s/(^| )$i( |s|$)/"$1$def{$i}$2"/gie; 
##</code><code>##

s/^\s+//; #trim leading whitespace

s/\s+$//; #trim trailing whitespace

s/(\S+)\s{2,}/"$1 "/gie; #replace more then one space with one space

s/\s{2,}(\S+)/" $1"/gie; #replace more then one space with one space

##</code><code>##

T:
Problem #3
A:
WIlliam Meyer
G:
triangle ABC with angle bisectors segment AZ, segment BY, segment CX
triangle DEF with angle bisectors segment DJ, segment EI, segment FH
P:
angle bisectors in similar triangles same ratio as corresponding sides
Pr:
triangle ABC with altitudes segment AZ, segment BY, segment CX => G
triangle DEF with altitudes segment DJ, segment EI, segment FH => G
( m segment AB / m segment DE ) = ( m segment BC / m segment EF ) = ( m segment AC / m segment DF )
angle BAC congruent angle EDF => def similar triangles
angle ABC congruent angle DEF => def similar triangles
m angle ABY * 2 = m angle ABC => def angle bisector
m angle DEI * 2 = m angle DEF => def angle bisector
m angle DEI * 2 = m angle ABC => sub #-1, #-3
m angle DEI * 2 = m angle ABY * 2 => sub #-1, #-3
angle DEI congruent angle ABY => division &amp;amp;amp;amp;amp; doca
triangle AYB similar triangle DIE => AA #-1, #-7
( m segment AB / m segment DE ) = ( m segment BY / m segment EI ) => similar triangles
( m segment BY / m segment EF ) = ( m segment BC / m segment EF ) = ( m segment AC / m segment DF ) => sub #-1, #-5
( m segment BC / m segment EF ) = (    m segment CX / m segment FH ) => similar reasoning #-2
( m segment AB / m segment DE ) = ( m segment CX / m segment FH ) = ( m segment AC / m segment DF ) => similar reasoning #-2
( m segment AC / m segment DF ) = ( m segment AZ / m segment DJ ) => similar reasoning #-4
( m segment AB / m segment DE ) = ( m segment BC / m segment EF ) = ( m segment AZ / m segment DJ ) => similar reasoning #-4

##</code><code>##

#!/usr/bin/perl -w
use strict;

my ($file_parse, $file_output, %def, $seen_pr, $tab, @stmts, @reasons, $len_stmts, $len_reasons, @pad, $i);

$file_parse="untitled:Desktop Folder:test2";         # default to be read
$file_output="untitled:Desktop Folder:test2output";  # default to be written
$tab=4;                                              # default tab length
$seen_pr=0;                                          # wether "Pr:" has been seen in while loop W
%def = (                                             # used for parsing the symbols in $file_parse
    "T:" => "Title",
    "A:" => "Author(s)",
    "G:" => "Given(s)",
    "P:" => "Proof Statement(s)",
    "T1" => "Statements",
    "T2" => "Reasons",
    "point" => "·",
    "triangle" => "?",
    "angle" => "‹",
    "w" => "with",
    "m" => "measure",
    "s" => "segment"
);


#####
# Some code establishing what file you are working on and what to output to
#####

print "Will parse $file_parse (y/n):";
$_=<>;
if (!/y/i) {
    print "Which file: ";
    $file_parse=<>;
    chomp $file_parse;
}

print "Will write $file_output (y/n):";
$_=<>;
if (!/y/i) {
    print "Which file: ";
    $file_output=<>;
    chomp $file_output;
}


#####
# Start a loop to go through the file to be parsed
#####

open (PARSE, "<$file_parse") or die ("Can't open $file_parse: $!\n");

open (OUTPUT, ">$file_output") or die ("Can't open $file_output: $!\n");

W: while (<PARSE>) {
    chomp;

    s/^\s+//; #trim leading whitespace
    s/\s+$//; #trim trailing whitespace
    s/(\S+)\s{2,}/"$1 "/gie; #replace more then one space with one space
    s/\s{2,}(\S+)/" $1"/gie; #replace more then one space with one space

    foreach $i (split " ", $_) {
        if (exists $def{$i} and !/:/) {
            s/(^| )$i( |s|$)/"$1$def{$i}$2"/gie; #replace symbols defined in %def with there meaning
        }
    }

    if (!/pr:/i and $seen_pr==0) {                      
        if (/:/) {                                 # if $_ contains a ":" then regard as token and print out
            $_ = uc();
            print OUTPUT "\n" if !/t:/i;                   
            print OUTPUT $def{$_} . ":\n";
            next W;
        } else {                                   # Print the items under the token
            print OUTPUT " " x $tab . $_ . "\n"; 
            next W;
        }
    } elsif ($seen_pr==0) {
        $seen_pr=1;
        print OUTPUT "\n";
        next W;
    }


    m/(.+) => (.+)/; #format is statement => reason
    push @stmts, $1; #constuct an array of statements
    push @reasons, $2; #constuct an array of reasons
}
close (PARSE);


#####
# Find the longest statement and reason for formatting
#####

$len_stmts   = (sort {$b <=> $a} map {length} @stmts  )[0];
$len_reasons = (sort {$b <=> $a} map {length} @reasons)[0];


#####
# Really difficult to understand way of formatting output
#####

push @pad, ( ( length($#stmts+1) + $len_stmts + 4) / 2) - int( length( $def{"T1"} ) / 2 )  - length( $def{"T1"} ) % 2;
push @pad, ( ( length($#stmts+1) + $len_stmts + 4) / 2) - int( length( $def{"T1"} ) / 2 ) +1;
push @pad, ( ( length($#reasons+1) + $len_reasons + 2) / 2) - int( length( $def{"T2"} ) ) / 2 - length( $def{"T2"} ) % 2;
push @pad, ( ( length($#reasons+1) + $len_reasons + 2) / 2) - int( length( $def{"T2"} ) ) / 2;

print OUTPUT "_" x $pad[0] . $def{"T1"} . "_" x $pad[1] . "|" . "_" x $pad[2] . $def{"T2"} . "_" x $pad[3] . "\n";

for ($i=0; $i<$#stmts+1; $i++) {
    $reasons[$i] =~ s/#-(\d+?)/($i+1)-$1/ge; #replace #-? with the line # you are on minus ?
    print OUTPUT $i+1 . "." . " " x (length($#stmts+1) - length($i+1)+1) . $stmts[$i] . " " x ($len_stmts - length($stmts[$i])) . "  |  " . $reasons[$i] . "\n"; #print the statements and resons
}
close (OUTPUT);