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# encoding: utf-8
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"""
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Stdout/stderr redirector, at the OS level, using file descriptors.
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This also works under windows.
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"""
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__docformat__ = "restructuredtext en"
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#-------------------------------------------------------------------------------
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# Copyright (C) 2008 The IPython Development Team
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#
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# Distributed under the terms of the BSD License. The full license is in
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# the file COPYING, distributed as part of this software.
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#-------------------------------------------------------------------------------
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import os
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import sys
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STDOUT = 1
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STDERR = 2
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class FDRedirector(object):
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""" Class to redirect output (stdout or stderr) at the OS level using
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file descriptors.
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"""
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def __init__(self, fd=STDOUT):
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""" fd is the file descriptor of the outpout you want to capture.
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It can be STDOUT or STERR.
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"""
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self.fd = fd
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self.started = False
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self.piper = None
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self.pipew = None
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def start(self):
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""" Setup the redirection.
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"""
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if not self.started:
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self.oldhandle = os.dup(self.fd)
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self.piper, self.pipew = os.pipe()
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os.dup2(self.pipew, self.fd)
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os.close(self.pipew)
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self.started = True
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def flush(self):
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""" Flush the captured output, similar to the flush method of any
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stream.
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"""
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if self.fd == STDOUT:
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sys.stdout.flush()
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elif self.fd == STDERR:
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sys.stderr.flush()
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def stop(self):
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""" Unset the redirection and return the captured output.
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"""
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if self.started:
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self.flush()
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os.dup2(self.oldhandle, self.fd)
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os.close(self.oldhandle)
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f = os.fdopen(self.piper, 'r')
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output = f.read()
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f.close()
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self.started = False
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return output
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else:
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return ''
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def getvalue(self):
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""" Return the output captured since the last getvalue, or the
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start of the redirection.
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"""
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output = self.stop()
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self.start()
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return output
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