com.twitter.common.args.constraints.RangeNumberVerifier.java Source code

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Here is the source code for com.twitter.common.args.constraints.RangeNumberVerifier.java

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// =================================================================================================
// Copyright 2011 Twitter, Inc.
// -------------------------------------------------------------------------------------------------
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this work except in compliance with the License.
// You may obtain a copy of the License in the LICENSE file, or 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 com.twitter.common.args.constraints;

import java.lang.annotation.Annotation;
import java.math.BigDecimal;

import com.google.common.base.Function;
import com.google.common.base.Functions;

import com.twitter.common.args.Verifier;
import com.twitter.common.args.VerifierFor;

import static com.google.common.base.Preconditions.checkArgument;

/**
 * Verifies that a number (inclusively) lies within a range.
 *
 * @author William Farner
 */
@VerifierFor(Range.class)
public class RangeNumberVerifier implements Verifier<Number> {
    @Override
    public void verify(Number value, Annotation annotation) {
        Range range = getRange(annotation);

        checkArgument(range.lower() < range.upper(), "Range lower bound must be greater than upper bound.");

        double dblValue = value.doubleValue();
        checkArgument(dblValue >= range.lower() && dblValue <= range.upper(),
                String.format("Value must be in range [%f, %f]", range.lower(), range.upper()));
    }

    @Override
    public String toString(Class<? extends Number> argType, Annotation annotation) {
        Range range = getRange(annotation);

        Function<Number, Number> converter;
        if (Float.class.isAssignableFrom(argType) || Double.class.isAssignableFrom(argType)
                || BigDecimal.class.isAssignableFrom(argType)) {

            converter = Functions.identity();
        } else {
            converter = new Function<Number, Number>() {
                @Override
                public Number apply(Number item) {
                    return item.longValue();
                }
            };
        }

        return String.format("must be >= %s and <= %s", converter.apply(range.lower()),
                converter.apply(range.upper()));
    }

    private Range getRange(Annotation annotation) {
        checkArgument(annotation instanceof Range, "Annotation is not a range: " + annotation);

        return (Range) annotation;
    }
}