public static double Score(this string Source, string Test, double Fuzziness = 0)
{
double total_char_score = 0, abbrv_size = Test.Length,
fuzzies = 1, final_score, abbrv_score;
int word_size = Source.Length;
bool start_of_word_bonus = false;
//If strings are equal, return 1.0
if (Source == Test) return 1.0;
int index_in_string,
index_char_lowercase,
index_char_uppercase,
min_index;
double char_score;
string c;
for (int i = 0; i < abbrv_size; i++)
{
c = Test[i].ToString();
index_char_uppercase = Source.IndexOf(c.ToUpper());
index_char_lowercase = Source.IndexOf(c.ToLower());
min_index = Math.Min(index_char_lowercase, index_char_uppercase);
//Finds first valid occurrence
//In upper or lowercase
index_in_string = min_index > -1 ?
min_index : Math.Max(index_char_lowercase, index_char_uppercase);
//If no value is found
//Check if fuzziness is allowed
if (index_in_string == -1)
{
if (Fuzziness > 0)
{
fuzzies += 1 - Fuzziness;
continue;
}
else return 0;
}
else
char_score = 0.1;
//Check if current char is the same case
//Then add bonus
if (Source[index_in_string].ToString() == c) char_score += 0.1;
//Check if char matches the first letter
//And add bonus for consecutive letters
if (index_in_string == 0)
{
char_score += 0.6;
//Check if the abbreviation
//is in the start of the word
start_of_word_bonus = i == 0;
}
else
{
// Acronym Bonus
// Weighing Logic: Typing the first character of an acronym is as if you
// preceded it with two perfect character matches.
if (Source.ElementAtOrDefault(index_in_string - 1).ToString() == " ") char_score += 0.8;
}
//Remove the start of string, so we don't reprocess it
Source = Source.Substring(index_in_string + 1);
//sum chars scores
total_char_score += char_score;
}
abbrv_score = total_char_score / abbrv_size;
//Reduce penalty for longer words
final_score = ((abbrv_score * (abbrv_size / word_size)) + abbrv_score) / 2;
//Reduce using fuzzies;
final_score = final_score / fuzzies;
//Process start of string bonus
if (start_of_word_bonus && final_score <= 0.85)
final_score += 0.15;
return final_score;
}