RealDeltaLive.java

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 * PlantUML : a free UML diagram generator
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 * Original Author:  Arnaud Roques
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package net.sourceforge.plantuml.real;

import java.util.function.DoubleSupplier;

// Like RealDelta, except the offset is read live, via a DoubleSupplier,
// instead of being baked in as a fixed double at construction time. Used
// (through RealUtils.withLiveOffset()) wherever the offset comes from a
// mutable field that can still change after this Real is constructed --
// e.g. a margin grown by a self-message loop discovered later during
// layout -- so that every getCurrentValue()/ensureBiggerThan() caller
// always sees the offset's FINAL value: getCurrentValue() is only ever
// read during/after RealLine.compile(), which itself runs once, strictly
// after every such mutation has already happened, regardless of when this
// Real itself was constructed or when its constraint was registered.
class RealDeltaLive extends RealMoveable {

	private final Real delegated;
	private final DoubleSupplier delta;

	RealDeltaLive(Real delegated, DoubleSupplier delta) {
		super(((AbstractReal) delegated).getLine(), "[DelegatedLive]");
		this.delegated = delegated;
		this.delta = delta;
	}

	@Override
	double getCurrentValueInternal() {
		return delegated.getCurrentValue() + delta.getAsDouble();
	}

	public Real addAtLeast(double d) {
		return new RealDeltaLive(delegated.addAtLeast(d), delta);
	}

	public void ensureBiggerThan(Real other) {
		delegated.ensureBiggerThan(new RealDeltaLive(other, () -> -delta.getAsDouble()));
	}

	void move(double d) {
		((RealMoveable) delegated).move(d);
	}

}