Two new generally useful modules: types defines names for all built-in types,
StringIO implements pseudo files writing into and reading from strings.
diff --git a/Lib/StringIO.py b/Lib/StringIO.py
new file mode 100644
index 0000000..715e71e
--- /dev/null
+++ b/Lib/StringIO.py
@@ -0,0 +1,130 @@
+# class StringIO implements file-like objects that read/write a
+# string buffer (a.k.a. "memory files").
+#
+# This implements (nearly) all stdio methods.
+#
+# f = StringIO() # ready for writing
+# f = StringIO(buf) # ready for reading
+# f.close() # explicitly release resources held
+# flag = f.isatty() # always false
+# pos = f.tell() # get current position
+# f.seek(pos) # set current position
+# f.seek(pos, mode) # mode 0: absolute; 1: relative; 2: relative to EOF
+# buf = f.read() # read until EOF
+# buf = f.read(n) # read up to n bytes
+# buf = f.readline() # read until end of line ('\n') or EOF
+# list = f.readlines()# list of f.readline() results until EOF
+# f.write(buf) # write at current position
+# f.writelines(list) # for line in list: f.write(line)
+# f.getvalue() # return whole file's contents as a string
+#
+# Notes:
+# - Using a real file is often faster (but less convenient).
+# - fileno() is left unimplemented so that code which uses it triggers
+# an exception early.
+# - Seeking far beyond EOF and then writing will insert real null
+# bytes that occupy space in the buffer.
+# - There's a simple test set (see end of this file).
+
+import string
+
+class StringIO:
+ def __init__(self, buf = ''):
+ self.buf = buf
+ self.pos = 0
+ self.closed = 0
+ def close(self):
+ if not self.closed:
+ self.closed = 1
+ del self.buf, self.pos
+ def isatty(self):
+ return 0
+ def seek(self, pos, mode = 0):
+ if mode == 1:
+ pos = pos + self.pos
+ elif mode == 2:
+ pos = pos + len(self.buf)
+ self.pos = max(0, pos)
+ def tell(self):
+ return self.pos
+ def read(self, n = 0):
+ if n <= 0:
+ newpos = len(self.buf)
+ else:
+ newpos = min(self.pos+n, len(self.buf))
+ r = self.buf[self.pos:newpos]
+ self.pos = newpos
+ return r
+ def readline(self):
+ i = string.find(self.buf, '\n', self.pos)
+ if i < 0:
+ newpos = len(self.buf)
+ else:
+ newpos = i+1
+ r = self.buf[self.pos:newpos]
+ self.pos = newpos
+ return r
+ def readlines(self):
+ lines = []
+ line = self.readline()
+ while line:
+ lines.append(line)
+ line = self.readline()
+ return lines
+ def write(self, s):
+ if not s: return
+ if self.pos > len(self.buf):
+ self.buf = self.buf + '\0'*(self.pos - len(self.buf))
+ newpos = self.pos + len(s)
+ self.buf = self.buf[:self.pos] + s + self.buf[newpos:]
+ self.pos = newpos
+ def writelines(self, list):
+ self.write(string.joinfields(list, ''))
+ def getvalue(self):
+ return self.buf
+
+
+# A little test suite
+
+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 = StringIO()
+ 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()