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Support Collection target types in custom IndexAccessors

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Prior to this commit, an IndexAccessor could not provide support for a
Collection target type, since the built-in support for indexing into a
Collection in SpEL's Indexer took precedence.

This commit allows an IndexAccessor to support custom Collection target
types by separating the built-in List and Collection support and
applying the built-in Collection support after custom index accessors
have been applied.

Closes gh-32736
This commit is contained in:
Sam Brannen
2024-05-01 16:11:49 +03:00
parent 4e6591e1a9
commit 153d1bc923
2 changed files with 84 additions and 20 deletions
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53
spring-expression/src/main/java/org/springframework/expression/spel/ast/Indexer.java
View File

@@ -212,6 +212,22 @@ public class Indexer extends SpelNodeImpl {
// At this point, we need a TypeDescriptor for a non-null target object
Assert.state(targetDescriptor != null, "No type descriptor");
// Indexing into an array
if (target.getClass().isArray()) {
int intIndex = convertIndexToInt(state, index);
this.indexedType = IndexedType.ARRAY;
return new ArrayIndexingValueRef(state.getTypeConverter(), target, intIndex, targetDescriptor);
}
// Indexing into a List
if (target instanceof List<?> list) {
int intIndex = convertIndexToInt(state, index);
this.indexedType = IndexedType.LIST;
return new CollectionIndexingValueRef(list, intIndex, targetDescriptor,
state.getTypeConverter(), state.getConfiguration().isAutoGrowCollections(),
state.getConfiguration().getMaximumAutoGrowSize());
}
// Indexing into a Map
if (target instanceof Map<?, ?> map) {
Object key = index;
@@ -223,26 +239,11 @@ public class Indexer extends SpelNodeImpl {
return new MapIndexingValueRef(state.getTypeConverter(), map, key, targetDescriptor);
}
// If the object is something that looks indexable by an integer,
// attempt to treat the index value as a number
if (target.getClass().isArray() || target instanceof Collection || target instanceof String) {
int idx = (Integer) state.convertValue(index, TypeDescriptor.valueOf(Integer.class));
if (target.getClass().isArray()) {
this.indexedType = IndexedType.ARRAY;
return new ArrayIndexingValueRef(state.getTypeConverter(), target, idx, targetDescriptor);
}
else if (target instanceof Collection<?> collection) {
if (target instanceof List) {
this.indexedType = IndexedType.LIST;
}
return new CollectionIndexingValueRef(collection, idx, targetDescriptor,
state.getTypeConverter(), state.getConfiguration().isAutoGrowCollections(),
state.getConfiguration().getMaximumAutoGrowSize());
}
else {
this.indexedType = IndexedType.STRING;
return new StringIndexingValueRef((String) target, idx, targetDescriptor);
}
// Indexing into a String
if (target instanceof String string) {
int intIndex = convertIndexToInt(state, index);
this.indexedType = IndexedType.STRING;
return new StringIndexingValueRef(string, intIndex, targetDescriptor);
}
// Check for a custom IndexAccessor.
@@ -280,6 +281,14 @@ public class Indexer extends SpelNodeImpl {
}
}
// Fallback indexing support for collections
if (target instanceof Collection<?> collection) {
int intIndex = convertIndexToInt(state, index);
return new CollectionIndexingValueRef(collection, intIndex, targetDescriptor,
state.getTypeConverter(), state.getConfiguration().isAutoGrowCollections(),
state.getConfiguration().getMaximumAutoGrowSize());
}
// As a last resort, try to treat the index value as a property of the context object.
TypeDescriptor valueType = indexValue.getTypeDescriptor();
if (valueType != null && String.class == valueType.getType()) {
@@ -458,6 +467,10 @@ public class Indexer extends SpelNodeImpl {
}
}
private static int convertIndexToInt(ExpressionState state, Object index) {
return (Integer) state.convertValue(index, TypeDescriptor.valueOf(Integer.class));
}
private static Class<?> getObjectType(Object obj) {
return (obj instanceof Class<?> clazz ? clazz : obj.getClass());
}

51
spring-expression/src/test/java/org/springframework/expression/spel/IndexingTests.java
View File

@@ -21,9 +21,12 @@ import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import java.math.BigDecimal;
import java.util.AbstractCollection;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.NoSuchElementException;
@@ -44,6 +47,7 @@ import org.springframework.expression.IndexAccessor;
import org.springframework.expression.PropertyAccessor;
import org.springframework.expression.TypedValue;
import org.springframework.expression.spel.standard.SpelExpressionParser;
import org.springframework.expression.spel.support.ReflectiveIndexAccessor;
import org.springframework.expression.spel.support.SimpleEvaluationContext;
import org.springframework.expression.spel.support.StandardEvaluationContext;
import org.springframework.expression.spel.testresources.Person;
@@ -735,6 +739,25 @@ class IndexingTests {
.havingCause().withMessage("unknown bird: property");
}
@Test // gh-32736
void readIndexWithCollectionTargetType() {
context.addIndexAccessor(new ColorCollectionIndexAccessor());
Expression expression = parser.parseExpression("[0]");
// List.of() relies on built-in list support.
assertThat(expression.getValue(context, List.of(Color.RED))).isEqualTo(Color.RED);
ColorCollection colorCollection = new ColorCollection();
// Preconditions for this use case.
assertThat(colorCollection).isInstanceOf(Collection.class);
assertThat(colorCollection).isNotInstanceOf(List.class);
// ColorCollection relies on custom ColorCollectionIndexAccessor.
assertThat(expression.getValue(context, colorCollection)).isEqualTo(Color.RED);
}
static class BirdNameToColorMappings {
public final String property = "enigma";
@@ -755,6 +778,34 @@ class IndexingTests {
}
}
static class ColorCollection extends AbstractCollection<Color> {
public Color get(int index) {
return switch (index) {
case 0 -> Color.RED;
case 1 -> Color.BLUE;
default -> throw new NoSuchElementException("No color at index " + index);
};
}
@Override
public Iterator<Color> iterator() {
throw new UnsupportedOperationException();
}
@Override
public int size() {
throw new UnsupportedOperationException();
}
}
static class ColorCollectionIndexAccessor extends ReflectiveIndexAccessor {
ColorCollectionIndexAccessor() {
super(ColorCollection.class, int.class, "get");
}
}
/**
* {@link IndexAccessor} that knows how to read and write indexes in a
* Jackson {@link ArrayNode}.