239 lines
9.0 KiB
C++
239 lines
9.0 KiB
C++
// 将正则表达式转换为非确定性有限自动机
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#include "nfa.h"
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// 处理正则表达式，描述终态
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NFA RexToNFA() {
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//由于里面存在||,所以不同正则间使用空格分隔代表| l代表letter，_代表下划线，0代表数字(也可以是d，但是为了使用已经有的函数)，
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//[lu]代表l|u
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string rex = "+ - * / % = > < == <= >= != && || ( ) { } , ; [l_][l_0]* -?00* -?[0-9]+\\.[0-9]+";
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//下面给出正则对应的输出(终态)
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vector<WordType> finalState = {
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OP_ADD, OP_SUB,OP_MUL,OP_DIV,OP_MOD,OP_ASSIGN,OP_GT,OP_LT, OP_EQ,OP_LE,OP_GE,OP_NE, OP_AND, OP_OR,SE_LBRAC, SE_RBRAC,
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SE_LCBRAC,SE_RCBRAC,SE_COMMA,SE_SEMI,IDN,INT_VAL,FLOAT_CONST
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};
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stringstream ss(rex);
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string target;
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// 创建初始状态
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int stateIndex = 0;
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int finalIndex = 0;
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State* startState = new State(stateIndex++);
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set<State*, StatePtrCompare> endStates;
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set<State*, StatePtrCompare> allStates = { startState };
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// 按空格分割
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while (getline(ss, target,' ')) {
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//如获得[l_][l_0]*
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State* currentState = startState;
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cout<<target<<endl;
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if (target == "-?[0-9]+\\.[0-9]+") {
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// 处理浮点数
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for (size_t i = 0; i < target.length(); i++) {
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State* newState = new State(stateIndex++);
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allStates.insert(newState);
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InputCharType input = getInputCharType(target[i]);
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currentState->addTransition(input, newState);
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currentState = newState;
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}
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currentState->setFinalState(true, finalState[endStates.size()]);
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endStates.insert(currentState);
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continue;
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}
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for (size_t i = 0; i < target.length();i++) {
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//创建一个新状态，startState通过输入InputCharType到达该状态
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State* newState = new State(stateIndex++);
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allStates.insert(newState);
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//需要往后看一个符号
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if (target[i] == '[') {
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//[...]构成一种输入，查看]后面是否有？或者*，来判断当前状态的构成
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for (i=i+1; i < target.length() && target[i] != ']'; i++) {
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InputCharType input = getInputCharType(target[i]);
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if (input != EPSILON) {
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// 添加转移函数，从当前状态向新状态转移
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currentState->addTransition(input, newState);
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}
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}
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}
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else {
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InputCharType input = getInputCharType(target[i]);
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currentState->addTransition(input, newState);
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}
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//往后查看一个输入
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if (i + 1 < target.length() && target[i + 1] == '?') {
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//创建EPSILON转移状态
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State* epsState = new State(stateIndex++);
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allStates.insert(epsState);
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currentState->addTransition(EPSILON, epsState);
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newState->addTransition(EPSILON, epsState);
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currentState = epsState;
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// 跳过'?'字符
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i++;
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}
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else if (i + 1 < target.length() && target[i + 1] == '*') {
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State* epsState = new State(stateIndex++);
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allStates.insert(epsState);
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currentState->addTransition(EPSILON, epsState);
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newState->addTransition(EPSILON, epsState);
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epsState->addTransition(EPSILON, currentState);
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currentState = epsState;
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// 跳过'*'字符
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i++;
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}
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else {
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currentState = newState;
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}
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//判断是否是终止状态
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if (i == (target.length() - 1)) {
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// 到达最后一个字符，将当前状态设置为终止状态
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currentState->setFinalState(true, finalState[endStates.size()]);
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endStates.insert(currentState);
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}
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}//for
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}
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// 返回字符集合对应的NFA
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cout<<"ok"<<endl;
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return NFA(startState, endStates, allStates);
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}
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void printNFA(const NFA& nfa) {
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cout << "Start state: " << nfa.startState->id << endl;
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cout << "End states: "<<endl;
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for (auto state : nfa.endStates) {
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cout << state->id << " " << getWordTypeName(state->wordType) << " " << (state->isFinalState == true) << endl;
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}
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cout << endl;
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cout << "States and transitions:" << endl;
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for (auto state : nfa.states) {
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cout << "State " << state->id << ":" << endl;
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for (auto transition : state->transitions) {
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cout << "\tInput " << getInputChartypeName(transition.first) << ": ";
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for (auto targetState : transition.second) {
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cout << targetState->id << " ";
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}
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cout << endl;
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}
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}
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}
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set<State*, StatePtrCompare> move(const set<State*, StatePtrCompare>& states, InputCharType input) {
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set<State*, StatePtrCompare> targetStates;
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for (State* state : states) {
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auto it = state->transitions.find(input);
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if (it != state->transitions.end()) {
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for (State* targetState : it->second) {
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if (targetStates.find(targetState) == targetStates.end()) {
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targetStates.insert(targetState);
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}
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}
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}
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}
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return targetStates;
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}
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set<State*, StatePtrCompare> epsilonClosure(const set<State*, StatePtrCompare>& states) {
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set<State*, StatePtrCompare> closure = states;
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stack<State*> stateStack;
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for (State* state : states) {
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stateStack.push(state);
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}
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while (!stateStack.empty()) {
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State* currentState = stateStack.top();
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stateStack.pop();
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auto it = currentState->transitions.find(EPSILON);
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if (it != currentState->transitions.end()) {
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for (State* nextState : it->second) {
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if (closure.find(nextState) == closure.end()) {//防止同一状态多次进栈，set自带去重
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closure.insert(nextState);
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stateStack.push(nextState);
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}
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}
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}
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}
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return closure;
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}
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DFA nfaToDFA(const NFA& nfa) {
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map<set<State*, StatePtrCompare>, State*, SetComparator> dfaStatesMap; // 用于映射NFA状态集合到DFA状态的映射表
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queue<set<State*, StatePtrCompare>> nfaStatesQueue; // 用于BFS遍历的集合队列
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set<State*, StatePtrCompare> dfaStates;
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set<State*, StatePtrCompare> dfaEndStates;
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set<State*, StatePtrCompare> nfaStartClosure = epsilonClosure({ nfa.startState });
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State* dfaStartState = new State(0);
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dfaStatesMap[nfaStartClosure] = dfaStartState;
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dfaStates.insert(dfaStartState);
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nfaStatesQueue.push(nfaStartClosure);
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int nextStateId = 1;
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//set<State*, StatePtrCompare> nfaStartClosure
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while (!nfaStatesQueue.empty()) {
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set<State*, StatePtrCompare> currentNFAStates = nfaStatesQueue.front();
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nfaStatesQueue.pop();
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State* currentDFAState = dfaStatesMap[currentNFAStates];
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// 检查是否有终止状态，如果有，设置DFA状态为终止状态
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for (State* nfaState : currentNFAStates) {
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if (nfaState->isFinalState) {
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// cout << nfaState->id << "is FinalState" << endl;
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currentDFAState->setFinalState(true, nfaState->wordType);
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dfaEndStates.insert(currentDFAState);
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break;
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}
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}
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// 遍历所有输入字符类型
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for (int i = 0; i < static_cast<int>(EPSILON); i++) {
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InputCharType inputCharType = static_cast<InputCharType>(i);
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set<State*, StatePtrCompare> nextNFAStates = epsilonClosure(move(currentNFAStates, inputCharType));
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if (nextNFAStates.empty()) {
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continue;
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}
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// 如果NFA状态集合不存在于映射表中，则创建新的DFA状态
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if (dfaStatesMap.find(nextNFAStates) == dfaStatesMap.end()) {
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State* newDFAState = new State(nextStateId++);
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dfaStatesMap[nextNFAStates] = newDFAState;
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dfaStates.insert(newDFAState);
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nfaStatesQueue.push(nextNFAStates);
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}
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currentDFAState->addTransition(inputCharType, dfaStatesMap[nextNFAStates]);
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}
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}
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return DFA(dfaStartState, dfaEndStates, dfaStates);
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}
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void printDFA(const DFA& dfa) {
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cout << "Start state: " << dfa.startState->id << endl;
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cout << "End states: "<<endl;
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for (auto state : dfa.endStates) {
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cout << state->id << " " << getWordTypeName(state->wordType) << endl;
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}
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cout << endl;
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cout << "States and transitions:" << endl;
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for (auto state : dfa.states) {
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cout << "State " << state->id << ":" << endl;
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for (auto transition : state->transitions) {
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cout << "\tInput " << getInputChartypeName(transition.first) << ": ";
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for (auto targetState : transition.second) {
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cout << targetState->id << " ";
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}
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cout << endl;
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}
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}
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}
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