Added fast alternate io.BytesIO implementation and its test suite.
Removed old test suite for StringIO.
Modified truncate() to imply a seek to given argument value.
diff --git a/Lib/io.py b/Lib/io.py
index 3172554..3a1546a 100644
--- a/Lib/io.py
+++ b/Lib/io.py
@@ -490,6 +490,7 @@
terminator(s) recognized.
"""
# For backwards compatibility, a (slowish) readline().
+ self._checkClosed()
if hasattr(self, "peek"):
def nreadahead():
readahead = self.peek(1)
@@ -531,7 +532,7 @@
lines will be read if the total size (in bytes/characters) of all
lines so far exceeds hint.
"""
- if hint is None:
+ if hint is None or hint <= 0:
return list(self)
n = 0
lines = []
@@ -726,6 +727,8 @@
if pos is None:
pos = self.tell()
+ # XXX: Should seek() be used, instead of passing the position
+ # XXX directly to truncate?
return self.raw.truncate(pos)
### Flush and close ###
@@ -765,7 +768,7 @@
return self.raw.isatty()
-class BytesIO(BufferedIOBase):
+class _BytesIO(BufferedIOBase):
"""Buffered I/O implementation using an in-memory bytes buffer."""
@@ -779,13 +782,19 @@
def getvalue(self):
"""Return the bytes value (contents) of the buffer
"""
+ if self.closed:
+ raise ValueError("getvalue on closed file")
return bytes(self._buffer)
def read(self, n=None):
+ if self.closed:
+ raise ValueError("read from closed file")
if n is None:
n = -1
if n < 0:
n = len(self._buffer)
+ if len(self._buffer) <= self._pos:
+ return self._buffer[:0]
newpos = min(len(self._buffer), self._pos + n)
b = self._buffer[self._pos : newpos]
self._pos = newpos
@@ -802,6 +811,8 @@
if isinstance(b, str):
raise TypeError("can't write str to binary stream")
n = len(b)
+ if n == 0:
+ return 0
newpos = self._pos + n
if newpos > len(self._buffer):
# Inserts null bytes between the current end of the file
@@ -813,28 +824,38 @@
return n
def seek(self, pos, whence=0):
+ if self.closed:
+ raise ValueError("seek on closed file")
try:
pos = pos.__index__()
except AttributeError as err:
raise TypeError("an integer is required") from err
if whence == 0:
self._pos = max(0, pos)
+ if pos < 0:
+ raise ValueError("negative seek position %r" % (pos,))
elif whence == 1:
self._pos = max(0, self._pos + pos)
elif whence == 2:
self._pos = max(0, len(self._buffer) + pos)
else:
- raise IOError("invalid whence value")
+ raise ValueError("invalid whence value")
return self._pos
def tell(self):
+ if self.closed:
+ raise ValueError("tell on closed file")
return self._pos
def truncate(self, pos=None):
+ if self.closed:
+ raise ValueError("truncate on closed file")
if pos is None:
pos = self._pos
+ elif pos < 0:
+ raise ValueError("negative truncate position %r" % (pos,))
del self._buffer[pos:]
- return pos
+ return self.seek(pos)
def readable(self):
return True
@@ -845,6 +866,16 @@
def seekable(self):
return True
+# Use the faster implementation of BytesIO if available
+try:
+ import _bytesio
+
+ class BytesIO(_bytesio._BytesIO, BufferedIOBase):
+ __doc__ = _bytesio._BytesIO.__doc__
+
+except ImportError:
+ BytesIO = _BytesIO
+
class BufferedReader(_BufferedIOMixin):
@@ -978,6 +1009,12 @@
raise BlockingIOError(e.errno, e.strerror, overage)
return written
+ def truncate(self, pos=None):
+ self.flush()
+ if pos is None:
+ pos = self.raw.tell()
+ return self.raw.truncate(pos)
+
def flush(self):
if self.closed:
raise ValueError("flush of closed file")
@@ -1097,6 +1134,13 @@
else:
return self.raw.tell() - len(self._read_buf)
+ def truncate(self, pos=None):
+ if pos is None:
+ pos = self.tell()
+ # Use seek to flush the read buffer.
+ self.seek(pos)
+ return BufferedWriter.truncate(self)
+
def read(self, n=None):
if n is None:
n = -1
@@ -1145,11 +1189,7 @@
def truncate(self, pos: int = None) -> int:
"""Truncate size to pos."""
- self.flush()
- if pos is None:
- pos = self.tell()
- self.seek(pos)
- return self.buffer.truncate()
+ self._unsupported("truncate")
def readline(self) -> str:
"""Read until newline or EOF.
@@ -1346,6 +1386,12 @@
def seekable(self):
return self._seekable
+ def readable(self):
+ return self.buffer.readable()
+
+ def writable(self):
+ return self.buffer.writable()
+
def flush(self):
self.buffer.flush()
self._telling = self._seekable
@@ -1539,7 +1585,16 @@
finally:
decoder.setstate(saved_state)
+ def truncate(self, pos=None):
+ self.flush()
+ if pos is None:
+ pos = self.tell()
+ self.seek(pos)
+ return self.buffer.truncate()
+
def seek(self, cookie, whence=0):
+ if self.closed:
+ raise ValueError("tell on closed file")
if not self._seekable:
raise IOError("underlying stream is not seekable")
if whence == 1: # seek relative to current position
@@ -1626,6 +1681,8 @@
return line
def readline(self, limit=None):
+ if self.closed:
+ raise ValueError("read from closed file")
if limit is None:
limit = -1