check.java~356~

java写的词法分析器

                      }
                    state = 0;
                    tknln = 0;
                    return tkn;
                  }
                }
                else
                if(oneortwo==2){//If there is two operators,output '<=','>=','=='or'!='
                    oneortwo=0;
                    if(chr[forward-2]=='<'){
                      token tkn=new token("<=","Operator",line+1,position-1);//Output '<='
                      for(int count=tknln-1;count>=0;count--){
                        stringbuffer.deleteCharAt(count);
                      }
                      state = 0;
                      tknln = 0;
                      return tkn;
                    }
                    else
                    if(chr[forward-2]=='>'){
                      token tkn=new token(">=","Operator",line+1,position-1);//Output '>='
                      for(int count=tknln-1;count>=0;count--){
                        stringbuffer.deleteCharAt(count);
                      }
                      state = 0;
                      tknln = 0;
                      return tkn;
                    }
                    else
                    if(chr[forward-2]=='='){
                      token tkn=new token("==","Operator",line+1,position-1);//Output '=='
                      for(int count=tknln-1;count>=0;count--){
                        stringbuffer.deleteCharAt(count);
                      }
                      state = 0;
                      tknln = 0;
                      return tkn;
                    }
                    else
                    if(chr[forward-2]=='!'){
                      token tkn=new token("!=","Operator",line+1,position-1);//Output '!='
                      for(int count=tknln-1;count>=0;count--){
                        stringbuffer.deleteCharAt(count);
                      }
                      state = 0;
                      tknln = 0;
                      return tkn;
                    }

                }
                else
                if(oneortwo>=3){//If there is three operators in sequence,output "Other"
                    oneortwo=0;
                    token tkn=new token(stringbuffer.toString(),"Other"+"\t",line+1,position-tknln+1);
                    for(int count=tknln-1;count>=0;count--){
                        stringbuffer.deleteCharAt(count);
                      }
                    state = 0;
                    tknln=0;
                    return tkn;
                }
              }
              break;

case 8:
        c=chr[forward];
        ++forward;
        position++;
        if(c=='<'){//Go to case 7 to check if it is '<='
          state=7;
          oneortwo++;
        }
        else{
          state=9;
          forward--;
          position--;
        }
        break;
case 9:
        c=chr[forward];
        ++forward;
        position++;
        if(c=='>'){//If it is '>' ,go to case 7
          state=7;
          oneortwo++;
        }
        else{
          state=10;
          forward--;
          position--;
        }
        break;
case 10:
        c=chr[forward];
        ++forward;
        position++;
        if(c=='!'){//If it is '!' ,go to case 10
          state=7;
          oneortwo++;
        }
        else{
          state=11;
          forward--;
          position--;
        }
        break;
case 11:          //delimiters (  {  }  (  )  ; )
        c=chr[forward];
        ++forward;
        position++;
        if(c=='{'){
          token tkn=new token("{","Delimiter",line+1,position);
          state = 0;
          return tkn;
        }
        else {
          forward--;
          position--;
          state=12;
        }
        break;
case 12:
          c=chr[forward];
          ++forward;
          position++;
          if(c=='}'){
           token tkn=new token("}","Delimiter",line+1,position);
           state = 0;
          return tkn;
           }
          else {
           forward--;
           position--;
          state=13;
          }
          break;
case 13:
          c=chr[forward];
          ++forward;
          position++;
          if(c=='('){
          token tkn=new token("(","Delimiter",line+1,position);
          state = 0;
          return tkn;
           }
           else {
          forward--;
          position--;
          state=14;
           }
           break;
case 14:
          c=chr[forward];
          ++forward;
          position++;
          if(c==')'){
          token tkn=new token(")","Delimiter",line+1,position);
          state = 0;
          return tkn;
           }
          else {
          forward--;
          position--;
           state=15;
          }
          break;
case 15:
          c=chr[forward];
          ++forward;
          position++;
           if(c==';'){
           token tkn=new token(";","Delimiter",line+1,position);
           state = 0;
           return tkn;
           }
           else {
           forward--;
           position--;
           state=16;
           }
           break;
case 16:
           c=chr[forward];
           forward++;
           position++;
           if((Character.isDigit(c)||c=='.'||c=='E')&&oneortwo<=1){
             if(c=='.'){
               oneortwo++;
               is_float=true;
               is_exponent=false;
               is_int=false;
             }
             else if(c=='E'){
               is_exponent=true;
               is_float=false;
               is_int=false;
               oneortwo++;
             }
             stringbuffer.append(c);
             tknln++;
             state=16;
           }
           else{
             if ( (oneortwo >= 2) || chr[forward - 1] == '.' ||
                 chr[forward - 1] == 'E') {
               token tkn = new token(stringbuffer.toString(), "Error", line + 1,
                                     position - tknln );
               for(int count=tknln-1;count>=0;count--){
                  stringbuffer.deleteCharAt(count);
                }
                forward--;
               state=0;
               tknln=0;
               return tkn;
             }
             else {
               if (is_float) {
                 token tkn = new token(stringbuffer.toString(), "FloatNumber",line + 1, position - tknln );
                 for(int count=tknln-1;count>=0;count--){
                  stringbuffer.deleteCharAt(count);
                }
                forward--;
                 is_float=false;
                 state=0;
                 tknln=0;
                 return tkn;
               }
               else
               if (is_exponent) {
                 token tkn = new token(stringbuffer.toString(), "ExpNumber",
                                       line + 1, position - tknln );
                 for(int count=tknln-1;count>=0;count--){
                  stringbuffer.deleteCharAt(count);
                }
                forward--;
                 is_exponent=false;
                 state=0;
                 tknln=0;
                 return tkn;
               }
               else
               if(is_int==true)
               {
                 token tkn = new token(stringbuffer.toString(), "IntNumber",
                                       line + 1, position - tknln );
                 for(int count=tknln-1;count>=0;count--){
                  stringbuffer.deleteCharAt(count);
                }
                forward--;
                 state=0;
                 tknln=0;
                 return tkn;
               }
               else break;
             }
           }
           break;
      }
    }
  }
  public int getforward(){
    return forward;
  }
  public int getchrnum(){
    return chrnum;
  }
  public void charforward(){  //for the time that the stringbuffer used
       tknln++;
       ++forward;
       position++;
  }
}