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[C++] Minor improvements to PredictionContext #3616

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Merged
parrt merged 1 commit into from
Apr 2, 2022
Merged

[C++] Minor improvements to PredictionContext #3616

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18 changes: 9 additions & 9 deletions runtime/Cpp/runtime/src/atn/PredictionContext.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -223,13 +223,13 @@ Ref<const PredictionContext> PredictionContext::mergeSingletons(Ref<const Single
auto rootMerge = mergeRoot(a, b, rootIsWildcard);
if (rootMerge) {
if (mergeCache) {
return mergeCache->put(a, b, rootMerge);
return mergeCache->put(a, b, std::move(rootMerge));
}
return rootMerge;
}

auto parentA = a->parent;
auto parentB = b->parent;
const auto& parentA = a->parent;
const auto& parentB = b->parent;
if (a->returnState == b->returnState) { // a == b
auto parent = merge(parentA, parentB, rootIsWildcard, mergeCache);

Expand Down Expand Up @@ -343,29 +343,29 @@ Ref<const PredictionContext> PredictionContext::mergeArrays(Ref<const ArrayPredi

// walk and merge to yield mergedParents, mergedReturnStates
while (i < a->returnStates.size() && j < b->returnStates.size()) {
auto parentA = a->parents[i];
auto parentB = b->parents[j];
const auto& parentA = a->parents[i];
const auto& parentB = b->parents[j];
if (a->returnStates[i] == b->returnStates[j]) {
// same payload (stack tops are equal), must yield merged singleton
size_t payload = a->returnStates[i];
// $+$ = $
bool both$ = payload == EMPTY_RETURN_STATE && !parentA && !parentB;
bool ax_ax = (parentA && parentB) && *parentA == *parentB; // ax+ax -> ax
if (both$ || ax_ax) {
mergedParents[k] = std::move(parentA); // choose left
mergedParents[k] = parentA; // choose left
mergedReturnStates[k] = payload;
} else { // ax+ay -> a'[x,y]
mergedParents[k] = merge(std::move(parentA), std::move(parentB), rootIsWildcard, mergeCache);
mergedParents[k] = merge(parentA, parentB, rootIsWildcard, mergeCache);
mergedReturnStates[k] = payload;
}
i++; // hop over left one as usual
j++; // but also skip one in right side since we merge
} else if (a->returnStates[i] < b->returnStates[j]) { // copy a[i] to M
mergedParents[k] = std::move(parentA);
mergedParents[k] = parentA;
mergedReturnStates[k] = a->returnStates[i];
i++;
} else { // b > a, copy b[j] to M
mergedParents[k] = std::move(parentB);
mergedParents[k] = parentB;
mergedReturnStates[k] = b->returnStates[j];
j++;
}
Expand Down