编译原理语法分析报告

1、编译原理课程实验报告题目 语法分析器的设计与实现专业 软件工程 班级 学号 姓名 指导教师 哈尔滨工程大学软件学院2015年5月实验2：语法分析一、实验目的1 巩固对语法分析的基本功能和原理的认识。2 通过对语法分析表的自动生成加深语法分析表的认识。3 理解并处理语法分析中的异常和错误。二、实验内容本程序是基于已构建好的某一个语法的预测分析表来对用户的输入字符串进行分析，判断输入的字符串是否属于该文法的句子。基本实现思想：接收用户输入的字符串（字符串以“#”表示结束）后，对用做分析栈的一维数组和存放分析表的二维数组进行初始化。然后取出分析栈的栈顶字符，判断是否为终结符，若为终结符则判断是否为“

2、#”且与当前输入符号一样，若是则语法分析结束，输入的字符串为文法的一个句子，否则出错若不为“#”且与当前输入符号一样则将栈顶符号出栈，当前输入符号从输入字符串中除去，进入下一个字符的分析。若不为“#”且不与当前输入符号一样，则出错。若栈顶符号为非终结符时，查看预测分析表，看栈顶符号和当前输入符号是否构成产生式，若产生式的右部为，则将栈顶符号出栈，取出栈顶符号进入下一个字符的分析。若不为，将产生式的右部逆序的入栈，取出栈顶符号进入下一步分析。程序流程图：本程序中使用以下文法作对用户输入的字符串进行分析：ETEE+TE|TFTT*FT|Fi|(E)该文法的预测分析表为：代码：package ;im

3、port java.io.*;public class LL String Vn = "E", "E'", "T", "T'", "F" ; / 非终结符集String Vt = "i", "+", "*", "(", ")", "#" ; / 终结符集String P = new String56; / 预测分析表String fenxi ; / 分析栈int

4、 count = 1; / 步骤int count1 = 1;/分析栈指针int count2 = 0, count3 = 0;/预测分析表指针String inputString = "" / 输入的字符串boolean flag;public void setCount(int count, int count1, int count2, int count3)this.count = count; this.count1 = count1;this.count2 = count2;this.count3 = count3;flag = false;public voi

5、d setFenxi() / 初始化分析栈fenxi = new String20;fenxi0 = "#"fenxi1 = "E"public void setP() / 初始化预测分析表for (int i = 0; i < 5; i+) for (int j = 0; j < 6; j+) Pij = "error"P00 = "->TE'"P03 = "->TE'"P11 = "->+TE'"P14 = "

6、;->"P15 = "->"P20 = "->FT'"P23 = "->FT'"P31 = "->"P32 = "->*FT'"P34 = "->"P35 = "->"P40 = "->i"P43 = "->(E)"/ 打印出预测分析表System.out.println(" 已构建好的预测分析表");S

7、ystem.out.println("-");for (int i=0; i<6; i+) System.out.print(" "+Vti);System.out.println();System.out.println("-");for (int i=0; i<5; i+) System.out.print(" "+Vni+" ");for (int j=0; j<6; j+) int l = 0;if (j>0) l = 10-Pij-1.length();for

8、(int k=0; k<l; k+) System.out.print(" ");System.out.print(Pij+" ");System.out.println();System.out.println("-");public void setInputString(String input) inputString = input;public boolean judge() String inputChar = inputString.substring(0, 1); / 当前输入字符boolean flage =

9、 false;if (count1 >= 0) for (int i=0; i<6; i+) if (fenxicount1.equals(Vti) / 判断分析栈栈顶的字符是否为终结符flage = true;break;if (flage) / 为终结符时if (fenxicount1.equals(inputChar) if (fenxicount1.equals("#")&&inputString.length()=1) / 栈顶符号为结束标志时/ System.out.println("最后一个");String f

10、enxizhan = ""for (int i=0; i<=P.length; i+) / 拿到分析栈里的全部内容（滤去null）if (fenxii = null) break; else fenxizhan = fenxizhan + fenxii;/ 输出当前分析栈情况，输入字符串，所用产生式或匹配System.out.print(" " + count);String countToString = Integer.toString(count);int farWay = 14 - countToString.length();for (i

11、nt k=0; k<farWay; k+) System.out.print(" ");System.out.print(fenxizhan);farWay = 20 - fenxizhan.length();for (int k=0; k<farWay; k+) System.out.print(" ");System.out.print(inputString);farWay = 25 - inputString.length();for (int k=0; k<farWay; k+) System.out.print("

12、 ");System.out.println("接受");flag = true;return true; else / 分析栈栈顶符号不为结束标志符号时String fenxizhan = ""for (int i=0; i<=P.length; i+) / 拿到分析栈里的全部内容（滤去null）if (fenxii = null) break; else fenxizhan = fenxizhan + fenxii;/ 输出当前分析栈情况，输入字符串，所用产生式或匹配System.out.print(" "+cou

13、nt);String countToString = Integer.toString(count);int farWay = 14 - countToString.length();for (int k=0; k<farWay; k+) System.out.print(" ");System.out.print(fenxizhan);farWay = 20 - fenxizhan.length();for (int k=0; k<farWay; k+) System.out.print(" ");System.out.print(inpu

14、tString);farWay = 25 - inputString.length();for (int k=0; k<farWay; k+) System.out.print(" ");System.out.println(""" + inputChar + """ + "匹配");/ 将栈顶符号出栈，栈顶指针减一fenxicount1 = null;count1 -= 1;if (inputString.length() > 1) / 当当前输入字符串的长度大于1时，将当前输入字

15、符从输入字符串中除去inputString = inputString.substring(1, inputString.length(); else / 当前输入串长度为1时inputChar = inputString;/ System.out.println(" "+count+" "+fenxizhan+"/ "+inputString +" "+Pcount3count2);/ System.out.println(count + inputChar + "匹配 ");count+;j

16、udge();else / 判断与与输入符号是否一样为结束标志System.out.println(" 分析到第" + count + "步时出错！");flag = false;return false; else / 非终结符时boolean fla = false; for (int i=0; i<6; i+) / 查询当前输入符号位于终结符集的位置if (inputChar.equals(Vti) fla = true;count2 = i;break;if(!fla)System.out.println(" 分析到第"

17、 + count + "步时出错！");flag = false;return false;for (int i=0; i<5; i+) / 查询栈顶的符号位于非终结符集的位置if (fenxicount1.equals(Vni) count3 = i;break;if (Pcount3count2 != "error") / 栈顶的非终结符与输入的终结符存在产生式时String p = Pcount3count2;String s1 = p.substring(2, p.length(); / 获取对应的产生式if (s1.equals(&quo

18、t;") / 产生式推出“”时String fenxizhan = ""for (int i=0; i<=P.length; i+) if (fenxii = null) break; else fenxizhan = fenxizhan + fenxii;/ 输出当前分析栈情况，输入字符串，所用产生式或匹配System.out.print(" " + count);String countToString = Integer.toString(count);int farWay = 14 - countToString.length()

19、;for (int k=0; k<farWay; k+) System.out.print(" ");System.out.print(fenxizhan);farWay = 20 - fenxizhan.length();for (int k=0; k<farWay; k+) System.out.print(" ");System.out.print(inputString);farWay = 25 - inputString.length();for (int k=0; k<farWay; k+) System.out.print

20、(" ");System.out.println(fenxicount1 + Pcount3count2);/ 将栈顶符号出栈，栈顶指针指向下一个元素fenxicount1 = null;count1 -= 1;count+;judge(); else / 产生式不推出“”时int k = s1.length();String fenxizhan = ""for (int i=0; i<=P.length; i+) if (fenxii = null) break; else fenxizhan = fenxizhan + fenxii;/ 输出当

21、前分析栈情况，输入字符串，所用产生式或匹配System.out.print(" "+count);String countToString = Integer.toString(count);int farWay = 14 - countToString.length();for (int o=0; o<farWay; o+) System.out.print(" ");System.out.print(fenxizhan);farWay = 20 - fenxizhan.length();for (int o=0; o<farWay; o+

22、) System.out.print(" ");System.out.print(inputString);farWay = 25 - inputString.length();for (int o=0; o<farWay; o+) System.out.print(" ");System.out.println(fenxicount1 + Pcount3count2);for (int i=1; i<=k; i+) / 将产生式右部的各个符号入栈String s2 = s1.substring(s1.length() - 1, s1.len

23、gth();s1 = s1.substring(0, s1.length() - 1);if (s2.equals("'") s2 = s1.substring(s1.length() - 1, s1.length()+ s2;i+;s1 = s1.substring(0, s1.length() - 1);fenxicount1 = s2;if (i < k)count1+;/ System.out.println("count1=" + count1);/ System.out.println(" "+count+&

24、quot; "+fenxizhan+"/ "+inputString +" "+Pcount3count2);count+;/ System.out.println(count);judge(); else System.out.println(" 分析到第" + count + "步时出错！");flag = false;return false;return flag;public static void main(String args) LL l = new LL();l.setP();Strin

25、g input = ""boolean flag = true;while (flag) try InputStreamReader isr = new InputStreamReader(System.in);BufferedReader br = new BufferedReader(isr);System.out.println();System.out.print("请输入字符串(输入exit退出)：");input = br.readLine(); catch (Exception e) e.printStackTrace();if(input.equals("exit")flag = false;elsel.setInputString(input);l.setCount(1, 1, 0, 0);l.setFenxi();System.out.println();System.out.println("分析过程");System.out.println("-&q