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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()
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