/**
* Finds the next {@link ForEachExecution} in the collection iterated by <code>
* foreachContextIterator</code> that is for the same {@link DelayedReference#getQueryElement()
* property init} as the <code>reference</code> and that is for the same {@link
* ForEachExecution#getSourceModelElement() source element} as the <code>reference</code>. If no
* such element is found, <code>null</code> is returned
*
* <p>Postcondition: if a non-<code>null</code> result is returned, the <code>
* foreachContextIterator</code> is at that element so that calling {@link Iterator#remove()}
* removes the element just returned
*
* @param foreachContextIterator must not be <code>null</code>
*/
private ForEachExecution getNextForeachContext(
Iterator<ForEachExecution> foreachContextIterator, DelayedReference reference) {
ForEachExecution result = null;
while (foreachContextIterator.hasNext() && result == null) {
ForEachExecution fec = foreachContextIterator.next();
if (fec.getForeachPedicatePropertyInit().equals(reference.getQueryElement())
&& reference.getModelElement().equals(fec.getSourceModelElement())) {
result = fec;
}
}
return result;
}
private ForEachExecution produceNewForEachContext(
DelayedReference reference, ForeachProductionResult producedResult) {
ForEachExecution newContext = TextblocksFactory.eINSTANCE.createForEachExecution();
newContext.setForeachPedicatePropertyInit(
(ForeachPredicatePropertyInit) reference.getQueryElement());
newContext.setSourceModelElement((EObject) reference.getModelElement());
newContext.setContextElement(
(EObject) producedResult.getForeachExpressionResultForWhichProduced());
newContext.setTemplateUsedForProduction(producedResult.getTemplateUsedForProduction());
newContext.setResultModelElement((EObject) reference.getRealValue());
return newContext;
}
/**
* For a {@link ForEachExecution} that is known to be for the same source element and <code>
* foreach</code> clause as <code>producedResult</code>, checks if the template used by the
* previous execution as documented by <code>nextOldForeachContext</code> is the same as that used
* in <code>producedResult</code>.
*/
private boolean isTargetElementReusable(
ForEachExecution nextOldForeachContext, ForeachProductionResult producedResult) {
return nextOldForeachContext.getTemplateUsedForProduction()
== producedResult.getTemplateUsedForProduction();
}
/**
* A <code>foreach</code> expression was (re-)evaluated, and for each result, based on any <code>
* when</code>/ <code>as</code> {@link com.sap.furcas.metamodel.FURCAS.TCS.PredicateSemantic}
* elements, the corresponding template's production rule was executed by the parser. This
* produced a {@link ModelElementProxy} which has not yet been turned into a real {@link EObject}
* yet nor has it been entered into the target feature.
*
* <p>Prior executions of the same <code>foreach</code> predicate on the same source model element
* may have happened. In this case, there will be {@link ForEachExecution} records documenting
* this. If no such records are found, all proxies produced will be materialized as {@link
* EObject}s and {@link #setReference(DelayedReference, Object, IModelAdapter, ModelElementProxy,
* IModelInjector, int) added/set} to/into the target feature described by the <code>reference
* </code>.
*
* <p>If {@link ForEachExecution} objects are found for the source element and <code>foreach
* </code> predicate, their {@link ForEachExecution#getResultModelElement() result elements} are
* obtained and compared to the new {@link ForeachProductionResult production instructions} which
* also contain the {@link Template} used to produce the target element. The template is used to
* compare the element types in order to try to re-use already existing elements.
*
* <p>In case a target object from a prior evaluation can be re-used, it is set as the proxy's
* {@link ModelElementProxy#setRealObject(Object) real object}, and no new target object is
* created for this <code>foreach</code> result. Otherwise, a new target object is created. The
* re-used or created object is then used to replace (single multiplicity) or to add to
* (many-multiplicity) the target feature.
*
* <p>As to the re-use strategy, we distinguish between re-using the {@link ForEachExecution} hull
* only and the {@link ForEachExecution#getResultModelElement() result element} that was produced
* in an earlier run. Two element collections are compared, namely those listed as {@link
* ForEachExecution#getResultModelElement() result elements} of earlier evaluations on the <code>
* reference</code>'s {@link DelayedReference#getTextBlock() text block} for the same <code>
* foreach</code> predicate; and those described by <code>producedResults</code> which contains
* proxies and the templates telling the types and modes with which they were created. The two
* collections are iterated in parallel. If the {@link ForEachExecution}'s template matches that
* in the current <code>producedResults</code> element, the {@link
* ForEachExecution#getResultModelElement() old result element} is re-used by {@link
* ModelElementProxy#setRealObject(Object) setting} it on the proxy. Otherwise, a new element is
* produced using {@link ModelInjector#createOrResolve(ModelElementProxy, ANTLR3LocationToken,
* ANTLR3LocationToken)} and the existing {@link ForEachExecution} is updated for the new result
* element, template, etc. If the collection of {@link ForEachExecution} elements is shorter than
* that of the <code>producedResults</code>, additional {@link ForEachExecution} elements are
* added to the <code>reference</code>'s {@link TextBlock#getForEachExecutions() textblock's
* foreach context list}. Extraneous elements are deleted from it.
*
* <p>It's obvious that there may be more sophisticated re-use strategies based on longest
* sequence etc., but those may be added later.
*
* @param injector TODO
* @param producedResults the {@link ForeachProductionResult#getTemplateUsedForProduction()
* templates} need to be set only if text blocks are being produced by the parser run
*/
private void setReferenceAndUpdateForeachContexts(
DelayedReference reference,
IModelAdapter modelAdapter,
IModelInjector injector,
List<ForeachProductionResult> producedResults)
throws ModelElementCreationException, ModelAdapterException {
Iterator<ForEachExecution> foreachContextIterator = null;
ForEachExecution nextOldForeachContext = null;
if (reference.getTextBlock() != null) {
foreachContextIterator =
((TextBlock) reference.getTextBlock()).getForEachExecutions().iterator();
nextOldForeachContext = getNextForeachContext(foreachContextIterator, reference);
}
int i = 0;
for (ForeachProductionResult producedResult : producedResults) {
// check for a re-usable target element of ForEachContext with its result element
if (nextOldForeachContext != null
&& isTargetElementReusable(nextOldForeachContext, producedResult)) {
// re-use the target object referenced by the ForEachContext and the ForEachContext itself
producedResult
.getProducedProxy()
.setRealObject(nextOldForeachContext.getResultModelElement());
if (producedResult.getForeachExpressionResultForWhichProduced() instanceof EObject) {
nextOldForeachContext.setContextElement(
(EObject) producedResult.getForeachExpressionResultForWhichProduced());
} else if (producedResult.getForeachExpressionResultForWhichProduced() instanceof EObject) {
nextOldForeachContext.setContextString(
(String) producedResult.getForeachExpressionResultForWhichProduced());
}
reference.setRealValue(nextOldForeachContext.getResultModelElement());
} else {
// target element is not re-usable, a new one needs to be produced
setReference(
reference,
producedResult.getForeachExpressionResultForWhichProduced(),
modelAdapter,
producedResult.getProducedProxy(),
injector,
i);
if (reference.getTextBlock() != null
&& producedResult.getTemplateUsedForProduction() != null) {
// if we have a ForEachContext element for the current source element and foreach
// predicate,
// re-use and update it:
if (nextOldForeachContext == null) {
// no ForEachContext element; produce a new one and append
ForEachExecution newContext = produceNewForEachContext(reference, producedResult);
((TextBlock) reference.getTextBlock()).getForEachExecutions().add(newContext);
} else {
// ForEachContext names a template/element that can't be re-used; update it
// correspondingly
Object result = producedResult.getForeachExpressionResultForWhichProduced();
if (result instanceof EObject) {
nextOldForeachContext.setContextElement(
(EObject) producedResult.getForeachExpressionResultForWhichProduced());
} else if (result instanceof String) {
nextOldForeachContext.setContextString(
(String) producedResult.getForeachExpressionResultForWhichProduced());
}
nextOldForeachContext.setTemplateUsedForProduction(
producedResult.getTemplateUsedForProduction());
nextOldForeachContext.setResultModelElement(
(EObject) producedResult.getProducedProxy().getRealObject());
}
}
}
if (nextOldForeachContext != null
&& foreachContextIterator != null
&& foreachContextIterator.hasNext()) {
nextOldForeachContext = foreachContextIterator.next();
} else {
nextOldForeachContext = null;
}
i++;
}
// delete remaining old ForEachContext entries from reference's textblock
while (nextOldForeachContext != null) {
foreachContextIterator.remove();
nextOldForeachContext = getNextForeachContext(foreachContextIterator, reference);
}
}
