手工构造预测语法分析程序

package com.syntax.analysis; import static org.junit.Assert.*; import java.io.BufferedReader; import java.io.BufferedWriter; import java.io.File; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.FileWriter; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.io.Reader; import java.util.Scanner; import org.junit.Test; public class SyntaxAnalysisTest { private static Stacks stack = new Stacks(); private static char s[] = null; private static String msg = ""; // + * m ( ) # static PreAnalysisTable S = new PreAnalysisTable("E", "E", "TA", "TA", "E","E"); static PreAnalysisTable A = new PreAnalysisTable("E", "E", "UB", "UB", "E","E"); static PreAnalysisTable B = new PreAnalysisTable("E", "E", "m", ")s(", "E","E"); static PreAnalysisTable T = new PreAnalysisTable("TA+", "E", "E", "E", "",""); static PreAnalysisTable U = new PreAnalysisTable("", "UB*", "TA", "TA", "",""); // public static String readFile(String filename) { // String inputStr = ""; // int end = 0; // try { // File file = new File(filename); // if (file.isFile() && new File(filename).exists()) { // BufferedReader reader = new BufferedReader( // new InputStreamReader(new FileInputStream(new File( // filename)), "UTF-8")); // while ((end = reader.read()) != -1) { // inputStr += (char) end; // } // reader.close(); // return inputStr; // } else { // System.out.println("file is not exist!"); // } // } catch (FileNotFoundException e) { // e.printStackTrace(); // } catch (IOException e) { // e.printStackTrace(); // } // return null; // } public static char[] subS(char s[]){ String str=""; for(int i=0;i<s.length;i++){ str+=s[i]; } str=str.substring(1, str.length()); return str.toCharArray(); } public static boolean compare(int b) { String ttt = stack.getPop().toString(); char d = ttt.charAt(0);//栈顶符号 // System.out.println(d); if (d == '+' || d == '*' || d == 'm' || d == '(' || d == ')') { if (s[b] == d) { msg =""+ s[b]; msg += "匹配"; b++; stack.pop(); s=subS(s); return true; } else { System.out.println("error"); return false; } } // ----------------------------------- else if (d == 'S') { if (s[b] == 'm') { msg = "S->AT"; stack.pop(); for (int i = 0; i < S.getForm().length(); i++) { stack.push(S.getForm().toCharArray()[i]); } return true; } else if (s[b] == '(') { msg = "S->AT"; stack.pop(); for (int i = 0; i < S.getForlbracket().length(); i++) { stack.push(S.getForlbracket().toCharArray()[i]); } return true; } else { System.out.println("error"); return false; } } // -------------------------------------- else if (d == 'A') { if (s[b] == 'm') { msg = "A->BU"; stack.pop(); for (int i = 0; i < A.getForm().length(); i++) { stack.push(A.getForm().toCharArray()[i]); } return true; } else if (s[b] == '(') { msg = "A->BU"; stack.pop(); for (int i = 0; i < A.getForlbracket().length(); i++) { stack.push(A.getForlbracket().toCharArray()[i]); } return true; } else { System.out.println("error"); return false; } } // -------------------------------------- else if (d == 'B') { if (s[b] == 'm') { stack.pop(); msg = "B->m"; for (int i = 0; i < B.getForm().length(); i++) { stack.push(B.getForm().toCharArray()[i]); } return true; } else if (s[b] == '(') { stack.pop(); for (int i = 0; i < B.getForlbracket().length(); i++) { stack.push(B.getForlbracket().toCharArray()[i]); } msg = "B->(S)"; return true; } else { System.out.println("error"); return false; } } // --------------------------------------- else if (d == 'U') { if (s[b] == '+') { stack.pop(); msg = "U->$"; return true; } else if (s[b] == '*') { stack.pop(); for (int i = 0; i < U.getForstar().length(); i++) { stack.push(U.getForstar().toCharArray()[i]); } msg = "U->*BU"; return true; } else if (s[b] == '#') { stack.pop(); msg = "U->$"; return true; } else if (s[b] == ')') { stack.pop(); msg = "U->$"; return true; } else { System.out.println("error"); return false; } } // ------------------------------------ else if (d == 'T') { if (s[b] == '+') { stack.pop(); for (int i = 0; i < T.getForadd().length(); i++) { stack.push(T.getForadd().toCharArray()[i]); } msg = "T->+AT"; return true; } else if (s[b] == ')') { stack.pop(); msg = "T->$"; return true; } else if (s[b] == '#') { stack.pop(); msg = "T->$"; return true; } else { System.out.println("error"); return false; } } else if (d == '#') { msg = "接受"; System.out.print("接受"); return false; } else { System.out.println("error"); return false; } } //打印字符数组 public static String printArray(char b[]){ String str=""; for(int i=0;i<b.length;i++){ str+=b[i]; } return str; } public static void main(String args[]) throws IOException { // Stacks stack = new Stacks(); Scanner scan; String inStr = "";// 输入串 int slength = 0; int b = 0; while (true) { // 清空栈 stack.clear(); System.out.println("\r\n请输入待分析的字符串："); scan = new Scanner(System.in); inStr = scan.nextLine(); inStr+="#"; s=inStr.toCharArray();//输入串数组 // 输入exit代表退出 if (inStr.equals("exit")) { break; } // 取得输入穿的长度 slength =inStr.length(); // 先把#和文法的开始符号入栈 stack.push("#"); stack.push("S"); System.out.println("用预测分析法分析符号串的过程：\r\n"); System.out.println("step\tStack\tString\tRule"); int st = 1;// st用于记录分析步骤 System.out.print(st+"\t");//打印步骤号 stack.print();//打印栈中元素 System.out.print(printArray(s)+"\t"); //System.out.println("S->AT"); while(b<slength&&compare(b)){ System.out.println(msg); st++;//步骤号 System.out.print(st+"\t"); stack.print(); System.out.print(printArray(s)+"\t");//剩余输入串 } } } }