TypeScript 中的拼写更正

/**
 * Given a name and a list of symbols whose names are *not* equal to the name, return a spelling suggestion if there is one that is close enough.
 * Names less than length 3 only check for case-insensitive equality, not levenshtein distance.
 *
 * If there is a candidate that's the same except for case, return that.
 * If there is a candidate that's within one edit of the name, return that.
 * Otherwise, return the candidate with the smallest Levenshtein distance,
 *    except for candidates:
 *      * With no name
 *      * Whose meaning doesn't match the `meaning` parameter.
 *      * Whose length differs from the target name by more than 0.34 of the length of the name.
 *      * Whose levenshtein distance is more than 0.4 of the length of the name
 *        (0.4 allows 1 substitution/transposition for every 5 characters,
 *         and 1 insertion/deletion at 3 characters)
 */
function getSpellingSuggestionForName(
  name: string,
  symbols: Symbol[],
  meaning: SymbolFlags
): Symbol | undefined {
  const maximumLengthDifference = Math.min(2, Math.floor(name.length * 0.34))
  let bestDistance = Math.floor(name.length * 0.4) + 1 // If the best result isn't better than this, don't bother.
  let bestCandidate: Symbol | undefined
  let justCheckExactMatches = false
  const nameLowerCase = name.toLowerCase()
  for (const candidate of symbols) {
    const candidateName = symbolName(candidate)
    if (
      !(
        candidate.flags & meaning &&
        Math.abs(candidateName.length - nameLowerCase.length) <=
          maximumLengthDifference
      )
    ) {
      continue
    }
    const candidateNameLowerCase = candidateName.toLowerCase()
    if (candidateNameLowerCase === nameLowerCase) {
      return candidate
    }
    if (justCheckExactMatches) {
      continue
    }
    if (candidateName.length < 3) {
      // Don't bother, user would have noticed a 2-character name having an extra character
      continue
    }
    // Only care about a result better than the best so far.
    const distance = levenshteinWithMax(
      nameLowerCase,
      candidateNameLowerCase,
      bestDistance - 1
    )
    if (distance === undefined) {
      continue
    }
    if (distance < 3) {
      justCheckExactMatches = true
      bestCandidate = candidate
    } else {
      Debug.assert(distance < bestDistance) // Else `levenshteinWithMax` should return undefined
      bestDistance = distance
      bestCandidate = candidate
    }
  }
  return bestCandidate
}