UnaryOperator.java

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package org.apache.sling.scripting.sightly.compiler.expression.nodes;

import org.apache.commons.lang.StringUtils;
import org.apache.sling.scripting.sightly.impl.compiler.CompileTimeObjectModel;

/**
 * Unary operators used in expressions.
 */
public enum UnaryOperator {

    /** Evaluates to logical negation of the operand */
    NOT {
        @Override
        public Object eval(Object operand) {
            return !CompileTimeObjectModel.toBoolean(operand);
        }
    },

    /** Evaluates whether the operand is a string of only whitespace characters */
    IS_WHITESPACE  {
        @Override
        public Object eval(Object operand) {
            return StringUtils.isWhitespace(CompileTimeObjectModel.toString(operand));
        }
    },

    /**
     * Evaluates the length of a collection
     */
    LENGTH {
        @Override
        public Object eval(Object operand) {
            return CompileTimeObjectModel.toCollection(operand).size();
        }
    };

    public abstract Object eval(Object operand);

}