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| 1 | +// 1. Compute Levenshtein distance between two strings |
| 2 | +function levenshtein(a: string, b: string): number { |
| 3 | + const dp: number[][] = Array(a.length + 1) |
| 4 | + .fill(0) |
| 5 | + .map(() => Array(b.length + 1).fill(0)); |
| 6 | + for (let i = 0; i <= a.length; i++) dp[i][0] = i; |
| 7 | + for (let j = 0; j <= b.length; j++) dp[0][j] = j; |
| 8 | + |
| 9 | + for (let i = 1; i <= a.length; i++) { |
| 10 | + for (let j = 1; j <= b.length; j++) { |
| 11 | + dp[i][j] = Math.min( |
| 12 | + dp[i - 1][j] + 1, // deletion |
| 13 | + dp[i][j - 1] + 1, // insertion |
| 14 | + dp[i - 1][j - 1] + (a[i - 1] === b[j - 1] ? 0 : 1), // substitution |
| 15 | + ); |
| 16 | + } |
| 17 | + } |
| 18 | + return dp[a.length][b.length]; |
| 19 | +} |
| 20 | + |
| 21 | +// 2. Score one item against the query (normalized score 0–1) |
| 22 | +function scoreItem<T>( |
| 23 | + item: T, |
| 24 | + keys: Array<keyof T | string>, |
| 25 | + queryTokens: string[], |
| 26 | +): number { |
| 27 | + let best = Infinity; |
| 28 | + for (const key of keys) { |
| 29 | + const field = String(item[key as keyof T] ?? "").toLowerCase(); |
| 30 | + const fieldTokens = field.split(/\s+/); |
| 31 | + const tokenScores = queryTokens.map((qt) => { |
| 32 | + const minNormalized = Math.min( |
| 33 | + ...fieldTokens.map((ft) => { |
| 34 | + const rawDist = levenshtein(ft, qt); |
| 35 | + const maxLen = Math.max(ft.length, qt.length); |
| 36 | + return maxLen === 0 ? 0 : rawDist / maxLen; // normalized 0–1 |
| 37 | + }), |
| 38 | + ); |
| 39 | + return minNormalized; |
| 40 | + }); |
| 41 | + const avg = tokenScores.reduce((a, b) => a + b, 0) / tokenScores.length; |
| 42 | + best = Math.min(best, avg); |
| 43 | + } |
| 44 | + return best; |
| 45 | +} |
| 46 | + |
| 47 | +// 3. The search entrypoint |
| 48 | +export function customFuzzySearch<T>( |
| 49 | + list: T[], |
| 50 | + keys: Array<keyof T | string>, |
| 51 | + query: string, |
| 52 | + limit: number = 5, |
| 53 | + maxDistance: number = 0.6, |
| 54 | +): T[] { |
| 55 | + const q = query.toLowerCase().trim(); |
| 56 | + const queryTokens = q.split(/\s+/); |
| 57 | + |
| 58 | + return list |
| 59 | + .map((item) => ({ item, score: scoreItem(item, keys, queryTokens) })) |
| 60 | + .filter((x) => x.score <= maxDistance) |
| 61 | + .sort((a, b) => a.score - b.score) |
| 62 | + .slice(0, limit) |
| 63 | + .map((x) => x.item); |
| 64 | +} |
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