scanf(str,&b)
public
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]
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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