Function diffStr

internal/diff_str.ts:158–208

(A: string, B: string)

 * ```
 */
export function diffStr(A: string, B: string): DiffResult<string>[] {
  // Compute multi-line diff
  const diffResult = diff(
    tokenize(`${unescape(A)}\n`),
    tokenize(`${unescape(B)}\n`),
  );

  const added = [];
  const removed = [];
  for (const result of diffResult) {
    if (result.type === "added") {
      added.push(result);
    }
    if (result.type === "removed") {
      removed.push(result);
    }
  }

  // Compute word-diff
  const hasMoreRemovedLines = added.length < removed.length;
  const aLines = hasMoreRemovedLines ? added : removed;
  const bLines = hasMoreRemovedLines ? removed : added;
  let bIdx = 0;
  for (const a of aLines) {
    let tokens = [] as Array<DiffResult<string>>;
    let b: undefined | ChangedDiffResult<string>;
    const aTokens = tokenize(a.value, true);
    // Search another diff line with at least one common token
    while (bIdx < bLines.length) {
      b = bLines[bIdx++];
      const bTokens = tokenize(b!.value, true);
      tokens = hasMoreRemovedLines
        ? diff(bTokens, aTokens)
        : diff(aTokens, bTokens);
      if (
        tokens.some(({ type, value }) =>
          type === "common" && NON_WHITESPACE_REGEXP.test(value)
        )
      ) {
        break;
      }
    }
    // Register word-diff details
    a.details = createDetails(a, tokens);
    if (b) {
      b.details = createDetails(b, tokens);
    }
  }

  return diffResult;
}