編譯原理語法分析報告

1、編譯原理課程實驗報告題目 語法分析器的設(shè)計與實現(xiàn)專業(yè) 軟件工程 班級 學(xué)號 姓名 指導(dǎo)教師 哈爾濱工程大學(xué)軟件學(xué)院2015年5月實驗2：語法分析一、實驗?zāi)康? 鞏固對語法分析的基本功能和原理的認(rèn)識。2 通過對語法分析表的自動生成加深語法分析表的認(rèn)識。3 理解并處理語法分析中的異常和錯誤。二、實驗內(nèi)容本程序是基于已構(gòu)建好的某一個語法的預(yù)測分析表來對用戶的輸入字符串進行分析，判斷輸入的字符串是否屬于該文法的句子?；緦崿F(xiàn)思想：接收用戶輸入的字符串（字符串以“#”表示結(jié)束）后，對用做分析棧的一維數(shù)組和存放分析表的二維數(shù)組進行初始化。然后取出分析棧的棧頂字符，判斷是否為終結(jié)符，若為終結(jié)符則判斷是否為“

2、#”且與當(dāng)前輸入符號一樣，若是則語法分析結(jié)束，輸入的字符串為文法的一個句子，否則出錯若不為“#”且與當(dāng)前輸入符號一樣則將棧頂符號出棧，當(dāng)前輸入符號從輸入字符串中除去，進入下一個字符的分析。若不為“#”且不與當(dāng)前輸入符號一樣，則出錯。若棧頂符號為非終結(jié)符時，查看預(yù)測分析表，看棧頂符號和當(dāng)前輸入符號是否構(gòu)成產(chǎn)生式，若產(chǎn)生式的右部為，則將棧頂符號出棧，取出棧頂符號進入下一個字符的分析。若不為，將產(chǎn)生式的右部逆序的入棧，取出棧頂符號進入下一步分析。程序流程圖：本程序中使用以下文法作對用戶輸入的字符串進行分析：ETEE+TE|TFTT*FT|Fi|(E)該文法的預(yù)測分析表為：代碼：package ;im

3、port java.io.*;public class LL String Vn = "E", "E'", "T", "T'", "F" ; / 非終結(jié)符集String Vt = "i", "+", "*", "(", ")", "#" ; / 終結(jié)符集String P = new String56; / 預(yù)測分析表String fenxi ; / 分析棧int

4、 count = 1; / 步驟int count1 = 1;/分析棧指針int count2 = 0, count3 = 0;/預(yù)測分析表指針String inputString = "" / 輸入的字符串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() / 初始化分析棧fenxi = new String20;fenxi0 = "#"fenxi1 = "E"public void setP() / 初始化預(yù)測分析表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)"/ 打印出預(yù)測分析表System.out.println(" 已構(gòu)建好的預(yù)測分析表");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); / 當(dāng)前輸入字符boolean flage =

9、 false;if (count1 >= 0) for (int i=0; i<6; i+) if (fenxicount1.equals(Vti) / 判斷分析棧棧頂?shù)淖址欠駷榻K結(jié)符flage = true;break;if (flage) / 為終結(jié)符時if (fenxicount1.equals(inputChar) if (fenxicount1.equals("#")&&inputString.length()=1) / 棧頂符號為結(jié)束標(biāo)志時/ System.out.println("最后一個");String f

10、enxizhan = ""for (int i=0; i<=P.length; i+) / 拿到分析棧里的全部內(nèi)容（濾去null）if (fenxii = null) break; else fenxizhan = fenxizhan + fenxii;/ 輸出當(dāng)前分析棧情況，輸入字符串，所用產(chǎn)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 / 分析棧棧頂符號不為結(jié)束標(biāo)志符號時String fenxizhan = ""for (int i=0; i<=P.length; i+) / 拿到分析棧里的全部內(nèi)容（濾去null）if (fenxii = null) break; else fenxizhan = fenxizhan + fenxii;/ 輸出當(dāng)前分析棧情況，輸入字符串，所用產(chǎn)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");/ 將棧頂符號出棧，棧頂指針減一fenxicount1 = null;count1 -= 1;if (inputString.length() > 1) / 當(dāng)當(dāng)前輸入字符串的長度大于1時，將當(dāng)前輸入字

15、符從輸入字符串中除去inputString = inputString.substring(1, inputString.length(); else / 當(dāng)前輸入串長度為1時inputChar = inputString;/ System.out.println(" "+count+" "+fenxizhan+"/ "+inputString +" "+Pcount3count2);/ System.out.println(count + inputChar + "匹配 ");count+;j

16、udge();else / 判斷與與輸入符號是否一樣為結(jié)束標(biāo)志System.out.println(" 分析到第" + count + "步時出錯！");flag = false;return false; else / 非終結(jié)符時boolean fla = false; for (int i=0; i<6; i+) / 查詢當(dāng)前輸入符號位于終結(jié)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 + "步時出錯！");flag = false;return false;for (int i=0; i<5; i+) / 查詢棧頂?shù)姆栁挥诜墙K結(jié)符集的位置if (fenxicount1.equals(Vni) count3 = i;break;if (Pcount3count2 != "error") / 棧頂?shù)姆墙K結(jié)符與輸入的終結(jié)符存在產(chǎn)生式時String p = Pcount3count2;String s1 = p.substring(2, p.length(); / 獲取對應(yīng)的產(chǎn)生式if (s1.equals(&quo

18、t;") / 產(chǎn)生式推出“”時String fenxizhan = ""for (int i=0; i<=P.length; i+) if (fenxii = null) break; else fenxizhan = fenxizhan + fenxii;/ 輸出當(dāng)前分析棧情況，輸入字符串，所用產(chǎn)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);/ 將棧頂符號出棧，棧頂指針指向下一個元素fenxicount1 = null;count1 -= 1;count+;judge(); else / 產(chǎn)生式不推出“”時int k = s1.length();String fenxizhan = ""for (int i=0; i<=P.length; i+) if (fenxii = null) break; else fenxizhan = fenxizhan + fenxii;/ 輸出當(dāng)

21、前分析棧情況，輸入字符串，所用產(chǎn)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+) / 將產(chǎn)生式右部的各個符號入棧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 + "步時出錯！");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("請輸入字符串(輸入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("分析過程");System.out.println("-&q