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# -*- Mode: Python; tab-width: 4 -*- |
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import string |
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""" |
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A collection of producers. |
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Each producer implements a particular feature: They can be combined |
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in various ways to get interesting and useful behaviors. |
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For example, you can feed dynamically-produced output into the compressing |
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producer, then wrap this with the 'chunked' transfer-encoding producer. |
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""" |
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View Code Duplication |
class simple_producer: |
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"producer for a string" |
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def __init__ (self, data, buffer_size=1024): |
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self.data = data |
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self.buffer_size = buffer_size |
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def more (self): |
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if len (self.data) > self.buffer_size: |
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result = self.data[:self.buffer_size] |
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self.data = self.data[self.buffer_size:] |
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return result |
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else: |
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result = self.data |
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self.data = '' |
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return result |
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class scanning_producer: |
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"like simple_producer, but more efficient for large strings" |
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def __init__ (self, data, buffer_size=1024): |
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self.data = data |
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self.buffer_size = buffer_size |
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self.pos = 0 |
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def more (self): |
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if self.pos < len(self.data): |
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lp = self.pos |
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rp = min ( |
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len(self.data), |
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self.pos + self.buffer_size |
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) |
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result = self.data[lp:rp] |
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self.pos = self.pos + len(result) |
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return result |
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else: |
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return '' |
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View Code Duplication |
class lines_producer: |
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"producer for a list of lines" |
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def __init__ (self, lines): |
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self.lines = lines |
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def ready (self): |
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return len(self.lines) |
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def more (self): |
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if self.lines: |
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chunk = self.lines[:50] |
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self.lines = self.lines[50:] |
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return string.join (chunk, '\r\n') + '\r\n' |
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else: |
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return '' |
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class buffer_list_producer: |
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"producer for a list of buffers" |
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# i.e., data == string.join (buffers, '') |
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def __init__ (self, buffers): |
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self.index = 0 |
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self.buffers = buffers |
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def more (self): |
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if self.index >= len(self.buffers): |
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return '' |
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else: |
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data = self.buffers[self.index] |
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self.index = self.index + 1 |
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return data |
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class file_producer: |
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"producer wrapper for file[-like] objects" |
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# match http_channel's outgoing buffer size |
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out_buffer_size = 1<<16 |
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def __init__ (self, file): |
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self.done = 0 |
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self.file = file |
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def more (self): |
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if self.done: |
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return '' |
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else: |
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data = self.file.read (self.out_buffer_size) |
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if not data: |
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self.file.close() |
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del self.file |
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self.done = 1 |
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return '' |
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else: |
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return data |
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# A simple output producer. This one does not [yet] have |
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# the safety feature builtin to the monitor channel: runaway |
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# output will not be caught. |
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# don't try to print from within any of the methods |
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# of this object. |
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class output_producer: |
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"Acts like an output file; suitable for capturing sys.stdout" |
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def __init__ (self): |
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self.data = '' |
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def write (self, data): |
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lines = string.splitfields (data, '\n') |
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data = string.join (lines, '\r\n') |
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self.data = self.data + data |
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def writeline (self, line): |
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self.data = self.data + line + '\r\n' |
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def writelines (self, lines): |
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self.data = self.data + string.joinfields ( |
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lines, |
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'\r\n' |
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) + '\r\n' |
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def ready (self): |
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return (len (self.data) > 0) |
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def flush (self): |
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pass |
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def softspace (self, *args): |
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pass |
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def more (self): |
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if self.data: |
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result = self.data[:512] |
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self.data = self.data[512:] |
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return result |
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else: |
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return '' |
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class composite_producer: |
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"combine a fifo of producers into one" |
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def __init__ (self, producers): |
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self.producers = producers |
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def more (self): |
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while len(self.producers): |
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p = self.producers.first() |
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d = p.more() |
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if d: |
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return d |
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else: |
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self.producers.pop() |
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else: |
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return '' |
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class globbing_producer: |
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""" |
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'glob' the output from a producer into a particular buffer size. |
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helps reduce the number of calls to send(). [this appears to |
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gain about 30% performance on requests to a single channel] |
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""" |
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def __init__ (self, producer, buffer_size=1<<16): |
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self.producer = producer |
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self.buffer = '' |
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self.buffer_size = buffer_size |
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def more (self): |
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while len(self.buffer) < self.buffer_size: |
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data = self.producer.more() |
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if data: |
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self.buffer = self.buffer + data |
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else: |
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break |
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r = self.buffer |
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self.buffer = '' |
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return r |
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class hooked_producer: |
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""" |
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A producer that will call <function> when it empties,. |
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with an argument of the number of bytes produced. Useful |
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for logging/instrumentation purposes. |
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""" |
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def __init__ (self, producer, function): |
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self.producer = producer |
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self.function = function |
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self.bytes = 0 |
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def more (self): |
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if self.producer: |
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result = self.producer.more() |
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if not result: |
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self.producer = None |
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self.function (self.bytes) |
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else: |
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self.bytes = self.bytes + len(result) |
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return result |
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else: |
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return '' |
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# HTTP 1.1 emphasizes that an advertised Content-Length header MUST be |
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# correct. In the face of Strange Files, it is conceivable that |
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# reading a 'file' may produce an amount of data not matching that |
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# reported by os.stat() [text/binary mode issues, perhaps the file is |
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# being appended to, etc..] This makes the chunked encoding a True |
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# Blessing, and it really ought to be used even with normal files. |
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# How beautifully it blends with the concept of the producer. |
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class chunked_producer: |
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"""A producer that implements the 'chunked' transfer coding for HTTP/1.1. |
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Here is a sample usage: |
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request['Transfer-Encoding'] = 'chunked' |
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request.push ( |
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producers.chunked_producer (your_producer) |
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) |
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request.done() |
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""" |
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def __init__ (self, producer, footers=None): |
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self.producer = producer |
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self.footers = footers |
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def more (self): |
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if self.producer: |
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data = self.producer.more() |
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if data: |
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return '%x\r\n%s\r\n' % (len(data), data) |
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else: |
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self.producer = None |
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if self.footers: |
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return string.join ( |
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['0'] + self.footers, |
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'\r\n' |
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) + '\r\n\r\n' |
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else: |
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return '0\r\n\r\n' |
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else: |
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return '' |
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# Unfortunately this isn't very useful right now (Aug 97), because |
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# apparently the browsers don't do on-the-fly decompression. Which |
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# is sad, because this could _really_ speed things up, especially for |
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# low-bandwidth clients (i.e., most everyone). |
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try: |
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import zlib |
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except ImportError: |
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zlib = None |
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class compressed_producer: |
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""" |
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Compress another producer on-the-fly, using ZLIB |
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[Unfortunately, none of the current browsers seem to support this] |
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""" |
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# Note: It's not very efficient to have the server repeatedly |
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# compressing your outgoing files: compress them ahead of time, or |
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# use a compress-once-and-store scheme. However, if you have low |
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# bandwidth and low traffic, this may make more sense than |
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# maintaining your source files compressed. |
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# |
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# Can also be used for compressing dynamically-produced output. |
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def __init__ (self, producer, level=5): |
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self.producer = producer |
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self.compressor = zlib.compressobj (level) |
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def more (self): |
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if self.producer: |
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cdata = '' |
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# feed until we get some output |
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while not cdata: |
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data = self.producer.more() |
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if not data: |
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self.producer = None |
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return self.compressor.flush() |
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else: |
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cdata = self.compressor.compress (data) |
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return cdata |
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else: |
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return '' |
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class escaping_producer: |
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"A producer that escapes a sequence of characters" |
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" Common usage: escaping the CRLF.CRLF sequence in SMTP, NNTP, etc..." |
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def __init__ (self, producer, esc_from='\r\n.', esc_to='\r\n..'): |
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self.producer = producer |
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self.esc_from = esc_from |
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self.esc_to = esc_to |
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self.buffer = '' |
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from asynchat import find_prefix_at_end |
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self.find_prefix_at_end = find_prefix_at_end |
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def more (self): |
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esc_from = self.esc_from |
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esc_to = self.esc_to |
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buffer = self.buffer + self.producer.more() |
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if buffer: |
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buffer = string.replace (buffer, esc_from, esc_to) |
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i = self.find_prefix_at_end (buffer, esc_from) |
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if i: |
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# we found a prefix |
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self.buffer = buffer[-i:] |
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return buffer[:-i] |
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else: |
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# no prefix, return it all |
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self.buffer = '' |
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return buffer |
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else: |
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return buffer |
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