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Permazen core API classes which provide objects, fields, indexes, queries, and schema management on top of a key/value store.
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/*
 * Copyright (C) 2015 Archie L. Cobbs. All rights reserved.
 */

package io.permazen.core;

import java.util.Collection;

/**
 * Visitor pattern interface for {@link Field}s.
 *
 * @param  switch method return type
 * @see Field#visit Field.visit()
 */
public interface FieldSwitch {

    /**
     * Handle a {@link SetField}.
     *
     * 
     * The implementation in {@link FieldSwitch} delegates to {@link #caseCollectionField caseCollectionField()}.
     *
     * @param field visiting field
     * @param  set element type
     * @return visitor return value
     */
    default  R caseSetField(SetField field) {
        return this.caseCollectionField(field);
    }

    /**
     * Handle a {@link ListField}.
     *
     * 

     * The implementation in {@link FieldSwitch} delegates to {@link #caseCollectionField caseCollectionField()}.
     *
     * @param field visiting field
     * @param  list element type
     * @return visitor return value
     */
    default  R caseListField(ListField field) {
        return this.caseCollectionField(field);
    }

    /**
     * Handle a {@link MapField}.
     *
     * 

     * The implementation in {@link FieldSwitch} delegates to {@link #caseComplexField caseComplexField()}.
     *
     * @param field visiting field
     * @param  map key type
     * @param  map value type
     * @return visitor return value
     */
    default  R caseMapField(MapField field) {
        return this.caseComplexField(field);
    }

    /**
     * Handle a {@link SimpleField}.
     *
     * 

     * The implementation in {@link FieldSwitch} delegates to {@link #caseField caseField()}.
     *
     * @param field visiting field
     * @param  field type
     * @return visitor return value
     */
    default  R caseSimpleField(SimpleField field) {
        return this.caseField(field);
    }

    /**
     * Handle a {@link ReferenceField}.
     *
     * 

     * The implementation in {@link FieldSwitch} delegates to {@link #caseSimpleField caseSimpleField()}.
     *
     * @param field visiting field
     * @return visitor return value
     */
    default R caseReferenceField(ReferenceField field) {
        return this.caseSimpleField(field);
    }

    /**
     * Handle a {@link CounterField}.
     *
     * 

     * The implementation in {@link FieldSwitch} delegates to {@link #caseField caseField()}.
     *
     * @param field visiting field
     * @return visitor return value
     */
    default R caseCounterField(CounterField field) {
        return this.caseField(field);
    }

    /**
     * Handle an {@link EnumField}.
     *
     * 

     * The implementation in {@link FieldSwitch} delegates to {@link #caseSimpleField caseSimpleField()}.
     *
     * @param field visiting field
     * @return visitor return value
     */
    default R caseEnumField(EnumField field) {
        return this.caseSimpleField(field);
    }

    /**
     * Handle an {@link EnumArrayField}.
     *
     * 

     * The implementation in {@link FieldSwitch} delegates to {@link #caseSimpleField caseSimpleField()}.
     *
     * @param field visiting field
     * @return visitor return value
     */
    default R caseEnumArrayField(EnumArrayField field) {
        return this.caseSimpleField(field);
    }

    /**
     * Visitor pattern roll-up method.
     *
     * 

     * The implementation in {@link FieldSwitch} delegates to {@link #caseComplexField caseComplexField()}.
     *
     * @param field visiting field
     * @param  field type
     * @param  collection element type
     * @return visitor return value
     */
    default , E> R caseCollectionField(CollectionField field) {
        return this.caseComplexField(field);
    }

    /**
     * Visitor pattern roll-up method.
     *
     * 

     * The implementation in {@link FieldSwitch} delegates to {@link #caseField caseField()}.
     *
     * @param field visiting field
     * @param  field type
     * @return visitor return value
     */
    default  R caseComplexField(ComplexField field) {
        return this.caseField(field);
    }

    /**
     * Visitor pattern roll-up method.
     *
     * 
     * The implementation in {@link FieldSwitch} always throws {@link UnsupportedOperationException}.
     *
     * @param field visiting field
     * @param  field type
     * @return visitor return value
     */
    default  R caseField(Field field) {
        throw new UnsupportedOperationException(String.format("field type not handled: %s", field));
    }
}