codekingpro/portable-devtools

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.
4export 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}
38