Find potential Morse-code string matches using input with question mark as wildcard

Question

I have an function that checks if string( parameter) matches values in an array and returns an array of possibilities key

function find_possible_match( $criteria ) {

  $possible_match = array();


      $possibilities = array(
"a"=>".-",
"b"=>"-...", 
"c"=>"-.-.", 
"d"=>"-..", 
"e"=>".", 
"f"=>"..-.", 
"g"=>"--.", 
"h"=>"....", 
"i"=>"..", 
"j"=>".---", 
"k"=>"-.-", 
"l"=>".-..", 
"m"=>"--", 
"n"=>"-.", 
"o"=>"---", 
"p"=>".--.", 
"q"=>"--.-", 
"r"=>".-.", 
"s"=>"...", 
"t"=>"-", 
"u"=>"..-", 
"v"=>"...-", 
"w"=>".--", 
"x"=>"-..-", 
"y"=>"-.--", 
"z"=>"--..", 
"0"=>"-----",
"1"=>".----", 
"2"=>"..---", 
"3"=>"...--", 
"4"=>"....-", 
"5"=>".....", 
"6"=>"-....", 
"7"=>"--...", 
"8"=>"---..", 
"9"=>"----.",
"."=>".-.-.-",
","=>"--..--",
"?"=>"..--..",
"/"=>"-..-.",
" "=>" ");


  foreach ( $possibilities as $key => $value ) {

         if( $value == $criteria ){
            array_push(  $possible_match , $key );
        }
  }

  return $possible_match;
} 

this is pretty standard is all criteria where string like

find_possible_match( ".-" );

will return [a]... etc

but the twist is that, what if the params has an unknown, example

find_possible_match("?");

should return [e, t], likewise

find_possible_match("?.")

should return ['i','n'] and

find_possible_match(".?")

should return ['i','a']

? in this case is the wildcard. How do i modify the above code to do just that. Thank you

Answer 1

You could use preg_match() you check if the $criteria match to $value. You could replace the $criteria according to regular expression requirements (escape dot, convert ? to [.-]):

function find_possible_match( $criteria ) {

    $criteria = str_replace(['.','?'],['\.','[.-]'],$criteria);
    $regexp = '~^'.$criteria.'$~';

    $possibilities = array(
        "a"=>".-",
        "b"=>"-...",
        "c"=>"-.-.",
        "d"=>"-..",
        "e"=>".",
        "f"=>"..-.",
        "g"=>"--.",
        "h"=>"....",
        "i"=>"..",
        "j"=>".---",
        "k"=>"-.-",
        "l"=>".-..",
        "m"=>"--",
        "n"=>"-.",
        "o"=>"---",
        "p"=>".--.",
        "q"=>"--.-",
        "r"=>".-.",
        "s"=>"...",
        "t"=>"-",
        "u"=>"..-",
        "v"=>"...-",
        "w"=>".--",
        "x"=>"-..-",
        "y"=>"-.--",
        "z"=>"--..",
        "0"=>"-----",
        "1"=>".----",
        "2"=>"..---",
        "3"=>"...--",
        "4"=>"....-",
        "5"=>".....",
        "6"=>"-....",
        "7"=>"--...",
        "8"=>"---..",
        "9"=>"----.",
        "."=>".-.-.-",
        ","=>"--..--",
        "?"=>"..--..",
        "/"=>"-..-.",
        " "=>" ");


    $possible_match = array();
    foreach ($possibilities as $key => $value) {
        if (preg_match($regexp, $value)) {
            array_push($possible_match, $key);
        }
    }
    return $possible_match;
}

print_r(find_possible_match(".-")); // ['a']
print_r(find_possible_match("?")); // ['e','t']
print_r(find_possible_match("?.")); // ['i','n']
print_r(find_possible_match(".?")); // ['i','a']

Outputs:

Array
(
    [0] => a
)
Array
(
    [0] => e
    [1] => t
)
Array
(
    [0] => i
    [1] => n
)
Array
(
    [0] => a
    [1] => i
)