cifa.java

编译原理的词法分析程序 是用java编的

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.io.*;

public class Lexical extends JFrame{
	private JTextField path;
	private JButton selectButton, displayButton;
	private JTextArea output;
	private OpenFile open = new OpenFile(this);
	private File file;
	private Container container = getContentPane();
	private BufferRead reader;
	private char c;
	private String descrip;
	private boolean finish;
	
	private String table[] = {
			"", "ID", "NUM", "if", "then", "else", "program", "begin", "end", "+", "-", "*", 
			"/", "(", ")", ">", ">=", "<", "<=", "<>", ":=", ";", ".", ","
	};
	
	public Lexical(){
		super("Lexical");
		path = new JTextField(30);
		path.setEditable(false);
		selectButton = new JButton("Select File");
		selectButton.addActionListener(
			new ActionListener(){
				public void actionPerformed(ActionEvent event){
					if((file = open.open()) != null){
						displayButton.setEnabled(true);
						path.setText(file.toString());
					}
				}
			}
		);
		displayButton = new JButton("Display");
		displayButton.setEnabled(false);
		displayButton.addActionListener(
			new ActionListener(){
				public void actionPerformed(ActionEvent event){
					reader = new BufferRead(file);
					output.setText("");
					finish = false;	
					analyze();				
				}
			}
		);
		
		output = new JTextArea(33,50);
		container.setLayout(new FlowLayout());
		container.add(path);
		container.add(selectButton);
		container.add(displayButton);
		container.add(new JScrollPane(output));
		
		setSize(600, 650);
		setVisible(true);
		setResizable(false);
		Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize(); 
		setLocation((int)(screenSize.getWidth()/5),
				(int)(screenSize.getHeight()/11));	
		this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);		
	}
	
	String nexttoken(){
		int state = 0;
		String token = new String("");
		boolean point = false;
		while(true){
			switch(state){
			case 0:
				c = reader.getNextChar();
				if(c == ' ' || c == '\t' || c == '\n') continue;
				token = token.concat((new Character(c)).toString());
				if(c == '\0'){
					descrip = new String("FINISH");
					finish = true;
					return new String("NULL");
				}else if(Character.isLetter(c)) state = 1;
				else if(Character.isDigit(c)) state = 2;
				else if(c == '+' || c == '-' || c == '*' || c == '/' ||
						 c == '(' || c == ';' || c == ',') state = 3;	
				else if(c == ')') state = 4;
				else if(c == '.') state = 99;
				else if(c == '>' || c == '<') state = 5;				
				else if(c == ':') state = 6;							
				else state = 99;
				break;		
		case 1:
			c = reader.getNextChar();
			if(c == ' ' || c == '\t' || c == '\n' || c == '+' || c == '-' || c == '*' || c == '/' || c == '(' ||
					   c == ')' || c == ';'	|| c == ',' || c == '>' || c == '<' || c == ':' || c == '\0'){
				reader.unget();
				descrip = new String("table");
				return token;
			}
			else if(false == Character.isLetterOrDigit(c)) state = 99;
			token = token.concat((new Character(c)).toString());
			break;
		case 2:
			c = reader.getNextChar();
			if(c == ' ' || c == '\t' || c == '\n' || c == '+' || c == '-' || c == '*' || c == '/' || 
					   c == ')' || c == ';'	|| c == ',' || c == '>' || c == '<' || c == ':' || c == '\0'){
				reader.unget();
				descrip = new String("NUM");
				return token;
			}else if(c == '.'){
				if(point) state = 99;
				else{
					point = true;					
				}
			}else if(false == Character.isDigit(c)) state = 99;
			token = token.concat((new Character(c)).toString());
			break;
		case 3:
			c = reader.getNextChar();
			if(c == ' ' || c == '\t' || c == '\n') continue;
			else if(Character.isLetterOrDigit(c) || c == '('){
				reader.unget();
				descrip = new String("table");
				return token;
			}else{
				reader.unget();
				state = 99;
			}
			break;
		case 4:
			c = reader.getNextChar();
			if(c == ' ' || c == '\t' || c == '\n' || c == '+' || c == '-' || 
					c == '*' || c == '/' || c == '>' || c == '<' || c == ';' || c == '\0'){
				reader.unget();
				descrip = new String("table");
				return token;
			}else{
				reader.unget();
				state = 99;
			}
			break;
		case 5:
			c = reader.getNextChar();
			if(c == '='){
				token = token.concat((new Character(c)).toString());
				state = 7;
			}else if(Character.isLetterOrDigit(c) || c == '('){
				reader.unget();
				descrip = new String("table");
				return token;
			}else{
				reader.unget();
				state = 99;
			}
			break;
		case 6:
			c = reader.getNextChar();
			if(c == '='){
				token = token.concat((new Character(c)).toString());
				state = 7;
			}else{
				reader.unget();
				state = 99;
			}
			break;
		case 7:
			c = reader.getNextChar();			
			if(c == ' ' || c == '\t' || c == '\n' || c == '\0' || Character.isLetterOrDigit(c) || c == '('){
				reader.unget();
				descrip = new String("table");
				return token;
			}else{
				reader.unget();
				state = 99;
			}
			break;
		case 99:
			c = reader.getNextChar();
			if(c == '\0'){
				descrip = new String("ERROR");
				return new String("error");
			}
			if(!(c == ' ' || c == '\t' || c == '\n')) continue;			
			else{
				descrip = new String("ERROR");
				return new String("error");
			}			
		}
		}
	}
	
	void analyze(){
		do{
			String token = nexttoken();
			if(descrip.equals("FINISH")) break;
			else if(descrip.equals("NUM"))
				output.append("2" + "     " + token + "\n");
			else if(descrip.equals("ERROR")){
				output.append("error\n");
			}
			else{
				int i;
				for(i = 3; i < table.length; i++){
					if(table[i].equals(token)){
						output.append((new Integer(i)).toString());
						if(i < 10) output.append("     ");
						else output.append("    ");
						output.append(token + "\n");
						break;
					}
				}
				if(i >= table.length)
					output.append("1" + "     " + token + "\n");
			}			
			if(finish) break;
		}while(true);
	}
	public static void main(String args[]){
		Lexical test = new Lexical();
	}
}

class BufferRead{
	final int MAX = 200, HALF = 99;
	private char buffer[];
	private int forward, r;
	private BufferedReader input;
	private static boolean un = false;
	
	public BufferRead(File name){
		buffer = new char[MAX];
		forward = -1;
		try{
			input = new BufferedReader(new FileReader(name));
			buffer[HALF] = buffer[MAX - 1] = '\0';
			input.read(buffer, 0, HALF);
		}catch(Exception e){}
	
	}
	
	public char getNextChar(){
		if(un){
			un = false;
			return buffer[forward];
		}
		forward++;
		if('\0' == buffer[forward]){
			if(forward == HALF){
				try{				
					if((r = input.read(buffer, HALF + 1, HALF)) < HALF){
						buffer[HALF  + r] = '\0';
					}
				}catch(Exception e){}
				forward++;
			}else if(forward == MAX - 1){
				try{
					if((r = input.read(buffer, 0, HALF)) < HALF){
						buffer[r - 1] = '\0';
					}
				}catch(Exception e){}
				forward = 0;
			}else
				return '\0';
		}
		return buffer[forward];
	}
	
	public void unget(){
		un = true;
	}
}

class OpenFile{
	private JFileChooser fileChooser = new JFileChooser();	
	Component component;
	public OpenFile(Component c){
		component = c;
		fileChooser.setFileSelectionMode(JFileChooser.FILES_ONLY);
	}
	
	public File open(){
		int result = fileChooser.showOpenDialog(component);	
		
		if(result == JFileChooser.CANCEL_OPTION)
			return null;
		
		File fileName = fileChooser.getSelectedFile();
		
		if(fileName == null || fileName.getName().equals("")){		
			JOptionPane.showMessageDialog(component, "Invalid File Name",
				"Invalid File Name", JOptionPane.ERROR_MESSAGE);
			return null;
		}else{
			return fileName;
		}
	}
}