*** empty log message ***

Lib/ArrayIO.py

@@ -0,0 +1,122 @@
+# 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()