[WIP] Canner system

[glelouet]

Depends on #113 for the yaml tests

This feature allows to specify how fields are accessed (inside a container, "can"), with developer extension in mind

• weak reference and no container(=default) options
• developer extensions
• javafx container in the external modules (binds to external libs)
• WeakHashMap for caching, abstract FieldType createField(Object) for cache miss

User Usage

add the field option corresponding :

WeakRefTest:
  var:
     hash:
        class: string
        options:
           - weakref

Which generates:

public class WeakRefTest {
    private WeakReference<String> hash;

    /**
     * set the {@link #hash}
     */
    public void setHash(String hash) {
        this.hash = new WeakReference<String>(hash);
    }

    /**
     * @return the {@link #hash}
     */
    public String getHash() {
        return hash.get();
    }
}

Dev extension

Model :

The available canners are listed by the generator, the stream of which can be concatenated to override values

	Stream<Entry<String, Class<? extends FieldCanner>>> FlatStructureGenerator::streamCanners() {
		return Stream.of(
				new SimpleEntry<>("weakref", WeakReferenceCanner.class),
				new SimpleEntry<>("", NoCanner.class));
	}

If the option received by the FlatStructureGenerator is such an alias of canner, it is stored in the FieldOptions

	protected void FlatStructureGenerator::applyToFieldOptions(String optStr, FieldOptions options) {
       …
		if (cannersAliases().contains(optStr)) {
			options.setCanner(optStr);
			return;
		}

At the moment only the empty one (NoCanner) and the Weak Reference one (WeakReferenceCanner) are present.

Those canners can change the actual field type ( String -> WeakReference\<String> ) , the way it is get ( field -> field.get() ), set (field=param -> field= new WeakReference<String>(param)), and app specific property accessor.
Default "additional" method is scheduled to allow more complex code additions.

Extension :

If a developer wants to change (ad or replace), he can create his own class, and register them in his own Generator subclass. for example,

	Stream<Entry<String, Class<? extends FieldCanner>>> FlatStructureGenerator::streamCanners() {
		return Stream.concat(
				super.streamCanners(), 
				Stream.of(new SimpleEntry<>("", WeakReferenceCanner.class)));

would make the default accessor using weak references. Which would fail for primitive but hey ! he can.

[glelouet]

I think mutator would be a better name.