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*/

package com.google.refine.expr.functions.booleans;

import java.util.Properties;

import com.google.refine.expr.EvalError;
import com.google.refine.grel.ControlFunctionRegistry;
import com.google.refine.grel.Function;

public class Not implements Function {

    @Override
    public Object call(Properties bindings, Object[] args) {
        if (args.length == 1 && args[0] instanceof Boolean) {
            return !objectToBoolean(args[0]);
        }
        return new EvalError(ControlFunctionRegistry.getFunctionName(this) + " expects a boolean");
    }

    public static boolean objectToBoolean(Object o) {
        return o == null ? false : (
            (o instanceof Boolean) ? ((Boolean) o).booleanValue() : Boolean.parseBoolean(o.toString()));
    }
    
    @Override
    public String getDescription() {
        return "Returns the opposite of b";
    }
    
    @Override
    public String getParams() {
        return "boolean b";
    }
    
    @Override
    public String getReturns() {
        return "boolean";
    }
}
