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authorGuido van Rossum <guido@python.org>1996-02-28 23:58:09 (GMT)
committerGuido van Rossum <guido@python.org>1996-02-28 23:58:09 (GMT)
commit405ab2378e89b6eb5148c096de113558cb52dad4 (patch)
treeb5ecc51ae348f6377441d38b2e94f5976a795fb4 /Lib
parent01fbc688967f4d68e2a080dd0de56c582e220432 (diff)
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Diffstat (limited to 'Lib')
-rwxr-xr-xLib/ArrayIO.py122
1 files changed, 122 insertions, 0 deletions
diff --git a/Lib/ArrayIO.py b/Lib/ArrayIO.py
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+++ b/Lib/ArrayIO.py
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+# port of StringIO.py using arrays
+# ArrayIO.py
+# jjk 02/28/96 001 direct mod of StringIO, test suite checks out
+# jjk 02/28/96 002 inherit from StringIO, test suite checks out
+# jjk 02/28/96 003 add __xx__() functions
+#
+# class ArrayIO implements file-like objects that read/write a
+# string buffer (a.k.a. "memory files").
+#
+# all methods that interface with ArrayIO pass strings. Internally, however,
+# ArrayIO uses an array object.
+#
+# the interface is the same as StringIO.py
+# also handles len(a), a[i], a[i]='x', a[i:j], a[i:j] = aString
+#
+
+import string
+import array
+import StringIO
+
+class ArrayIO(StringIO.StringIO):
+# jjk 02/28/96
+ def __init__(self, buf = ''):
+ #jjk 02/28/96
+ self.buf = array.array('c', buf)
+ self.pos = 0
+ self.closed = 0
+ def __len__(self):
+ #jjk 02/28/96
+ return len(self.buf)
+ def __getitem__(self, key):
+ #jjk 02/28/96
+ return self.buf[key]
+ def __setitem__(self, key, item):
+ #jjk 02/28/96
+ self.buf[key] = item
+ def __getslice__(self, i, j):
+ #jjk 02/28/96
+ return self.buf[i:j].tostring()
+ def __setslice__(self, i, j, aString):
+ #jjk 02/28/96
+ self.buf[i:j] = array.array('c', aString)
+ def read(self, n = 0):
+ #jjk 02/28/96
+ r = StringIO.StringIO.read(self, n)
+ return (r.tostring())
+ def _findCharacter(self, char, start):
+ #probably very slow
+ #jjk 02/28/96
+ for i in range(max(start, 0), len(self.buf)):
+ if (self.buf[i] == char):
+ return(i)
+ return(-1)
+ def readline(self):
+ #jjk 02/28/96
+ i = self._findCharacter('\n', self.pos)
+ if i < 0:
+ newpos = len(self.buf)
+ else:
+ newpos = i+1
+ r = self.buf[self.pos:newpos].tostring()
+ self.pos = newpos
+ return r
+ def write(self, s):
+ #jjk 02/28/96
+ if not s: return
+ if self.pos > len(self.buf):
+ self.buf.fromstring('\0'*(self.pos - len(self.buf)))
+ newpos = self.pos + len(s)
+ self.buf[self.pos:newpos] = array.array('c', s)
+ self.pos = newpos
+ def getvalue(self):
+ #jjk 02/28/96
+ return self.buf.tostring()
+
+
+# A little test suite
+# identical to test suite in StringIO.py , except for "f = ArrayIO()"
+# too bad I couldn't inherit this :-)
+
+def test():
+ import sys
+ if sys.argv[1:]:
+ file = sys.argv[1]
+ else:
+ file = '/etc/passwd'
+ lines = open(file, 'r').readlines()
+ text = open(file, 'r').read()
+ f = ArrayIO()
+ for line in lines[:-2]:
+ f.write(line)
+ f.writelines(lines[-2:])
+ if f.getvalue() != text:
+ raise RuntimeError, 'write failed'
+ length = f.tell()
+ print 'File length =', length
+ f.seek(len(lines[0]))
+ f.write(lines[1])
+ f.seek(0)
+ print 'First line =', `f.readline()`
+ here = f.tell()
+ line = f.readline()
+ print 'Second line =', `line`
+ f.seek(-len(line), 1)
+ line2 = f.read(len(line))
+ if line != line2:
+ raise RuntimeError, 'bad result after seek back'
+ f.seek(len(line2), 1)
+ list = f.readlines()
+ line = list[-1]
+ f.seek(f.tell() - len(line))
+ line2 = f.read()
+ if line != line2:
+ raise RuntimeError, 'bad result after seek back from EOF'
+ print 'Read', len(list), 'more lines'
+ print 'File length =', f.tell()
+ if f.tell() != length:
+ raise RuntimeError, 'bad length'
+ f.close()
+
+if __name__ == '__main__':
+ test()