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lyubomyr-shaydarivMarcono1234
lyubomyr-shaydariv
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Marcono1234
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Support arbitrary Number implementation for Object and Number deserialization (#1290)
* Object and Number type adapters number deserialization can be configured * Change wording of ToNumberStrategy documentation * Use inline links in doc sparingly If the element has already been linked before, don't create a link for every subsequent occurrence. See also (slightly dated) https://www.oracle.com/technical-resources/articles/java/javadoc-tool.html#inlinelinks * Link to default to-number policies in ToNumberStrategy doc * Reduce code duplication for deserializing Number * Hide default factory constants of NumberTypeAdapter and ObjectTypeAdapter This encapsulates the logic a little bit better. Additionally refactored factory created by NumberTypeAdapter to only create TypeAdapter once and then have factory reuse that adapter for better performance. Co-authored-by: Marcono1234 <Marcono1234@users.noreply.github.com>
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‎gson/src/main/java/com/google/gson/Gson.java

Lines changed: 10 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -47,6 +47,7 @@
4747
import com.google.gson.internal.bind.JsonTreeReader;
4848
import com.google.gson.internal.bind.JsonTreeWriter;
4949
import com.google.gson.internal.bind.MapTypeAdapterFactory;
50+
import com.google.gson.internal.bind.NumberTypeAdapter;
5051
import com.google.gson.internal.bind.ObjectTypeAdapter;
5152
import com.google.gson.internal.bind.ReflectiveTypeAdapterFactory;
5253
import com.google.gson.internal.bind.TypeAdapters;
@@ -146,6 +147,8 @@ public final class Gson {
146147
final LongSerializationPolicy longSerializationPolicy;
147148
final List<TypeAdapterFactory> builderFactories;
148149
final List<TypeAdapterFactory> builderHierarchyFactories;
150+
final ToNumberStrategy objectToNumberStrategy;
151+
final ToNumberStrategy numberToNumberStrategy;
149152

150153
/**
151154
* Constructs a Gson object with default configuration. The default configuration has the
@@ -188,7 +191,7 @@ public Gson() {
188191
DEFAULT_PRETTY_PRINT, DEFAULT_LENIENT, DEFAULT_SPECIALIZE_FLOAT_VALUES,
189192
LongSerializationPolicy.DEFAULT, null, DateFormat.DEFAULT, DateFormat.DEFAULT,
190193
Collections.<TypeAdapterFactory>emptyList(), Collections.<TypeAdapterFactory>emptyList(),
191-
Collections.<TypeAdapterFactory>emptyList());
194+
Collections.<TypeAdapterFactory>emptyList(), ToNumberPolicy.DOUBLE, ToNumberPolicy.LAZILY_PARSED_NUMBER);
192195
}
193196

194197
Gson(Excluder excluder, FieldNamingStrategy fieldNamingStrategy,
@@ -198,7 +201,8 @@ public Gson() {
198201
LongSerializationPolicy longSerializationPolicy, String datePattern, int dateStyle,
199202
int timeStyle, List<TypeAdapterFactory> builderFactories,
200203
List<TypeAdapterFactory> builderHierarchyFactories,
201-
List<TypeAdapterFactory> factoriesToBeAdded) {
204+
List<TypeAdapterFactory> factoriesToBeAdded,
205+
ToNumberStrategy objectToNumberStrategy, ToNumberStrategy numberToNumberStrategy) {
202206
this.excluder = excluder;
203207
this.fieldNamingStrategy = fieldNamingStrategy;
204208
this.instanceCreators = instanceCreators;
@@ -216,12 +220,14 @@ public Gson() {
216220
this.timeStyle = timeStyle;
217221
this.builderFactories = builderFactories;
218222
this.builderHierarchyFactories = builderHierarchyFactories;
223+
this.objectToNumberStrategy = objectToNumberStrategy;
224+
this.numberToNumberStrategy = numberToNumberStrategy;
219225

220226
List<TypeAdapterFactory> factories = new ArrayList<TypeAdapterFactory>();
221227

222228
// built-in type adapters that cannot be overridden
223229
factories.add(TypeAdapters.JSON_ELEMENT_FACTORY);
224-
factories.add(ObjectTypeAdapter.FACTORY);
230+
factories.add(ObjectTypeAdapter.getFactory(objectToNumberStrategy));
225231

226232
// the excluder must precede all adapters that handle user-defined types
227233
factories.add(excluder);
@@ -241,7 +247,7 @@ public Gson() {
241247
doubleAdapter(serializeSpecialFloatingPointValues)));
242248
factories.add(TypeAdapters.newFactory(float.class, Float.class,
243249
floatAdapter(serializeSpecialFloatingPointValues)));
244-
factories.add(TypeAdapters.NUMBER_FACTORY);
250+
factories.add(NumberTypeAdapter.getFactory(numberToNumberStrategy));
245251
factories.add(TypeAdapters.ATOMIC_INTEGER_FACTORY);
246252
factories.add(TypeAdapters.ATOMIC_BOOLEAN_FACTORY);
247253
factories.add(TypeAdapters.newFactory(AtomicLong.class, atomicLongAdapter(longAdapter)));

‎gson/src/main/java/com/google/gson/GsonBuilder.java

Lines changed: 27 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -95,6 +95,8 @@ public final class GsonBuilder {
9595
private boolean prettyPrinting = DEFAULT_PRETTY_PRINT;
9696
private boolean generateNonExecutableJson = DEFAULT_JSON_NON_EXECUTABLE;
9797
private boolean lenient = DEFAULT_LENIENT;
98+
private ToNumberStrategy objectToNumberStrategy = ToNumberPolicy.DOUBLE;
99+
private ToNumberStrategy numberToNumberStrategy = ToNumberPolicy.LAZILY_PARSED_NUMBER;
98100

99101
/**
100102
* Creates a GsonBuilder instance that can be used to build Gson with various configuration
@@ -326,6 +328,30 @@ public GsonBuilder setFieldNamingStrategy(FieldNamingStrategy fieldNamingStrateg
326328
return this;
327329
}
328330

331+
/**
332+
* Configures Gson to apply a specific number strategy during deserialization of {@link Object}.
333+
*
334+
* @param objectToNumberStrategy the actual object-to-number strategy
335+
* @return a reference to this {@code GsonBuilder} object to fulfill the "Builder" pattern
336+
* @see ToNumberPolicy#DOUBLE The default object-to-number strategy
337+
*/
338+
public GsonBuilder setObjectToNumberStrategy(ToNumberStrategy objectToNumberStrategy) {
339+
this.objectToNumberStrategy = objectToNumberStrategy;
340+
return this;
341+
}
342+
343+
/**
344+
* Configures Gson to apply a specific number strategy during deserialization of {@link Number}.
345+
*
346+
* @param numberToNumberStrategy the actual number-to-number strategy
347+
* @return a reference to this {@code GsonBuilder} object to fulfill the "Builder" pattern
348+
* @see ToNumberPolicy#LAZILY_PARSED_NUMBER The default number-to-number strategy
349+
*/
350+
public GsonBuilder setNumberToNumberStrategy(ToNumberStrategy numberToNumberStrategy) {
351+
this.numberToNumberStrategy = numberToNumberStrategy;
352+
return this;
353+
}
354+
329355
/**
330356
* Configures Gson to apply a set of exclusion strategies during both serialization and
331357
* deserialization. Each of the {@code strategies} will be applied as a disjunction rule.
@@ -600,7 +626,7 @@ public Gson create() {
600626
generateNonExecutableJson, escapeHtmlChars, prettyPrinting, lenient,
601627
serializeSpecialFloatingPointValues, longSerializationPolicy,
602628
datePattern, dateStyle, timeStyle,
603-
this.factories, this.hierarchyFactories, factories);
629+
this.factories, this.hierarchyFactories, factories, objectToNumberStrategy, numberToNumberStrategy);
604630
}
605631

606632
private void addTypeAdaptersForDate(String datePattern, int dateStyle, int timeStyle,

‎gson/src/main/java/com/google/gson/ToNumberPolicy.java

Lines changed: 99 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,99 @@
1+
/*
2+
* Copyright (C) 2021 Google Inc.
3+
*
4+
* Licensed under the Apache License, Version 2.0 (the "License");
5+
* you may not use this file except in compliance with the License.
6+
* You may obtain a copy of the License at
7+
*
8+
* http://www.apache.org/licenses/LICENSE-2.0
9+
*
10+
* Unless required by applicable law or agreed to in writing, software
11+
* distributed under the License is distributed on an "AS IS" BASIS,
12+
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13+
* See the License for the specific language governing permissions and
14+
* limitations under the License.
15+
*/
16+
17+
package com.google.gson;
18+
19+
import java.io.IOException;
20+
import java.math.BigDecimal;
21+
22+
import com.google.gson.internal.LazilyParsedNumber;
23+
import com.google.gson.stream.JsonReader;
24+
import com.google.gson.stream.MalformedJsonException;
25+
26+
/**
27+
* An enumeration that defines two standard number reading strategies and a couple of
28+
* strategies to overcome some historical Gson limitations while deserializing numbers as
29+
* {@link Object} and {@link Number}.
30+
*
31+
* @see ToNumberStrategy
32+
*/
33+
public enum ToNumberPolicy implements ToNumberStrategy {
34+
35+
/**
36+
* Using this policy will ensure that numbers will be read as {@link Double} values.
37+
* This is the default strategy used during deserialization of numbers as {@link Object}.
38+
*/
39+
DOUBLE {
40+
@Override public Double readNumber(JsonReader in) throws IOException {
41+
return in.nextDouble();
42+
}
43+
},
44+
45+
/**
46+
* Using this policy will ensure that numbers will be read as a lazily parsed number backed
47+
* by a string. This is the default strategy used during deserialization of numbers as
48+
* {@link Number}.
49+
*/
50+
LAZILY_PARSED_NUMBER {
51+
@Override public Number readNumber(JsonReader in) throws IOException {
52+
return new LazilyParsedNumber(in.nextString());
53+
}
54+
},
55+
56+
/**
57+
* Using this policy will ensure that numbers will be read as {@link Long} or {@link Double}
58+
* values depending on how JSON numbers are represented: {@code Long} if the JSON number can
59+
* be parsed as a {@code Long} value, or otherwise {@code Double} if it can be parsed as a
60+
* {@code Double} value. If the parsed double-precision number results in a positive or negative
61+
* infinity ({@link Double#isInfinite()}) or a NaN ({@link Double#isNaN()}) value and the
62+
* {@code JsonReader} is not {@link JsonReader#isLenient() lenient}, a {@link MalformedJsonException}
63+
* is thrown.
64+
*/
65+
LONG_OR_DOUBLE {
66+
@Override public Number readNumber(JsonReader in) throws IOException, JsonParseException {
67+
String value = in.nextString();
68+
try {
69+
return Long.parseLong(value);
70+
} catch (NumberFormatException longE) {
71+
try {
72+
Double d = Double.valueOf(value);
73+
if ((d.isInfinite() || d.isNaN()) && !in.isLenient()) {
74+
throw new MalformedJsonException("JSON forbids NaN and infinities: " + d + in);
75+
}
76+
return d;
77+
} catch (NumberFormatException doubleE) {
78+
throw new JsonParseException("Cannot parse " + value, doubleE);
79+
}
80+
}
81+
}
82+
},
83+
84+
/**
85+
* Using this policy will ensure that numbers will be read as numbers of arbitrary length
86+
* using {@link BigDecimal}.
87+
*/
88+
BIG_DECIMAL {
89+
@Override public BigDecimal readNumber(JsonReader in) throws IOException {
90+
String value = in.nextString();
91+
try {
92+
return new BigDecimal(value);
93+
} catch (NumberFormatException e) {
94+
throw new JsonParseException("Cannot parse " + value, e);
95+
}
96+
}
97+
}
98+
99+
}

‎gson/src/main/java/com/google/gson/ToNumberStrategy.java

Lines changed: 71 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,71 @@
1+
/*
2+
* Copyright (C) 2021 Google Inc.
3+
*
4+
* Licensed under the Apache License, Version 2.0 (the "License");
5+
* you may not use this file except in compliance with the License.
6+
* You may obtain a copy of the License at
7+
*
8+
* http://www.apache.org/licenses/LICENSE-2.0
9+
*
10+
* Unless required by applicable law or agreed to in writing, software
11+
* distributed under the License is distributed on an "AS IS" BASIS,
12+
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13+
* See the License for the specific language governing permissions and
14+
* limitations under the License.
15+
*/
16+
17+
package com.google.gson;
18+
19+
import java.io.IOException;
20+
21+
import com.google.gson.stream.JsonReader;
22+
23+
/**
24+
* A strategy that is used to control how numbers should be deserialized for {@link Object} and {@link Number}
25+
* when a concrete type of the deserialized number is unknown in advance. By default, Gson uses the following
26+
* deserialization strategies:
27+
*
28+
* <ul>
29+
* <li>{@link Double} values are returned for JSON numbers if the deserialization type is declared as
30+
* {@code Object}, see {@link ToNumberPolicy#DOUBLE};</li>
31+
* <li>Lazily parsed number values are returned if the deserialization type is declared as {@code Number},
32+
* see {@link ToNumberPolicy#LAZILY_PARSED_NUMBER}.</li>
33+
* </ul>
34+
*
35+
* <p>For historical reasons, Gson does not support deserialization of arbitrary-length numbers for
36+
* {@code Object} and {@code Number} by default, potentially causing precision loss. However,
37+
* <a href="https://tools.ietf.org/html/rfc8259#section-6">RFC 8259</a> permits this:
38+
*
39+
* <pre>
40+
* This specification allows implementations to set limits on the range
41+
* and precision of numbers accepted. Since software that implements
42+
* IEEE 754 binary64 (double precision) numbers [IEEE754] is generally
43+
* available and widely used, good interoperability can be achieved by
44+
* implementations that expect no more precision or range than these
45+
* provide, in the sense that implementations will approximate JSON
46+
* numbers within the expected precision. A JSON number such as 1E400
47+
* or 3.141592653589793238462643383279 may indicate potential
48+
* interoperability problems, since it suggests that the software that
49+
* created it expects receiving software to have greater capabilities
50+
* for numeric magnitude and precision than is widely available.
51+
* </pre>
52+
*
53+
* <p>To overcome the precision loss, use for example {@link ToNumberPolicy#LONG_OR_DOUBLE} or
54+
* {@link ToNumberPolicy#BIG_DECIMAL}.</p>
55+
*
56+
* @see ToNumberPolicy
57+
* @see GsonBuilder#setObjectToNumberStrategy(ToNumberStrategy)
58+
* @see GsonBuilder#setNumberToNumberStrategy(ToNumberStrategy)
59+
*/
60+
public interface ToNumberStrategy {
61+
62+
/**
63+
* Reads a number from the given JSON reader. A strategy is supposed to read a single value from the
64+
* reader, and the read value is guaranteed never to be {@code null}.
65+
*
66+
* @param in JSON reader to read a number from
67+
* @return number read from the JSON reader.
68+
* @throws IOException
69+
*/
70+
public Number readNumber(JsonReader in) throws IOException;
71+
}

‎gson/src/main/java/com/google/gson/internal/bind/NumberTypeAdapter.java

Lines changed: 82 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,82 @@
1+
/*
2+
* Copyright (C) 2020 Google Inc.
3+
*
4+
* Licensed under the Apache License, Version 2.0 (the "License");
5+
* you may not use this file except in compliance with the License.
6+
* You may obtain a copy of the License at
7+
*
8+
* http://www.apache.org/licenses/LICENSE-2.0
9+
*
10+
* Unless required by applicable law or agreed to in writing, software
11+
* distributed under the License is distributed on an "AS IS" BASIS,
12+
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13+
* See the License for the specific language governing permissions and
14+
* limitations under the License.
15+
*/
16+
17+
package com.google.gson.internal.bind;
18+
19+
import com.google.gson.Gson;
20+
import com.google.gson.JsonSyntaxException;
21+
import com.google.gson.ToNumberStrategy;
22+
import com.google.gson.ToNumberPolicy;
23+
import com.google.gson.TypeAdapter;
24+
import com.google.gson.TypeAdapterFactory;
25+
import com.google.gson.reflect.TypeToken;
26+
import com.google.gson.stream.JsonReader;
27+
import com.google.gson.stream.JsonToken;
28+
import com.google.gson.stream.JsonWriter;
29+
30+
import java.io.IOException;
31+
32+
/**
33+
* Type adapter for {@link Number}.
34+
*/
35+
public final class NumberTypeAdapter extends TypeAdapter<Number> {
36+
/**
37+
* Gson default factory using {@link ToNumberPolicy#LAZILY_PARSED_NUMBER}.
38+
*/
39+
private static final TypeAdapterFactory LAZILY_PARSED_NUMBER_FACTORY = newFactory(ToNumberPolicy.LAZILY_PARSED_NUMBER);
40+
41+
private final ToNumberStrategy toNumberStrategy;
42+
43+
private NumberTypeAdapter(ToNumberStrategy toNumberStrategy) {
44+
this.toNumberStrategy = toNumberStrategy;
45+
}
46+
47+
private static TypeAdapterFactory newFactory(ToNumberStrategy toNumberStrategy) {
48+
final NumberTypeAdapter adapter = new NumberTypeAdapter(toNumberStrategy);
49+
return new TypeAdapterFactory() {
50+
@SuppressWarnings("unchecked")
51+
@Override public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) {
52+
return type.getRawType() == Number.class ? (TypeAdapter<T>) adapter : null;
53+
}
54+
};
55+
}
56+
57+
public static TypeAdapterFactory getFactory(ToNumberStrategy toNumberStrategy) {
58+
if (toNumberStrategy == ToNumberPolicy.LAZILY_PARSED_NUMBER) {
59+
return LAZILY_PARSED_NUMBER_FACTORY;
60+
} else {
61+
return newFactory(toNumberStrategy);
62+
}
63+
}
64+
65+
@Override public Number read(JsonReader in) throws IOException {
66+
JsonToken jsonToken = in.peek();
67+
switch (jsonToken) {
68+
case NULL:
69+
in.nextNull();
70+
return null;
71+
case NUMBER:
72+
case STRING:
73+
return toNumberStrategy.readNumber(in);
74+
default:
75+
throw new JsonSyntaxException("Expecting number, got: " + jsonToken);
76+
}
77+
}
78+
79+
@Override public void write(JsonWriter out, Number value) throws IOException {
80+
out.value(value);
81+
}
82+
}

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