org.apache.sling.scripting.sightly.use.ProviderOutcome Maven / Gradle / Ivy
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package org.apache.sling.scripting.sightly.use;
/**
* Result returned by a {@link UseProvider}.
*/
public final class ProviderOutcome {
// a generic failure without a cause returned by #failure()
private static final ProviderOutcome GENERIC_FAILURE = new ProviderOutcome(false, null, null);
// whether this is a success or failure
private final boolean success;
// the result value in case of success (may be null)
private final Object result;
// the reason for failure in case of failure (may be null)
private final Throwable cause;
/**
* Creates an outcome instance
*
* @param success {@code true} to indicate success or {@code false} to indicate failure
* @param result optional result value in case of success, may be {@code null}
* @param cause optional cause in case of failure, may be {@code null}
*/
private ProviderOutcome(boolean success, Object result, Throwable cause) {
this.success = success;
this.result = result;
this.cause = cause;
}
/**
* Create a successful outcome
*
* @param result the result
* @return a successful result
*/
public static ProviderOutcome success(Object result) {
return new ProviderOutcome(true, result, null);
}
/**
* Create a failed outcome without a specific {@link #getCause() cause}. This method must be used for creating outcomes that don't
* signal an error but rather the fact that the {@link UseProvider} is not capable of fulfilling the request.
*
* @return a failed outcome
*/
public static ProviderOutcome failure() {
return GENERIC_FAILURE;
}
/**
* Create a failed outcome with the given {@link #getCause() cause}. This method must be used when the {@link UseProvider} is
* capable of fulfilling the request but an error condition prevents the provider from doing so.
*
* @param cause The reason for this failure, which may be {@code null}
* @return a failed outcome
*/
public static ProviderOutcome failure(Throwable cause) {
return new ProviderOutcome(false, null, cause);
}
/**
* If the given obj is not {@code null} return a {@link #success(Object) successful outcome}, with the given result. Otherwise, return
* {@link #failure()}.
*
* @param obj the result
* @return an outcome based on whether the parameter is null or not
*/
public static ProviderOutcome notNullOrFailure(Object obj) {
return (obj == null) ? failure() : success(obj);
}
/**
* Check if the outcome has been successful
*
* @return the outcome success status
*/
public boolean isSuccess() {
return success;
}
/**
* Check whether the outcome is a failure
*
* @return the outcome failure status
*/
public boolean isFailure() {
return !isSuccess();
}
/**
* Get the result in this outcome.
*
* @return the result of the container
* @throws IllegalStateException if the outcome is a failure
*/
public Object getResult() {
if (!success) {
throw new IllegalStateException("Outcome has not been successful");
}
return result;
}
/**
* Returns the cause for this failure outcome or {@code null} if this outcome is a success or no cause has been defined with the
* {@link #failure(Throwable)} method.
*
* @return the cause for this failure outcome.
*/
public Throwable getCause() {
return cause;
}
}