001 /*
002 * Copyright (C) 2011 The Guava Authors
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
005 * in compliance with the License. You may obtain a copy of the License at
006 *
007 * http://www.apache.org/licenses/LICENSE-2.0
008 *
009 * Unless required by applicable law or agreed to in writing, software distributed under the
010 * License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
011 * express or implied. See the License for the specific language governing permissions and
012 * limitations under the License.
013 */
014
015 package com.google.common.primitives;
016
017 import static com.google.common.base.Preconditions.checkArgument;
018 import static com.google.common.base.Preconditions.checkNotNull;
019 import static com.google.common.primitives.UnsignedInts.INT_MASK;
020 import static com.google.common.primitives.UnsignedInts.compare;
021 import static com.google.common.primitives.UnsignedInts.toLong;
022
023 import com.google.common.annotations.Beta;
024 import com.google.common.annotations.GwtCompatible;
025 import com.google.common.annotations.GwtIncompatible;
026
027 import java.math.BigInteger;
028
029 import javax.annotation.Nullable;
030
031 /**
032 * A wrapper class for unsigned {@code int} values, supporting arithmetic operations.
033 *
034 * <p>In some cases, when speed is more important than code readability, it may be faster simply to
035 * treat primitive {@code int} values as unsigned, using the methods from {@link UnsignedInts}.
036 *
037 * <p>See the Guava User Guide article on <a href=
038 * "http://code.google.com/p/guava-libraries/wiki/PrimitivesExplained#Unsigned_support">
039 * unsigned primitive utilities</a>.
040 *
041 * @author Louis Wasserman
042 * @since 11.0
043 */
044 @Beta
045 @GwtCompatible(emulated = true)
046 public final class UnsignedInteger extends Number implements Comparable<UnsignedInteger> {
047 public static final UnsignedInteger ZERO = asUnsigned(0);
048 public static final UnsignedInteger ONE = asUnsigned(1);
049 public static final UnsignedInteger MAX_VALUE = asUnsigned(-1);
050
051 private final int value;
052
053 private UnsignedInteger(int value) {
054 this.value = value & 0xffffffff;
055 }
056
057 /**
058 * Returns an {@code UnsignedInteger} that, when treated as signed, is
059 * equal to {@code value}.
060 */
061 public static UnsignedInteger asUnsigned(int value) {
062 return new UnsignedInteger(value);
063 }
064
065 /**
066 * Returns an {@code UnsignedInteger} that is equal to {@code value},
067 * if possible. The inverse operation of {@link #longValue()}.
068 */
069 public static UnsignedInteger valueOf(long value) {
070 checkArgument((value & INT_MASK) == value,
071 "value (%s) is outside the range for an unsigned integer value", value);
072 return asUnsigned((int) value);
073 }
074
075 /**
076 * Returns a {@code UnsignedInteger} representing the same value as the specified
077 * {@link BigInteger}. This is the inverse operation of {@link #bigIntegerValue()}.
078 *
079 * @throws IllegalArgumentException if {@code value} is negative or {@code value >= 2^32}
080 */
081 public static UnsignedInteger valueOf(BigInteger value) {
082 checkNotNull(value);
083 checkArgument(value.signum() >= 0 && value.bitLength() <= Integer.SIZE,
084 "value (%s) is outside the range for an unsigned integer value", value);
085 return asUnsigned(value.intValue());
086 }
087
088 /**
089 * Returns an {@code UnsignedInteger} holding the value of the specified {@code String}, parsed
090 * as an unsigned {@code int} value.
091 *
092 * @throws NumberFormatException if the string does not contain a parsable unsigned {@code int}
093 * value
094 */
095 public static UnsignedInteger valueOf(String string) {
096 return valueOf(string, 10);
097 }
098
099 /**
100 * Returns an {@code UnsignedInteger} holding the value of the specified {@code String}, parsed
101 * as an unsigned {@code int} value in the specified radix.
102 *
103 * @throws NumberFormatException if the string does not contain a parsable unsigned {@code int}
104 * value
105 */
106 public static UnsignedInteger valueOf(String string, int radix) {
107 return asUnsigned(UnsignedInts.parseUnsignedInt(string, radix));
108 }
109
110 /**
111 * Returns the result of adding this and {@code val}. If the result would have more than 32 bits,
112 * returns the low 32 bits of the result.
113 */
114 public UnsignedInteger add(UnsignedInteger val) {
115 checkNotNull(val);
116 return asUnsigned(this.value + val.value);
117 }
118
119 /**
120 * Returns the result of subtracting this and {@code val}. If the result would be negative,
121 * returns the low 32 bits of the result.
122 */
123 public UnsignedInteger subtract(UnsignedInteger val) {
124 checkNotNull(val);
125 return asUnsigned(this.value - val.value);
126 }
127
128 /**
129 * Returns the result of multiplying this and {@code val}. If the result would have more than 32
130 * bits, returns the low 32 bits of the result.
131 */
132 @GwtIncompatible("Does not truncate correctly")
133 public UnsignedInteger multiply(UnsignedInteger val) {
134 checkNotNull(val);
135 return asUnsigned(value * val.value);
136 }
137
138 /**
139 * Returns the result of dividing this by {@code val}.
140 */
141 public UnsignedInteger divide(UnsignedInteger val) {
142 checkNotNull(val);
143 return asUnsigned(UnsignedInts.divide(value, val.value));
144 }
145
146 /**
147 * Returns the remainder of dividing this by {@code val}.
148 */
149 public UnsignedInteger remainder(UnsignedInteger val) {
150 checkNotNull(val);
151 return asUnsigned(UnsignedInts.remainder(value, val.value));
152 }
153
154 /**
155 * Returns the value of this {@code UnsignedInteger} as an {@code int}. This is an inverse
156 * operation to {@link #asUnsigned}.
157 *
158 * <p>Note that if this {@code UnsignedInteger} holds a value {@code >= 2^31}, the returned value
159 * will be equal to {@code this - 2^32}.
160 */
161 @Override
162 public int intValue() {
163 return value;
164 }
165
166 /**
167 * Returns the value of this {@code UnsignedInteger} as a {@code long}.
168 */
169 @Override
170 public long longValue() {
171 return toLong(value);
172 }
173
174 /**
175 * Returns the value of this {@code UnsignedInteger} as a {@code float}, analogous to a widening
176 * primitive conversion from {@code int} to {@code float}, and correctly rounded.
177 */
178 @Override
179 public float floatValue() {
180 return longValue();
181 }
182
183 /**
184 * Returns the value of this {@code UnsignedInteger} as a {@code float}, analogous to a widening
185 * primitive conversion from {@code int} to {@code double}, and correctly rounded.
186 */
187 @Override
188 public double doubleValue() {
189 return longValue();
190 }
191
192 /**
193 * Returns the value of this {@code UnsignedInteger} as a {@link BigInteger}.
194 */
195 public BigInteger bigIntegerValue() {
196 return BigInteger.valueOf(longValue());
197 }
198
199 /**
200 * Compares this unsigned integer to another unsigned integer.
201 * Returns {@code 0} if they are equal, a negative number if {@code this < other},
202 * and a positive number if {@code this > other}.
203 */
204 @Override
205 public int compareTo(UnsignedInteger other) {
206 checkNotNull(other);
207 return compare(value, other.value);
208 }
209
210 @Override
211 public int hashCode() {
212 return value;
213 }
214
215 @Override
216 public boolean equals(@Nullable Object obj) {
217 if (obj instanceof UnsignedInteger) {
218 UnsignedInteger other = (UnsignedInteger) obj;
219 return value == other.value;
220 }
221 return false;
222 }
223
224 /**
225 * Returns a string representation of the {@code UnsignedInteger} value, in base 10.
226 */
227 @Override
228 public String toString() {
229 return toString(10);
230 }
231
232 /**
233 * Returns a string representation of the {@code UnsignedInteger} value, in base {@code radix}.
234 * If {@code radix < Character.MIN_RADIX} or {@code radix > Character.MAX_RADIX}, the radix
235 * {@code 10} is used.
236 */
237 public String toString(int radix) {
238 return UnsignedInts.toString(value, radix);
239 }
240 }