Programming Praxis

2 Responses to “Formatting Text, Again”

1. matthew said

   October 13, 2014 at 11:29 PM

   I thought that might be the next stage. Here’s a version of my C++ program – it attempts to spread out the padding space evenly through the line (and goes in alternating directions – perhaps we should use the Morse-Thue sequence for this to ensure there aren’t any other regularities).

   It’s a bit long-winded, but here it is:

   #include <stdlib.h>
   #include <iostream>
   #include <sstream>
   #include <string>
   
   // spaces is the number of spaces already in the line
   // n is the desired length of the line
   void padline(std::string &line, int n, int spaces, int lineno)
   {
     int lsize = line.size();
     if (lsize < n && spaces > 0) {
       int needed = n-lsize;
       line.resize(n); // Make room
       int t = 0; // Sort of a token bucket
       int nleft = spaces;
       int i = lsize-1; // Indexes for string copying
       int j = n-1;
       while (nleft > 0) {
         line[j] = line[i]; // Move a character up
         if (line[i] == ' ') {
           nleft--;
           int scount = 0; // Number of spaces to insert
           if (lineno%2) {
             t += needed; // Add some more tokens
             while (t >= spaces) { t -= spaces; scount++; }
           } else {
             t -= needed; // Reverse of above
             while (t < 0) { t += spaces; scount++; }
           }
           for (int i = 0; i < scount; i++) { line[--j] = ' '; }
         }
         --j; --i;
       }
     }
   }
   
   int main(int argc, char *argv[])
   {
      std::string line;
      std::string outline;
      int current = 0;
      enum { START, NORMAL, PARA } state = START;
      int max = atoi(argv[1]);
      int spaces = 0;
      int lineno = 0;
      while(std::getline(std::cin, line)) {
         std::istringstream s(line);
         std::string word;
         bool empty = true;
         while(s >> word) {
            int wlen = word.size();
            switch (state) {
            case START:
               state = NORMAL;
               break;
            case NORMAL:
               if (current + wlen > max) {
                  current = 0;
                  padline(outline,max,spaces,lineno);
                  lineno++;
                  std::cout << outline << "\n";
                  outline = "";
                  spaces = 0;
               } else {
                  outline += " ";
                  spaces++;
               }
               break;
            case PARA:
               current = 0;
               lineno++;
               std::cout << outline << "\n\n";
               outline = "";
               spaces = 0;
               state = NORMAL;
               break;
            }
            current += wlen + 1;
            outline += word;
            empty = false;
         }
         if (empty && state == NORMAL) state = PARA;
      }
      if (state != START) std::cout << outline << "\n";
   }
   
2. James Curtis-Smith said

   October 14, 2014 at 3:20 AM

   use strict;
   use warnings;
   
   my $width = shift @ARGV || 60;
   $/ = undef;
   
   print f($_) foreach split m{\n\s*\n}mxs, <>;
   
   sub pad {
     my ( $len, $ll, @line ) = @_;
     my $s   = (@line-1)/2;
     my $sta = ($len - $ll)/$s+0.0001;
     my $n=0;
     foreach(0..($s-1)) {
       $n += $sta;
       $line[2*$_] .= q( )x($n+.5);
       $n -= int ($n+.5);
     }
     return @line;
   }
   
   sub f {
     my ($ll,@out,@line) = (-1);
     foreach( split m{\s+}, shift ) {
       if( $ll + 1 + length $_ > $width ) {
         push @out, pad( $width, $ll, @line ), "\n";
         @line=();
         $ll = -1;
       } else {
         push @line, q( ) if @line;
       }
       $ll+= 1 + length $_;
       push @line,$_;
     }
     push @out, @line,"\n\n";
     return join q(), @out;
   }