distance-iterator.js 1.5 KB

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  1. // Iterator that traverses in the range of [min, max], stepping
  2. // by distance from a given start position. I.e. for [0, 4], with
  3. // start of 2, this will iterate 2, 3, 1, 4, 0.
  4. export default function (start, minLine, maxLine) {
  5. let wantForward = true, backwardExhausted = false, forwardExhausted = false, localOffset = 1;
  6. return function iterator() {
  7. if (wantForward && !forwardExhausted) {
  8. if (backwardExhausted) {
  9. localOffset++;
  10. }
  11. else {
  12. wantForward = false;
  13. }
  14. // Check if trying to fit beyond text length, and if not, check it fits
  15. // after offset location (or desired location on first iteration)
  16. if (start + localOffset <= maxLine) {
  17. return start + localOffset;
  18. }
  19. forwardExhausted = true;
  20. }
  21. if (!backwardExhausted) {
  22. if (!forwardExhausted) {
  23. wantForward = true;
  24. }
  25. // Check if trying to fit before text beginning, and if not, check it fits
  26. // before offset location
  27. if (minLine <= start - localOffset) {
  28. return start - localOffset++;
  29. }
  30. backwardExhausted = true;
  31. return iterator();
  32. }
  33. // We tried to fit hunk before text beginning and beyond text length, then
  34. // hunk can't fit on the text. Return undefined
  35. return undefined;
  36. };
  37. }