1 /*
2 * Copyright (c) 2025, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package oracle.code.json;
27
28 import oracle.code.json.impl.JsonNumberImpl;
29
30 import java.math.BigDecimal;
31 import java.math.BigInteger;
32
33 /**
34 * The interface that represents JSON number, an arbitrary-precision
35 * number represented in base 10 using decimal digits.
36 * <p>
37 * A {@code JsonNumber} can be produced by {@link Json#parse(String)}.
38 * Alternatively, {@link #of(double)} and its overloads can be used to obtain
39 * a {@code JsonNumber} from a {@code Number}.
40 * When a JSON number is parsed, a {@code JsonNumber} object is created
41 * as long as the parsed value adheres to the JSON number
42 * <a href="https://datatracker.ietf.org/doc/html/rfc8259#section-6">
43 * syntax</a>. The value of the {@code JsonNumber}
44 * can be retrieved from {@link #toString()} as the string representation
45 * from which the JSON number is originally parsed, with
46 * {@link #toNumber()} as a {@code Number} instance, or with
47 * {@link #toBigDecimal()}.
48 *
49 * @spec https://datatracker.ietf.org/doc/html/rfc8259#section-6 RFC 8259:
50 * The JavaScript Object Notation (JSON) Data Interchange Format - Numbers
51 * @since 99
52 */
53 public non-sealed interface JsonNumber extends JsonValue {
54
55 /**
56 * {@return the {@code Number} parsed or translated from the
57 * {@link #toString string representation} of this {@code JsonNumber}}
58 * <p>
59 * This method operates on the string representation and depending on that
60 * representation computes and returns an instance of {@code Long}, {@code BigInteger},
61 * {@code Double}, or {@code BigDecimal}.
62 * <p>
63 * If the string representation is the decimal string representation of
64 * a {@code long} value, parsable by {@link Long#parseLong(String)},
65 * then that {@code long} value is returned in its boxed form as {@code Long}.
66 * Otherwise, if the string representation is the decimal string representation of a
67 * {@code BigInteger}, translatable by {@link BigInteger#BigInteger(String)},
68 * then that {@code BigInteger} is returned.
69 * Otherwise, if the string representation is the decimal string representation of
70 * a {@code double} value, parsable by {@link Double#parseDouble(String)},
71 * and the {@code double} value is not {@link Double#isInfinite() infinite}, then that
72 * {@code double} value is returned in its boxed form as {@code Double}.
73 * Otherwise, and in all other cases, the string representation is the decimal string
74 * representation of a {@code BigDecimal}, translatable by
75 * {@link BigDecimal#BigDecimal(String)}, and that {@code BigDecimal} is
76 * returned.
77 * <p>
78 * The computation may not preserve all information in the string representation.
79 * In all of the above cases one or more leading zero digits are not preserved.
80 * In the third case, returning {@code Double}, decimal to binary conversion may lose
81 * decimal precision, and will not preserve one or more trailing zero digits in the fraction
82 * part.
83 *
84 * @apiNote
85 * Pattern matching can be used to match against {@code Long},
86 * {@code Double}, {@code BigInteger}, or {@code BigDecimal} reference
87 * types. For example:
88 * {@snippet lang=java:
89 * switch(jsonNumber.toNumber()) {
90 * case Long l -> { ... }
91 * case Double d -> { ... }
92 * case BigInteger bi -> { ... }
93 * case BigDecimal bd -> { ... }
94 * default -> { } // should not happen
95 * }
96 *}
97 * @throws NumberFormatException if the {@code Number} cannot be parsed or translated from the string representation
98 * @see #toBigDecimal()
99 * @see #toString()
100 */
101 Number toNumber();
102
103 /**
104 * {@return the {@code BigDecimal} translated from the
105 * {@link #toString string representation} of this {@code JsonNumber}}
106 * <p>
107 * The string representation is the decimal string representation of a
108 * {@code BigDecimal}, translatable by {@link BigDecimal#BigDecimal(String)},
109 * and that {@code BigDecimal} is returned.
110 * <p>
111 * The translation may not preserve all information in the string representation.
112 * The sign is not preserved for the decimal string representation {@code -0.0}. One or more
113 * leading zero digits are not preserved.
114 *
115 * @throws NumberFormatException if the {@code BigDecimal} cannot be translated from the string representation
116 */
117 BigDecimal toBigDecimal();
118
119 /**
120 * Creates a JSON number whose string representation is the
121 * decimal string representation of the given {@code double} value,
122 * produced by applying the value to {@link Double#toString(double)}.
123 *
124 * @param num the given {@code double} value.
125 * @return a JSON number created from a {@code double} value
126 * @throws IllegalArgumentException if the given {@code double} value
127 * is {@link Double#isNaN() NaN} or is {@link Double#isInfinite() infinite}.
128 */
129 static JsonNumber of(double num) {
130 // non-integral types
131 return new JsonNumberImpl(num);
132 }
133
134 /**
135 * Creates a JSON number whose string representation is the
136 * decimal string representation of the given {@code long} value,
137 * produced by applying the value to {@link Long#toString(long)}.
138 *
139 * @param num the given {@code long} value.
140 * @return a JSON number created from a {@code long} value
141 */
142 static JsonNumber of(long num) {
143 // integral types
144 return new JsonNumberImpl(num);
145 }
146
147 /**
148 * Creates a JSON number whose string representation is the
149 * string representation of the given {@code BigInteger} value.
150 *
151 * @param num the given {@code BigInteger} value.
152 * @return a JSON number created from a {@code BigInteger} value
153 */
154 static JsonNumber of(BigInteger num) {
155 return new JsonNumberImpl(num);
156 }
157
158 /**
159 * Creates a JSON number whose string representation is the
160 * string representation of the given {@code BigDecimal} value.
161 *
162 * @param num the given {@code BigDecimal} value.
163 * @return a JSON number created from a {@code BigDecimal} value
164 */
165 static JsonNumber of(BigDecimal num) {
166 return new JsonNumberImpl(num);
167 }
168
169 /**
170 * {@return the decimal string representation of this {@code JsonNumber}}
171 *
172 * If this {@code JsonNumber} is created by parsing a JSON number in a JSON document,
173 * it preserves the string representation in the document, regardless of its
174 * precision or range. For example, a JSON number like
175 * {@code 3.141592653589793238462643383279} in the JSON document will be
176 * returned exactly as it appears.
177 * If this {@code JsonNumber} is created via one of the factory methods,
178 * such as {@link JsonNumber#of(double)}, then the string representation is
179 * specified by the factory method.
180 */
181 @Override
182 String toString();
183
184 /**
185 * {@return true if the given {@code obj} is equal to this {@code JsonNumber}}
186 * The comparison is based on the string representation of this {@code JsonNumber},
187 * ignoring the case.
188 *
189 * @see #toString()
190 */
191 @Override
192 boolean equals(Object obj);
193
194 /**
195 * {@return the hash code value of this {@code JsonNumber}} The returned hash code
196 * is calculated based on the string representation of this {@code JsonNumber},
197 * ignoring the case.
198 *
199 * @see #toString()
200 */
201 @Override
202 int hashCode();
203 }