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package sun.tools.jstat;

A class that represents a mathematical expression as a tree structure containing operators as interior nodes and operands as leaves. The operands can be literals or lazily bound variables.
Author:Brian Doherty
Since:1.5
/** * A class that represents a mathematical expression as a tree structure * containing operators as interior nodes and operands as leaves. The * operands can be literals or lazily bound variables. * * @author Brian Doherty * @since 1.5 */
public class Expression { private static int nextOrdinal; private boolean debug = Boolean.getBoolean("Expression.debug"); private Expression left; private Expression right; private Operator operator; private int ordinal = nextOrdinal++; private boolean required = false; Expression() { if (debug) { System.out.println("Expression " + ordinal + " created"); } } void setLeft(Expression left) { if (debug) { System.out.println("Setting left on " + ordinal + " to " + left); } this.left = left; this.left.setRequired(required); } Expression getLeft() { return left; } void setRight(Expression right) { if (debug) { System.out.println("Setting right on " + ordinal + " to " + right); } this.right = right; this.right.setRequired(required); } Expression getRight() { return right; } void setOperator(Operator o) { if (debug) { System.out.println("Setting operator on " + ordinal + " to " + o); } this.operator = o; } Operator getOperator() { return operator; } void setRequired(boolean r) { this.required = r; if (left != null) { left.setRequired(required); } if (right != null) { right.setRequired(required); } } boolean isRequired() { return required; } public String toString() { StringBuilder b = new StringBuilder(); b.append('('); if (left != null) { b.append(left.toString()); } if (operator != null) { b.append(operator.toString()); if (right != null) { b.append(right.toString()); } } b.append(')'); return b.toString(); } }