require 'optparse'
def main
output = nil
parser = OptionParser.new
parser.banner = "Usage: #{File.basename($0)} [--output=PATH] <parse.y>"
parser.on('--output=PATH', 'An output file.') {|path|
output = path
}
parser.on('--help', 'Prints this message and quit.') {
puts parser.help
exit true
}
begin
parser.parse!
rescue OptionParser::ParseError => err
$stderr.puts err.message
$stderr.puts parser.help
exit false
end
unless ARGV.size == 1
abort "wrong number of arguments (#{ARGV.size} for 1)"
end
out = ""
File.open(ARGV[0]) {|f|
prelude f, out
grammar f, out
usercode f, out
}
if output
File.open(output, 'w') {|f|
f.write out
}
else
print out
end
end
def prelude(f, out)
while line = f.gets
case line
when %r</\*%%%\*/>
out << '/*' << $/
when %r</\*%>
out << '*/' << $/
when %r<%\*/>
out << $/
when /\A%%/
out << '%%' << $/
return
when /\A%token/
out << line.sub(/<\w+>/, '<val>')
when /\A%type/
out << line.sub(/<\w+>/, '<val>')
else
out << line
end
end
end
def grammar(f, out)
while line = f.gets
case line
when %r</\*%%%\*/>
out << '#if 0' << $/
when %r</\*%c%\*/>
out << '/*' << $/
when %r</\*%c>
out << '*/' << $/
when %r</\*%>
out << '#endif' << $/
when %r<%\*/>
out << $/
when /\A%%/
out << '%%' << $/
return
else
out << line
end
end
end
def usercode(f, out)
while line = f.gets
out << line
end
end
main