From 85d894559029cad1e5ed0f71b9a63242d4631b87 Mon Sep 17 00:00:00 2001 From: Guido van Rossum Date: Thu, 23 Jun 1994 11:53:27 +0000 Subject: Two new generally useful modules: types defines names for all built-in types, StringIO implements pseudo files writing into and reading from strings. --- Lib/StringIO.py | 130 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Lib/types.py | 43 +++++++++++++++++++ 2 files changed, 173 insertions(+) create mode 100644 Lib/StringIO.py create mode 100644 Lib/types.py 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() diff --git a/Lib/types.py b/Lib/types.py new file mode 100644 index 0000000..531d405 --- /dev/null +++ b/Lib/types.py @@ -0,0 +1,43 @@ +# Define names for all type symbols known in the standard interpreter. +# Types that are part of optional modules (e.g. array) are not listed. + +import sys + +NoneType = type(None) +TypeType = type(NoneType) + +IntType = type(0) +LongType = type(0L) +FloatType = type(0.0) + +StringType = type('') + +TupleType = type(()) +ListType = type([]) +DictionaryType = type({}) + +def func(): pass +FunctionType = type(func) + +class C: + def meth(self): pass +ClassType = type(C) +UnboundMethodType = type(C.meth) # Same as MethodType +x = C() +InstanceType = type(x) +MethodType = type(x.meth) + +BuiltinFunctionType = type(len) # Also used for built-in methods + +ModuleType = type(sys) + +FileType = type(sys.stdin) +XRangeType = type(xrange(0)) + +try: + raise TypeError +except TypeError: + TracebackType = type(sys.exc_traceback) + FrameType = type(sys.exc_traceback.tb_frame) + +del sys, func, C, x # These are not for export -- cgit v0.12