52 lines
1.7 KiB
Python
52 lines
1.7 KiB
Python
# Copyright (C) 2018 and later: Unicode, Inc. and others.
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# License & terms of use: http://www.unicode.org/copyright.html
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import io
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class CommentStripper(object):
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"""Removes lines starting with "//" from a file stream."""
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def __init__(self, f):
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self.f = f
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self.state = 0
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def read(self, size=-1):
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bytes = self.f.read(size)
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# TODO: Do we need to read more bytes if comments were stripped
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# in order to obey the size request?
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return "".join(self._strip_comments(bytes))
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def _strip_comments(self, bytes):
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for byte in bytes:
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if self.state == 0:
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# state 0: start of a line
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if byte == "/":
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self.state = 1
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elif byte == "\n":
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self.state = 0
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yield byte
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else:
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self.state = 2
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yield byte
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elif self.state == 1:
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# state 1: read a single '/'
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if byte == "/":
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self.state = 3
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elif byte == "\n":
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self.state = 0
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yield "/" # the one that was skipped
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yield "\n"
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else:
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self.state = 2
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yield "/" # the one that was skipped
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yield byte
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elif self.state == 2:
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# state 2: middle of a line, no comment
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if byte == "\n":
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self.state = 0
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yield byte
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elif self.state == 3:
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# state 3: inside a comment
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if byte == "\n":
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self.state = 0
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