package fsm;

/**
 * @author Cherry
 * @date 2022年1月21日
 * @time 19:30
 * @brief 该类用于生成 FMS 表,用于状态转换和终止状态判断
 */

public class FSMTable implements FSM {

 private final int ASCII_COUNT = 128;
 private final int STATE_COUNT = 6; //该整型-浮点FMS只有六个状态

 private int[][] fmsTable = new int[STATE_COUNT][ASCII_COUNT];
 private boolean[] accept = new boolean[] {false, true, true, false, true, false};

 public FSMTable() {
 //FMS表初始化为 -1
 for (int i = 0; i < STATE_COUNT; i++) {
 for (int j = 0; j < ASCII_COUNT; j++) {
 fmsTable[i][j] = -1;
 }
 }

 fmsTable[0]['.'] = 3;
 fmsTable[1]['.'] = 2;
 fmsTable[1]['e'] = 5;
 fmsTable[2]['e'] = 5;

 initFMSTable(0, 1);
 initFMSTable(1, 1);
 initFMSTable(2, 2);
 initFMSTable(3, 2);
 initFMSTable(5, 4);
 initFMSTable(4, 4);
 }

 /**
 * 将输入数字进行状态转化的对应 FMS 表初始化
 * @param begin_state 初始状态
 * @param end_state 结束状态
 */
 private void initFMSTable(int begin_state, int end_state) {
 for (int i = 0; i < 10; i++) {
 fmsTable[begin_state][i + '0'] = end_state;
 }
 }

 /**
 * 状态转换函数 Next,在当前状态下输入字符 c 后可转换到哪一个状态
 * @param state 当前状态
 * @param c 输入的字符
 * @return 转换后的状态
 */
 @Override
 public int yy_text(int state, byte c) {
 if (state == FSM.STATUS_FAILURE) {
 return FSM.STATUS_FAILURE;
 } else {
 return fmsTable[state][c];
 }
 }

 /**
 * 判断当前状态是否为可接收状态
 * @return boolean
 */
 @Override
 public boolean isAcceptState(int state) {
 if (state == FSM.STATUS_FAILURE) {
 return false;
 } else {
 return accept[state];
 }
 }
}