Mercurial > cpython-lru_cache-weakref

annotate Lib/StringIO.py @ 3216:d00a79ebb027 legacy-trunk

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Added missing imgpbm and imgsgi modules
author Jack Jansen <jack.jansen@cwi.nl>
date Thu, 12 Oct 1995 10:23:27 +0000
parents 1eeeba09a306
children 81f45f69388e
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
1680
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
1 # class StringIO implements file-like objects that read/write a
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
2 # string buffer (a.k.a. "memory files").
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
3 #
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
4 # This implements (nearly) all stdio methods.
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
5 #
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
6 # f = StringIO() # ready for writing
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
7 # f = StringIO(buf) # ready for reading
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
8 # f.close() # explicitly release resources held
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
9 # flag = f.isatty() # always false
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
10 # pos = f.tell() # get current position
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
11 # f.seek(pos) # set current position
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
12 # f.seek(pos, mode) # mode 0: absolute; 1: relative; 2: relative to EOF
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
13 # buf = f.read() # read until EOF
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
14 # buf = f.read(n) # read up to n bytes
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
15 # buf = f.readline() # read until end of line ('\n') or EOF
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
16 # list = f.readlines()# list of f.readline() results until EOF
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
17 # f.write(buf) # write at current position
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
18 # f.writelines(list) # for line in list: f.write(line)
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
19 # f.getvalue() # return whole file's contents as a string
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
20 #
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
21 # Notes:
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
22 # - Using a real file is often faster (but less convenient).
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
23 # - fileno() is left unimplemented so that code which uses it triggers
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
24 # an exception early.
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
25 # - Seeking far beyond EOF and then writing will insert real null
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
26 # bytes that occupy space in the buffer.
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
27 # - There's a simple test set (see end of this file).
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
28
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
29 import string
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
30
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
31 class StringIO:
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
32 def __init__(self, buf = ''):
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
33 self.buf = buf
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
34 self.pos = 0
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
35 self.closed = 0
2770
dc2adf79e523 set softspace to 0 in __init__
Guido van Rossum <guido@python.org>
parents: 1680
diff changeset
36 self.softspace = 0
1680
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
37 def close(self):
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
38 if not self.closed:
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
39 self.closed = 1
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
40 del self.buf, self.pos
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
41 def isatty(self):
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
42 return 0
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
43 def seek(self, pos, mode = 0):
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
44 if mode == 1:
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
45 pos = pos + self.pos
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
46 elif mode == 2:
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
47 pos = pos + len(self.buf)
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
48 self.pos = max(0, pos)
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
49 def tell(self):
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
50 return self.pos
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
51 def read(self, n = 0):
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
52 if n <= 0:
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
53 newpos = len(self.buf)
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
54 else:
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
55 newpos = min(self.pos+n, len(self.buf))
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
56 r = self.buf[self.pos:newpos]
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
57 self.pos = newpos
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
58 return r
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
59 def readline(self):
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
60 i = string.find(self.buf, '\n', self.pos)
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
61 if i < 0:
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
62 newpos = len(self.buf)
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
63 else:
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
64 newpos = i+1
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
65 r = self.buf[self.pos:newpos]
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
66 self.pos = newpos
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
67 return r
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
68 def readlines(self):
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
69 lines = []
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
70 line = self.readline()
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
71 while line:
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
72 lines.append(line)
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
73 line = self.readline()
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
74 return lines
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
75 def write(self, s):
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
76 if not s: return
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
77 if self.pos > len(self.buf):
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
78 self.buf = self.buf + '\0'*(self.pos - len(self.buf))
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
79 newpos = self.pos + len(s)
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
80 self.buf = self.buf[:self.pos] + s + self.buf[newpos:]
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
81 self.pos = newpos
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
82 def writelines(self, list):
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
83 self.write(string.joinfields(list, ''))
2852
1eeeba09a306 Added flush() method.
Sjoerd Mullender <sjoerd@acm.org>
parents: 2770
diff changeset
84 def flush(self):
1eeeba09a306 Added flush() method.
Sjoerd Mullender <sjoerd@acm.org>
parents: 2770
diff changeset
85 pass
1680
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
86 def getvalue(self):
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
87 return self.buf
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
88
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
89
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
90 # A little test suite
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
91
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
92 def test():
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
93 import sys
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
94 if sys.argv[1:]:
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
95 file = sys.argv[1]
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
96 else:
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
97 file = '/etc/passwd'
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
98 lines = open(file, 'r').readlines()
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
99 text = open(file, 'r').read()
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
100 f = StringIO()
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
101 for line in lines[:-2]:
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
102 f.write(line)
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
103 f.writelines(lines[-2:])
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
104 if f.getvalue() != text:
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
105 raise RuntimeError, 'write failed'
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
106 length = f.tell()
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
107 print 'File length =', length
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
108 f.seek(len(lines[0]))
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
109 f.write(lines[1])
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
110 f.seek(0)
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
111 print 'First line =', `f.readline()`
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
112 here = f.tell()
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
113 line = f.readline()
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
114 print 'Second line =', `line`
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
115 f.seek(-len(line), 1)
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
116 line2 = f.read(len(line))
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
117 if line != line2:
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
118 raise RuntimeError, 'bad result after seek back'
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
119 f.seek(len(line2), 1)
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
120 list = f.readlines()
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
121 line = list[-1]
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
122 f.seek(f.tell() - len(line))
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
123 line2 = f.read()
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
124 if line != line2:
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
125 raise RuntimeError, 'bad result after seek back from EOF'
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
126 print 'Read', len(list), 'more lines'
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
127 print 'File length =', f.tell()
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
128 if f.tell() != length:
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
129 raise RuntimeError, 'bad length'
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
130 f.close()
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
131
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
132 if __name__ == '__main__':
0a60460e99f0 Two new generally useful modules: types defines names for all built-in types,
Guido van Rossum <guido@python.org>
parents:
diff changeset
133 test()