6. Pattern Matching

# The verbose version are match, sub, gsub, sub! and gsub!;
# pattern needs to be a Regexp object; it yields a MatchData
# object.
pattern.match(string)
string.sub(pattern, replacement)
string.gsub(pattern, replacement)
# As usual in Ruby, sub! does the same as sub but also modifies
# the object, the same for gsub!/gsub.

# Sugared syntax yields the position of the match (or nil if no
# match). Note that the object at the right of the operator needs
# not to be a Regexp object (it can be a String). The "dont
# match" operator yields true or false.
meadow =~ /sheep/   # position of the match, nil if no match
meadow !~ /sheep/   # true if doesn't match, false if it does
# There is no sugared version for the substitution

meadow =~ /\bovines?\b/i and print "Here be sheep!"

string = "good food"
string.sub!(/o*/, 'e')

# % echo ababacaca | ruby -ne 'puts $& if /(a|ba|b)+(a|ac)+/'
# ababa

# The "global" (or "multiple") match is handled by String#scan
scan (/(\d+)/) {
    puts "Found number #{$1}"
}

# String#scan yields an Array if not used with a block
numbers = scan(/\d+/)

digits = "123456789"
nonlap = digits.scan(/(\d\d\d)/)
yeslap = digits.scan(/(?=(\d\d\d))/)
puts "Non-overlapping:  #{nonlap.join(' ')}"
puts "Overlapping:      #{yeslap.join(' ')}";
# Non-overlapping:  123 456 789
# Overlapping:      123 234 345 456 567 678 789

string = "And little lambs eat ivy"
string =~ /l[^s]*s/
puts "(#$`) (#$&) (#$')"
# (And ) (little lambs) ( eat ivy)

# Ruby doesn't have the same problem:
dst = src.sub('this', 'that')

progname = $0.sub('^.*/', '')

bindirs = %w(/usr/bin /bin /usr/local/bin)
libdirs = bindirs.map { |l| l.sub('bin', 'lib') }

/\S+/               # as many non-whitespace bytes as possible
/[A-Za-z'-]+/       # as many letters, apostrophes, and hyphens

/\b([A-Za-z]+)\b/   # usually best
/\s([A-Za-z]+)\s/   # fails at ends or w/ punctuation

require 'socket'
str = 'www.ruby-lang.org and www.rubygarden.org'
re = /
      (               # capture the hostname in $1
        (?:           # these parens for grouping only
          (?! [-_] )  # lookahead for neither underscore nor dash
          [\w-] +     # hostname component
          \.          # and the domain dot
        ) +           # now repeat that whole thing a bunch of times
        [A-Za-z]      # next must be a letter
        [\w-] +       # now trailing domain part
      )               # end of $1 capture
     /x               # /x for nice formatting

str.gsub! re do       # pass a block to execute replacement
    host = TCPsocket.gethostbyname($1)
    "#{$1} [#{host[3]}]"
end

puts str
#-----------------------------
# to match whitespace or #-characters in an extended re you need to escape
# them.

foo = 42
str = 'blah #foo# blah'
str.gsub! %r/       # replace
              \#    #   a pound sign
              (\w+) #   the variable name
              \#    #   another pound sign
          /x do
              eval $1           # with the value of a local variable
          end
puts str  # => blah 42 blah

# The 'g' modifier doesn't exist in Ruby, a regexp can't be used
# directly in a while loop; instead, use String#scan { |match| .. } 
fish = 'One fish two fish red fish blue fish'
WANT = 3
count = 0
fish.scan(/(\w+)\s+fish\b/i) {
    if (count += 1) == WANT
        puts "The third fish is a #{$1} one."
    end
}

if fish =~ /(?:\w+\s+fish\s+){2}(\w+)\s+fish/i
    puts "The third fish is a #{$1} one."
end

pond = 'One fish two fish red fish blue fish'
# String#scan without a block gives an array of matches, each match
# being an array of all the specified groups
colors = pond.scan(/(\w+)\s+fish\b/i).flatten  # get all matches
color  = colors[2]                          # then the one we want
# or without a temporary array
color = pond.scan(/(\w+)\s+fish\b/i).flatten[2]  # just grab element 3
puts "The third fish in the pond is #{color}."

count = 0
fishes = 'One fish two fish red fish blue fish'
evens = fishes.scan(/(\w+)\s+fish\b/i).select { (count+=1) % 2 == 0 }
print "Even numbered fish are #{evens.join(' ')}."

count = 0
fishes.gsub(/
   \b               # makes next \w more efficient
   ( \w+ )          # this is what we\'ll be changing
   (
     \s+ fish \b
   )
            /x) {
    if (count += 1) == 4
        'sushi' + $2
    else
        $1 + $2
    end
}

pond = 'One fish two fish red fish blue fish swim here.'
puts "Last fish is #{pond.scan(/\b(\w+)\s+fish\b/i).flatten[-1]}"

/
    A               # find some pattern A
    (?!             # mustn\'t be able to find
        .*          # something
        A           # and A
    )
    $               # through the end of the string
/x

# The "s" perl modifier is "m" in Ruby (not very nice since there is
# also an "m" in perl..)
pond = "One fish two fish red fish blue fish swim here."
if (pond =~ /
                    \b  (  \w+) \s+ fish \b
                (?! .* \b fish \b )
            /mix)
    puts "Last fish is #{$1}."
else
    puts "Failed!"
end

#-----------------------------
#!/usr/bin/ruby -w
# killtags - very bad html killer
$/ = nil;                              # each read is whole file
while file = gets() do
    file.gsub!(/<.*?>/m,'');           # strip tags (terribly)
    puts file                          # print file to STDOUT
end
#-----------------------------
#!/usr/bin/ruby -w
#headerfy - change certain chapter headers to html
$/ = ''
while file = gets() do
    pattern = /
                  \A                   # start of record
                  (                    # capture in $1
                      Chapter          # text string
                      \s+              # mandatory whitespace
                      \d+              # decimal number
                      \s*              # optional whitespace
                      :                # a real colon
                      . *              # anything not a newline till end of line
                  )
               /x
    puts file.gsub(pattern,'<H1>\1</H1>')
end
#-----------------------------
#% ruby -00pe "gsub!(/\A(Chapter\s+\d+\s*:.*)/,'<H1>\1</H1>')" datafile

#!/usr/bin/ruby -w
#-----------------------------
for file in ARGV
    file = File.open(ARGV.shift)
    while file.gets('') do             # each read is a paragraph
        print "chunk #{$.} in $ARGV has <<#{$1}>>\n" while /^START(.*?)^END/m
    end                                # /m activates the multiline mode
end
#-----------------------------

#-----------------------------
$/ = nil;
file = File.open("datafile")
chunks = file.gets.split(/pattern/)
#-----------------------------
# .Ch, .Se and .Ss divide chunks of STDIN
chunks = gets(nil).split(/^\.(Ch|Se|Ss)$/)
print "I read #{chunks.size} chunks.\n"
#-----------------------------

while gets
    if ~/BEGIN/ .. ~/END/
        # line falls between BEGIN and END inclusive
    end
end

while gets
    if ($. == firstnum) .. ($. == lastnum)
        # operate between firstnum and lastnum line number
    end
end

# in ruby versions prior to 1.8, the above two conditional
# expressions could be shortened to:
#     if /BEGIN/ .. /END/
# and
#     if firstnum .. lastnum
# but these now only work this way from the command line  

#-----------------------------

while gets
    if ~/BEGIN/ ... ~/END/
        # line falls between BEGIN and END on different lines
    end
end

while gets
    if ($. == first) ... ($. == last)
        # operate between first and last line number on different lines
    end
end

#-----------------------------
# command-line to print lines 15 through 17 inclusive (see below)
ruby -ne 'print if 15 .. 17' datafile

# print out all <XMP> .. </XMP> displays from HTML doc
while gets
    print if ~%r#<XMP>#i .. ~%r#</XMP>#i;
end
    
# same, but as shell command
# ruby -ne 'print if %r#<XMP>#i .. %r#</XMP>#i' document.html
#-----------------------------
# ruby -ne 'BEGIN { $top=3; $bottom=5 }; \
#     print if $top .. $bottom' /etc/passwd                 #  FAILS
# ruby -ne 'BEGIN { $top=3; $bottom=5 }; \
#     print if $. == $top .. $. ==  $bottom' /etc/passwd    # works
# ruby -ne 'print if 3 .. 5' /etc/passwd                    # also works
#-----------------------------
print if ~/begin/ .. ~/end/;
print if ~/begin/ ... ~/end/;
#-----------------------------
while gets
    $in_header = $. == 1  .. ~/^$/ ? true : false
    $in_body   = ~/^$/ .. ARGF.eof ? true : false
end
#-----------------------------
seen = {}
ARGF.each do |line|
    next unless line =~ /^From:?\s/i .. line =~ /^$/;
    line.scan(%r/([^<>(),;\s]+\@[^<>(),;\s]+)/).each do |addr|
        puts addr unless seen[addr]
        seen[addr] ||= 1 
    end
end

def glob2pat(globstr)
    patmap = {
        '*' => '.*',
        '?' => '.',
        '[' => '[',
        ']' => ']',
    }
    globstr.gsub!(/(.)/) { |c| patmap[c] || Regexp::escape(c) }
    '^' + globstr + '$'
end

# avoid interpolating patterns like this if the pattern
# isn't going to change:
pattern = ARGV.shift
ARGF.each do |line|
    print line if line =~ /#{pattern}/
end

# the above creates a new regex each iteration. Instead,
# use the /o modifier so the regex is compiled only once

pattern = ARGV.shift
ARGF.each do |line|
    print line if line =~ /#{pattern}/o
end

#-----------------------------

#!/usr/bin/ruby
# popgrep1 - grep for abbreviations of places that say "pop"
# version 1: slow but obvious way
popstates = %w(CO ON MI WI MN)
ARGF.each do |line|
    popstates.each do |state|
        if line =~ /\b#{state}\b/
            print line
            last
        end
    end
end

#-----------------------------
#!/usr/bin/ruby
# popgrep2 - grep for abbreviations of places that say "pop"
# version 2: eval strings; fast but hard to quote
popstates = %w(CO ON MI WI MN)
code = "ARGF.each do |line|\n"
popstates.each do |state|
    code += "\tif line =~ /\\b#{state}\\b/; print(line); next; end\n"
end
code += "end\n"
print "CODE IS\n---\n#{code}\n---\n" if false # turn on for debugging
eval code

# CODE IS
# ---
# ARGF.each do |line|
#         if line =~ /\bCO\b/; print(line); next; end
#         if line =~ /\bON\b/; print(line); next; end
#         if line =~ /\bMI\b/; print(line); next; end
#         if line =~ /\bWI\b/; print(line); next; end
#         if line =~ /\bMN\b/; print(line); next; end
# end
# 
# ---

## alternatively, the same idea as above but compiling 
## to a case statement: (not in perlcookbook)
#!/usr/bin/ruby -w
# popgrep2.5 - grep for abbreviations of places that say "pop"
# version 2.5: eval strings; fast but hard to quote
popstates = %w(CO ON MI WI MN)
code = "ARGF.each do |line|\n    case line\n"
popstates.each do |state|
    code += "        when /\\b#{state}\\b/ : print line\n"
end
code += "    end\nend\n"
print "CODE IS\n---\n#{code}\n---\n" if false # turn on for debugging
eval code

# CODE IS
# ---
# ARGF.each do |line|
#     case line
#         when /\bCO\b/ : print line
#         when /\bON\b/ : print line
#         when /\bMI\b/ : print line
#         when /\bWI\b/ : print line
#         when /\bMN\b/ : print line
#     end
# end
# 
# ---

# Note: (above) Ruby 1.8+ allows the 'when EXP : EXPR' on one line
# with the colon separator.

#-----------------------------
#!/usr/bin/ruby
# popgrep3 - grep for abbreviations of places that say "pop"
# version3: build a match_any function
popstates = %w(CO ON MI WI MN)
expr = popstates.map{|e|"line =~ /\\b#{e}\\b/"}.join('||')
eval "def match_any(line); #{expr};end"
ARGF.each do |line|
    print line if match_any(line)
end
#-----------------------------

##  building a match_all function is a trivial
##  substitution of && for ||
##  here is a generalized example:
#!/usr/bin/ruby -w
## grepauth - print lines that mention both foo and bar
class MultiMatch 
    def initialize(*patterns)
        _any = build_match('||',patterns)
        _all = build_match('&&',patterns)
        eval "def match_any(line);#{_any};end\n"
        eval "def match_all(line);#{_all};end\n"
      end
    def build_match(sym,args)
        args.map{|e|"line =~ /#{e}/"}.join(sym)
    end
end

mm = MultiMatch.new('foo','bar')
ARGF.each do |line|
    print line if mm.match_all(line)
end
#-----------------------------

#!/usr/bin/ruby
# popgrep4 - grep for abbreviations of places that say "pop"
# version4: pretty fast, but simple: compile all re's first:
popstates = %w(CO ON MI WI MN)
popstates = popstates.map{|re| %r/\b#{re}\b/}
ARGF.each do |line|
    popstates.each do |state_re|
        if line =~ state_re
            print line
            break
        end
    end
end

## speeds trials on the jargon file(412): 26006 lines, 1.3MB
## popgrep1   => 7.040s
## popgrep2   => 0.656s
## popgrep2.5 => 0.633s
## popgrep3   => 0.675s
## popgrep4   => 1.027s

# unless speed is criticial, the technique in popgrep4 is a
# reasonable balance between speed and logical simplicity.

begin
    print "Pattern? "
    pat = $stdin.gets.chomp
    Regexp.new(pat)
rescue 
    warn "Invalid Pattern"
    retry
end

# uses the 'amatch' extension found on:
# http://raa.ruby-lang.org/project/amatch/
require 'amatch'
matcher = Amatch.new('balast')
#$relative, $distance = 0, 1
File.open('/usr/share/dict/words').each_line do |line|
    print line if matcher.search(line) <= 1
end
__END__
ballast
ballasts
balustrade
balustrades
blast
blasted
blaster
blasters
blasting
blasts

str.scan(/\G(\d)/).each do |token|
    puts "found #{token}"
end
#-----------------------------
n = "   49 here"
n.gsub!(/\G /,'0')
puts n
#-----------------------------
str = "3,4,5,9,120"
str.scan(/\G,?(\d+)/).each do |num|
    puts "Found number: #{num}"
end
#-----------------------------
# Ruby doesn't have the String.pos or a /c re modifier like Perl 
# But it does have StringScanner in the standard library (strscn)
# which allows similar functionality:

require 'strscan'
text = 'the year 1752 lost 10 days on the 3rd of September'
sc = StringScanner.new(text)
while sc.scan(/.*?(\d+)/)
    print "found: #{sc[1]}\n"   
end
if sc.scan(/\S+/)
    puts "Found #{sc[0]} after last number"
end
#-----------------------------
# assuming continuing from above:
puts "The position in 'text' is: #{sc.pos}"
sc.pos = 30
puts "The position in 'text' is: #{sc.pos}"

#-----------------------------
# greedy pattern
str.gsub!(/<.*>/m,'')   # not good

# non-greedy (minimal) pattern
str.gsub!(/<.*?>/m,'')   # not great


#-----------------------------
#<b><i>this</i> and <i>that</i> are important</b> Oh, <b><i>me too!</i></b>
#-----------------------------
%r{ <b><i>(.*?)</i></b> }mx
#-----------------------------
%r/BEGIN((?:(?!BEGIN).)*)END/
#-----------------------------
%r{ <b><i>(  (?: (?!</b>|</i>). )*  ) </i></b> }mx
#-----------------------------
%r{ <b><i>(  (?: (?!</[ib]>). )*  ) </i></b> }mx
#-----------------------------
%r{
    <b><i> 
    [^<]*  # stuff not possibly bad, and not possibly the end.
    (?:
 # at this point, we can have '<' if not part of something bad
     (?!  </?[ib]>  )   # what we can't have
     <                  # okay, so match the '<'
     [^<]*              # and continue with more safe stuff
    ) *
    </i></b>
 }mx

#-----------------------------
$/ = ""
ARGF.each do |para|
    para.scan %r/
                  \b     # start at word boundary
                  (\S+)  # find chunk of non-whitespace
                  \b     # until a word boundary
                  (      
                    \s+  # followed by whitespace
                    \1   # and that same chunk again
                    \b   # and a word boundary
                  ) +    # one or more times
                /xi do
        puts "dup word '#{$1}' at paragraph #{$.}" 
    end
end
#-----------------------------
astr = 'nobody'
bstr = 'bodysnatcher'
if "#{astr} #{bstr}" =~ /^(\w+)(\w+) \2(\w+)$/
    print "#{$2} overlaps in #{$1}-#{$2}-#{$3}"
end
#-----------------------------
#!/usr/bin/ruby -w
# prime_pattern -- find prime factors of argument using patterns
ARGV << 180
cap = 'o' * ARGV.shift
while cap =~ /^(oo+?)\1+$/
    print $1.size, " "
    cap.gsub!(/#{$1}/,'o')
end
puts cap.size
#-----------------------------
#diophantine
# solve for 12x + 15y + 16z = 281, maximizing x
if ('o' * 281).match(/^(o*)\1{11}(o*)\2{14}(o*)\3{15}$/)
    x, y, z = $1.size, $2.size, $3.size
    puts "One solution is: x=#{x}; y=#{y}; z=#{z}"
else 
    puts "No solution."
end
#    => One solution is: x=17; y=3; z=2

#-----------------------------
# using different quantifiers:
('o' * 281).match(/^(o+)\1{11}(o+)\2{14}(o+)\3{15}$/)
#    => One solution is: x=17; y=3; z=2

('o' * 281).match(/^(o*?)\1{11}(o*)\2{14}(o*)\3{15}$/)
#    => One solution is: x=0; y=7; z=11

('o' * 281).match(/^(o+?)\1{11}(o*)\2{14}(o*)\3{15}$/)
#    => One solution is: x=1; y=3; z=14

# alpha OR beta
%r/alpha|beta/

# alpha AND beta
%r/(?=.*alpha)(?=.*beta)/m

# alpha AND beta,  no overlap
%r/alpha.*beta|beta.*alpha/m

# NOT beta
%r/^(?:(?!beta).)*$/m

# NOT bad BUT good
%r/(?=(?:(?!BAD).)*$)GOOD/m
#-----------------------------

if !(string =~ /pattern/)   # ugly
    something()
end

if string !~ /pattern/   # preferred
    something()
end


#-----------------------------
if string =~ /pat1/  && string =~ /pat2/
    something()
end
#-----------------------------
if string =~ /pat1/ || string =~ /pat2/
    something()
end
#-----------------------------
#!/usr/bin/ruby -w
# minigrep - trivial grep
pat = ARGV.shift
ARGF.each do |line|
    print line if line =~ /#{pat}/o
end
#-----------------------------
 "labelled" =~ /^(?=.*bell)(?=.*lab)/m
#-----------------------------
$string =~ /bell/ && $string =~ /lab/
#-----------------------------
$murray_hill = "blah bell blah "
if $murray_hill =~ %r{
                         ^              # start of string
                        (?=             # zero-width lookahead
                            .*          # any amount of intervening stuff
                            bell        # the desired bell string
                        )               # rewind, since we were only looking
                        (?=             # and do the same thing
                            .*          # any amount of intervening stuff
                            lab         # and the lab part
                        )
                     }mx                # /m means . can match newline

    print "Looks like Bell Labs might be in Murray Hill!\n";
end
#-----------------------------
"labelled" =~ /(?:^.*bell.*lab)|(?:^.*lab.*bell)/
#-----------------------------
$brand = "labelled";
if $brand =~ %r{
                (?:                 # non-capturing grouper
                    ^ .*?           # any amount of stuff at the front
                      bell          # look for a bell
                      .*?           # followed by any amount of anything
                      lab           # look for a lab
                  )                 # end grouper
            |                       # otherwise, try the other direction
                (?:                 # non-capturing grouper
                    ^ .*?           # any amount of stuff at the front
                      lab           # look for a lab
                      .*?           # followed by any amount of anything
                      bell          # followed by a bell
                  )                 # end grouper
            }mx                     # /m means . can match newline
    print "Our brand has bell and lab separate.\n";
end
#-----------------------------
$map =~ /^(?:(?!waldo).)*$/s
#-----------------------------
$map = "the great baldo"
if $map =~ %r{
                ^                   # start of string
                (?:                 # non-capturing grouper
                    (?!             # look ahead negation
                        waldo       # is he ahead of us now?
                    )               # is so, the negation failed
                    .               # any character (cuzza /s)
                ) *                 # repeat that grouping 0 or more
                $                   # through the end of the string
             }mx                    # /m means . can match newline
    print "There's no waldo here!\n";
end
#-----------------------------
 7:15am  up 206 days, 13:30,  4 users,  load average: 1.04, 1.07, 1.04

USER     TTY      FROM              LOGIN@  IDLE   JCPU   PCPU  WHAT

tchrist  tty1                       5:16pm 36days 24:43   0.03s  xinit

tchrist  tty2                       5:19pm  6days  0.43s  0.43s  -tcsh

tchrist  ttyp0    chthon            7:58am  3days 23.44s  0.44s  -tcsh

gnat     ttyS4    coprolith         2:01pm 13:36m  0.30s  0.30s  -tcsh
#-----------------------------
#% w | minigrep '^(?!.*ttyp).*tchrist'
#-----------------------------
%r{
    ^                       # anchored to the start
    (?!                     # zero-width look-ahead assertion
        .*                  # any amount of anything (faster than .*?)
        ttyp                # the string you don't want to find
    )                       # end look-ahead negation; rewind to start
    .*                      # any amount of anything (faster than .*?)
    tchrist                 # now try to find Tom
}x
#-----------------------------
#% w | grep tchrist | grep -v ttyp
#-----------------------------
#% grep -i 'pattern' files
#% minigrep '(?i)pattern' files
#-----------------------------

#-----------------------------
# basically, the Perl Cookbook categorizes this as an
# unsolvable problem ...
#-----------------------------
1 while addr.gsub!(/\([^()]*\)/,'')
#-----------------------------
Dear someuser@host.com,

Please confirm the mail address you gave us Wed May  6 09:38:41
MDT 1998 by replying to this message.  Include the string
"Rumpelstiltskin" in that reply, but spelled in reverse; that is,
start with "Nik...".  Once this is done, your confirmed address will
be entered into our records.

ans = $stdin.gets.chomp
re = %r/^#{Regexp.quote(ans)}/
case 
    when "SEND"  =~ re : puts "Action is send"
    when "STOP"  =~ re : puts "Action is stop"
    when "ABORT" =~ re : puts "Action is abort"
    when "EDIT"  =~ re : puts "Action is edit"
end
#-----------------------------
require 'abbrev'
table = Abbrev.abbrev %w-send stop abort edit-
loop do
    print "Action: "
    ans = $stdin.gets.chomp
    puts "Action for #{ans} is #{table[ans.downcase]}"
end


#-----------------------------
# dummy values are defined for 'file', 'PAGER', and
# the 'invoke_editor' and 'deliver_message' methods
# do not do anything interesting in this example.
#!/usr/bin/ruby -w
require 'abbrev'

file = 'pleac_ruby.data'
PAGER = 'less'

def invoke_editor
    puts "invoking editor"
end

def deliver_message
    puts "delivering message"
end

actions = {
    'edit'  => self.method(:invoke_editor),
    'send'  => self.method(:deliver_message),
    'list'  => proc {system(PAGER, file)},
    'abort' => proc {puts "See ya!"; exit},
    ""      => proc {puts "Unknown Command"}
}

dtable = Abbrev.abbrev(actions.keys)
loop do
    print "Action: "
    ans = $stdin.gets.chomp.delete(" \t")
    actions[ dtable[ans.downcase] || "" ].call
end

#-----------------------------
#% gunzip -c ~/mail/archive.gz | urlify > archive.urlified
#-----------------------------
#% urlify ~/mail/*.inbox > ~/allmail.urlified
#-----------------------------
#!/usr/bin/ruby -w
# urlify - wrap HTML links around URL-like constructs

urls = '(https?|telnet|gopher|file|wais|ftp)';
ltrs = '\w';
gunk = '/#~:.?+=&%@!\-';
punc = '.:?\-';
any  = "#{ltrs}#{gunk}#{punc}";

ARGF.each do |line|
    line.gsub! %r/
        \b                    # start at word boundary
        (                     # begin $1  {
         #{urls}     :        # need resource and a colon
         [#{any}] +?          # followed by on or more
                              #  of any valid character, but
                              #  be conservative and take only
                              #  what you need to....
        )                     # end   $1  }
        (?=                   # look-ahead non-consumptive assertion
         [#{punc}]*           # either 0 or more punctuation
         [^#{any}]            #   followed by a non-url char
         |                    # or else
         $                    #   then end of the string
        )
    /iox do 
        %Q|<A HREF="#{$1}">#{$1}</A>|
    end
    print line
end

%r/^m*(d?c{0,3}|c[dm])(l?x{0,3}|x[lc])(v?i{0,3}|i[vx])$/i
#-----------------------------
str.sub!(/(\S+)(\s+)(\S+)/, '\3\2\1')
#-----------------------------
%r/(\w+)\s*=\s*(.*)\s*$/             # keyword is $1, value is $2
#-----------------------------
%r/.{80,}/
#-----------------------------
%r|(\d+)/(\d+)/(\d+) (\d+):(\d+):(\d+)|
#-----------------------------
str.gsub!(%r|/usr/bin|,'/usr/local/bin')
#-----------------------------
str.gsub!(/%([0-9A-Fa-f][0-9A-Fa-f])/){ $1.hex.chr }
#-----------------------------
str.gsub!(%r{
    /\*                    # Match the opening delimiter
    .*?                    # Match a minimal number of characters
    \*/                    # Match the closing delimiter
}xm,'')
#-----------------------------
str.sub!(/^\s+/, '')
str.sub!(/\s+$/, '')

# but really, in Ruby we'd just do:
str.strip!
#-----------------------------
str.gsub!(/\\n/,"\n")
#-----------------------------
str.sub!(/^.*::/, '')
#-----------------------------
%r/^([01]?\d\d|2[0-4]\d|25[0-5])\.([01]?\d\d|2[0-4]\d|25[0-5])\.
    ([01]?\d\d|2[0-4]\d|25[0-5])\.([01]?\d\d|2[0-4]\d|25[0-5])$/x
#-----------------------------
str.sub!(%r|^.*/|, '')
#-----------------------------
cols = ( (ENV['TERMCAP'] || " ") =~ /:co#(\d+):/ ) ? $1 : 80;
#-----------------------------
name = " #{$0} #{ARGV}".gsub(%r| /\S+/|, ' ')
#-----------------------------
require 'rbconfig'
include Config
raise "This isn't Linux" unless CONFIG['target_os'] =~ /linux/i;
#-----------------------------
str.gsub!(%r/\n\s+/, ' ')
#-----------------------------
nums = str.scan(/(\d+\.?\d*|\.\d+)/)
#-----------------------------
capwords = str.scan(%r/(\b[^\Wa-z0-9_]+\b)/)
#-----------------------------
lowords = str.scan(%r/(\b[^\WA-Z0-9_]+\b)/)
#-----------------------------
icwords = str.scan(%r/(\b[^\Wa-z0-9_][^\WA-Z0-9_]*\b)/)
#-----------------------------
links = str.scan(%r/<A[^>]+?HREF\s*=\s*["']?([^'" >]+?)[ '"]?>/mi)   #'
#-----------------------------
initial = str =~ /^\S+\s+(\S)\S*\s+\S/ ? $1 : ""
#-----------------------------
str.gsub!(%r/"([^"]*)"/, %q-``\1''-)   #"
#-----------------------------

$/ = ""
sentences = []
ARGF.each do |para|
    para.gsub!(/\n/, ' ')
    para.gsub!(/ {3,}/,'  ')
    sentences << para.scan(/(\S.*?[!?.])(?=  |\Z)/)
end

#-----------------------------
%r/(\d{4})-(\d\d)-(\d\d)/            # YYYY in $1, MM in $2, DD in $3
#-----------------------------
%r/ ^
      (?:
       1 \s (?: \d\d\d \s)?            # 1, or 1 and area code
       |                               # ... or ...
       \(\d\d\d\) \s                   # area code with parens
       |                               # ... or ...
       (?: \+\d\d?\d? \s)?             # optional +country code
       \d\d\d ([\s\-])                 # and area code
      )
      \d\d\d (\s|\1)                   # prefix (and area code separator)
      \d\d\d\d                         # exchange
        $
 /x
#-----------------------------
%r/\boh\s+my\s+gh?o(d(dess(es)?|s?)|odness|sh)\b/i
#-----------------------------
lines = []
lines << $1 while input.sub!(/^([^\012\015]*)(\012\015?|\015\012?)/,'')