278 lines
8.3 KiB
Java
278 lines
8.3 KiB
Java
/*
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* Copyright (C) 2011 The Guava Authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
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* in compliance with the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software distributed under the
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* License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
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* express or implied. See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.google.common.primitives;
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import static com.google.common.base.Preconditions.checkArgument;
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import static com.google.common.base.Preconditions.checkNotNull;
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import static com.google.common.primitives.UnsignedInts.INT_MASK;
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import static com.google.common.primitives.UnsignedInts.compare;
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import static com.google.common.primitives.UnsignedInts.toLong;
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import java.math.BigInteger;
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import javax.annotation.CheckReturnValue;
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import javax.annotation.Nullable;
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import com.google.common.annotations.GwtCompatible;
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import com.google.common.annotations.GwtIncompatible;
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/**
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* A wrapper class for unsigned {@code int} values, supporting arithmetic
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* operations.
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*
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* <p>
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* In some cases, when speed is more important than code readability, it may be
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* faster simply to treat primitive {@code int} values as unsigned, using the
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* methods from {@link UnsignedInts}.
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*
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* <p>
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* See the Guava User Guide article on <a href=
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* "http://code.google.com/p/guava-libraries/wiki/PrimitivesExplained#Unsigned_support">
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* unsigned primitive utilities</a>.
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*
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* @author Louis Wasserman
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* @since 11.0
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*/
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@GwtCompatible(emulated = true)
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public final class UnsignedInteger extends Number implements Comparable<UnsignedInteger> {
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public static final UnsignedInteger ZERO = fromIntBits(0);
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public static final UnsignedInteger ONE = fromIntBits(1);
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public static final UnsignedInteger MAX_VALUE = fromIntBits(-1);
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private final int value;
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private UnsignedInteger(int value) {
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// GWT doesn't consistently overflow values to make them 32-bit, so we need to
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// force it.
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this.value = value & 0xffffffff;
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}
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/**
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* Returns an {@code UnsignedInteger} corresponding to a given bit
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* representation. The argument is interpreted as an unsigned 32-bit value.
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* Specifically, the sign bit of {@code bits} is interpreted as a normal bit,
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* and all other bits are treated as usual.
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*
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* <p>
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* If the argument is nonnegative, the returned result will be equal to
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* {@code bits}, otherwise, the result will be equal to {@code 2^32 + bits}.
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*
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* <p>
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* To represent unsigned decimal constants, consider {@link #valueOf(long)}
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* instead.
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*
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* @since 14.0
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*/
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public static UnsignedInteger fromIntBits(int bits) {
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return new UnsignedInteger(bits);
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}
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/**
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* Returns an {@code UnsignedInteger} that is equal to {@code value}, if
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* possible. The inverse operation of {@link #longValue()}.
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*/
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public static UnsignedInteger valueOf(long value) {
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checkArgument((value & INT_MASK) == value, "value (%s) is outside the range for an unsigned integer value",
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value);
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return fromIntBits((int) value);
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}
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/**
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* Returns a {@code UnsignedInteger} representing the same value as the
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* specified {@link BigInteger}. This is the inverse operation of
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* {@link #bigIntegerValue()}.
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*
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* @throws IllegalArgumentException if {@code value} is negative or
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* {@code value >= 2^32}
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*/
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public static UnsignedInteger valueOf(BigInteger value) {
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checkNotNull(value);
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checkArgument(value.signum() >= 0 && value.bitLength() <= Integer.SIZE,
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"value (%s) is outside the range for an unsigned integer value", value);
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return fromIntBits(value.intValue());
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}
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/**
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* Returns an {@code UnsignedInteger} holding the value of the specified
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* {@code String}, parsed as an unsigned {@code int} value.
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*
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* @throws NumberFormatException if the string does not contain a parsable
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* unsigned {@code int} value
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*/
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public static UnsignedInteger valueOf(String string) {
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return valueOf(string, 10);
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}
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/**
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* Returns an {@code UnsignedInteger} holding the value of the specified
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* {@code String}, parsed as an unsigned {@code int} value in the specified
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* radix.
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*
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* @throws NumberFormatException if the string does not contain a parsable
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* unsigned {@code int} value
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*/
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public static UnsignedInteger valueOf(String string, int radix) {
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return fromIntBits(UnsignedInts.parseUnsignedInt(string, radix));
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}
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/**
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* Returns the result of adding this and {@code val}. If the result would have
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* more than 32 bits, returns the low 32 bits of the result.
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*
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* @since 14.0
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*/
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@CheckReturnValue
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public UnsignedInteger plus(UnsignedInteger val) {
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return fromIntBits(this.value + checkNotNull(val).value);
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}
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/**
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* Returns the result of subtracting this and {@code val}. If the result would
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* be negative, returns the low 32 bits of the result.
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*
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* @since 14.0
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*/
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@CheckReturnValue
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public UnsignedInteger minus(UnsignedInteger val) {
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return fromIntBits(value - checkNotNull(val).value);
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}
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/**
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* Returns the result of multiplying this and {@code val}. If the result would
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* have more than 32 bits, returns the low 32 bits of the result.
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*
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* @since 14.0
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*/
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@CheckReturnValue
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@GwtIncompatible("Does not truncate correctly")
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public UnsignedInteger times(UnsignedInteger val) {
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// TODO(user): make this GWT-compatible
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return fromIntBits(value * checkNotNull(val).value);
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}
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/**
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* Returns the result of dividing this by {@code val}.
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*
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* @throws ArithmeticException if {@code val} is zero
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* @since 14.0
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*/
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@CheckReturnValue
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public UnsignedInteger dividedBy(UnsignedInteger val) {
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return fromIntBits(UnsignedInts.divide(value, checkNotNull(val).value));
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}
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/**
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* Returns this mod {@code val}.
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*
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* @throws ArithmeticException if {@code val} is zero
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* @since 14.0
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*/
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@CheckReturnValue
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public UnsignedInteger mod(UnsignedInteger val) {
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return fromIntBits(UnsignedInts.remainder(value, checkNotNull(val).value));
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}
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/**
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* Returns the value of this {@code UnsignedInteger} as an {@code int}. This is
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* an inverse operation to {@link #fromIntBits}.
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*
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* <p>
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* Note that if this {@code UnsignedInteger} holds a value {@code >= 2^31}, the
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* returned value will be equal to {@code this - 2^32}.
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*/
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@Override
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public int intValue() {
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return value;
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}
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/**
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* Returns the value of this {@code UnsignedInteger} as a {@code long}.
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*/
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@Override
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public long longValue() {
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return toLong(value);
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}
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/**
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* Returns the value of this {@code UnsignedInteger} as a {@code float},
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* analogous to a widening primitive conversion from {@code int} to
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* {@code float}, and correctly rounded.
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*/
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@Override
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public float floatValue() {
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return longValue();
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}
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/**
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* Returns the value of this {@code UnsignedInteger} as a {@code float},
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* analogous to a widening primitive conversion from {@code int} to
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* {@code double}, and correctly rounded.
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*/
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@Override
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public double doubleValue() {
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return longValue();
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}
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/**
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* Returns the value of this {@code UnsignedInteger} as a {@link BigInteger}.
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*/
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public BigInteger bigIntegerValue() {
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return BigInteger.valueOf(longValue());
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}
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/**
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* Compares this unsigned integer to another unsigned integer. Returns {@code 0}
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* if they are equal, a negative number if {@code this < other}, and a positive
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* number if {@code this > other}.
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*/
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@Override
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public int compareTo(UnsignedInteger other) {
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checkNotNull(other);
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return compare(value, other.value);
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}
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@Override
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public int hashCode() {
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return value;
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}
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@Override
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public boolean equals(@Nullable Object obj) {
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if (obj instanceof UnsignedInteger) {
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UnsignedInteger other = (UnsignedInteger) obj;
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return value == other.value;
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}
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return false;
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}
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/**
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* Returns a string representation of the {@code UnsignedInteger} value, in base
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* 10.
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*/
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@Override
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public String toString() {
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return toString(10);
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}
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/**
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* Returns a string representation of the {@code UnsignedInteger} value, in base
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* {@code radix}. If {@code radix < Character.MIN_RADIX} or
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* {@code radix > Character.MAX_RADIX}, the radix {@code 10} is used.
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*/
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public String toString(int radix) {
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return UnsignedInts.toString(value, radix);
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}
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}
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