/*
    * SPDX-FileCopyrightText: none
    * SPDX-License-Identifier: CC0-1.0
    */
   
   package dev.metaschema.core.metapath.item.function;
   
   import java.util.stream.Stream;
   
  import dev.metaschema.core.metapath.DynamicContext;
  import dev.metaschema.core.metapath.item.ICollectionValue;
  import dev.metaschema.core.metapath.item.IItem;
  import dev.metaschema.core.metapath.item.ISequence;
  import edu.umd.cs.findbugs.annotations.NonNull;
  
  /**
   * A common interface for all key specifier implementations.
   */
  @FunctionalInterface
  public interface IKeySpecifier {
  
    /**
     * Perform a lookup on the provided target item.
     *
     * @param targetItem
     *          the item to query
     * @param dynamicContext
     *          the dynamic context to use for expression evaluation
     * @param focus
     *          the focus item for expression evaluation
     * @return a stream of collection values matching this key specifier
     */
    Stream<? extends ICollectionValue> lookup(
        @NonNull IItem targetItem,
        @NonNull DynamicContext dynamicContext,
        @NonNull ISequence<?> focus);
  }