[a916ccc] | 1 | # This program is public domain |
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| 2 | """ |
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[d22da51] | 3 | @organization: Module loader contains class Loader which uses |
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| 4 | some readers to return values contained in a file readed. |
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[77c1c29d] | 5 | @ author : Paul Kienzler |
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| 6 | @modifiied by gervaise alina |
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[a916ccc] | 7 | """ |
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| 8 | import imp,os,sys |
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| 9 | import logging |
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| 10 | import os.path |
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[d22da51] | 11 | logging.basicConfig(level=logging.ERROR, |
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| 12 | format='%(asctime)s %(levelname)s %(message)s', |
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[d3619421] | 13 | filename='test_log.txt', |
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[d22da51] | 14 | filemode='w') |
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| 15 | |
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[a916ccc] | 16 | def _findReaders(dir): |
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| 17 | # List of plugin objects |
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| 18 | plugins = [] |
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| 19 | # Go through files in plug-in directory |
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| 20 | try: |
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| 21 | |
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| 22 | list = os.listdir(dir) |
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| 23 | for item in list: |
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| 24 | |
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| 25 | toks = os.path.splitext(os.path.basename(item)) |
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| 26 | if toks[1]=='.py' and not toks[0]=='__init__': |
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| 27 | name = toks[0] |
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| 28 | path = [os.path.abspath(dir)] |
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| 29 | file = None |
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| 30 | try: |
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| 31 | (file, path, info) = imp.find_module(name, path) |
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| 32 | module = imp.load_module( name, file, item, info ) |
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| 33 | if hasattr(module, "Reader"): |
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| 34 | try: |
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| 35 | plugins.append(module.Reader()) |
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| 36 | except: |
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[94daf8a] | 37 | logging.error("Error accessing Reader in %s\n %s" % (name, sys.exc_value)) |
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[a916ccc] | 38 | except : |
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[94daf8a] | 39 | logging.error("Error importing %s\n %s" % (name, sys.exc_value)) |
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[a916ccc] | 40 | finally: |
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| 41 | if not file==None: |
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| 42 | file.close() |
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| 43 | except: |
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| 44 | # Should raise and catch at a higher level and display error on status bar |
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| 45 | pass |
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| 46 | return plugins |
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[d22da51] | 47 | |
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| 48 | |
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[1b0b3ca] | 49 | class Loader(object): |
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[d22da51] | 50 | """ |
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| 51 | Loader class extracts data from a given file. |
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| 52 | This provides routines for opening files based on extension, |
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| 53 | and readers built-in file extensions. |
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| 54 | It uses functionalities for class Load |
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| 55 | @note: For loader to operate properly each readers used should |
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| 56 | contain a class name "Reader" that contains a field call ext. |
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| 57 | Can be used as follow: |
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| 58 | L=Loader() |
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| 59 | self.assertEqual(l.__contains__('.tiff'),True) |
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| 60 | #Recieves data |
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| 61 | data=L.load(path) |
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| 62 | """ |
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| 63 | #Store instance of class Load |
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[a916ccc] | 64 | __load = None |
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[d22da51] | 65 | |
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| 66 | |
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[1b0b3ca] | 67 | class Load(object): |
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[a916ccc] | 68 | |
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| 69 | def __init__(self): |
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[d22da51] | 70 | #Dictionary containing readers and extension as keys |
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[a916ccc] | 71 | self.readers = {} |
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[d22da51] | 72 | #Load all readers in plugins |
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[579ba85] | 73 | |
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| 74 | #TODO: misuse of __setitem__ |
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| 75 | #TODO: this bad call is done twice: here, and in Loader.__init__ |
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| 76 | #self.__setitem__() |
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[d22da51] | 77 | |
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[a916ccc] | 78 | |
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[2fd516b] | 79 | def __setitem__(self,dir=None, ext=None, reader=None): |
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[d22da51] | 80 | """ |
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| 81 | __setitem__ sets in a dictionary(self.readers) a given reader |
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| 82 | with a file extension that it can read. |
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| 83 | @param ext: extension given of type string |
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| 84 | @param reader:instance Reader class |
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[2fd516b] | 85 | @param dir: directory name where plugins readers will be saved |
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[d22da51] | 86 | @raise : ValueError will be raise if a "plugins" directory is not found |
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| 87 | and the user didn't add a reader as parameter or if the user didn't |
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| 88 | add a reader as a parameter and plugins directory doesn't contain |
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| 89 | plugin reader. |
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| 90 | if an extension is not specified and a reader does not contain a field |
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[d3619421] | 91 | ext , a warning is printed in test_log.txt file. |
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[d22da51] | 92 | @note: when called without parameters __setitem__ will try to load |
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[2fd516b] | 93 | readers inside a "readers" directory |
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| 94 | if call with a directory name will try find readers |
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| 95 | from that directory "dir" |
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[d22da51] | 96 | """ |
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[2fd516b] | 97 | if dir==None: |
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[d3619421] | 98 | dir = 'readers' |
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[579ba85] | 99 | |
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| 100 | #TODO Probably name the new path something else... |
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| 101 | |
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| 102 | #TODO: The whole concept of plug-ins was missed here. |
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| 103 | # First we want to always load the reader we have (in 'readers') |
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| 104 | # and THEN we want to add any additional readers found in |
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| 105 | # a pre-defined plug-in path (that path should be a variable). |
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[d3619421] | 106 | dir=os.path.join(os.path.dirname(os.path.abspath(__file__)),dir) |
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[16d8e5f] | 107 | |
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[8d6440f] | 108 | if (reader==None and ext==None) or dir:#1st load |
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[a916ccc] | 109 | plugReader=None |
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[2fd516b] | 110 | if os.path.isdir(dir): |
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| 111 | plugReader=_findReaders(dir)# import all module in plugins |
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[579ba85] | 112 | |
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| 113 | #TODO The following just doesn't make sense |
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| 114 | # ../C:\Python25\lib... ???? |
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[2fd516b] | 115 | if os.path.isdir('../'+dir): |
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| 116 | plugReader=_findReaders('../'+dir) |
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[d3619421] | 117 | |
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| 118 | |
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[a916ccc] | 119 | if plugReader !=None: |
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[d3619421] | 120 | list=[] |
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[a916ccc] | 121 | for preader in plugReader:# for each modules takes list of extensions |
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[579ba85] | 122 | #TODO should use hasattr rather than a try/except block |
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[2fd516b] | 123 | try: |
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| 124 | list=preader.ext |
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[d3619421] | 125 | except AttributeError,msg: |
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| 126 | logging.warning(msg) |
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| 127 | pass |
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| 128 | #raise AttributeError," %s instance has no attribute 'ext'"\ |
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| 129 | #%(preader.__class__) |
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| 130 | if list !=[]: |
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| 131 | for item in list: |
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| 132 | ext=item |
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| 133 | if ext not in self.readers:#assign extension with its reader |
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| 134 | self.readers[ext] = [] |
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| 135 | self.readers[ext].insert(0,preader) |
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[d22da51] | 136 | #Reader and extension are given |
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[a916ccc] | 137 | elif reader !=None and ext !=None: |
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| 138 | if ext not in self.readers: |
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| 139 | self.readers[ext] = [] |
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| 140 | self.readers[ext].insert(0,reader) |
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| 141 | elif reader!=None: |
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[d22da51] | 142 | #only reader is receive try to find a field ext |
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[2fd516b] | 143 | try: |
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| 144 | list=preader.ext |
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| 145 | except: |
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| 146 | raise AttributeError," Reader instance has no attribute 'ext'" |
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| 147 | for item in list: |
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| 148 | |
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| 149 | ext=item |
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| 150 | if ext not in self.readers:#assign extension with its reader |
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| 151 | self.readers[ext] = [] |
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| 152 | self.readers[ext].insert(0,reader) |
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| 153 | |
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[a916ccc] | 154 | else: |
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| 155 | raise ValueError,"missing reader" |
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[d22da51] | 156 | |
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[a916ccc] | 157 | |
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| 158 | def __getitem__(self, ext): |
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[d22da51] | 159 | """ |
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| 160 | __getitem__ get a list of readers that can read a file with that extension |
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| 161 | @param ext: file extension |
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| 162 | @return self.readers[ext]:list of readers that can read a file |
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| 163 | with that extension |
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| 164 | """ |
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[a916ccc] | 165 | return self.readers[ext] |
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| 166 | |
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| 167 | def __contains__(self, ext): |
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[d22da51] | 168 | """ |
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| 169 | @param ext:file extension |
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| 170 | @return: True or False whether there is a reader file with that extension |
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| 171 | """ |
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[a916ccc] | 172 | return ext in self.readers |
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| 173 | |
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| 174 | |
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| 175 | def formats(self, name=True, ext=False): |
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| 176 | """ |
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| 177 | Return a list of the registered formats. If name=True then |
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| 178 | named formats are returned. If ext=True then extensions |
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| 179 | are returned. |
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| 180 | """ |
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| 181 | names = [a for a in self.readers.keys() if not a.startswith('.')] |
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| 182 | exts = [a for a in self.readers.keys() if a.startswith('.')] |
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| 183 | names.sort() |
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| 184 | exts.sort() |
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| 185 | ret = [] |
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| 186 | if name: ret += names |
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| 187 | if ext: ret += exts |
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| 188 | return ret |
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| 189 | |
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| 190 | def lookup(self, path): |
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| 191 | """ |
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| 192 | Return the loader associated with the file type of path. |
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| 193 | """ |
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| 194 | file = os.path.basename(path) |
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| 195 | idx = file.find('.') |
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| 196 | ext = file[idx:] if idx >= 0 else '' |
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[d22da51] | 197 | |
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[a916ccc] | 198 | try: |
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| 199 | return self.readers[ext] |
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| 200 | except: |
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[d3619421] | 201 | logging.warning("Unknown file type '%s'"%ext) |
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[3dd7cce] | 202 | raise RuntimeError, "Unknown file type '%s'"%ext |
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[d22da51] | 203 | |
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| 204 | |
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[a916ccc] | 205 | |
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| 206 | def load(self, path, format=None): |
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| 207 | """ |
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[d22da51] | 208 | Call reader for the file type of path. |
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| 209 | @param path: path to file to load |
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| 210 | @param format: extension of file to load |
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| 211 | @return Data if sucessful |
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| 212 | or None is not reader was able to read that file |
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| 213 | Raises ValueError if no reader is available. |
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| 214 | May raise a loader-defined exception if loader fails. |
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[a916ccc] | 215 | """ |
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[1b0b3ca] | 216 | try: |
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| 217 | os.path.isfile( os.path.abspath(path)) |
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| 218 | except: |
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[16d8e5f] | 219 | raise ValueError," file path unknown" |
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[d22da51] | 220 | |
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[a916ccc] | 221 | if format is None: |
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[d22da51] | 222 | try: |
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| 223 | readers = self.lookup(path) |
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[4245594] | 224 | except : |
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| 225 | raise |
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[a916ccc] | 226 | else: |
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| 227 | readers = self.readers[format] |
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| 228 | if readers!=None: |
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| 229 | for fn in readers: |
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| 230 | try: |
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| 231 | value=fn.read(path) |
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| 232 | return value |
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[8176aad] | 233 | except: |
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| 234 | logging.error("Load Error: %s"% (sys.exc_value)) |
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[d22da51] | 235 | else: |
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| 236 | raise ValueError,"Loader contains no reader" |
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| 237 | |
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| 238 | |
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[a916ccc] | 239 | def __init__(self): |
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| 240 | """ Create singleton instance """ |
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| 241 | # Check whether we already have an instance |
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[1b0b3ca] | 242 | if Loader.__load is None: |
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[a916ccc] | 243 | # Create and remember instance |
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[1b0b3ca] | 244 | Loader.__load = Loader.Load() |
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| 245 | Loader.__load.__setitem__() |
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[a916ccc] | 246 | # Store instance reference as the only member in the handle |
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[1b0b3ca] | 247 | self.__dict__['_Loader__load'] = Loader.__load |
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[a916ccc] | 248 | |
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| 249 | def __getattr__(self, attr): |
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| 250 | """ Delegate access to implementation """ |
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| 251 | return getattr(self.__load, attr) |
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| 252 | |
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| 253 | def __setattr__(self, attr, value): |
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| 254 | """ Delegate access to implementation """ |
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| 255 | return setattr(self.__load, attr, value) |
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