update from Atlas with major reorg

14-it-generator/isis2json/iso2709.py

@@ -0,0 +1,167 @@
+#!/usr/bin/env python
+# -*- encoding: utf-8 -*-
+
+# ISO-2709 file reader
+#
+# Copyright (C) 2010 BIREME/PAHO/WHO
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published
+# by the Free Software Foundation, either version 2.1 of the License, or
+# (at your option) any later version.
+
+# This program 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 Lesser General Public License for more details.
+
+# You should have received a copy of the GNU Lesser General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+from struct import unpack
+
+CR =  '\x0D' # \r
+LF =  '\x0A' # \n
+IS1 = '\x1F' # ECMA-48 Unit Separator
+IS2 = '\x1E' # ECMA-48 Record Separator / ISO-2709 field separator
+IS3 = '\x1D' # ECMA-48 Group Separator / ISO-2709 record separator
+LABEL_LEN = 24
+LABEL_FORMAT = '5s c 4s c c 5s 3s c c c c'
+TAG_LEN = 3
+DEFAULT_ENCODING = 'ASCII'
+SUBFIELD_DELIMITER = '^'
+
+class IsoFile(object):
+
+    def __init__(self, filename, encoding = DEFAULT_ENCODING):
+        self.file = open(filename, 'rb')
+        self.encoding = encoding
+
+    def __iter__(self):
+        return self
+
+    def next(self):
+        return IsoRecord(self)
+
+    __next__ = next # Python 3 compatibility
+
+    def read(self, size):
+        ''' read and drop all CR and LF characters '''
+        # TODO: this is inneficient but works, patches accepted!
+        # NOTE: our fixtures include files which have no linebreaks,
+        # files with CR-LF linebreaks and files with LF linebreaks
+        chunks = []
+        count = 0
+        while count < size:
+            chunk = self.file.read(size-count)
+            if len(chunk) == 0:
+                break
+            chunk = chunk.replace(CR+LF,'')
+            if CR in chunk:
+                chunk = chunk.replace(CR,'')
+            if LF in chunk:
+                chunk = chunk.replace(LF,'')
+            count += len(chunk)
+            chunks.append(chunk)
+        return ''.join(chunks)
+
+    def close(self):
+        self.file.close()
+
+class IsoRecord(object):
+    label_part_names = ('rec_len rec_status impl_codes indicator_len identifier_len'
+                        ' base_addr user_defined'
+                        # directory map:
+                        ' fld_len_len start_len impl_len reserved').split()
+    rec_len = 0
+
+    def __init__(self, iso_file=None):
+        self.iso_file = iso_file
+        self.load_label()
+        self.load_directory()
+        self.load_fields()
+
+    def __len__(self):
+        return self.rec_len
+
+    def load_label(self):
+        label = self.iso_file.read(LABEL_LEN)
+        if len(label) == 0:
+            raise StopIteration
+        elif len(label) != 24:
+            raise ValueError('Invalid record label: "%s"' % label)
+        parts = unpack(LABEL_FORMAT, label)
+        for name, part in zip(self.label_part_names, parts):
+            if name.endswith('_len') or name.endswith('_addr'):
+                part = int(part)
+            setattr(self, name, part)
+
+    def show_label(self):
+        for name in self.label_part_names:
+            print('%15s : %r' % (name, getattr(self, name)))
+
+    def load_directory(self):
+        fmt_dir = '3s %ss %ss %ss' % (self.fld_len_len, self.start_len, self.impl_len)
+        entry_len = TAG_LEN + self.fld_len_len + self.start_len + self.impl_len
+        self.directory = []
+        while True:
+            char = self.iso_file.read(1)
+            if char.isdigit():
+                entry = char + self.iso_file.read(entry_len-1)
+                entry = Field(* unpack(fmt_dir, entry))
+                self.directory.append(entry)
+            else:
+                break
+
+    def load_fields(self):
+        for field in self.directory:
+            if self.indicator_len > 0:
+                field.indicator = self.iso_file.read(self.indicator_len)
+            # XXX: lilacs30.iso has an identifier_len == 2,
+            # but we need to ignore it to succesfully read the field contents
+            # TODO: find out when to ignore the idenfier_len,
+            # or fix the lilacs30.iso fixture
+            #
+            ##if self.identifier_len > 0: #
+            ##    field.identifier = self.iso_file.read(self.identifier_len)
+            value = self.iso_file.read(len(field))
+            assert len(value) == len(field)
+            field.value = value[:-1] # remove trailing field separator
+        self.iso_file.read(1) # discard record separator
+
+    def __iter__(self):
+        return self
+
+    def next(self):
+        for field in self.directory:
+            yield(field)
+
+    __next__ = next # Python 3 compatibility
+
+    def dump(self):
+        for field in self.directory:
+            print('%3s %r' % (field.tag, field.value))
+
+class Field(object):
+
+    def __init__(self, tag, len, start, impl):
+        self.tag = tag
+        self.len = int(len)
+        self.start = int(start)
+        self.impl = impl
+
+    def show(self):
+        for name in 'tag len start impl'.split():
+            print('%15s : %r' % (name, getattr(self, name)))
+
+    def __len__(self):
+        return self.len
+
+def test():
+    import doctest
+    doctest.testfile('iso2709_test.txt')
+
+
+if __name__=='__main__':
+    test()
+