Object
The trick here is doing a match where you grab one line of input at a time. The linebreak may or may not occur at the boundary where the string matches a format specifier. And if it does, some rule about whitespace may or may not be in effect…
That's why this is much more elaborate than the string version.
For each line: Match succeeds (non-emptily) and the last attempted spec/string sub-match succeeded:
could the last spec keep matching? yes: save interim results and continue (next line)
The last attempted spec/string did not match:
are we on the next-to-last spec in the string?
yes: is fmt_string.string_left all spaces? yes: does current spec care about input space? yes: fatal failure no: save interim results and continue no: continue [this state could be analyzed further]
# File scanf.rb, line 590 def scanf(str,&b) return block_scanf(str,&b) if b return [] unless str.size > 0 start_position = pos rescue 0 matched_so_far = 0 source_buffer = "" result_buffer = [] final_result = [] fstr = Scanf::FormatString.new(str) loop do if eof || (tty? &&! fstr.match(source_buffer)) final_result.concat(result_buffer) break end source_buffer << gets current_match = fstr.match(source_buffer) spec = fstr.last_spec_tried if spec.matched if spec.mid_match? result_buffer.replace(current_match) next end elsif (fstr.matched_count == fstr.spec_count - 1) if /\A\s*\z/.match(fstr.string_left) break if spec.count_space? result_buffer.replace(current_match) next end end final_result.concat(current_match) matched_so_far += source_buffer.size source_buffer.replace(fstr.string_left) matched_so_far -= source_buffer.size break if fstr.last_spec fstr.prune end seek(start_position + matched_so_far, IO::SEEK_SET) rescue Errno::ESPIPE soak_up_spaces if fstr.last_spec && fstr.space return final_result end