Copyright (c) 2013, 2018 GK Software AG and others.
This program and the accompanying materials
are made available under the terms of the Eclipse Public License 2.0
which accompanies this distribution, and is available at
https://www.eclipse.org/legal/epl-2.0/
SPDX-License-Identifier: EPL-2.0
Contributors:
    Stephan Herrmann - initial API and implementation
    IBM Corporation - bug fixes
/*******************************************************************************
 * Copyright (c) 2013, 2018 GK Software AG and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     Stephan Herrmann - initial API and implementation
 *     IBM Corporation - bug fixes
 *******************************************************************************/
package org.eclipse.jdt.internal.compiler.lookup;


Implementation of 18.1.3 in JLS8
/**
 * Implementation of 18.1.3 in JLS8
 */
public class TypeBound extends ReductionResult {
	
	InferenceVariable left;
	
	// this flag contributes to the workaround controlled by InferenceContext18.ARGUMENT_CONSTRAINTS_ARE_SOFT:
	boolean isSoft;

	// here we accumulate null tagBits from any types that have been related to this type bound during incorporation:
	long nullHints;
	
	static TypeBound createBoundOrDependency(InferenceSubstitution theta, TypeBinding type, InferenceVariable variable) {
        // Part of JLS8 sect 18.1.3:
		return new TypeBound(variable, theta.substitute(theta, type), SUBTYPE, true);
	}

	
Create a true type bound or a dependency. /** Create a true type bound or a dependency. */
	TypeBound(InferenceVariable inferenceVariable, TypeBinding typeBinding, int relation) {
		this(inferenceVariable, typeBinding, relation, false);
	}
	
	TypeBound(InferenceVariable inferenceVariable, TypeBinding typeBinding, int relation, boolean isSoft) {
		this.left = inferenceVariable;
		this.right = typeBinding;
		if (((inferenceVariable.tagBits | this.right.tagBits) & TagBits.AnnotationNullMASK) != 0) {
			if ((inferenceVariable.tagBits & TagBits.AnnotationNullMASK) == (this.right.tagBits & TagBits.AnnotationNullMASK)) {
				// strip off identical nullness on both sides:
				this.left = (InferenceVariable) inferenceVariable.withoutToplevelNullAnnotation();
				this.right = this.right.withoutToplevelNullAnnotation();
			} else {
				long mask = 0;
				// extract hint, e.g.: T#0 <: @NonNull Right  =>  T#0 hinted as @NonNull
				switch (relation) {
					case SAME: 		mask = TagBits.AnnotationNullMASK; break;
					case SUBTYPE: 	mask = TagBits.AnnotationNonNull; break;  // sub of @Nullable is irrelevant
					case SUPERTYPE: mask = TagBits.AnnotationNullable; break; // super of @NonNull is irrelevant
				}
				inferenceVariable.prototype().nullHints |= this.right.tagBits & mask;
			}
		}
		this.relation = relation;
		this.isSoft = isSoft;
	}

	
distinguish bounds from dependencies. /** distinguish bounds from dependencies. */
	boolean isBound() {
		return this.right.isProperType(true);
	}
	
	@Override
	public int hashCode() {
		return this.left.hashCode() + this.right.hashCode() + this.relation;
	}
	
	@Override
	public boolean equals(Object obj) {
		if (obj instanceof TypeBound) {
			TypeBound other = (TypeBound) obj;
			return (this.relation == other.relation) && TypeBinding.equalsEquals(this.left, other.left) && TypeBinding.equalsEquals(this.right, other.right);
		}
		return false;
	}
	
	// debugging:
	@Override
	public String toString() {
		boolean isBound = this.right.isProperType(true);
		StringBuffer buf = new StringBuffer();
		buf.append(isBound ? "TypeBound  " : "Dependency "); //$NON-NLS-1$ //$NON-NLS-2$
		buf.append(this.left.sourceName);
		buf.append(relationToString(this.relation));
		buf.append(this.right.readableName());
		return buf.toString();
	}
}