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Fixes #6558 - Allow configuring return type in JSON array parsing.
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Introduced `arrayConverter` in both JSON and AsyncJSON.Factory.

Signed-off-by: Simone Bordet <simone.bordet@gmail.com>
(cherry picked from commit 342396c)
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@sbordet
sbordet committed Aug 4, 2021
1 parent 4e3e99c commit 266d8f0
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Showing 3 changed files with 120 additions and 9 deletions.
37 changes: 35 additions & 2 deletions jetty-util-ajax/src/main/java/org/eclipse/jetty/util/ajax/AsyncJSON.java
View file
Expand Up @@ -19,7 +19,9 @@
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.concurrent.ConcurrentHashMap;
import java.util.function.Function;

import org.eclipse.jetty.util.BufferUtil;
import org.eclipse.jetty.util.Index;
Expand Down Expand Up @@ -62,6 +64,8 @@
* </pre>
* <p>Class {@code com.acme.Person} must either implement {@link Convertible},
* or be mapped with a {@link Convertor} via {@link Factory#putConvertor(String, Convertor)}.</p>
* <p>JSON arrays are by default represented with a {@code List<Object>}, but the
* Java representation can be customized via {@link Factory#setArrayConverter(Function)}.</p>
*/
public class AsyncJSON
{
Expand All @@ -75,8 +79,31 @@ public static class Factory
{
private Index.Mutable<CachedString> cache;
private Map<String, Convertor> convertors;
private Function<List<?>, Object> arrayConverter = list -> list;
private boolean detailedParseException;

/**
* @return the function to customize the Java representation of JSON arrays
* @see #setArrayConverter(Function)
*/
public Function<List<?>, Object> getArrayConverter()
{
return arrayConverter;
}

/**
* <p>Sets the function to convert JSON arrays from their default Java
* representation, a {@code List<Object>}, to another Java data structure
* such as an {@code Object[]}.</p>
*
* @param arrayConverter the function to customize the Java representation of JSON arrays
* @see #getArrayConverter()
*/
public void setArrayConverter(Function<List<?>, Object> arrayConverter)
{
this.arrayConverter = Objects.requireNonNull(arrayConverter);
}

/**
* @return whether a parse failure should report the whole JSON string or just the last chunk
*/
Expand Down Expand Up @@ -870,9 +897,10 @@ private boolean parseArray(ByteBuffer buffer)
case ']':
{
buffer.get();
Object array = stack.peek().value;
@SuppressWarnings("unchecked")
List<Object> array = (List<Object>)stack.peek().value;
stack.pop();
stack.peek().value(array);
stack.peek().value(convertArray(array));
return true;
}
case ',':
Expand Down Expand Up @@ -1067,6 +1095,11 @@ private boolean parseObjectFieldValue(ByteBuffer buffer)
return true;
}

private Object convertArray(List<?> array)
{
return factory.getArrayConverter().apply(array);
}

private Object convertObject(Map<String, Object> object)
{
Object result = convertObject("x-class", object);
Expand Down
45 changes: 38 additions & 7 deletions jetty-util-ajax/src/main/java/org/eclipse/jetty/util/ajax/JSON.java
View file
Expand Up @@ -19,11 +19,14 @@
import java.lang.reflect.Array;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.concurrent.ConcurrentHashMap;
import java.util.function.Function;

import org.eclipse.jetty.util.Loader;
import org.eclipse.jetty.util.TypeUtil;
Expand Down Expand Up @@ -81,6 +84,7 @@ public class JSON

private final Map<String, Convertor> _convertors = new ConcurrentHashMap<>();
private int _stringBufferSize = 1024;
private Function<List<?>, Object> _arrayConverter = List::toArray;

/**
* @return the initial stringBuffer size to use when creating JSON strings
Expand Down Expand Up @@ -461,7 +465,9 @@ protected Map<String, Object> newMap()
*
* @param size the size of the array
* @return a new array representing the JSON array
* @deprecated use {@link #setArrayConverter(Function)} instead.
*/
@Deprecated
protected Object[] newArray(int size)
{
return new Object[size];
Expand Down Expand Up @@ -601,6 +607,28 @@ public Convertor getConvertorFor(String name)
return _convertors.get(name);
}

/**
* @return the function to customize the Java representation of JSON arrays
* @see #setArrayConverter(Function)
*/
public Function<List<?>, Object> getArrayConverter()
{
return _arrayConverter;
}

/**
* <p>Sets the function to convert JSON arrays from their default Java
* representation, a {@code List<Object>}, to another Java data structure
* such as an {@code Object[]}.</p>
*
* @param arrayConverter the function to customize the Java representation of JSON arrays
* @see #getArrayConverter()
*/
public void setArrayConverter(Function<List<?>, Object> arrayConverter)
{
_arrayConverter = Objects.requireNonNull(arrayConverter);
}

/**
* <p>Parses the given JSON source into an object.</p>
* <p>Although the JSON specification does not allow comments (of any kind)
Expand Down Expand Up @@ -928,14 +956,16 @@ protected Object parseArray(Source source)
switch (size)
{
case 0:
return newArray(0);
list = Collections.emptyList();
break;
case 1:
Object array = newArray(1);
Array.set(array, 0, item);
return array;
list = Collections.singletonList(item);
break;
default:
return list.toArray(newArray(list.size()));
break;
}
return getArrayConverter().apply(list);

case ',':
if (comma)
throw new IllegalStateException();
Expand Down Expand Up @@ -970,6 +1000,7 @@ else if (list == null)
item = null;
}
}
break;
}
}

Expand Down Expand Up @@ -1199,7 +1230,7 @@ public Number parseNumber(Source source)
break doubleLoop;
}
}
return Double.parseDouble(buffer.toString());
return Double.valueOf(buffer.toString());
}

protected void seekTo(char seek, Source source)
Expand Down Expand Up @@ -1585,7 +1616,7 @@ public interface Generator
*/
public static class Literal implements Generator
{
private String _json;
private final String _json;

/**
* Constructs a literal JSON instance.
Expand Down
47 changes: 47 additions & 0 deletions jetty-util-ajax/src/test/java/org/eclipse/jetty/util/ajax/AsyncJSONTest.java
View file
Expand Up @@ -19,15 +19,19 @@
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.function.Function;

import org.hamcrest.Matchers;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.provider.MethodSource;
import org.junit.jupiter.params.provider.ValueSource;

import static java.nio.charset.StandardCharsets.UTF_8;
import static org.hamcrest.MatcherAssert.assertThat;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertFalse;
import static org.junit.jupiter.api.Assertions.assertNotNull;
import static org.junit.jupiter.api.Assertions.assertSame;
import static org.junit.jupiter.api.Assertions.assertThrows;
import static org.junit.jupiter.api.Assertions.assertTrue;
Expand Down Expand Up @@ -520,4 +524,47 @@ public void testEncodedCaching()
assertSame(foo, item);
}
}

@Test
public void testArrayConverter()
{
// Test root arrays.
testArrayConverter("[1]", Function.identity());

// Test non-root arrays.
testArrayConverter("{\"array\": [1]}", object ->
{
@SuppressWarnings("unchecked")
Map<String, Object> map = (Map<String, Object>)object;
return map.get("array");
});
}

private void testArrayConverter(String json, Function<Object, Object> extractor)
{
AsyncJSON.Factory factory = new AsyncJSON.Factory();
AsyncJSON async = factory.newAsyncJSON();
JSON sync = new JSON();

async.parse(UTF_8.encode(json));
Object result = extractor.apply(async.complete());
// AsyncJSON historically defaults to list.
assertThat(result, Matchers.instanceOf(List.class));
// JSON historically defaults to array.
result = extractor.apply(sync.parse(new JSON.StringSource(json)));
assertNotNull(result);
assertTrue(result.getClass().isArray(), json + " -> " + result);

// Configure AsyncJSON to return arrays.
factory.setArrayConverter(List::toArray);
async.parse(UTF_8.encode(json));
result = extractor.apply(async.complete());
assertNotNull(result);
assertTrue(result.getClass().isArray(), json + " -> " + result);

// Configure JSON to return lists.
sync.setArrayConverter(list -> list);
result = extractor.apply(sync.parse(new JSON.StringSource(json)));
assertThat(result, Matchers.instanceOf(List.class));
}
}

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