'] = untar
26    registry['.tar.gz'] = untar
27
28    # Multiple loaders for one extension
29    registry['.cx'] = cx1
30    registry['.cx'] = cx2
31    registry['.cx'] = cx3
32   
33    # Can also register a format name for explicit control from caller
34    registry['cx3'] = cx3
35
36    # Retrieve loaders for a file name
37    registry.lookup('hello.cx') -> [cx3,cx2,cx1]
38
39    # Run loader on a filename
40    registry.load('hello.cx') ->
41        try:
42            return cx3('hello.cx')
43        except:
44            try:
45                return cx2('hello.cx')
46            except:
47                return cx1('hello.cx')
48
49    # Load in a specific format ignoring extension
50    registry.load('hello.cx',format='cx3') ->
51        return cx3('hello.cx')
52    """
53    def __init__(self):
54        self.loaders = {}
55    def __setitem__(self, ext, loader):
56        if ext not in self.loaders:
57            self.loaders[ext] = []
58        self.loaders[ext].insert(0,loader)
59    def __getitem__(self, ext):
60        return self.loaders[ext]
61    def __contains__(self, ext):
62        return ext in self.loaders
63    def formats(self, name=True, ext=False):
64        """
65        Return a list of the registered formats.  If name=True then
66        named formats are returned.  If ext=True then extensions
67        are returned.
68        """
69        names = [a for a in self.loaders.keys() if not a.startswith('.')]
70        exts = [a for a in self.loaders.keys() if a.startswith('.')]
71        names.sort()
72        exts.sort()
73        ret = []
74        if name: ret += names
75        if ext: ret += exts
76        return ret
77       
78    def lookup(self, path):
79        """
80        Return the loader associated with the file type of path.
81        """       
82        file = os.path.basename(path)
83        idx = file.find('.')
84        ext = file[idx:] if idx >= 0 else ''
85        try:
86            return self.loaders[ext]
87        except:
88            #raise ValueError, "Unknown file type '%s'"%ext
89            print  "Unknown file type '%s'"%ext
90       
91    def loads(self, path, format=None):
92        """
93        Call the loader for the file type of path.
94
95        Raises ValueError if no loader is available.
96        May raise a loader-defined exception if loader fails.
97        """
98        if format is None:
99            loaders = self.lookup(path)
100        else:
101            loaders = self.loaders[format]
102        for fn in loaders:
103            print fn
104            try:
105                value=fn.read(path)
106                return value
107            except ValueError,msg:
108                #pass
109                print str(msg)
110
111    def load(self, path, format=None):
112        """
113        Call the loader for the file type of path.
114
115        Raises ValueError if no loader is available.
116        May raise a loader-defined exception if loader fails.
117        """
118        if format is None:
119            loaders = self.lookup(path)
120        else:
121            loaders = self.loaders[format]
122        if loaders!=None:
123            for fn in loaders:
124                try:
125                    return fn.read(path)
126                    #value=fn.read(path)
127                    #return value
128                except ValueError,msg:
129                    #pass
130                    print str(msg)
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