diff/lib/util/distance-iterator.js

A JavaScript text diff implementation.

/*istanbul ignore start*/
"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports["default"] = _default;
/*istanbul ignore end*/
// Iterator that traverses in the range of [min, max], stepping
// by distance from a given start position. I.e. for [0, 4], with
// start of 2, this will iterate 2, 3, 1, 4, 0.
function
/*istanbul ignore start*/
_default
/*istanbul ignore end*/
(start, minLine, maxLine) {
  var wantForward = true,
    backwardExhausted = false,
    forwardExhausted = false,
    localOffset = 1;
  return function iterator() {
    if (wantForward && !forwardExhausted) {
      if (backwardExhausted) {
        localOffset++;
      } else {
        wantForward = false;
      }

      // Check if trying to fit beyond text length, and if not, check it fits
      // after offset location (or desired location on first iteration)
      if (start + localOffset <= maxLine) {
        return start + localOffset;
      }
      forwardExhausted = true;
    }
    if (!backwardExhausted) {
      if (!forwardExhausted) {
        wantForward = true;
      }

      // Check if trying to fit before text beginning, and if not, check it fits
      // before offset location
      if (minLine <= start - localOffset) {
        return start - localOffset++;
      }
      backwardExhausted = true;
      return iterator();
    }

    // We tried to fit hunk before text beginning and beyond text length, then
    // hunk can't fit on the text. Return undefined
  };
}
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