词法分析 scanner 源代码 详细注释

package Scanner.SCANNER; public class Judgement { private String[] KeyWord={"else","if","int","return","void","while"};//关键字存储器 private String[] Sign={"+","-","*","/","<","<=",">",">=","==","!=","=",";",",","(",")","[","]","{","}"};//符号存储器 public char[] Buffer;//缓冲存储区 private int flag=0;//扫描器指针 private String str=new String();//判断字符 public String strout;//判断后输出字符 public int[] Keynum={41,42,43,44,45,46};//关键字对应码种 private String str1[]=new String[20]; //字符串缓冲器，用来缓存字符串，判断是否重复 private int c[]=new int[20]; //字母个数标示 private int n=0;//缓冲区指针 /*-----------------------------------指针操作-------------------------------*/ //取当前指针 public int setFLag(int a){ flag=a; return flag; } public int GetFlag(){ return flag; } //指针前移 public int IncFlag(){ flag++; return flag; } //指针后移 public int DecFlag(){ flag--; return flag; } /*-----------------------------------存储器操作-----------------------------*/ //关键字读，写，修改 public void ReadKeyWord(){ //显示现有KeyWord } public Boolean WirteKeyWord(String NewKey){ //添加一个值为NewKey的新Key.成功返回true... boolean flag=false; return flag; } public Boolean ChangeKeyWord(String OldKey,String NewKey){ //修改一个值为OldKey的Key,新值为NewKey,成功返回true... boolean flag=false; return flag; } //符号读，写，修改 public void ReadSignWord(){ //显示现有Sign } public Boolean WirteSign(String NewSign){ //添加一个值为NewSign的新Sign.成功返回true... boolean flag=false; return flag; } public Boolean ChangeSigWord(String OldKey,String NewKey){ //修改一个值为OldSign的Sign,新值为NewSign,成功返回true... boolean flag=false; return flag; } /*----------------------------------------判断操作p---------------------------*/ //IsDigit,判断是否是数字 public Boolean IsDigit(){ //判断是否是Digit,是返回true... int mn=0;//整数标志 Boolean Flag=false;// //继续判断是否是数字或者“.”或者字母 while(flag<Buffer.length&& !Character.isSpace(Buffer[flag])&& Buffer[flag]!='('&& Buffer[flag]!=')'&& Buffer[flag]!='+'&& Buffer[flag]!='*'&& Buffer[flag]!='/'&& Buffer[flag]!='>'&& Buffer[flag]!='<'&& Buffer[flag]!='='&& Buffer[flag]!=','&& Buffer[flag]!=';'|| ((flag<Buffer.length && Character.isDigit(Buffer[flag]))||(flag<Buffer.length && Buffer[flag]=='.')||(flag<Buffer.length && Character.isLetter(Buffer[flag])))){ str=str+str.valueOf(Buffer[flag]); flag++; } /*---------分析str--------*/ //存在字母 for (int i=0;i<str.length();i++){ if(str.charAt(i)!='.'&& !Character.isDigit(str.charAt(i))) mn=1; } // 判断是否是浮点数，或者整数 if(mn==0){ for(int k=0;k<str.length();k++) { if(str.charAt(k)=='.') Flag=true; } //这里是貌似有问题哦 if(Flag){ float f=Float.valueOf(str); strout=str+"\t"+Float.toHexString(f)+"\n"; } else //整数 {int x=Integer.valueOf(str); strout=str+"\t"+Integer.toBinaryString(x)+"\n"; } } //判断是否是科学计数法 else{ int xy=0,ab=0; for(int i=0;i<str.length();i++) if(Character.isLetter(str.charAt(i))||str.charAt(i)=='-') { xy++; ab=i; } if(xy==1 && str.charAt(ab)=='e') strout=str+"\t"+"e"+str+"\n"; else if(xy==2 && str.charAt(ab)=='-' && str.charAt(ab-1)=='e') { strout=str+"\t"+"-e"+str+"\n"; } else strout=str+"\t"+"非法标志符"+"\n"; } str=""; //清空str return true; } //IsLetter,判断是否是字母或者KeyWord public Boolean IsLetter(){ //判断是否是Letter,是则返回true... for(int i=0;i<20;i++) { c[i]=i; } //是数字或者是字母 while((flag<Buffer.length && Character.isLetter(Buffer[flag]))||(flag<Buffer.length && Character.isDigit(Buffer[flag]))){ str=str+str.valueOf(Buffer[flag]); flag++; } int q=1; while(q==1){ for(int i=0;i<KeyWord.length;i++){ if(str.equalsIgnoreCase(KeyWord[i])){ strout=str+"\t"+Keynum[i]+"\n"; q=0; return true; } q=0; } } int p=1; //判断是否存在非字符或数字符号 for(int i=0;i<str.length();i++) { if(!Character.isLetter(str.charAt(i))&&!Character.isDigit(str.charAt(i))) p=0; } if(p==1) { for(int j=0;n>0 && j<n;j++) { if( str.equals(str1[j])) { strout=str+"\t"+c[j]+"\n"; str=""; } } //无重复 if(str!="") {str1[n]=str; strout=str+"\t"+c[n]+"\n"; n++;} str=""; } else { strout=str+"\t"+"非法标志符"+"\n"; } str=""; Boolean flag1=true; return flag1; } //IsSign,判断是否是符号 public Boolean IsSign(){ //判断是否是Sign,是则返回true... Boolean flag1=true; return flag1; } }