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Copy pathdistance-iterator.js
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45 lines (38 loc) · 1.26 KB
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// 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.
export default function(start, minLine, maxLine) {
let 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 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 -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
};
}