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.wip/Language/public/Automata.hpp

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+
+#pragma once
+
+#include "Utils.hpp"
+#include "List.hpp"
+#include "Map.hpp"
+#include "Tree.hpp"
+
+namespace tp {
+
+	// Non-Deterministic Finite-State Automata
+	template <typename tAlphabetType, typename tStateType>
+	class FiniteStateAutomation {
+	public:
+		struct State;
+
+	public:
+		class Transition {
+			friend FiniteStateAutomation;
+
+		public:
+			enum Type { ANY, EPSILON, SYMBOL };
+
+		public:
+			Transition(Type type, State* state, tAlphabetType symbol = tAlphabetType()) {
+				mState = state;
+				mType = type;
+				mSymbol = symbol;
+			}
+
+			[[nodiscard]] bool isTransition(const tAlphabetType& symbol) const {
+				return (mType == ANY || mType == EPSILON) || (mSymbol == symbol);
+			}
+
+			[[nodiscard]] bool doesConsumes(const tAlphabetType& symbol) const {
+				return (mType == ANY || (mType == SYMBOL && mSymbol == symbol));
+			}
+
+			[[nodiscard]] bool isEpsilon() const { return mType == EPSILON; }
+
+			const State* getState() const { return mState; }
+			const tAlphabetType& getSymbol() const { return mSymbol; }
+
+		private:
+			State* mState = nullptr;
+			Type mType;
+			tAlphabetType mSymbol;
+		};
+
+		class State {
+			friend FiniteStateAutomation;
+
+		public:
+			State() = default;
+
+		public:
+			void setValue(const tStateType& stateValue) { mStateVal = stateValue; }
+			void setAcceptance(bool isAccepting) { mIsAccepting = isAccepting; }
+			[[nodiscard]] bool isAccepting() const { return mIsAccepting; }
+			const tStateType& getStateVal() const { return mStateVal; }
+			[[nodiscard]] const Buffer<Transition>* getTransitions() const { return &mTransitions; }
+
+		private:
+			Buffer<Transition> mTransitions{};
+			tStateType mStateVal = tStateType();
+			bool mIsAccepting = false;
+		};
+
+	private:
+		List<State> mStates;
+		State* mStartState = nullptr;
+		Range<ualni> mAlphabetRange = { ENV_UALNI_MAX, ENV_UALNI_MIN };
+
+	public:
+		FiniteStateAutomation() = default;
+
+		State* addState(const tStateType& state, bool accepting) {
+			auto node = mStates.newNode();
+			node->data.mIsAccepting = accepting;
+			node->data.mStateVal = state;
+			mStates.pushBack(node);
+			return &node->data;
+		}
+
+		void addTransition(State* from, State* to, const tAlphabetType& symbol) {
+			from->mTransitions.append(Transition(Transition::SYMBOL, to, symbol));
+			if (mAlphabetRange.mBegin < ualni(symbol)) mAlphabetRange.mBegin = ualni(symbol);
+			if (mAlphabetRange.mEnd > ualni(symbol)) mAlphabetRange.mEnd = ualni(symbol);
+		}
+
+		void addEpsilonTransition(State* from, State* to) { from->mTransitions.append(Transition(Transition::SYMBOL, to)); }
+
+		void addAnyTransition(State* from, State* to) { from->mTransitions.append(Transition(Transition::ANY, to)); }
+
+		void setStartState(State* start) { mStartState = start; }
+
+		[[nodiscard]] State* getStartState() const { return mStartState; }
+
+		[[nodiscard]] bool isValid() const {
+			if (!mStartState) {
+				return false;
+			}
+			return true;
+		}
+
+		[[nodiscard]] ualni numStates() const { return mStates.length(); }
+
+		[[nodiscard]] const List<State>* getStates() const { return &mStates; }
+
+		[[nodiscard]] Range<ualni> getAlphabetRange() const { return mAlphabetRange; }
+
+	private:
+		typedef AvlTree<AvlNumericKey<State*>, bool> StatesSet;
+
+		// Expands initial set with states that are reachable from initial set with no input consumption (E-transitions)
+		static void expandSet(StatesSet& set) {
+			List<State*> workingSet;
+
+			set.forEach([&](AvlNumericKey<State*>& key, bool) { workingSet.pushBack(key.val); });
+
+			while (workingSet.length()) {
+				auto first = workingSet.first()->data;
+				set.insert(first, {});
+
+				for (auto transition : first->mTransitions) {
+					if (!transition->isEpsilon()) continue;
+					if (set.find(transition->mState)) continue;
+					workingSet.pushBack(transition->mState);
+				}
+
+				workingSet.popFront();
+			}
+		}
+
+		// States that are reachable from initial set with symbol transition
+		static void findMoveSet(StatesSet& from, StatesSet& moveSet, tAlphabetType symbol) {
+			from.forEach([&](AvlNumericKey<State*>& key, bool) {
+				for (auto transition : key.val->mTransitions) {
+					if (transition->isEpsilon()) continue;
+					if (!transition->isTransition(symbol)) continue;
+					if (moveSet.find(transition->mState)) continue;
+					moveSet.insert(transition->mState, {});
+				}
+			});
+		}
+
+	public:
+		bool makeDeterministic() {
+			if (!isValid()) return false;
+
+			struct GroupKey {
+				const StatesSet* group;
+				static ualni hash(GroupKey key) { return 0; }
+				bool operator==(const GroupKey& key) const { return false; }
+			};
+
+			struct GroupInfo {
+				StatesSet* group = nullptr;
+				AvlTree<AvlNumericKey<StatesSet*>, tAlphabetType> transitions;
+				State* newState = nullptr;
+				bool accepting = false;
+				tStateType stateVal = tStateType();
+			};
+
+			Buffer<StatesSet> groups = { {} };
+			Map<GroupKey, GroupInfo, DefaultAllocator, GroupKey::hash> groupInfos;
+
+			groups.first().insert(getStartState(), false);
+
+			expandSet(groups.first());
+
+			groupInfos.put({ &groups.first() }, { &groups.first() });
+
+			// 1) find new states
+			List<StatesSet*> workingSet;
+			workingSet.pushBack(&groups.first());
+
+			while (workingSet.length()) {
+				StatesSet* group = workingSet.first()->data;
+				GroupInfo* info = &groupInfos.get({ group });
+
+				for (auto symbol : getAlphabetRange()) {
+
+					// calculate new possible state
+					StatesSet potentialGroup;
+
+					findMoveSet(*group, potentialGroup, tAlphabetType(symbol));
+					expandSet(potentialGroup);
+
+					if (!potentialGroup.size()) continue;
+
+					// find existing or create group
+					StatesSet* targetGroup = nullptr;
+					auto iter = groupInfos.presents({ &potentialGroup });
+					if (iter) {
+						targetGroup = groupInfos.getSlotVal(iter).group;
+					} else {
+						targetGroup = &groups.append(potentialGroup);
+						groupInfos.put({ targetGroup }, { targetGroup });
+						workingSet.pushBack(targetGroup);
+					}
+
+					// assert transition is added
+					info->transitions.insert(targetGroup, tAlphabetType(symbol));
+				}
+
+				workingSet.popFront();
+			}
+
+			// 2) find new states termination values
+			for (auto group : groupInfos) {
+				GroupInfo* info = &group->val;
+				ualni accepting = 0;
+
+				info->group->forEach([&](AvlNumericKey<State*>& key, bool) {
+					if (key.val->mIsAccepting) {
+						accepting++;
+						info->accepting = true;
+						info->stateVal = key.val->mStateVal;
+					}
+				});
+
+				if (!accepting) {
+					info->accepting = false;
+					info->stateVal = info->group->head()->key.val->mStateVal;
+				}
+			}
+
+			// 3) transfer
+			mStates.removeAll();
+
+			// create states
+			for (auto group : groupInfos) {
+				group->val.newState = addState(group->val.stateVal, group->val.accepting);
+			}
+
+			// create transitions
+			for (auto group : groupInfos) {
+				auto functor = [&](AvlNumericKey<StatesSet*> targetGroupKey, tAlphabetType symbol) {
+					GroupInfo* targetGroup = &groupInfos.get({ (StatesSet*) targetGroupKey.val });
+					addTransition(group->val.newState, targetGroup->newState, symbol);
+				};
+				group->val.transitions.forEach(functor);
+			}
+
+			return true;
+		}
+	};
+}