/**
* Gets the context of this event within a stream
*
* @return the context in struct form
*/
public StructDefinition getContext() {
/* Most common case so far */
if (fStreamContext == null) {
return fEventContext;
}
/* streamContext is not null, but the context of the event is null */
if (fEventContext == null) {
return fStreamContext;
}
// TODO: cache if this is a performance issue
/* The stream context and event context are assigned. */
StructDeclaration mergedDeclaration = new StructDeclaration(1);
Builder<String> builder = ImmutableList.<String>builder();
List<Definition> fieldValues = new ArrayList<>();
/* Add fields from the stream */
for (String fieldName : fStreamContext.getFieldNames()) {
Definition definition = fStreamContext.getDefinition(fieldName);
mergedDeclaration.addField(fieldName, definition.getDeclaration());
builder.add(fieldName);
fieldValues.add(definition);
}
ImmutableList<String> fieldNames = builder.build();
/*
* Add fields from the event context, overwrite the stream ones if
* needed.
*/
for (String fieldName : fEventContext.getFieldNames()) {
Definition definition = fEventContext.getDefinition(fieldName);
mergedDeclaration.addField(fieldName, definition.getDeclaration());
if (fieldNames.contains(fieldName)) {
fieldValues.set((fieldNames.indexOf(fieldName)), definition);
} else {
builder.add(fieldName);
fieldValues.add(definition);
}
}
fieldNames = builder.build();
StructDefinition mergedContext =
new StructDefinition(
mergedDeclaration,
this,
"context", //$NON-NLS-1$
fieldNames,
fieldValues.toArray(new Definition[fieldValues.size()]));
return mergedContext;
}
