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Add invoke support. Make property behaviour consistent.
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@markt-asf
markt-asf committed Feb 22, 2024
1 parent d14dc23 commit 989791b
Showing 1 changed file with 91 additions and 44 deletions.
135 changes: 91 additions & 44 deletions api/src/main/java/jakarta/el/OptionalELResolver.java
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Original file line number Diff line number Diff line change
Expand Up @@ -22,32 +22,36 @@
import java.util.Optional;

/**
* Defines property resolution behaviour on {@link Optional}s.
* Defines property resolution, method invocation and type conversion behaviour on {@link Optional}s.
* <p>
* This resolver handles base objects that are instances of {@link Optional}.
* <p>
* If the {@link Optional#isEmpty()} is {@code true} for the base object and the property is {@code null} then the
* resulting value is {@code null}.
* <p>
* If the {@link Optional#isEmpty()} is {@code true} for the base object and the property is not {@code null} then the
* resulting value is the base object (an empty {@link Optional}).
* <p>
* If the {@link Optional#isPresent()} is {@code true} for the base object and the property is {@code null} then the
* resulting value is the result of calling {@link Optional#get()} on the base object.
* <p>
* If the {@link Optional#isPresent()} is {@code true} for the base object and the property is not {@code null} then the
* resulting value is the result of calling {@link ELResolver#getValue(ELContext, Object, Object)} using the
* {@link ELResolver} obtained from {@link ELContext#getELResolver()} with the following parameters:
* <ul>
* <li>The {@link ELContext} is the current context</li>
* <li>The base object is the result of calling {@link Optional#get()} on the current base object</li>
* <li>The property object is the current property object</li>
* </ul>
* <p>
* This resolver is always a read-only resolver.
* This resolver is always a read-only resolver since {@link Optional} instances are immutable.
*/
public class OptionalELResolver extends ELResolver {

/**
* {@inheritDoc}
*
* @return If the base object is an {@link Optional} and {@link Optional#isEmpty()} returns {@code true} then the
* resulting value is {@code null}.
* <p>
* If the base object is an {@link Optional}, {@link Optional#isPresent()} returns {@code true} and the
* property is {@code null} then the resulting value is the result of calling {@link Optional#get()} on
* the base object.
* <p>
* If the base object is an {@link Optional}, {@link Optional#isPresent()} returns {@code true} and the
* property is not {@code null} then the resulting value is the result of calling
* {@link ELResolver#getValue(ELContext, Object, Object)} using the {@link ELResolver} obtained from
* {@link ELContext#getELResolver()} with the following parameters:
* <ul>
* <li>The {@link ELContext} is the current context</li>
* <li>The base object is the result of calling {@link Optional#get()} on the current base object</li>
* <li>The property object is the current property object</li>
* </ul>
* <p>
* If the base object is not an {@link Optional} then the return value is undefined.
*/
@Override
public Object getValue(ELContext context, Object base, Object property) {
Objects.requireNonNull(context);
Expand All @@ -57,8 +61,6 @@ public Object getValue(ELContext context, Object base, Object property) {
if (((Optional<?>) base).isEmpty()) {
if (property == null) {
return null;
} else {
return base;
}
} else {
if (property == null) {
Expand All @@ -76,9 +78,11 @@ public Object getValue(ELContext context, Object base, Object property) {

/**
* {@inheritDoc}
* <p>
* If the base object is an {@link Optional} this method always returns {@code null} since instances of this
* resolver are always read-only.
*
* @return If the base object is an {@link Optional} this method always returns {@code null} since instances of this
* resolver are always read-only.
* <p>
* If the base object is not an {@link Optional} then the return value is undefined.
*/
@Override
public Class<?> getType(ELContext context, Object base, Object property) {
Expand Down Expand Up @@ -111,9 +115,11 @@ public void setValue(ELContext context, Object base, Object property, Object val

/**
* {@inheritDoc}
* <p>
* If the base object is an {@link Optional} this method always returns {@code true} since instances of this
* resolver are always read-only.
*
* @return If the base object is an {@link Optional} this method always returns {@code true} since instances of this
* resolver are always read-only.
* <p>
* If the base object is not an {@link Optional} then the return value is undefined.
*/
@Override
public boolean isReadOnly(ELContext context, Object base, Object property) {
Expand All @@ -130,8 +136,10 @@ public boolean isReadOnly(ELContext context, Object base, Object property) {

/**
* {@inheritDoc}
* <p>
* If the base object is an {@link Optional} this method always returns {@code Object.class}.
*
* @return If the base object is an {@link Optional} this method always returns {@code Object.class}.
* <p>
* If the base object is not an {@link Optional} then the return value is undefined.
*/
@Override
public Class<?> getCommonPropertyType(ELContext context, Object base) {
Expand All @@ -143,37 +151,76 @@ public Class<?> getCommonPropertyType(ELContext context, Object base) {
}


/**
* {@inheritDoc}
*
* @return If the base object is an {@link Optional} and {@link Optional#isEmpty()} returns {@code true} then this
* method returns the result of coercing {@code null} to the requested {@code type}.
* <p>
* If the base object is an {@link Optional} and {@link Optional#isPresent()} returns {@code true} then
* this method returns the result of coercing {@code Optional#get()} to the requested {@code type}.
* <p>
* If the base object is not an {@link Optional} then the return value is undefined.
*/
@Override
public <T> T convertToType(ELContext context, Object obj, Class<T> type) {
Objects.requireNonNull(context);
if (obj instanceof Optional) {
Object value = null;
if (((Optional<?>) obj).isPresent()) {
Object value = ((Optional<?>) obj).get();
value = ((Optional<?>) obj).get();
// If the value is assignable to the required type, do so.
if (type.isAssignableFrom(value.getClass())) {
context.setPropertyResolved(true);
@SuppressWarnings("unchecked")
T result = (T) value;
return result;
}
}

try {
Object convertedValue = context.convertToType(value, type);
context.setPropertyResolved(true);
@SuppressWarnings("unchecked")
T result = (T) convertedValue;
return result;
} catch (ELException e) {
/*
* TODO: This isn't pretty but it works. Significant refactoring would be required to avoid the
* exception. See also ELUtil.isCoercibleFrom().
*/
}
} else {
try {
Object convertedValue = context.convertToType(value, type);
context.setPropertyResolved(true);
@SuppressWarnings("unchecked")
T result = (T) convertedValue;
return result;
} catch (ELException e) {
/*
* TODO: This isn't pretty but it works. Significant refactoring would be required to avoid the
* exception. See also Util.isCoercibleFrom().
*/
}
}
return null;
}


/**
* {@inheritDoc}
*
* @return If the base object is an {@link Optional} and {@link Optional#isEmpty()} returns {@code true} then this
* method returns {@code null}.
* <p>
* If the base object is an {@link Optional} and {@link Optional#isPresent()} returns {@code true} then
* this method returns the result of invoking the specified method on the object obtained by calling
* {@link Optional#get()} with the specified parameters.
* <p>
* If the base object is not an {@link Optional} then the return value is undefined.
*/
@Override
public Object invoke(ELContext context, Object base, Object method, Class<?>[] paramTypes, Object[] params) {
Objects.requireNonNull(context);

if (base instanceof Optional && method != null) {
context.setPropertyResolved(base, method);
if (((Optional<?>) base).isEmpty()) {
return null;
} else {
Object resolvedBase = ((Optional<?>) base).get();
return context.getELResolver().invoke(context, resolvedBase, method, paramTypes, params);
}
}

return null;
}
}

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