Gary Sharp
123 lines
4.2 KiB
C#
123 lines
4.2 KiB
C#
using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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using System.Threading.Tasks;
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namespace Disco
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{
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public static class StringExtensions
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{
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/// <summary>
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/// A fuzzy string search algorithm.
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///
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/// Based on: ScoreSharp (https://github.com/bltavares/scoresharp)
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/// Based on: string_score from Joshaven Potter (https://github.com/joshaven/string_score)
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///
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/// MIT License
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/// </summary>
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public static double Score(this string Source, string Test, double Fuzziness = 0)
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{
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double total_char_score = 0, abbrv_size = Test.Length,
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fuzzies = 1, final_score, abbrv_score;
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int word_size = Source.Length;
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bool start_of_word_bonus = false;
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//If strings are equal, return 1.0
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if (Source == Test) return 1.0;
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int index_in_string,
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index_char_lowercase,
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index_char_uppercase,
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min_index;
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double char_score;
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string c;
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for (int i = 0; i < abbrv_size; i++)
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{
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c = Test[i].ToString();
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index_char_uppercase = Source.IndexOf(c.ToUpper());
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index_char_lowercase = Source.IndexOf(c.ToLower());
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min_index = Math.Min(index_char_lowercase, index_char_uppercase);
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//Finds first valid occurrence
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//In upper or lowercase
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index_in_string = min_index > -1 ?
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min_index : Math.Max(index_char_lowercase, index_char_uppercase);
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//If no value is found
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//Check if fuzziness is allowed
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if (index_in_string == -1)
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{
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if (Fuzziness > 0)
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{
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fuzzies += 1 - Fuzziness;
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continue;
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}
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else return 0;
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}
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else
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char_score = 0.1;
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//Check if current char is the same case
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//Then add bonus
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if (Source[index_in_string].ToString() == c) char_score += 0.1;
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//Check if char matches the first letter
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//And add bonus for consecutive letters
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if (index_in_string == 0)
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{
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char_score += 0.6;
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//Check if the abbreviation
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//is in the start of the word
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start_of_word_bonus = i == 0;
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}
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else
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{
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// Acronym Bonus
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// Weighing Logic: Typing the first character of an acronym is as if you
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// preceded it with two perfect character matches.
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if (Source.ElementAtOrDefault(index_in_string - 1).ToString() == " ") char_score += 0.8;
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}
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//Remove the start of string, so we don't reprocess it
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Source = Source.Substring(index_in_string + 1);
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//sum chars scores
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total_char_score += char_score;
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}
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abbrv_score = total_char_score / abbrv_size;
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//Reduce penalty for longer words
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final_score = ((abbrv_score * (abbrv_size / word_size)) + abbrv_score) / 2;
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//Reduce using fuzzies;
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final_score = final_score / fuzzies;
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//Process start of string bonus
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if (start_of_word_bonus && final_score <= 0.85)
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final_score += 0.15;
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return final_score;
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}
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/// <summary>
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/// A fuzzy string search algorithm.
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///
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/// Based on: ScoreSharp (https://github.com/bltavares/scoresharp)
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/// Based on: string_score from Joshaven Potter (https://github.com/joshaven/string_score)
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///
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/// MIT License
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/// </summary>
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public static double Score(this IEnumerable<string> Sources, string Test, double Fuzziness = 0)
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{
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return Sources
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.Where(s => s != null)
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.Select(s => s.Score(Test, Fuzziness))
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.Average();
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}
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}
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}
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