Connecting letters

Question

You should write a program or function which receives a block of chars represented as a string and outputs or returns a similar string in which the letters adjacent in the alphabet are connected.

A visual example (in the form of input => output):

b     d               b     d        
                      |\   /|        
                      | \ / |        
             =>       |  X  |        
                      | / \ |        
      e               |/   \e        
c     a               c     a        

Details

• Input will be a string containing spaces, newlines and exactly one of each of the first N lowercase letters. 1 <= N <= 26
• The lines of the input will be padded with spaces creating a full rectangular block.
• Every pair of letters adjacent in the alphabet will be on the same row, column or diagonal line and should be connected with a straight ascii line using \ / | or -. (The line might have a length of 0.)

• The following types of two-line overlaps should be handled:

  / and \ become X
  | and - become +
  / and / become /
  \ and \ become \
  | and | become |
  - and - become -
  [letter] and [anything] become [letter]
  

• No other kind of two-line overlap will occur.

• If more than two lines overlap any pair of them will be guaranteed to be one of the valid overlaps. (e.g. [letter] / | triplet will never occur)
• Apart from changing spaces into \ / | - X and + input and output should be identical.
• Trailing newline is optional but have to be the same for input and output.
• This is code-golf so the shortest entry wins.

Examples

Input:

b     d        


     h   gi    

      e  f     
c     a        

Output:

b     d        
|\   /|        
| \ / |        
|  X h+--gi    
| / \ |  |     
|/   \e--f     
c     a        

Input:

     dk    j   

 b    l        

 c   fg        

     a    m    

   i      h    
     e         

Output:

     dk----j   
    /||   /    
 b / |l  /     
 |X  | \/      
 c \ fg/\      
    \|/\ \     
     a  \ m    
    /|   \     
   i-+----h    
     e         

Input:

   eti  sqjh k  p  u  cfm vb owgzyx rnd la  

Output:

   eti--sqjh-k--p--u--cfm-vb-owgzyx-rnd-la  

Input:

a

Output:

a

Answer 1

Perl, 219

Some improvements may be still possible.

#!perl -p0
/
/;$x="@-";
sub g{map"(?=$_)(.@_)+[".chr(1+ord).chr(~-ord)."]",a..z}
sub f{for$p(g"{$x}"){s/$p/$&&((_."\177"x~-$x)x y!
!!)/se;$_=lc;s![\0\\]!@_!g}$x++}
f"/";y!\17!/!;f"|";f"\\";y/\17/X/;for$p(g){s/$p/$&=~y! |!-+!r/e}

Try me.

Answer 2

JavaScript (ES6) 246 266 280 285 307

Quite bulky ...

A function with string param and returning the modified string. A trailing newline is optional unless the input is just 1 row (I need a newline to find the row len)

Just to make someone happy

F=b=>b.match(/\w/g).sort().map(l=>(q=b.indexOf(l),~p)?[o=b.indexOf('\n'),~o,o+2,1].map((d,i)=>{k=(q-p)/d|0;if(k&&k*d+p==q)for(m='/|\\-'[i];(p+=k>0?d:-d)-q;c==m|c>'`'&c<'{'?0:b[p]=c>' '?c<'/'|c>'z'?'+':'X':m)c=b[p]}):p=q,p=-1,b=[...b])&&b.join('')

More readable

F=b=>
  b.match(/\w/g).sort().map(l=>
    (q=b.indexOf(l),~p)?
    [o=b.indexOf('\n'),~o,o+2,1].map((d,i)=>{
      k=(q-p)/d|0;
      if(k&&k*d+p==q)
        for(m='/|\\-'[i];
              (p+=k>0?d:-d)-q;
              c==m|c>'`'&c<'{'?0:b[p]=c>' '?c<'/'|c>'z'?'+':'X':m)
            c=b[p]
    })
    :p=q
  ,p=-1,b=[...b])
  &&b.join('')

Test In Firefox/FireBug console

console.log(F('\
b     d\n\
       \n\
       \n\
       \n\
       \n\
      e\n\
c     a\n'))

console.log(F('\
     dk    j\n\
            \n\
 b    l     \n\
            \n\
 c   fg     \n\
            \n\
     a    m \n\
            \n\
   i      h \n\
     e      \n'))

console.log(F('\
b     d    \n\
           \n\
           \n\
     h   gi\n\
           \n\
      e  f \n\
c     a    \n'))

Output

b     d
|\   /|
| \ / |
|  X  |
| / \ |
|/   \e
c     a

     dk----j
    /||   / 
 b / |l  /  
 |X  | \/   
 c \ fg/\   
    \|/\ \  
     a  \ m 
    /|   \  
   i-+----h 
     e      

b     d    
|\   /|    
| \ / |    
|  X h+--gi
| / \ |  | 
|/   \e--f 
c     a