spring Indexer 源码
spring Indexer 代码
文件路径：/spring-expression/src/main/java/org/springframework/expression/spel/ast/Indexer.java
/*
* Copyright 2002-2021 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.expression.spel.ast;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.Member;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import java.util.StringJoiner;
import org.springframework.asm.MethodVisitor;
import org.springframework.core.convert.TypeDescriptor;
import org.springframework.expression.AccessException;
import org.springframework.expression.EvaluationContext;
import org.springframework.expression.EvaluationException;
import org.springframework.expression.PropertyAccessor;
import org.springframework.expression.TypeConverter;
import org.springframework.expression.TypedValue;
import org.springframework.expression.spel.CodeFlow;
import org.springframework.expression.spel.ExpressionState;
import org.springframework.expression.spel.SpelEvaluationException;
import org.springframework.expression.spel.SpelMessage;
import org.springframework.expression.spel.support.ReflectivePropertyAccessor;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.ReflectionUtils;
/**
* An Indexer can index into some proceeding structure to access a particular piece of it.
* Supported structures are: strings / collections (lists/sets) / arrays.
*
* @author Andy Clement
* @author Phillip Webb
* @author Stephane Nicoll
* @author Sam Brannen
* @since 3.0
*/
// TODO support multidimensional arrays
// TODO support correct syntax for multidimensional [][][] and not [,,,]
public class Indexer extends SpelNodeImpl {
private enum IndexedType {ARRAY, LIST, MAP, STRING, OBJECT}
// These fields are used when the indexer is being used as a property read accessor.
// If the name and target type match these cached values then the cachedReadAccessor
// is used to read the property. If they do not match, the correct accessor is
// discovered and then cached for later use.
@Nullable
private String cachedReadName;
@Nullable
private Class<?> cachedReadTargetType;
@Nullable
private PropertyAccessor cachedReadAccessor;
// These fields are used when the indexer is being used as a property write accessor.
// If the name and target type match these cached values then the cachedWriteAccessor
// is used to write the property. If they do not match, the correct accessor is
// discovered and then cached for later use.
@Nullable
private String cachedWriteName;
@Nullable
private Class<?> cachedWriteTargetType;
@Nullable
private PropertyAccessor cachedWriteAccessor;
@Nullable
private IndexedType indexedType;
public Indexer(int startPos, int endPos, SpelNodeImpl expr) {
super(startPos, endPos, expr);
}
@Override
public TypedValue getValueInternal(ExpressionState state) throws EvaluationException {
return getValueRef(state).getValue();
}
@Override
public void setValue(ExpressionState state, @Nullable Object newValue) throws EvaluationException {
getValueRef(state).setValue(newValue);
}
@Override
public boolean isWritable(ExpressionState expressionState) throws SpelEvaluationException {
return true;
}
@Override
protected ValueRef getValueRef(ExpressionState state) throws EvaluationException {
TypedValue context = state.getActiveContextObject();
Object target = context.getValue();
TypeDescriptor targetDescriptor = context.getTypeDescriptor();
TypedValue indexValue;
Object index;
// This first part of the if clause prevents a 'double dereference' of the property (SPR-5847)
if (target instanceof Map && (this.children[0] instanceof PropertyOrFieldReference reference)) {
index = reference.getName();
indexValue = new TypedValue(index);
}
else {
// In case the map key is unqualified, we want it evaluated against the root object
// so temporarily push that on whilst evaluating the key
try {
state.pushActiveContextObject(state.getRootContextObject());
indexValue = this.children[0].getValueInternal(state);
index = indexValue.getValue();
Assert.state(index != null, "No index");
}
finally {
state.popActiveContextObject();
}
}
// Raise a proper exception in case of a null target
if (target == null) {
throw new SpelEvaluationException(getStartPosition(), SpelMessage.CANNOT_INDEX_INTO_NULL_VALUE);
}
// At this point, we need a TypeDescriptor for a non-null target object
Assert.state(targetDescriptor != null, "No type descriptor");
// Indexing into a Map
if (target instanceof Map<?, ?> map) {
Object key = index;
if (targetDescriptor.getMapKeyTypeDescriptor() != null) {
key = state.convertValue(key, targetDescriptor.getMapKeyTypeDescriptor());
}
this.indexedType = IndexedType.MAP;
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) {
if (target instanceof List) {
this.indexedType = IndexedType.LIST;
}
return new CollectionIndexingValueRef((Collection<?>) target, idx, targetDescriptor,
state.getTypeConverter(), state.getConfiguration().isAutoGrowCollections(),
state.getConfiguration().getMaximumAutoGrowSize());
}
else {
this.indexedType = IndexedType.STRING;
return new StringIndexingLValue((String) target, idx, targetDescriptor);
}
}
// Try and treat the index value as a property of the context object
// TODO: could call the conversion service to convert the value to a String
TypeDescriptor valueType = indexValue.getTypeDescriptor();
if (valueType != null && String.class == valueType.getType()) {
this.indexedType = IndexedType.OBJECT;
return new PropertyIndexingValueRef(
target, (String) index, state.getEvaluationContext(), targetDescriptor);
}
throw new SpelEvaluationException(
getStartPosition(), SpelMessage.INDEXING_NOT_SUPPORTED_FOR_TYPE, targetDescriptor);
}
@Override
public boolean isCompilable() {
if (this.indexedType == IndexedType.ARRAY) {
return (this.exitTypeDescriptor != null);
}
else if (this.indexedType == IndexedType.LIST) {
return this.children[0].isCompilable();
}
else if (this.indexedType == IndexedType.MAP) {
return (this.children[0] instanceof PropertyOrFieldReference || this.children[0].isCompilable());
}
else if (this.indexedType == IndexedType.OBJECT) {
// If the string name is changing the accessor is clearly going to change (so no compilation possible)
return (this.cachedReadAccessor != null &&
this.cachedReadAccessor instanceof ReflectivePropertyAccessor.OptimalPropertyAccessor &&
getChild(0) instanceof StringLiteral);
}
return false;
}
@Override
public void generateCode(MethodVisitor mv, CodeFlow cf) {
String descriptor = cf.lastDescriptor();
if (descriptor == null) {
// Stack is empty, should use context object
cf.loadTarget(mv);
}
if (this.indexedType == IndexedType.ARRAY) {
int insn;
if ("D".equals(this.exitTypeDescriptor)) {
mv.visitTypeInsn(CHECKCAST, "[D");
insn = DALOAD;
}
else if ("F".equals(this.exitTypeDescriptor)) {
mv.visitTypeInsn(CHECKCAST, "[F");
insn = FALOAD;
}
else if ("J".equals(this.exitTypeDescriptor)) {
mv.visitTypeInsn(CHECKCAST, "[J");
insn = LALOAD;
}
else if ("I".equals(this.exitTypeDescriptor)) {
mv.visitTypeInsn(CHECKCAST, "[I");
insn = IALOAD;
}
else if ("S".equals(this.exitTypeDescriptor)) {
mv.visitTypeInsn(CHECKCAST, "[S");
insn = SALOAD;
}
else if ("B".equals(this.exitTypeDescriptor)) {
mv.visitTypeInsn(CHECKCAST, "[B");
insn = BALOAD;
}
else if ("C".equals(this.exitTypeDescriptor)) {
mv.visitTypeInsn(CHECKCAST, "[C");
insn = CALOAD;
}
else {
mv.visitTypeInsn(CHECKCAST, "["+ this.exitTypeDescriptor +
(CodeFlow.isPrimitiveArray(this.exitTypeDescriptor) ? "" : ";"));
//depthPlusOne(exitTypeDescriptor)+"Ljava/lang/Object;");
insn = AALOAD;
}
SpelNodeImpl index = this.children[0];
cf.enterCompilationScope();
index.generateCode(mv, cf);
cf.exitCompilationScope();
mv.visitInsn(insn);
}
else if (this.indexedType == IndexedType.LIST) {
mv.visitTypeInsn(CHECKCAST, "java/util/List");
cf.enterCompilationScope();
this.children[0].generateCode(mv, cf);
cf.exitCompilationScope();
mv.visitMethodInsn(INVOKEINTERFACE, "java/util/List", "get", "(I)Ljava/lang/Object;", true);
}
else if (this.indexedType == IndexedType.MAP) {
mv.visitTypeInsn(CHECKCAST, "java/util/Map");
// Special case when the key is an unquoted string literal that will be parsed as
// a property/field reference
if ((this.children[0] instanceof PropertyOrFieldReference reference)) {
String mapKeyName = reference.getName();
mv.visitLdcInsn(mapKeyName);
}
else {
cf.enterCompilationScope();
this.children[0].generateCode(mv, cf);
cf.exitCompilationScope();
}
mv.visitMethodInsn(
INVOKEINTERFACE, "java/util/Map", "get", "(Ljava/lang/Object;)Ljava/lang/Object;", true);
}
else if (this.indexedType == IndexedType.OBJECT) {
ReflectivePropertyAccessor.OptimalPropertyAccessor accessor =
(ReflectivePropertyAccessor.OptimalPropertyAccessor) this.cachedReadAccessor;
Assert.state(accessor != null, "No cached read accessor");
Member member = accessor.member;
boolean isStatic = Modifier.isStatic(member.getModifiers());
String classDesc = member.getDeclaringClass().getName().replace('.', '/');
if (!isStatic) {
if (descriptor == null) {
cf.loadTarget(mv);
}
if (descriptor == null || !classDesc.equals(descriptor.substring(1))) {
mv.visitTypeInsn(CHECKCAST, classDesc);
}
}
if (member instanceof Method method) {
mv.visitMethodInsn((isStatic? INVOKESTATIC : INVOKEVIRTUAL), classDesc, member.getName(),
CodeFlow.createSignatureDescriptor(method), false);
}
else {
mv.visitFieldInsn((isStatic ? GETSTATIC : GETFIELD), classDesc, member.getName(),
CodeFlow.toJvmDescriptor(((Field) member).getType()));
}
}
cf.pushDescriptor(this.exitTypeDescriptor);
}
@Override
public String toStringAST() {
StringJoiner sj = new StringJoiner(",", "[", "]");
for (int i = 0; i < getChildCount(); i++) {
sj.add(getChild(i).toStringAST());
}
return sj.toString();
}
private void setArrayElement(TypeConverter converter, Object ctx, int idx, @Nullable Object newValue,
Class<?> arrayComponentType) throws EvaluationException {
if (arrayComponentType == Boolean.TYPE) {
boolean[] array = (boolean[]) ctx;
checkAccess(array.length, idx);
array[idx] = convertValue(converter, newValue, Boolean.class);
}
else if (arrayComponentType == Byte.TYPE) {
byte[] array = (byte[]) ctx;
checkAccess(array.length, idx);
array[idx] = convertValue(converter, newValue, Byte.class);
}
else if (arrayComponentType == Character.TYPE) {
char[] array = (char[]) ctx;
checkAccess(array.length, idx);
array[idx] = convertValue(converter, newValue, Character.class);
}
else if (arrayComponentType == Double.TYPE) {
double[] array = (double[]) ctx;
checkAccess(array.length, idx);
array[idx] = convertValue(converter, newValue, Double.class);
}
else if (arrayComponentType == Float.TYPE) {
float[] array = (float[]) ctx;
checkAccess(array.length, idx);
array[idx] = convertValue(converter, newValue, Float.class);
}
else if (arrayComponentType == Integer.TYPE) {
int[] array = (int[]) ctx;
checkAccess(array.length, idx);
array[idx] = convertValue(converter, newValue, Integer.class);
}
else if (arrayComponentType == Long.TYPE) {
long[] array = (long[]) ctx;
checkAccess(array.length, idx);
array[idx] = convertValue(converter, newValue, Long.class);
}
else if (arrayComponentType == Short.TYPE) {
short[] array = (short[]) ctx;
checkAccess(array.length, idx);
array[idx] = convertValue(converter, newValue, Short.class);
}
else {
Object[] array = (Object[]) ctx;
checkAccess(array.length, idx);
array[idx] = convertValue(converter, newValue, arrayComponentType);
}
}
private Object accessArrayElement(Object ctx, int idx) throws SpelEvaluationException {
Class<?> arrayComponentType = ctx.getClass().getComponentType();
if (arrayComponentType == Boolean.TYPE) {
boolean[] array = (boolean[]) ctx;
checkAccess(array.length, idx);
this.exitTypeDescriptor = "Z";
return array[idx];
}
else if (arrayComponentType == Byte.TYPE) {
byte[] array = (byte[]) ctx;
checkAccess(array.length, idx);
this.exitTypeDescriptor = "B";
return array[idx];
}
else if (arrayComponentType == Character.TYPE) {
char[] array = (char[]) ctx;
checkAccess(array.length, idx);
this.exitTypeDescriptor = "C";
return array[idx];
}
else if (arrayComponentType == Double.TYPE) {
double[] array = (double[]) ctx;
checkAccess(array.length, idx);
this.exitTypeDescriptor = "D";
return array[idx];
}
else if (arrayComponentType == Float.TYPE) {
float[] array = (float[]) ctx;
checkAccess(array.length, idx);
this.exitTypeDescriptor = "F";
return array[idx];
}
else if (arrayComponentType == Integer.TYPE) {
int[] array = (int[]) ctx;
checkAccess(array.length, idx);
this.exitTypeDescriptor = "I";
return array[idx];
}
else if (arrayComponentType == Long.TYPE) {
long[] array = (long[]) ctx;
checkAccess(array.length, idx);
this.exitTypeDescriptor = "J";
return array[idx];
}
else if (arrayComponentType == Short.TYPE) {
short[] array = (short[]) ctx;
checkAccess(array.length, idx);
this.exitTypeDescriptor = "S";
return array[idx];
}
else {
Object[] array = (Object[]) ctx;
checkAccess(array.length, idx);
Object retValue = array[idx];
this.exitTypeDescriptor = CodeFlow.toDescriptor(arrayComponentType);
return retValue;
}
}
private void checkAccess(int arrayLength, int index) throws SpelEvaluationException {
if (index >= arrayLength) {
throw new SpelEvaluationException(getStartPosition(), SpelMessage.ARRAY_INDEX_OUT_OF_BOUNDS,
arrayLength, index);
}
}
@SuppressWarnings("unchecked")
private <T> T convertValue(TypeConverter converter, @Nullable Object value, Class<T> targetType) {
T result = (T) converter.convertValue(
value, TypeDescriptor.forObject(value), TypeDescriptor.valueOf(targetType));
if (result == null) {
throw new IllegalStateException("Null conversion result for index [" + value + "]");
}
return result;
}
private class ArrayIndexingValueRef implements ValueRef {
private final TypeConverter typeConverter;
private final Object array;
private final int index;
private final TypeDescriptor typeDescriptor;
ArrayIndexingValueRef(TypeConverter typeConverter, Object array, int index, TypeDescriptor typeDescriptor) {
this.typeConverter = typeConverter;
this.array = array;
this.index = index;
this.typeDescriptor = typeDescriptor;
}
@Override
public TypedValue getValue() {
Object arrayElement = accessArrayElement(this.array, this.index);
return new TypedValue(arrayElement, this.typeDescriptor.elementTypeDescriptor(arrayElement));
}
@Override
public void setValue(@Nullable Object newValue) {
TypeDescriptor elementType = this.typeDescriptor.getElementTypeDescriptor();
Assert.state(elementType != null, "No element type");
setArrayElement(this.typeConverter, this.array, this.index, newValue, elementType.getType());
}
@Override
public boolean isWritable() {
return true;
}
}
@SuppressWarnings({"rawtypes", "unchecked"})
private class MapIndexingValueRef implements ValueRef {
private final TypeConverter typeConverter;
private final Map map;
@Nullable
private final Object key;
private final TypeDescriptor mapEntryDescriptor;
public MapIndexingValueRef(
TypeConverter typeConverter, Map map, @Nullable Object key, TypeDescriptor mapEntryDescriptor) {
this.typeConverter = typeConverter;
this.map = map;
this.key = key;
this.mapEntryDescriptor = mapEntryDescriptor;
}
@Override
public TypedValue getValue() {
Object value = this.map.get(this.key);
exitTypeDescriptor = CodeFlow.toDescriptor(Object.class);
return new TypedValue(value, this.mapEntryDescriptor.getMapValueTypeDescriptor(value));
}
@Override
public void setValue(@Nullable Object newValue) {
if (this.mapEntryDescriptor.getMapValueTypeDescriptor() != null) {
newValue = this.typeConverter.convertValue(newValue, TypeDescriptor.forObject(newValue),
this.mapEntryDescriptor.getMapValueTypeDescriptor());
}
this.map.put(this.key, newValue);
}
@Override
public boolean isWritable() {
return true;
}
}
private class PropertyIndexingValueRef implements ValueRef {
private final Object targetObject;
private final String name;
private final EvaluationContext evaluationContext;
private final TypeDescriptor targetObjectTypeDescriptor;
public PropertyIndexingValueRef(Object targetObject, String value,
EvaluationContext evaluationContext, TypeDescriptor targetObjectTypeDescriptor) {
this.targetObject = targetObject;
this.name = value;
this.evaluationContext = evaluationContext;
this.targetObjectTypeDescriptor = targetObjectTypeDescriptor;
}
@Override
public TypedValue getValue() {
Class<?> targetObjectRuntimeClass = getObjectClass(this.targetObject);
try {
if (Indexer.this.cachedReadName != null && Indexer.this.cachedReadName.equals(this.name) &&
Indexer.this.cachedReadTargetType != null &&
Indexer.this.cachedReadTargetType.equals(targetObjectRuntimeClass)) {
// It is OK to use the cached accessor
PropertyAccessor accessor = Indexer.this.cachedReadAccessor;
Assert.state(accessor != null, "No cached read accessor");
return accessor.read(this.evaluationContext, this.targetObject, this.name);
}
List<PropertyAccessor> accessorsToTry = AstUtils.getPropertyAccessorsToTry(
targetObjectRuntimeClass, this.evaluationContext.getPropertyAccessors());
for (PropertyAccessor accessor : accessorsToTry) {
if (accessor.canRead(this.evaluationContext, this.targetObject, this.name)) {
if (accessor instanceof ReflectivePropertyAccessor reflectivePropertyAccessor) {
accessor = reflectivePropertyAccessor.createOptimalAccessor(
this.evaluationContext, this.targetObject, this.name);
}
Indexer.this.cachedReadAccessor = accessor;
Indexer.this.cachedReadName = this.name;
Indexer.this.cachedReadTargetType = targetObjectRuntimeClass;
if (accessor instanceof ReflectivePropertyAccessor.OptimalPropertyAccessor optimalAccessor) {
Member member = optimalAccessor.member;
Indexer.this.exitTypeDescriptor = CodeFlow.toDescriptor(member instanceof Method method ?
method.getReturnType() : ((Field) member).getType());
}
return accessor.read(this.evaluationContext, this.targetObject, this.name);
}
}
}
catch (AccessException ex) {
throw new SpelEvaluationException(getStartPosition(), ex,
SpelMessage.INDEXING_NOT_SUPPORTED_FOR_TYPE, this.targetObjectTypeDescriptor.toString());
}
throw new SpelEvaluationException(getStartPosition(),
SpelMessage.INDEXING_NOT_SUPPORTED_FOR_TYPE, this.targetObjectTypeDescriptor.toString());
}
@Override
public void setValue(@Nullable Object newValue) {
Class<?> contextObjectClass = getObjectClass(this.targetObject);
try {
if (Indexer.this.cachedWriteName != null && Indexer.this.cachedWriteName.equals(this.name) &&
Indexer.this.cachedWriteTargetType != null &&
Indexer.this.cachedWriteTargetType.equals(contextObjectClass)) {
// It is OK to use the cached accessor
PropertyAccessor accessor = Indexer.this.cachedWriteAccessor;
Assert.state(accessor != null, "No cached write accessor");
accessor.write(this.evaluationContext, this.targetObject, this.name, newValue);
return;
}
List<PropertyAccessor> accessorsToTry = AstUtils.getPropertyAccessorsToTry(
contextObjectClass, this.evaluationContext.getPropertyAccessors());
for (PropertyAccessor accessor : accessorsToTry) {
if (accessor.canWrite(this.evaluationContext, this.targetObject, this.name)) {
Indexer.this.cachedWriteName = this.name;
Indexer.this.cachedWriteTargetType = contextObjectClass;
Indexer.this.cachedWriteAccessor = accessor;
accessor.write(this.evaluationContext, this.targetObject, this.name, newValue);
return;
}
}
}
catch (AccessException ex) {
throw new SpelEvaluationException(getStartPosition(), ex,
SpelMessage.EXCEPTION_DURING_PROPERTY_WRITE, this.name, ex.getMessage());
}
}
@Override
public boolean isWritable() {
return true;
}
}
@SuppressWarnings({"rawtypes", "unchecked"})
private class CollectionIndexingValueRef implements ValueRef {
private final Collection collection;
private final int index;
private final TypeDescriptor collectionEntryDescriptor;
private final TypeConverter typeConverter;
private final boolean growCollection;
private final int maximumSize;
public CollectionIndexingValueRef(Collection collection, int index, TypeDescriptor collectionEntryDescriptor,
TypeConverter typeConverter, boolean growCollection, int maximumSize) {
this.collection = collection;
this.index = index;
this.collectionEntryDescriptor = collectionEntryDescriptor;
this.typeConverter = typeConverter;
this.growCollection = growCollection;
this.maximumSize = maximumSize;
}
@Override
public TypedValue getValue() {
growCollectionIfNecessary();
if (this.collection instanceof List list) {
Object o = list.get(this.index);
exitTypeDescriptor = CodeFlow.toDescriptor(Object.class);
return new TypedValue(o, this.collectionEntryDescriptor.elementTypeDescriptor(o));
}
int pos = 0;
for (Object o : this.collection) {
if (pos == this.index) {
return new TypedValue(o, this.collectionEntryDescriptor.elementTypeDescriptor(o));
}
pos++;
}
throw new IllegalStateException("Failed to find indexed element " + this.index + ": " + this.collection);
}
@Override
public void setValue(@Nullable Object newValue) {
growCollectionIfNecessary();
if (this.collection instanceof List list) {
if (this.collectionEntryDescriptor.getElementTypeDescriptor() != null) {
newValue = this.typeConverter.convertValue(newValue, TypeDescriptor.forObject(newValue),
this.collectionEntryDescriptor.getElementTypeDescriptor());
}
list.set(this.index, newValue);
}
else {
throw new SpelEvaluationException(getStartPosition(), SpelMessage.INDEXING_NOT_SUPPORTED_FOR_TYPE,
this.collectionEntryDescriptor.toString());
}
}
private void growCollectionIfNecessary() {
if (this.index >= this.collection.size()) {
if (!this.growCollection) {
throw new SpelEvaluationException(getStartPosition(), SpelMessage.COLLECTION_INDEX_OUT_OF_BOUNDS,
this.collection.size(), this.index);
}
if (this.index >= this.maximumSize) {
throw new SpelEvaluationException(getStartPosition(), SpelMessage.UNABLE_TO_GROW_COLLECTION);
}
if (this.collectionEntryDescriptor.getElementTypeDescriptor() == null) {
throw new SpelEvaluationException(
getStartPosition(), SpelMessage.UNABLE_TO_GROW_COLLECTION_UNKNOWN_ELEMENT_TYPE);
}
TypeDescriptor elementType = this.collectionEntryDescriptor.getElementTypeDescriptor();
try {
Constructor<?> ctor = getDefaultConstructor(elementType.getType());
int newElements = this.index - this.collection.size();
while (newElements >= 0) {
// Insert a null value if the element type does not have a default constructor.
this.collection.add(ctor != null ? ctor.newInstance() : null);
newElements--;
}
}
catch (Throwable ex) {
throw new SpelEvaluationException(getStartPosition(), ex, SpelMessage.UNABLE_TO_GROW_COLLECTION);
}
}
}
@Nullable
private Constructor<?> getDefaultConstructor(Class<?> type) {
try {
return ReflectionUtils.accessibleConstructor(type);
}
catch (Throwable ex) {
return null;
}
}
@Override
public boolean isWritable() {
return true;
}
}
private class StringIndexingLValue implements ValueRef {
private final String target;
private final int index;
private final TypeDescriptor typeDescriptor;
public StringIndexingLValue(String target, int index, TypeDescriptor typeDescriptor) {
this.target = target;
this.index = index;
this.typeDescriptor = typeDescriptor;
}
@Override
public TypedValue getValue() {
if (this.index >= this.target.length()) {
throw new SpelEvaluationException(getStartPosition(), SpelMessage.STRING_INDEX_OUT_OF_BOUNDS,
this.target.length(), this.index);
}
return new TypedValue(String.valueOf(this.target.charAt(this.index)));
}
@Override
public void setValue(@Nullable Object newValue) {
throw new SpelEvaluationException(getStartPosition(), SpelMessage.INDEXING_NOT_SUPPORTED_FOR_TYPE,
this.typeDescriptor.toString());
}
@Override
public boolean isWritable() {
return true;
}
}
}
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