content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you under the Apache License, Version 2.0 (the
   * "License"); you may not use this file except in compliance
   * with the License.  You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package com.datastax.dse.driver.api.core.graph;
  
  import com.datastax.oss.driver.api.core.type.reflect.GenericType;
  import java.util.List;
  import java.util.Map;
  import java.util.Set;
  import org.apache.tinkerpop.gremlin.process.traversal.Path;
  import org.apache.tinkerpop.gremlin.structure.Edge;
  import org.apache.tinkerpop.gremlin.structure.Property;
  import org.apache.tinkerpop.gremlin.structure.Vertex;
  import org.apache.tinkerpop.gremlin.structure.VertexProperty;
  
  /**
   * A node in a tree-like structure representing a Graph or a Graph component.
   *
   * <p>It can be:
   *
   * <ul>
   *   <li>a scalar value of a primitive type (boolean, string, int, long, double);
   *   <li>a graph element (vertex, edge, path or property);
   *   <li>a list of nodes;
   *   <li>a set of nodes;
   *   <li>a map of nodes.
   * </ul>
   *
   * This interface provides test methods to find out what a node represents, and conversion methods
   * to cast it to a particular Java type. Two generic methods {@link #as(Class)} and {@link
   * #as(GenericType)} can produce any arbitrary Java type, provided that the underlying serialization
   * runtime has been correctly configured to support the requested conversion.
   */
  public interface GraphNode {
  
    /** Whether this node represents a {@code null} value. */
    boolean isNull();
  
    /**
     * Returns {@code true} if this node is a {@link Map}, and {@code false} otherwise.
     *
     * <p>If this method returns {@code true}, you can convert this node with {@link #asMap()}, or use
     * {@link #keys()} and {@link #getByKey(Object)} to access the individual fields (note that
     * entries are not ordered, so {@link #getByIndex(int)} does not work).
     */
    boolean isMap();
  
    /** The keys of this map node, or an empty iterator if it is not a map. */
    Iterable<?> keys();
  
    /**
     * Returns the value for the given key as a node.
     *
     * <p>If this node is not a map, or does not contain the specified key, {@code null} is returned.
     *
     * <p>If the property value has been explicitly set to {@code null}, implementors may return a
     * special "null node" instead of {@code null}.
     */
    GraphNode getByKey(Object key);
  
    /** Deserializes and returns this node as a {@link Map}. */
    <K, V> Map<K, V> asMap();
  
    /**
     * Returns {@code true} if this node is a {@link List}, and {@code false} otherwise.
     *
     * <p>If this method returns {@code true}, you can convert this node with {@link #asList()}, or
     * use {@link #size()} and {@link #getByIndex(int)} to access the individual fields.
     */
    boolean isList();
  
    /** The size of the current node, if it is a list or map, or {@code 0} otherwise. */
    int size();
  
    /**
     * Returns the element at the given index as a node.
     *
     * <p>If this node is not a list, or {@code index} is out of bounds (i.e. less than zero or {@code
     * >= size()}, {@code null} is returned; no exception will be thrown.
     *
     * <p>If the requested element has been explicitly set to {@code null}, implementors may return a
     * special "null node" instead of {@code null}.
     */
    GraphNode getByIndex(int index);
  
    /** Deserializes and returns this node as a {@link List}. */
    <T> List<T> asList();
  
    /**
     * Returns {@code true} if this node is a simple scalar value, (i.e., string, boolean or number),
     * and {@code false} otherwise.
     *
     * <p>If this method returns {@code true}, you can convert this node with {@link #asString()},
     * {@link #asBoolean()}, {@link #asInt()}, {@link #asLong()} or {@link #asDouble()}.
     */
    boolean isValue();
  
    /**
     * Returns this node as an integer.
     *
     * <p>If the underlying object is not convertible to integer, implementors may choose to either
     * throw {@link ClassCastException} or return [null | empty | some default value], whichever is
     * deemed more appropriate.
     */
    int asInt();
  
    /**
     * Returns this node as a boolean.
     *
     * <p>If the underlying object is not convertible to boolean, implementors may choose to either
     * throw {@link ClassCastException} or return [null | empty | some default value], whichever is
     * deemed more appropriate.
     */
    boolean asBoolean();
  
    /**
     * Returns this node as a long integer.
     *
     * <p>If the underlying object is not convertible to long, implementors may choose to either throw
     * {@link ClassCastException} or return [null | empty | some default value], whichever is deemed
     * more appropriate.
     */
    long asLong();
  
    /**
     * Returns this node as a long integer.
     *
     * <p>If the underlying object is not convertible to double, implementors may choose to either
     * throw {@link ClassCastException} or return [null | empty | some default value], whichever is
     * deemed more appropriate.
     */
    double asDouble();
  
    /**
     * A valid string representation of this node.
     *
     * <p>If the underlying object is not convertible to a string, implementors may choose to either
     * throw {@link ClassCastException} or return an empty string, whichever is deemed more
     * appropriate.
     */
    String asString();
  
    /**
     * Deserializes and returns this node as an instance of {@code clazz}.
     *
     * <p>Before attempting such a conversion, there must be an appropriate converter configured on
     * the underlying serialization runtime.
     */
    <ResultT> ResultT as(Class<ResultT> clazz);
  
    /**
     * Deserializes and returns this node as an instance of the given {@link GenericType type}.
     *
     * <p>Before attempting such a conversion, there must be an appropriate converter configured on
     * the underlying serialization runtime.
     */
    <ResultT> ResultT as(GenericType<ResultT> type);
  
    /**
     * Returns {@code true} if this node is a {@link Vertex}, and {@code false} otherwise.
     *
     * <p>If this method returns {@code true}, then {@link #asVertex()} can be safely called.
     */
    boolean isVertex();
  
    /** Returns this node as a Tinkerpop {@link Vertex}. */
    Vertex asVertex();
  
    /**
     * Returns {@code true} if this node is a {@link Edge}, and {@code false} otherwise.
     *
     * <p>If this method returns {@code true}, then {@link #asEdge()} can be safely called.
     */
    boolean isEdge();
  
    /** Returns this node as a Tinkerpop {@link Edge}. */
    Edge asEdge();
  
    /**
     * Returns {@code true} if this node is a {@link Path}, and {@code false} otherwise.
     *
     * <p>If this method returns {@code true}, then {@link #asPath()} can be safely called.
     */
    boolean isPath();
  
    /** Returns this node as a Tinkerpop {@link Path}. */
    Path asPath();
  
    /**
     * Returns {@code true} if this node is a {@link Property}, and {@code false} otherwise.
     *
     * <p>If this method returns {@code true}, then {@link #asProperty()} can be safely called.
     */
    boolean isProperty();
  
    /** Returns this node as a Tinkerpop {@link Property}. */
    <T> Property<T> asProperty();
  
    /**
     * Returns {@code true} if this node is a {@link VertexProperty}, and {@code false} otherwise.
     *
     * <p>If this method returns {@code true}, then {@link #asVertexProperty()} ()} can be safely
     * called.
     */
    boolean isVertexProperty();
  
    /** Returns this node as a Tinkerpop {@link VertexProperty}. */
    <T> VertexProperty<T> asVertexProperty();
  
    /**
     * Returns {@code true} if this node is a {@link Set}, and {@code false} otherwise.
     *
     * <p>If this method returns {@code true}, you can convert this node with {@link #asSet()}, or use
     * {@link #size()}.
     */
    boolean isSet();
  
    /** Deserializes and returns this node as a {@link Set}. */
    <T> Set<T> asSet();
  }
  