next: Command

packages/bits-ui/src/lib/bits/command/command-score.ts

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+// eslint-disable-next-line ts/ban-ts-comment
+// @ts-nocheck
+// The scores are arranged so that a continuous match of characters will
+// result in a total score of 1.
+//
+// The best case, this character is a match, and either this is the start
+// of the string, or the previous character was also a match.
+const SCORE_CONTINUE_MATCH = 1;
+// A new match at the start of a word scores better than a new match
+// elsewhere as it's more likely that the user will type the starts
+// of fragments.
+// NOTE: We score word jumps between spaces slightly higher than slashes, brackets
+// hyphens, etc.
+const SCORE_SPACE_WORD_JUMP = 0.9;
+const SCORE_NON_SPACE_WORD_JUMP = 0.8;
+// Any other match isn't ideal, but we include it for completeness.
+const SCORE_CHARACTER_JUMP = 0.17;
+// If the user transposed two letters, it should be significantly penalized.
+//
+// i.e. "ouch" is more likely than "curtain" when "uc" is typed.
+const SCORE_TRANSPOSITION = 0.1;
+// The goodness of a match should decay slightly with each missing
+// character.
+//
+// i.e. "bad" is more likely than "bard" when "bd" is typed.
+//
+// This will not change the order of suggestions based on SCORE_* until
+// 100 characters are inserted between matches.
+const PENALTY_SKIPPED = 0.999;
+// The goodness of an exact-case match should be higher than a
+// case-insensitive match by a small amount.
+//
+// i.e. "HTML" is more likely than "haml" when "HM" is typed.
+//
+// This will not change the order of suggestions based on SCORE_* until
+// 1000 characters are inserted between matches.
+const PENALTY_CASE_MISMATCH = 0.9999;
+// Match higher for letters closer to the beginning of the word
+const PENALTY_DISTANCE_FROM_START = 0.9;
+// If the word has more characters than the user typed, it should
+// be penalised slightly.
+//
+// i.e. "html" is more likely than "html5" if I type "html".
+//
+// However, it may well be the case that there's a sensible secondary
+// ordering (like alphabetical) that it makes sense to rely on when
+// there are many prefix matches, so we don't make the penalty increase
+// with the number of tokens.
+const PENALTY_NOT_COMPLETE = 0.99;
+
+const IS_GAP_REGEXP = /[\\/_+.#"@[({&]/;
+const COUNT_GAPS_REGEXP = /[\\/_+.#"@[({&]/g;
+const IS_SPACE_REGEXP = /[\s-]/;
+const COUNT_SPACE_REGEXP = /[\s-]/g;
+
+function commandScoreInner(
+	string,
+	abbreviation,
+	lowerString,
+	lowerAbbreviation,
+	stringIndex,
+	abbreviationIndex,
+	memoizedResults
+) {
+	if (abbreviationIndex === abbreviation.length) {
+		if (stringIndex === string.length) {
+			return SCORE_CONTINUE_MATCH;
+		}
+		return PENALTY_NOT_COMPLETE;
+	}
+
+	const memoizeKey = `${stringIndex},${abbreviationIndex}`;
+	if (memoizedResults[memoizeKey] !== undefined) {
+		return memoizedResults[memoizeKey];
+	}
+
+	const abbreviationChar = lowerAbbreviation.charAt(abbreviationIndex);
+	let index = lowerString.indexOf(abbreviationChar, stringIndex);
+	let highScore = 0;
+
+	let score, transposedScore, wordBreaks, spaceBreaks;
+
+	while (index >= 0) {
+		score = commandScoreInner(
+			string,
+			abbreviation,
+			lowerString,
+			lowerAbbreviation,
+			index + 1,
+			abbreviationIndex + 1,
+			memoizedResults
+		);
+		if (score > highScore) {
+			if (index === stringIndex) {
+				score *= SCORE_CONTINUE_MATCH;
+			} else if (IS_GAP_REGEXP.test(string.charAt(index - 1))) {
+				score *= SCORE_NON_SPACE_WORD_JUMP;
+				wordBreaks = string.slice(stringIndex, index - 1).match(COUNT_GAPS_REGEXP);
+				if (wordBreaks && stringIndex > 0) {
+					score *= PENALTY_SKIPPED ** wordBreaks.length;
+				}
+			} else if (IS_SPACE_REGEXP.test(string.charAt(index - 1))) {
+				score *= SCORE_SPACE_WORD_JUMP;
+				spaceBreaks = string.slice(stringIndex, index - 1).match(COUNT_SPACE_REGEXP);
+				if (spaceBreaks && stringIndex > 0) {
+					score *= PENALTY_SKIPPED ** spaceBreaks.length;
+				}
+			} else {
+				score *= SCORE_CHARACTER_JUMP;
+				if (stringIndex > 0) {
+					score *= PENALTY_SKIPPED ** (index - stringIndex);
+				}
+			}
+
+			if (string.charAt(index) !== abbreviation.charAt(abbreviationIndex)) {
+				score *= PENALTY_CASE_MISMATCH;
+			}
+		}
+
+		if (
+			(score < SCORE_TRANSPOSITION &&
+				lowerString.charAt(index - 1) ===
+					lowerAbbreviation.charAt(abbreviationIndex + 1)) ||
+			(lowerAbbreviation.charAt(abbreviationIndex + 1) ===
+				lowerAbbreviation.charAt(abbreviationIndex) && // allow duplicate letters. Ref #7428
+				lowerString.charAt(index - 1) !== lowerAbbreviation.charAt(abbreviationIndex))
+		) {
+			transposedScore = commandScoreInner(
+				string,
+				abbreviation,
+				lowerString,
+				lowerAbbreviation,
+				index + 1,
+				abbreviationIndex + 2,
+				memoizedResults
+			);
+
+			if (transposedScore * SCORE_TRANSPOSITION > score) {
+				score = transposedScore * SCORE_TRANSPOSITION;
+			}
+		}
+
+		if (score > highScore) {
+			highScore = score;
+		}
+
+		index = lowerString.indexOf(abbreviationChar, index + 1);
+	}
+
+	memoizedResults[memoizeKey] = highScore;
+	return highScore;
+}
+
+function formatInput(string) {
+	// convert all valid space characters to space so they match each other
+	return string.toLowerCase().replace(COUNT_SPACE_REGEXP, " ");
+}
+
+export function commandScore(string: string, abbreviation: string, aliases?: string[]): number {
+	/* NOTE:
+	 * in the original, we used to do the lower-casing on each recursive call, but this meant that toLowerCase()
+	 * was the dominating cost in the algorithm, passing both is a little ugly, but considerably faster.
+	 */
+	string = aliases && aliases.length > 0 ? `${`${string} ${aliases?.join(" ")}`}` : string;
+	return commandScoreInner(
+		string,
+		abbreviation,
+		formatInput(string),
+		formatInput(abbreviation),
+		0,
+		0,
+		{}
+	);
+}