astviewer.java

SkipOOMiniJOOL教学语言的编译器前端

package edu.ustc.cs.minijool.interp;

import java.awt.*;
import java.util.*;
import javax.swing.*;
import javax.swing.tree.*;

import org.eclipse.jdt.core.dom.*;
import org.eclipse.jdt.internal.corext.dom.GenericVisitor;

/**
 * 把AST用swing的树控件显示出来。
 *
 */
public class ASTViewer extends JFrame {
	
	/**
	 * 把以AST节点n为根的AST用树控件显示。
	 * @param n AST的根节点
	 */
	public void viewAST(ASTNode n) {
		this.setTitle("AST Viewer");
		this.setSize(600, 400);
		this.setLocation(300, 200);
		Container content = getContentPane();
		Object[] hierarchy = new HierachyBuilder().build(n);
		DefaultMutableTreeNode root = processHierarchy(hierarchy);
		JTree tree = new JTree(root);
		content.add(new JScrollPane(tree), BorderLayout.CENTER);
		setVisible(true);
	}

	/**
	 * Small routine that will make node out of the first entry in the array,
	 * then make nodes out of subsequent entries and make them child nodes of
	 * the first one. The process is repeated recursively for entries that are
	 * arrays.
	 */
	private DefaultMutableTreeNode processHierarchy(Object[] hierarchy) {
		DefaultMutableTreeNode node = new DefaultMutableTreeNode(hierarchy[0]);
		DefaultMutableTreeNode child;
		for (int i = 1; i < hierarchy.length; i++) {
			Object nodeSpecifier = hierarchy[i];
			if (nodeSpecifier instanceof Object[]) // Ie node with children
				child = processHierarchy((Object[]) nodeSpecifier);
			else
				child = new DefaultMutableTreeNode(nodeSpecifier); // Ie Leaf
			node.add(child);
		}
		return (node);
	}
}

/**
 * 从AST构造树的层次结构
 * 注意这个visitor与其他的不同之处在于返回true，这样JDT会自动访问每个节点的
 * 子节点
 */
class HierachyBuilder extends GenericVisitor {
	
	private final String PARENT = "parent";
	private final String THIS = "this";
	
	private java.util.List hierachy;
	private java.util.List p, c;
	
	/**
	 * 构造以AST节点n为根的AST的层次结构
	 * @param n AST的根节点
	 * @return 一个数组，其元素类型或者是String，或者是类似的一个数组。
	 */
	public Object[] build(ASTNode n) {
		hierachy = new ArrayList();
		hierachy.add("MiniJOOL Program");
		p = hierachy;
		n.accept(this);
		return hierachy.toArray();
	}
	
	public boolean visit(NumberLiteral n) {
		c = new ArrayList();
		c.add(getNodeName(n) + "    \"" + n.getToken() + "\"");
		n.setProperty(PARENT, p);
		n.setProperty(THIS, c);
		p = c;
		return true;
	}

	public boolean visit(SimpleName n) {
		c = new ArrayList();
		c.add(getNodeName(n) + "    \"" + n.getIdentifier() + "\"");
		n.setProperty(PARENT, p);
		n.setProperty(THIS, c);
		p = c;
		return true;
	}

	public boolean visit(InfixExpression n) {
		c = new ArrayList();
		c.add(getNodeName(n) + "    \"" + n.getOperator().toString() + "\"");
		n.setProperty(PARENT, p);
		n.setProperty(THIS, c);
		p = c;
		return true;
	}

	public boolean visit(Assignment n) {
		c = new ArrayList();
		c.add(getNodeName(n) + "    \"" + n.getOperator().toString() + "\"");
		n.setProperty(PARENT, p);
		n.setProperty(THIS, c);
		p = c;
		return true;
	}

	public boolean visit(PostfixExpression n) {
		c = new ArrayList();
		c.add(getNodeName(n) + "    \"" + n.getOperator().toString() + "\"");
		n.setProperty(PARENT, p);
		n.setProperty(THIS, c);
		p = c;
		return true;
	}

	public boolean visit(PrefixExpression n) {
		c = new ArrayList();
		c.add(getNodeName(n) + "    \"" + n.getOperator().toString() + "\"");
		n.setProperty(PARENT, p);
		n.setProperty(THIS, c);
		p = c;
		return true;
	}

	protected boolean visitNode(ASTNode n) {
		c = new ArrayList();
		c.add(getNodeName(n));
		n.setProperty(PARENT, p);
		n.setProperty(THIS, c);
		p = c;
		return true;
	}
	
	protected void endVisitNode(ASTNode n) {
		p = (java.util.List)n.getProperty(PARENT);
		c = (java.util.List)n.getProperty(THIS);
		if (c.size() == 1) {
			p.add(c.get(0));
		} else {
			p.add(c.toArray());
		}
	} 

	private String getNodeName(ASTNode n) {
		String fullName = n.getClass().getName();
		int pos = fullName.lastIndexOf('.');
		if (pos == -1) return fullName;
		return fullName.substring(pos + 1);
	}
}