02-19-2009
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Join Date: Feb 2009
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please explain this sed shell script to remove C++ comments.
#! /bin/sed -nf
# Remove C and C++ comments, by Brian Hiles (brian_hiles@rocketmail.com)
# Sped up (and bugfixed to some extent) by Paolo Bonzini (bonzini@gnu.org)
# Works its way through the line, copying to hold space the text up to the
# first special character (/, ", '). The original version went exactly a
# character at a time, hence the greater speed of this one. But the concept
# and especially the trick of building the line in hold space are entirely
# merit of Brian.
:loop
# This line is sufficient to remove C++ comments!
/^\/\// s,.*,,
/^$/{
x
p
n
b loop
}
/^"/{
:double
/^$/{
x
p
n
/^"/b break
b double
}
H
x
s,\n\(.[^\"]*\).*,\1,
x
s,.[^\"]*,,
/^"/b break
/^\\/{
H
x
s,\n\(.\).*,\1,
x
s/.//
}
b double
}
/^'/{
:single
/^$/{
x
p
n
/^'/b break
b single
}
H
x
s,\n\(.[^\']*\).*,\1,
x
s,.[^\']*,,
/^'/b break
/^\\/{
H
x
s,\n\(.\).*,\1,
x
s/.//
}
b single
}
/^\/\*/{
s/.//
:ccom
s,^.[^*]*,,
/^$/ n
/^\*\//{
s/..//
b loop
}
b ccom
}
:break
H
x
s,\n\(.[^"'/]*\).*,\1,
x
s/.[^"'/]*//
b loop
