Extract the Pod(-like) comments from the code. At its most basic there will
ne no need to distinguish between the different types of header, etc.
This uses a simple finite state machine, in a very procedural pattern. I
could “replace case with polymorphism” but I think it would obscure the
intent, scatter the code all over tha place. This machine is necessary
because POD requires that directives be preceded by blank lines, so reading
line by line is necessary, and preserving state about what is seen is
necesary.
# File lib/rdoc/parser/perl.rb, line 51
def scan
@top_level.comment ||= ""
state=:code_blank
line_number = 0
line = nil
# This started out as a really long nested case statement,
# which also led to repetitive code. I'd like to avoid that
# so I'm using a "table" instead.
# Firstly we need some procs to do the transition and processing
# work. Because these are procs they are closures, and they can
# use variables in the local scope.
#
# First, the "nothing to see here" stuff.
code_noop = lambda do
if line =~ /^\s+$/
state = :code_blank
end
end
pod_noop = lambda do
if line =~ /^\s+$/
state = :pod_blank
end
@top_level.comment += filter(line)
end
begin_noop = lambda do
if line =~ /^\s+$/
state = :begin_blank
end
@top_level.comment += filter(line)
end
# Now for the blocks that process code and comments...
transit_to_pod = lambda do
case line
when /^=(?:pod|head\d+)/
state = :pod_no_blank
@top_level.comment += filter(line)
when /^=over/
state = :over_no_blank
@top_level.comment += filter(line)
when /^=(?:begin|for)/
state = :begin_no_blank
end
end
process_pod = lambda do
case line
when /^\s*$/
state = :pod_blank
@top_level.comment += filter(line)
when /^=cut/
state = :code_no_blank
when /^=end/
$stderr.puts "'=end' unexpected at #{line_number} in #{@file_name}"
else
@top_level.comment += filter(line)
end
end
process_begin = lambda do
case line
when /^\s*$/
state = :begin_blank
@top_level.comment += filter(line)
when /^=end/
state = :code_no_blank
when /^=cut/
$stderr.puts "'=cut' unexpected at #{line_number} in #{@file_name}"
else
@top_level.comment += filter(line)
end
end
transitions = { :code_no_blank => code_noop,
:code_blank => transit_to_pod,
:pod_no_blank => pod_noop,
:pod_blank => process_pod,
:begin_no_blank => begin_noop,
:begin_blank => process_begin}
@content.each_line do |l|
line = l
line_number += 1
transitions[state].call
end # each line
@top_level
end