+/* Copyright (c) 2012-2017 The ANTLR Project. All rights reserved.
+ * Use of this file is governed by the BSD 3-clause license that
+ * can be found in the LICENSE.txt file in the project root.
+ */
+
+#include "atn/EmptyPredictionContext.h"
+#include "misc/MurmurHash.h"
+#include "atn/ArrayPredictionContext.h"
+#include "RuleContext.h"
+#include "ParserRuleContext.h"
+#include "atn/RuleTransition.h"
+#include "support/Arrays.h"
+#include "support/CPPUtils.h"
+
+#include "atn/PredictionContext.h"
+
+using namespace antlr4;
+using namespace antlr4::misc;
+using namespace antlr4::atn;
+
+using namespace antlrcpp;
+
+size_t PredictionContext::globalNodeCount = 0;
+const Ref<PredictionContext> PredictionContext::EMPTY = std::make_shared<EmptyPredictionContext>();
+
+//----------------- PredictionContext ----------------------------------------------------------------------------------
+
+PredictionContext::PredictionContext(size_t cachedHashCode) : id(globalNodeCount++), cachedHashCode(cachedHashCode) {
+}
+
+PredictionContext::~PredictionContext() {
+}
+
+Ref<PredictionContext> PredictionContext::fromRuleContext(const ATN &atn, RuleContext *outerContext) {
+ if (outerContext == nullptr) {
+ return PredictionContext::EMPTY;
+ }
+
+ // if we are in RuleContext of start rule, s, then PredictionContext
+ // is EMPTY. Nobody called us. (if we are empty, return empty)
+ if (outerContext->parent == nullptr || outerContext == &ParserRuleContext::EMPTY) {
+ return PredictionContext::EMPTY;
+ }
+
+ // If we have a parent, convert it to a PredictionContext graph
+ Ref<PredictionContext> parent = PredictionContext::fromRuleContext(atn, dynamic_cast<RuleContext *>(outerContext->parent));
+
+ ATNState *state = atn.states.at(outerContext->invokingState);
+ RuleTransition *transition = (RuleTransition *)state->transitions[0];
+ return SingletonPredictionContext::create(parent, transition->followState->stateNumber);
+}
+
+bool PredictionContext::isEmpty() const {
+ return this == EMPTY.get();
+}
+
+bool PredictionContext::hasEmptyPath() const {
+ // since EMPTY_RETURN_STATE can only appear in the last position, we check last one
+ return getReturnState(size() - 1) == EMPTY_RETURN_STATE;
+}
+
+size_t PredictionContext::hashCode() const {
+ return cachedHashCode;
+}
+
+size_t PredictionContext::calculateEmptyHashCode() {
+ size_t hash = MurmurHash::initialize(INITIAL_HASH);
+ hash = MurmurHash::finish(hash, 0);
+ return hash;
+}
+
+size_t PredictionContext::calculateHashCode(Ref<PredictionContext> parent, size_t returnState) {
+ size_t hash = MurmurHash::initialize(INITIAL_HASH);
+ hash = MurmurHash::update(hash, parent);
+ hash = MurmurHash::update(hash, returnState);
+ hash = MurmurHash::finish(hash, 2);
+ return hash;
+}
+
+size_t PredictionContext::calculateHashCode(const std::vector<Ref<PredictionContext>> &parents,
+ const std::vector<size_t> &returnStates) {
+ size_t hash = MurmurHash::initialize(INITIAL_HASH);
+
+ for (auto parent : parents) {
+ hash = MurmurHash::update(hash, parent);
+ }
+
+ for (auto returnState : returnStates) {
+ hash = MurmurHash::update(hash, returnState);
+ }
+
+ return MurmurHash::finish(hash, parents.size() + returnStates.size());
+}
+
+Ref<PredictionContext> PredictionContext::merge(const Ref<PredictionContext> &a,
+ const Ref<PredictionContext> &b, bool rootIsWildcard, PredictionContextMergeCache *mergeCache) {
+ assert(a && b);
+
+ // share same graph if both same
+ if (a == b || *a == *b) {
+ return a;
+ }
+
+ if (is<SingletonPredictionContext>(a) && is<SingletonPredictionContext>(b)) {
+ return mergeSingletons(std::dynamic_pointer_cast<SingletonPredictionContext>(a),
+ std::dynamic_pointer_cast<SingletonPredictionContext>(b), rootIsWildcard, mergeCache);
+ }
+
+ // At least one of a or b is array.
+ // If one is $ and rootIsWildcard, return $ as * wildcard.
+ if (rootIsWildcard) {
+ if (is<EmptyPredictionContext>(a)) {
+ return a;
+ }
+ if (is<EmptyPredictionContext>(b)) {
+ return b;
+ }
+ }
+
+ // convert singleton so both are arrays to normalize
+ Ref<ArrayPredictionContext> left;
+ if (is<SingletonPredictionContext>(a)) {
+ left = std::make_shared<ArrayPredictionContext>(std::dynamic_pointer_cast<SingletonPredictionContext>(a));
+ } else {
+ left = std::dynamic_pointer_cast<ArrayPredictionContext>(a);
+ }
+ Ref<ArrayPredictionContext> right;
+ if (is<SingletonPredictionContext>(b)) {
+ right = std::make_shared<ArrayPredictionContext>(std::dynamic_pointer_cast<SingletonPredictionContext>(b));
+ } else {
+ right = std::dynamic_pointer_cast<ArrayPredictionContext>(b);
+ }
+ return mergeArrays(left, right, rootIsWildcard, mergeCache);
+}
+
+Ref<PredictionContext> PredictionContext::mergeSingletons(const Ref<SingletonPredictionContext> &a,
+ const Ref<SingletonPredictionContext> &b, bool rootIsWildcard, PredictionContextMergeCache *mergeCache) {
+
+ if (mergeCache != nullptr) { // Can be null if not given to the ATNState from which this call originates.
+ auto existing = mergeCache->get(a, b);
+ if (existing) {
+ return existing;
+ }
+ existing = mergeCache->get(b, a);
+ if (existing) {
+ return existing;
+ }
+ }
+
+ Ref<PredictionContext> rootMerge = mergeRoot(a, b, rootIsWildcard);
+ if (rootMerge) {
+ if (mergeCache != nullptr) {
+ mergeCache->put(a, b, rootMerge);
+ }
+ return rootMerge;
+ }
+
+ Ref<PredictionContext> parentA = a->parent;
+ Ref<PredictionContext> parentB = b->parent;
+ if (a->returnState == b->returnState) { // a == b
+ Ref<PredictionContext> parent = merge(parentA, parentB, rootIsWildcard, mergeCache);
+
+ // If parent is same as existing a or b parent or reduced to a parent, return it.
+ if (parent == parentA) { // ax + bx = ax, if a=b
+ return a;
+ }
+ if (parent == parentB) { // ax + bx = bx, if a=b
+ return b;
+ }
+
+ // else: ax + ay = a'[x,y]
+ // merge parents x and y, giving array node with x,y then remainders
+ // of those graphs. dup a, a' points at merged array
+ // new joined parent so create new singleton pointing to it, a'
+ Ref<PredictionContext> a_ = SingletonPredictionContext::create(parent, a->returnState);
+ if (mergeCache != nullptr) {
+ mergeCache->put(a, b, a_);
+ }
+ return a_;
+ } else {
+ // a != b payloads differ
+ // see if we can collapse parents due to $+x parents if local ctx
+ Ref<PredictionContext> singleParent;
+ if (a == b || (*parentA == *parentB)) { // ax + bx = [a,b]x
+ singleParent = parentA;
+ }
+ if (singleParent) { // parents are same, sort payloads and use same parent
+ std::vector<size_t> payloads = { a->returnState, b->returnState };
+ if (a->returnState > b->returnState) {
+ payloads[0] = b->returnState;
+ payloads[1] = a->returnState;
+ }
+ std::vector<Ref<PredictionContext>> parents = { singleParent, singleParent };
+ Ref<PredictionContext> a_ = std::make_shared<ArrayPredictionContext>(parents, payloads);
+ if (mergeCache != nullptr) {
+ mergeCache->put(a, b, a_);
+ }
+ return a_;
+ }
+
+ // parents differ and can't merge them. Just pack together
+ // into array; can't merge.
+ // ax + by = [ax,by]
+ Ref<PredictionContext> a_;
+ if (a->returnState > b->returnState) { // sort by payload
+ std::vector<size_t> payloads = { b->returnState, a->returnState };
+ std::vector<Ref<PredictionContext>> parents = { b->parent, a->parent };
+ a_ = std::make_shared<ArrayPredictionContext>(parents, payloads);
+ } else {
+ std::vector<size_t> payloads = {a->returnState, b->returnState};
+ std::vector<Ref<PredictionContext>> parents = { a->parent, b->parent };
+ a_ = std::make_shared<ArrayPredictionContext>(parents, payloads);
+ }
+
+ if (mergeCache != nullptr) {
+ mergeCache->put(a, b, a_);
+ }
+ return a_;
+ }
+}
+
+Ref<PredictionContext> PredictionContext::mergeRoot(const Ref<SingletonPredictionContext> &a,
+ const Ref<SingletonPredictionContext> &b, bool rootIsWildcard) {
+ if (rootIsWildcard) {
+ if (a == EMPTY) { // * + b = *
+ return EMPTY;
+ }
+ if (b == EMPTY) { // a + * = *
+ return EMPTY;
+ }
+ } else {
+ if (a == EMPTY && b == EMPTY) { // $ + $ = $
+ return EMPTY;
+ }
+ if (a == EMPTY) { // $ + x = [$,x]
+ std::vector<size_t> payloads = { b->returnState, EMPTY_RETURN_STATE };
+ std::vector<Ref<PredictionContext>> parents = { b->parent, nullptr };
+ Ref<PredictionContext> joined = std::make_shared<ArrayPredictionContext>(parents, payloads);
+ return joined;
+ }
+ if (b == EMPTY) { // x + $ = [$,x] ($ is always first if present)
+ std::vector<size_t> payloads = { a->returnState, EMPTY_RETURN_STATE };
+ std::vector<Ref<PredictionContext>> parents = { a->parent, nullptr };
+ Ref<PredictionContext> joined = std::make_shared<ArrayPredictionContext>(parents, payloads);
+ return joined;
+ }
+ }
+ return nullptr;
+}
+
+Ref<PredictionContext> PredictionContext::mergeArrays(const Ref<ArrayPredictionContext> &a,
+ const Ref<ArrayPredictionContext> &b, bool rootIsWildcard, PredictionContextMergeCache *mergeCache) {
+
+ if (mergeCache != nullptr) {
+ auto existing = mergeCache->get(a, b);
+ if (existing) {
+ return existing;
+ }
+ existing = mergeCache->get(b, a);
+ if (existing) {
+ return existing;
+ }
+ }
+
+ // merge sorted payloads a + b => M
+ size_t i = 0; // walks a
+ size_t j = 0; // walks b
+ size_t k = 0; // walks target M array
+
+ std::vector<size_t> mergedReturnStates(a->returnStates.size() + b->returnStates.size());
+ std::vector<Ref<PredictionContext>> mergedParents(a->returnStates.size() + b->returnStates.size());
+
+ // walk and merge to yield mergedParents, mergedReturnStates
+ while (i < a->returnStates.size() && j < b->returnStates.size()) {
+ Ref<PredictionContext> a_parent = a->parents[i];
+ Ref<PredictionContext> b_parent = 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 && !a_parent && !b_parent;
+ bool ax_ax = (a_parent && b_parent) && *a_parent == *b_parent; // ax+ax -> ax
+ if (both$ || ax_ax) {
+ mergedParents[k] = a_parent; // choose left
+ mergedReturnStates[k] = payload;
+ }
+ else { // ax+ay -> a'[x,y]
+ Ref<PredictionContext> mergedParent = merge(a_parent, b_parent, rootIsWildcard, mergeCache);
+ mergedParents[k] = mergedParent;
+ 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] = a_parent;
+ mergedReturnStates[k] = a->returnStates[i];
+ i++;
+ }
+ else { // b > a, copy b[j] to M
+ mergedParents[k] = b_parent;
+ mergedReturnStates[k] = b->returnStates[j];
+ j++;
+ }
+ k++;
+ }
+
+ // copy over any payloads remaining in either array
+ if (i < a->returnStates.size()) {
+ for (std::vector<int>::size_type p = i; p < a->returnStates.size(); p++) {
+ mergedParents[k] = a->parents[p];
+ mergedReturnStates[k] = a->returnStates[p];
+ k++;
+ }
+ } else {
+ for (std::vector<int>::size_type p = j; p < b->returnStates.size(); p++) {
+ mergedParents[k] = b->parents[p];
+ mergedReturnStates[k] = b->returnStates[p];
+ k++;
+ }
+ }
+
+ // trim merged if we combined a few that had same stack tops
+ if (k < mergedParents.size()) { // write index < last position; trim
+ if (k == 1) { // for just one merged element, return singleton top
+ Ref<PredictionContext> a_ = SingletonPredictionContext::create(mergedParents[0], mergedReturnStates[0]);
+ if (mergeCache != nullptr) {
+ mergeCache->put(a, b, a_);
+ }
+ return a_;
+ }
+ mergedParents.resize(k);
+ mergedReturnStates.resize(k);
+ }
+
+ Ref<ArrayPredictionContext> M = std::make_shared<ArrayPredictionContext>(mergedParents, mergedReturnStates);
+
+ // if we created same array as a or b, return that instead
+ // TODO: track whether this is possible above during merge sort for speed
+ if (*M == *a) {
+ if (mergeCache != nullptr) {
+ mergeCache->put(a, b, a);
+ }
+ return a;
+ }
+ if (*M == *b) {
+ if (mergeCache != nullptr) {
+ mergeCache->put(a, b, b);
+ }
+ return b;
+ }
+
+ // ml: this part differs from Java code. We have to recreate the context as the parents array is copied on creation.
+ if (combineCommonParents(mergedParents)) {
+ mergedReturnStates.resize(mergedParents.size());
+ M = std::make_shared<ArrayPredictionContext>(mergedParents, mergedReturnStates);
+ }
+
+ if (mergeCache != nullptr) {
+ mergeCache->put(a, b, M);
+ }
+ return M;
+}
+
+bool PredictionContext::combineCommonParents(std::vector<Ref<PredictionContext>> &parents) {
+
+ std::set<Ref<PredictionContext>> uniqueParents;
+ for (size_t p = 0; p < parents.size(); ++p) {
+ Ref<PredictionContext> parent = parents[p];
+ if (uniqueParents.find(parent) == uniqueParents.end()) { // don't replace
+ uniqueParents.insert(parent);
+ }
+ }
+
+ for (size_t p = 0; p < parents.size(); ++p) {
+ parents[p] = *uniqueParents.find(parents[p]);
+ }
+
+ return true;
+}
+
+std::string PredictionContext::toDOTString(const Ref<PredictionContext> &context) {
+ if (context == nullptr) {
+ return "";
+ }
+
+ std::stringstream ss;
+ ss << "digraph G {\n" << "rankdir=LR;\n";
+
+ std::vector<Ref<PredictionContext>> nodes = getAllContextNodes(context);
+ std::sort(nodes.begin(), nodes.end(), [](const Ref<PredictionContext> &o1, const Ref<PredictionContext> &o2) {
+ return o1->id - o2->id;
+ });
+
+ for (auto current : nodes) {
+ if (is<SingletonPredictionContext>(current)) {
+ std::string s = std::to_string(current->id);
+ ss << " s" << s;
+ std::string returnState = std::to_string(current->getReturnState(0));
+ if (is<EmptyPredictionContext>(current)) {
+ returnState = "$";
+ }
+ ss << " [label=\"" << returnState << "\"];\n";
+ continue;
+ }
+ Ref<ArrayPredictionContext> arr = std::static_pointer_cast<ArrayPredictionContext>(current);
+ ss << " s" << arr->id << " [shape=box, label=\"" << "[";
+ bool first = true;
+ for (auto inv : arr->returnStates) {
+ if (!first) {
+ ss << ", ";
+ }
+ if (inv == EMPTY_RETURN_STATE) {
+ ss << "$";
+ } else {
+ ss << inv;
+ }
+ first = false;
+ }
+ ss << "]";
+ ss << "\"];\n";
+ }
+
+ for (auto current : nodes) {
+ if (current == EMPTY) {
+ continue;
+ }
+ for (size_t i = 0; i < current->size(); i++) {
+ if (!current->getParent(i)) {
+ continue;
+ }
+ ss << " s" << current->id << "->" << "s" << current->getParent(i)->id;
+ if (current->size() > 1) {
+ ss << " [label=\"parent[" << i << "]\"];\n";
+ } else {
+ ss << ";\n";
+ }
+ }
+ }
+
+ ss << "}\n";
+ return ss.str();
+}
+
+// The "visited" map is just a temporary structure to control the retrieval process (which is recursive).
+Ref<PredictionContext> PredictionContext::getCachedContext(const Ref<PredictionContext> &context,
+ PredictionContextCache &contextCache, std::map<Ref<PredictionContext>, Ref<PredictionContext>> &visited) {
+ if (context->isEmpty()) {
+ return context;
+ }
+
+ {
+ auto iterator = visited.find(context);
+ if (iterator != visited.end())
+ return iterator->second; // Not necessarly the same as context.
+ }
+
+ auto iterator = contextCache.find(context);
+ if (iterator != contextCache.end()) {
+ visited[context] = *iterator;
+
+ return *iterator;
+ }
+
+ bool changed = false;
+
+ std::vector<Ref<PredictionContext>> parents(context->size());
+ for (size_t i = 0; i < parents.size(); i++) {
+ Ref<PredictionContext> parent = getCachedContext(context->getParent(i), contextCache, visited);
+ if (changed || parent != context->getParent(i)) {
+ if (!changed) {
+ parents.clear();
+ for (size_t j = 0; j < context->size(); j++) {
+ parents.push_back(context->getParent(j));
+ }
+
+ changed = true;
+ }
+
+ parents[i] = parent;
+ }
+ }
+
+ if (!changed) {
+ contextCache.insert(context);
+ visited[context] = context;
+
+ return context;
+ }
+
+ Ref<PredictionContext> updated;
+ if (parents.empty()) {
+ updated = EMPTY;
+ } else if (parents.size() == 1) {
+ updated = SingletonPredictionContext::create(parents[0], context->getReturnState(0));
+ contextCache.insert(updated);
+ } else {
+ updated = std::make_shared<ArrayPredictionContext>(parents, std::dynamic_pointer_cast<ArrayPredictionContext>(context)->returnStates);
+ contextCache.insert(updated);
+ }
+
+ visited[updated] = updated;
+ visited[context] = updated;
+
+ return updated;
+}
+
+std::vector<Ref<PredictionContext>> PredictionContext::getAllContextNodes(const Ref<PredictionContext> &context) {
+ std::vector<Ref<PredictionContext>> nodes;
+ std::set<PredictionContext *> visited;
+ getAllContextNodes_(context, nodes, visited);
+ return nodes;
+}
+
+
+void PredictionContext::getAllContextNodes_(const Ref<PredictionContext> &context, std::vector<Ref<PredictionContext>> &nodes,
+ std::set<PredictionContext *> &visited) {
+
+ if (visited.find(context.get()) != visited.end()) {
+ return; // Already done.
+ }
+
+ visited.insert(context.get());
+ nodes.push_back(context);
+
+ for (size_t i = 0; i < context->size(); i++) {
+ getAllContextNodes_(context->getParent(i), nodes, visited);
+ }
+}
+
+std::string PredictionContext::toString() const {
+
+ return antlrcpp::toString(this);
+}
+
+std::string PredictionContext::toString(Recognizer * /*recog*/) const {
+ return toString();
+}
+
+std::vector<std::string> PredictionContext::toStrings(Recognizer *recognizer, int currentState) {
+ return toStrings(recognizer, EMPTY, currentState);
+}
+
+std::vector<std::string> PredictionContext::toStrings(Recognizer *recognizer, const Ref<PredictionContext> &stop, int currentState) {
+
+ std::vector<std::string> result;
+
+ for (size_t perm = 0; ; perm++) {
+ size_t offset = 0;
+ bool last = true;
+ PredictionContext *p = this;
+ size_t stateNumber = currentState;
+
+ std::stringstream ss;
+ ss << "[";
+ bool outerContinue = false;
+ while (!p->isEmpty() && p != stop.get()) {
+ size_t index = 0;
+ if (p->size() > 0) {
+ size_t bits = 1;
+ while ((1ULL << bits) < p->size()) {
+ bits++;
+ }
+
+ size_t mask = (1 << bits) - 1;
+ index = (perm >> offset) & mask;
+ last &= index >= p->size() - 1;
+ if (index >= p->size()) {
+ outerContinue = true;
+ break;
+ }
+ offset += bits;
+ }
+
+ if (recognizer != nullptr) {
+ if (ss.tellp() > 1) {
+ // first char is '[', if more than that this isn't the first rule
+ ss << ' ';
+ }
+
+ const ATN &atn = recognizer->getATN();
+ ATNState *s = atn.states[stateNumber];
+ std::string ruleName = recognizer->getRuleNames()[s->ruleIndex];
+ ss << ruleName;
+ } else if (p->getReturnState(index) != EMPTY_RETURN_STATE) {
+ if (!p->isEmpty()) {
+ if (ss.tellp() > 1) {
+ // first char is '[', if more than that this isn't the first rule
+ ss << ' ';
+ }
+
+ ss << p->getReturnState(index);
+ }
+ }
+ stateNumber = p->getReturnState(index);
+ p = p->getParent(index).get();
+ }
+
+ if (outerContinue)
+ continue;
+
+ ss << "]";
+ result.push_back(ss.str());
+
+ if (last) {
+ break;
+ }
+ }
+
+ return result;
+}
+
+//----------------- PredictionContextMergeCache ------------------------------------------------------------------------
+
+Ref<PredictionContext> PredictionContextMergeCache::put(Ref<PredictionContext> const& key1, Ref<PredictionContext> const& key2,
+ Ref<PredictionContext> const& value) {
+ Ref<PredictionContext> previous;
+
+ auto iterator = _data.find(key1);
+ if (iterator == _data.end())
+ _data[key1][key2] = value;
+ else {
+ auto iterator2 = iterator->second.find(key2);
+ if (iterator2 != iterator->second.end())
+ previous = iterator2->second;
+ iterator->second[key2] = value;
+ }
+
+ return previous;
+}
+
+Ref<PredictionContext> PredictionContextMergeCache::get(Ref<PredictionContext> const& key1, Ref<PredictionContext> const& key2) {
+ auto iterator = _data.find(key1);
+ if (iterator == _data.end())
+ return nullptr;
+
+ auto iterator2 = iterator->second.find(key2);
+ if (iterator2 == iterator->second.end())
+ return nullptr;
+
+ return iterator2->second;
+}
+
+void PredictionContextMergeCache::clear() {
+ _data.clear();
+}
+
+std::string PredictionContextMergeCache::toString() const {
+ std::string result;
+ for (auto pair : _data)
+ for (auto pair2 : pair.second)
+ result += pair2.second->toString() + "\n";
+
+ return result;
+}
+
+size_t PredictionContextMergeCache::count() const {
+ size_t result = 0;
+ for (auto entry : _data)
+ result += entry.second.size();
+ return result;
+}
+
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