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Utility classes and methods developed for Brooklyn but not dependendent on Brooklyn or much else
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/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.brooklyn.util.math;

import javax.annotation.Nullable;

import com.google.common.base.Preconditions;
import com.google.common.base.Predicate;

public class MathPredicates {

    /** @deprecated since 0.9.0 kept only to allow conversion of anonymous inner classes */
    @SuppressWarnings("unused") @Deprecated 
    private  static  Predicate greaterThanOld(final double val) {
        // TODO PERSISTENCE WORKAROUND
        return new Predicate() {
            public boolean apply(@Nullable T input) {
                return (input == null) ? false : input.doubleValue() > val;
            }
        };
    }

    /** @deprecated since 0.9.0 kept only to allow conversion of anonymous inner classes */
    @SuppressWarnings("unused") @Deprecated 
    private  static  Predicate greaterThanOrEqualOld(final double val) {
        // TODO PERSISTENCE WORKAROUND
        return new Predicate() {
            public boolean apply(@Nullable T input) {
                return (input == null) ? false : input.doubleValue() >= val;
            }
        };
    }

    /** @deprecated since 0.9.0 kept only to allow conversion of anonymous inner classes */
    @SuppressWarnings("unused") @Deprecated 
    private  static  Predicate lessThanOld(final double val) {
        // TODO PERSISTENCE WORKAROUND
        return new Predicate() {
            public boolean apply(@Nullable T input) {
                return (input == null) ? false : input.doubleValue() < val;
            }
        };
    }

    /** @deprecated since 0.9.0 kept only to allow conversion of anonymous inner classes */
    @SuppressWarnings("unused") @Deprecated 
    private  static  Predicate lessThanOrEqualOld(final double val) {
        // TODO PERSISTENCE WORKAROUND
        return new Predicate() {
            public boolean apply(@Nullable T input) {
                return (input == null) ? false : input.doubleValue() <= val;
            }
        };
    }

    /**
     * Creates a predicate comparing a given number with {@code val}. 
     * A number of {@code null} passed to the predicate will always return false.
     */
    public static  Predicate greaterThan(final double val) {
        return new GreaterThan(val);
    }

    protected static class GreaterThan implements Predicate {
        private final double val;
        protected GreaterThan(double val) {
            this.val = val;
        }
        public boolean apply(@Nullable T input) {
            return (input == null) ? false : input.doubleValue() > val;
        }
    }
    
    /**
     * Creates a predicate comparing a given number with {@code val}. 
     * A number of {@code null} passed to the predicate will always return false.
     */
    public static  Predicate greaterThanOrEqual(final double val) {
        return new GreaterThanOrEqual(val);
    }

    protected static class GreaterThanOrEqual implements Predicate {
        private final double val;
        protected GreaterThanOrEqual(double val) {
            this.val = val;
        }
        public boolean apply(@Nullable T input) {
            return (input == null) ? false : input.doubleValue() >= val;
        }
    }
    
    /**
     * Creates a predicate comparing a given number with {@code val}. 
     * A number of {@code null} passed to the predicate will always return false.
     */
    public static  Predicate lessThan(final double val) {
        return new LessThan(val);
    }

    protected static class LessThan implements Predicate {
        private final double val;
        protected LessThan(double val) {
            this.val = val;
        }
        public boolean apply(@Nullable T input) {
            return (input == null) ? false : input.doubleValue() < val;
        }
    }
    
    /**
     * Creates a predicate comparing a given number with {@code val}. 
     * A number of {@code null} passed to the predicate will always return false.
     */
    public static  Predicate lessThanOrEqual(final double val) {
        return new LessThanOrEqual(val);
    }
    
    protected static class LessThanOrEqual implements Predicate {
        private final double val;
        protected LessThanOrEqual(double val) {
            this.val = val;
        }
        public boolean apply(@Nullable T input) {
            return (input == null) ? false : input.doubleValue() <= val;
        }
    }
    
    /**
     * Creates a predicate comparing a given number with {@code val}. 
     * A number of {@code null} passed to the predicate will always return false.
     */
    public static  Predicate equalsApproximately(final Number val, final double delta) {
        return new EqualsApproximately(val, delta);
    }
    /** Convenience for {@link #equalsApproximately(double,double)} with a delta of 10^{-6}. */
    public static  Predicate equalsApproximately(final Number val) {
        return equalsApproximately(val, 0.0000001);
    }

    private static final class EqualsApproximately implements Predicate {
        private final double val;
        private final double delta;
        private EqualsApproximately(Number val, double delta) {
            this.val = val.doubleValue();
            Preconditions.checkArgument(delta>=0, "delta must be non-negative");
            this.delta = delta;
        }
        public boolean apply(@Nullable T input) {
            return (input == null) ? false : Math.abs(input.doubleValue() - val) <= delta;
        }
        @Override
        public String toString() {
            return "equals-approximately("+val+" +- "+delta+")";
        }
    }


}