def _nt_prefix
start_index = index
if node_cache[:prefix].has_key?(index)
cached = node_cache[:prefix][index]
@index = cached.interval.end if cached
return cached
end
i0 = index
if input.index('&', index) == index
r1 = instantiate_node(AndPredicate,input, index...(index + 1))
@index += 1
else
terminal_parse_failure('&')
r1 = nil
end
if r1
r0 = r1
else
if input.index('!', index) == index
r2 = instantiate_node(NotPredicate,input, index...(index + 1))
@index += 1
else
terminal_parse_failure('!')
r2 = nil
end
if r2
r0 = r2
else
if input.index('~', index) == index
r3 = instantiate_node(TransientPrefix,input, index...(index + 1))
@index += 1
else
terminal_parse_failure('~')
r3 = nil
end
if r3
r0 = r3
else
self.index = i0
r0 = nil
end
end
end
node_cache[:prefix][start_index] = r0
return r0
end