编译原理 词法分析实验报告 java版

1、词法分析代码。 import java.io.*;import java.util.Vector;import java.util.regex.*;public class Compiler public static String stringCompiler=""private static final String KEY_WORD="if", "then", "while"," do"," read"," write","call&quo

2、t;,"begin", "end", "const", "var", "procedure", "odd" private static boolean isKeyWord(String s)/是否是关键字boolean b=false;for(int i=0;i<KEY_WORD.length;i+)if(s.equals(KEY_WORDi)b=true;return b; class Element String s; String kind; String ge

3、ts()return s; String getkind()return kind; Element(String s,String kind) this.s = s; this.kind = kind; static Vector<Element> sheet = new Vector<Element>(8); File result = new File("result.txt"); File result1 = new File("result1.txt"); boolean work() System.out.printl

4、n("输入PL/O语言为："); try FileWriter fw1 = new FileWriter(result1); BufferedWriter bw1 = new BufferedWriter(fw1); FileReader fr1 = new FileReader("input.txt"); BufferedReader br1 = new BufferedReader(fr1); String s = br1.readLine(); label1: while(s!=null) for(int i = 0;i<s.length()

5、;i+) if(s.indexOf("/")!=-1) /两个'/'符 s=s.substring(0, s.indexOf("/"); s=s.replaceAll("t", " "); s=s.replaceAll("n", " "); s=s.toLowerCase(); bw1.write(s); System.out.println(s); bw1.newLine(); s = br1.readLine(); continue label1; els

6、e if(s.indexOf("/*")!=-1) / '/'符和'*'符 s=s.substring(0, s.indexOf("/*"); s.replaceAll("t", " "); s.replaceAll("n", " "); s.toLowerCase(); bw1.write(s.substring(0, i); System.out.println(s); s=s.substring(i,s.length(); while(s

7、!=null) if(s.indexOf("*/")!=-1) s=s.substring(s.lastIndexOf("*/"),s.length(); s=s.replaceAll("t", " "); s=s.replaceAll("n", " "); s=s.toLowerCase(); bw1.write(s); System.out.println(s); bw1.newLine(); s = br1.readLine(); continue label1; el

8、se s = br1.readLine(); else s=s.replaceAll("t", " "); s=s.replaceAll("n", " "); s=s.toLowerCase(); bw1.write(s); System.out.println(s); bw1.newLine(); s = br1.readLine(); continue label1; br1.close(); bw1.close(); return true; catch(IOException e) e.printStack

9、Trace(); return false; finally void analyser() try BufferedReader br = new BufferedReader(new FileReader(result1); BufferedWriter bw = new BufferedWriter(new FileWriter(result); String a = br.readLine(); while(a!=null) Matcher m = Ppile("/*.*/|'.+'|(+|-|>=|<=)|d+.d*|w+|".+&qu

10、ot;|S").matcher(a); while (m.find() checkScan(m.group(); String s=Compiler.stringCompiler; System.out.flush(); bw.write(s); Compiler.stringCompiler="" a = br.readLine(); br.close(); bw.close(); catch(IOException e) e.printStackTrace(); public void checkScan(String s)/扫描文件 if(Character

11、.isDigit(s.charAt(0) checkDigitCompiler(s); else if(s.length()=1) checkCharCompiler(s.charAt(0); else checkStringCompiler(s); private void checkDigitCompiler(String s)/检测数字 if(s.indexOf(".")!=-1) CompilerOut(Double.valueOf(s).toString(); sheet.add(new Element(s,"小数"); else Compil

12、erOut(s); sheet.add(new Element(s,"整数"); private void checkCharCompiler(char c)/检测单个字符 switch (c) case '<': sheet.add(new Element(new Character(c).toString() ,"小于号"); break; case '>': sheet.add(new Element(c+"","大于号"); break; case '=&

13、#39;: sheet.add(new Element(c+"","等于号"); break; case '+': sheet.add(new Element(c+"","加号"); break; case '-': sheet.add(new Element(c+"","减号"); break; case '*': sheet.add(new Element(c+"","乘号"); br

14、eak; case '/': sheet.add(new Element(c+"","除号"); break; case '(': sheet.add(new Element(c+"","左小括号"); break; case ')': sheet.add(new Element(c+"","右小括号"); break; case '': sheet.add(new Element(c+"",

15、"左中括号"); break; case '': sheet.add(new Element(c+"","右中括号"); break; case '': sheet.add(new Element(c+"","左大括号"); break; case '': sheet.add(new Element(c+"","右大括号"); break; case ',': sheet.add(new El

16、ement(c+"","逗号"); break; case '': sheet.add(new Element(c+"","分号"); break; case '!': sheet.add(new Element(c+"","取反"); break; case '.': sheet.add(new Element(c+"","点号"); break; case ':': s

17、heet.add(new Element(c+"","冒号"); case '?':sheet.add(new Element(c+"","问号"); break; default: sheet.add(new Element(c+"","标识符"); break; private void checkStringCompiler(String s)/检测多个字符 CompilerOut( s); if(isKeyWord(s) sheet.add(new E

18、lement(s,"关键字"); else sheet.add(new Element(s,"标识符"); private void CompilerOut(Object o)/向显示器输出结果预编译结果 if(o instanceof String) stringCompiler=stringCompiler+(String)o+" " else stringCompiler=stringCompiler+(Character)o).charValue()+" " public static void main(String args) throws Exception System.out.println("*"); Compiler c = new Compiler(); if(c.work() /System.out.println("已将处理后代码放入 result1.txt 中！"); else System.out.println("预处理失败！"); System.out.println("输入 y开始词法分析"); char k = 'y' while(k!=(ch