package polyglot.visit;

import polyglot.ast.Node;
import polyglot.util.CodeWriter;
import polyglot.types.SemanticException;

import java.io.IOException;
import java.io.FileWriter;
import java.io.Writer;

/** Visitor which dumps the AST to a file. */
public class DumpAst extends NodeVisitor
{
    protected Writer fw;
    protected CodeWriter w;

    public DumpAst(String name, int width) throws IOException {
        this.fw = new FileWriter(name);
	this.w = new CodeWriter(fw, width);
    }

    public DumpAst(CodeWriter w) {
	this.w = w;
    }

    /** 
     * Visit each node before traversal of children. Call <code>dump</code> for
     * that node. Then we begin a new <code>CodeWriter</code> block and traverse
     * the children.
     */
    public NodeVisitor enter(Node n) {
	w.write("(");
	n.dump(w);
	w.allowBreak(4," ");
	w.begin(0);
	return this;
    }

    /**
     * This method is called only after normal traversal of the children. Thus
     * we must end the <code>CodeWriter</code> block that was begun in 
     * <code>enter</code>.
     */
    public Node leave(Node old, Node n, NodeVisitor v) {
	w.end();
	w.write(")");
	w.allowBreak(0, " ");
	return n;
    }

    public void finish() {
	try {
	    w.flush();

	    if (fw != null) {
		fw.flush();
		fw.close();
	    }
	}
	catch (IOException e) {
	    e.printStackTrace();
	}
    }
}