ASTPrinter.java

/* -*- jde -*- ASTPrinter.java.in */

import java.util.*;

/*
 * Import your grammar packages here
 */
import minipython.analysis.*;
import minipython.node.*;

/**
 * Text display of the AST, with (optionally) color output.
 *
 * To print the AST we do a reverse depth first traversal. We do this
 * because it is easier to know which element is the last child in any
 * node. This makes it easier to do nice indenting.
 *
 * @author Roger Keays <rogerk@ieee.org>
 * 7/9/2001
 */
public class ASTPrinter extends ReversedDepthFirstAdapter
{
	
	//---Constants------------------------------------------------
	public static char ESC = 27;
	
	// Text attributes
	public static final int NORMAL = 0;	
	public static final int BOLD = 1;
	public static final int UNDERSCORE = 4;
	public static final int BLINK = 5;
	public static final int REVERSE = 7;
	public static final int CONCEALED = 8;
	
	// Foreground colors
	public static final int FG_BLACK  = 30;
	public static final int FG_RED = 31;
	public static final int FG_GREEN = 32;
	public static final int FG_YELLOW = 33;
	public static final int FG_BLUE = 34;
	public static final int FG_MAGENTA = 35;
	public static final int FG_CYAN = 36;
	public static final int FG_WHITE = 37;

	// Background colors
	public static final int BG_BLACK = 40;
	public static final int BG_RED = 41;
	public static final int BG_GREEN = 42;
	public static final int BG_YELLOW = 43;
	public static final int BG_BLUE = 44;
	public static final int BG_MAGENTA = 45;
	public static final int BG_CYAN = 46;
	public static final int BG_WHITE = 47;

	// variables. We use a stack to push on indent tokens...
    private String indent = "", output ="";
    private boolean last = false;
    private Stack indentchar = new Stack();
	private boolean color = false;

	/*
	 * The last node we visit. It prints out the entire text that we
	 * have built.
	 */
	public void outStart(Start node)
	{
		System.out.println( treeColor() + "\n  >" + output.substring
							(3, output.length()) + "\n" + resetColor());
    }
	

	/*
	 * As we visit each non-terminal node push on the indent we need
	 * for this node. The next node we visit will always be the last
	 * child of this node.
	 */
	public void defaultIn(Node node)
    {
	if (last) indentchar.push ("`");
	else indentchar.push("|");

	indent = indent + "   ";
	last = true;
    }

	/*
	 * As we leave a non-terminal node, we pull off the indent
	 * character and prepend this nodes line to the output text.
	 */
    public void defaultOut(Node node)
    {
		// replace the current indent with the one from the stack
		indent = indent.substring(0, indent.length() - 3);
		indent = indent.substring(0, indent.length() - 1) +
			(String) indentchar.pop();

		// prepend this line to the output.
		output = indent + "- " + setColor(BOLD, FG_CYAN, BG_BLACK) +
			node.getClass().getName().substring
			(node.getClass().getName().lastIndexOf('.') + 1) + treeColor() +
			"\n" + output;

		// replace any ` with a |
		indent = indent.substring(0, indent.length() - 1) + '|';
    }

	/*
	 * When we visit a terminals we just print it out. We always set
	 * last to false after this because the next node we visit will
	 * never be the last sibling.
	 */
    public void defaultCase(Node node)
    {
		// last sibling has a ` instead of a |
		if (last)
			indent = indent.substring(0, indent.length() - 1) + '`';

		// prepend this line to the output
		output =  indent + "- " + setColor(BOLD, FG_GREEN, BG_BLACK) +
			((Token) node).getText() + treeColor() + "\n" + output;

		// replace any ` with a |
		indent = indent.substring(0, indent.length() - 1) + '|';
		last = false;
    }
	
    public void caseEOF(EOF node)
    {
		last = false;
    }
	
	
	/*
	 * A method to change the color codes. This only works on
	 * color-enabled terminals. In Windows/MS-DOS you need to load the
	 * ansi.sys driver from config.sys or c:\winnt\system32\config.nt
	 * (NT/win2k). ANSI.sys only works under Win2k in DOS mode. In UNIX,
	 * you need an ansi-enabled terminal...
	 */
	public String setColor(int style, int fgColor, int bgColor)
	{
		if (color)
			return ESC + "[" + style + ";" + fgColor + ";" + bgColor +
				"m";
		else return "";
	}

	public String resetColor() 
	{
		return (setColor(NORMAL, FG_WHITE, BG_BLACK));
	}

	public String treeColor()
	{
		return (setColor(NORMAL, FG_YELLOW, BG_BLACK));
	}

	/*
	 * Not everyone wants color. It is disabled by default
	 */
	public void setColor(boolean b)
	{
		color = b;
	}
}