package edu.internet2.middleware.grouperClientExt.com.fasterxml.jackson.databind;
   
   import java.io.IOException;
   import java.math.BigDecimal;
   import java.math.BigInteger;
   import java.util.*;
   
   import edu.internet2.middleware.grouperClientExt.com.fasterxml.jackson.core.*;
   import edu.internet2.middleware.grouperClientExt.com.fasterxml.jackson.databind.node.JsonNodeType;
  import edu.internet2.middleware.grouperClientExt.com.fasterxml.jackson.databind.node.MissingNode;
  import edu.internet2.middleware.grouperClientExt.com.fasterxml.jackson.databind.util.ClassUtil;
  
  /**
   * Base class for all JSON nodes, which form the basis of JSON
   * Tree Model that Jackson implements.
   * One way to think of these nodes is to consider them
   * similar to DOM nodes in XML DOM trees.
   *<p>
   * As a general design rule, most accessors ("getters") are included
   * in this base class, to allow for traversing structure without
   * type casts. Most mutators, however, need to be accessed through
   * specific sub-classes (such as <code>ObjectNode</code>
   * and <code>ArrayNode</code>).
   * This seems sensible because proper type
   * information is generally available when building or modifying
   * trees, but less often when reading a tree (newly built from
   * parsed JSON content).
   *<p>
   * Actual concrete sub-classes can be found from package
   * {@link edu.internet2.middleware.grouperClientExt.com.fasterxml.jackson.databind.node}.
   *<p>
   * Note that it is possible to "read" from nodes, using
   * method {@link TreeNode#traverse(ObjectCodec)}, which will result in
   * a {@link JsonParser} being constructed. This can be used for (relatively)
   * efficient conversations between different representations; and it is what
   * core databind uses for methods like {@link ObjectMapper#treeToValue(TreeNode, Class)}
   * and {@link ObjectMapper#treeAsTokens(TreeNode)}
   */
  public abstract class JsonNode
      extends JsonSerializable.Base // i.e. implements JsonSerializable
      implements TreeNode, Iterable<JsonNode>
  {
      /*
      /**********************************************************
      /* Construction, related
      /**********************************************************
       */
      
      protected JsonNode() { }
  
      /**
       * Method that can be called to get a node that is guaranteed
       * not to allow changing of this node through mutators on
       * this node or any of its children.
       * This means it can either make a copy of this node (and all
       * mutable children and grand children nodes), or node itself
       * if it is immutable.
       *<p>
       * Note: return type is guaranteed to have same type as the
       * node method is called on; which is why method is declared
       * with local generic type.
       * 
       * @since 2.0
       * 
       * @return Node that is either a copy of this node (and all non-leaf
       *    children); or, for immutable leaf nodes, node itself.
       */
      public abstract <T extends JsonNode> T deepCopy();
  
      /*
      /**********************************************************
      /* TreeNode implementation
      /**********************************************************
       */
  
  //  public abstract JsonToken asToken();
  //  public abstract JsonToken traverse();
  //  public abstract JsonToken traverse(ObjectCodec codec);
  //  public abstract JsonParser.NumberType numberType();
  
      @Override
      public int size() { return 0; }
  
      /**
       * Convenience method that is functionally same as:
       *<pre>
       *    size() == 0
       *</pre>
       * for all node types.
       *
       * @since 2.10
       */
      public boolean isEmpty() { return size() == 0; }
  
      @Override
      public final boolean isValueNode()
      {
          switch (getNodeType()) {
              case ARRAY: case OBJECT: case MISSING:
                 return false;
             default:
                 return true;
         }
     }
 
     @Override
     public final boolean isContainerNode() {
         final JsonNodeType type = getNodeType();
         return type == JsonNodeType.OBJECT || type == JsonNodeType.ARRAY;
     }
 
     @Override
     public boolean isMissingNode() {
         return false;
     }
 
     @Override
     public boolean isArray() {
         return false;
     }
 
     @Override
     public boolean isObject() {
         return false;
     }
 
     /**
      * Method for accessing value of the specified element of
      * an array node. For other nodes, null is always returned.
      *<p>
      * For array nodes, index specifies
      * exact location within array and allows for efficient iteration
      * over child elements (underlying storage is guaranteed to
      * be efficiently indexable, i.e. has random-access to elements).
      * If index is less than 0, or equal-or-greater than
      * <code>node.size()</code>, null is returned; no exception is
      * thrown for any index.
      *<p>
      * NOTE: if the element value has been explicitly set as <code>null</code>
      * (which is different from removal!),
      * a {@link edu.internet2.middleware.grouperClientExt.com.fasterxml.jackson.databind.node.NullNode} will be returned,
      * not null.
      *
      * @return Node that represent value of the specified element,
      *   if this node is an array and has specified element.
      *   Null otherwise.
      */
     @Override
     public abstract JsonNode get(int index);
 
     /**
      * Method for accessing value of the specified field of
      * an object node. If this node is not an object (or it
      * does not have a value for specified field name), or
      * if there is no field with such name, null is returned.
      *<p>
      * NOTE: if the property value has been explicitly set as <code>null</code>
      * (which is different from removal!),
      * a {@link edu.internet2.middleware.grouperClientExt.com.fasterxml.jackson.databind.node.NullNode} will be returned,
      * not null.
      *
      * @return Node that represent value of the specified field,
      *   if this node is an object and has value for the specified
      *   field. Null otherwise.
      */
     @Override
     public JsonNode get(String fieldName) { return null; }
     /**
      * This method is similar to {@link #get(String)}, except
      * that instead of returning null if no such value exists (due
      * to this node not being an object, or object not having value
      * for the specified field),
      * a "missing node" (node that returns true for
      * {@link #isMissingNode}) will be returned. This allows for
      * convenient and safe chained access via path calls.
      */
 
     @Override
     public abstract JsonNode path(String fieldName);
 
     /**
      * This method is similar to {@link #get(int)}, except
      * that instead of returning null if no such element exists (due
      * to index being out of range, or this node not being an array),
      * a "missing node" (node that returns true for
      * {@link #isMissingNode}) will be returned. This allows for
      * convenient and safe chained access via path calls.
      */
     @Override
     public abstract JsonNode path(int index);
 
     @Override
     public Iterator<String> fieldNames() {
         return ClassUtil.emptyIterator();
     }
 
     /**
      * Method for locating node specified by given JSON pointer instances.
      * Method will never return null; if no matching node exists, 
      *   will return a node for which {@link #isMissingNode()} returns true.
      * 
      * @return Node that matches given JSON Pointer: if no match exists,
      *   will return a node for which {@link #isMissingNode()} returns true.
      * 
      * @since 2.3
      */
     @Override
     public final JsonNode at(JsonPointer ptr)
     {
         // Basically: value nodes only match if we have "empty" path left
         if (ptr.matches()) {
             return this;
         }
         JsonNode n = _at(ptr);
         if (n == null) {
             return MissingNode.getInstance();
         }
         return n.at(ptr.tail());
     }
 
     /**
      * Convenience method that is functionally equivalent to:
      *<pre>
      *   return at(JsonPointer.valueOf(jsonPointerExpression));
      *</pre>
      *<p>
      * Note that if the same expression is used often, it is preferable to construct
      * {@link JsonPointer} instance once and reuse it: this method will not perform
      * any caching of compiled expressions.
      * 
      * @param jsonPtrExpr Expression to compile as a {@link JsonPointer}
      *   instance
      * 
      * @return Node that matches given JSON Pointer: if no match exists,
      *   will return a node for which {@link TreeNode#isMissingNode()} returns true.
      * 
      * @since 2.3
      */
     @Override
     public final JsonNode at(String jsonPtrExpr) {
         return at(JsonPointer.compile(jsonPtrExpr));
     }
 
     /**
      * Helper method used by other methods for traversing the next step
      * of given path expression, and returning matching value node if any:
      * if no match, {@code null} is returned.
      *
      * @param ptr Path expression to use
      *
      * @return Either matching {@link JsonNode} for the first step of path or
      *    {@code null} if no match (including case that this node is not a container)
      */
     protected abstract JsonNode _at(JsonPointer ptr);
 
     /*
     /**********************************************************
     /* Public API, type introspection
     /**********************************************************
      */
 
     // // First high-level division between values, containers and "missing"
 
     /**
      * Return the type of this node
      *
      * @return the node type as a {@link JsonNodeType} enum value
      *
      * @since 2.2
      */
     public abstract JsonNodeType getNodeType();
 
     /**
      * Method that can be used to check if the node is a wrapper
      * for a POJO ("Plain Old Java Object" aka "bean".
      * Returns true only for
      * instances of <code>POJONode</code>.
      *
      * @return True if this node wraps a POJO
      */
     public final boolean isPojo() {
         return getNodeType() == JsonNodeType.POJO;
     }
 
     /**
      * @return True if this node represents a numeric JSON value
      */
     public final boolean isNumber() {
         return getNodeType() == JsonNodeType.NUMBER;
     }
 
     /**
      * 
      * @return True if this node represents an integral (integer)
      *   numeric JSON value
      */
     public boolean isIntegralNumber() { return false; }
 
     /**
      * @return True if this node represents a non-integral
      *   numeric JSON value
      */
     public boolean isFloatingPointNumber() { return false; }
 
     /**
      * Method that can be used to check whether contained value
      * is a number represented as Java <code>short</code>.
      * Note, however, that even if this method returns false, it
      * is possible that conversion would be possible from other numeric
      * types -- to check if this is possible, use
      * {@link #canConvertToInt()} instead.
      * 
      * @return True if the value contained by this node is stored as Java short
      */
     public boolean isShort() { return false; }
 
     /**
      * Method that can be used to check whether contained value
      * is a number represented as Java <code>int</code>.
      * Note, however, that even if this method returns false, it
      * is possible that conversion would be possible from other numeric
      * types -- to check if this is possible, use
      * {@link #canConvertToInt()} instead.
      * 
      * @return True if the value contained by this node is stored as Java int
      */
     public boolean isInt() { return false; }
 
     /**
      * Method that can be used to check whether contained value
      * is a number represented as Java <code>long</code>.
      * Note, however, that even if this method returns false, it
      * is possible that conversion would be possible from other numeric
      * types -- to check if this is possible, use
      * {@link #canConvertToLong()} instead.
      * 
      * @return True if the value contained by this node is stored as Java <code>long</code>
      */
     public boolean isLong() { return false; }
 
     /**
      * @since 2.2
      */
     public boolean isFloat() { return false; }
 
     public boolean isDouble() { return false; }
     public boolean isBigDecimal() { return false; }
     public boolean isBigInteger() { return false; }
 
     /**
      * Method that checks whether this node represents basic JSON String
      * value.
      */
     public final boolean isTextual() {
         return getNodeType() == JsonNodeType.STRING;
     }
 
     /**
      * Method that can be used to check if this node was created from
      * JSON boolean value (literals "true" and "false").
      */
     public final boolean isBoolean() {
         return getNodeType() == JsonNodeType.BOOLEAN;
     }
 
     /**
      * Method that can be used to check if this node was created from
      * JSON literal null value.
      */
     public final boolean isNull() {
         return getNodeType() == JsonNodeType.NULL;
     }
 
     /**
      * Method that can be used to check if this node represents
      * binary data (Base64 encoded). Although this will be externally
      * written as JSON String value, {@link #isTextual} will
      * return false if this method returns true.
      *
      * @return True if this node represents base64 encoded binary data
      */
     public final boolean isBinary() {
         return getNodeType() == JsonNodeType.BINARY;
     }
 
     /**
      * Method that can be used to check whether this node is a numeric
      * node ({@link #isNumber} would return true) AND its value fits
      * within Java's 32-bit signed integer type, <code>int</code>.
      * Note that floating-point numbers are convertible if the integral
      * part fits without overflow (as per standard Java coercion rules)
      *<p>
      * NOTE: this method does not consider possible value type conversion
      * from JSON String into Number; so even if this method returns false,
      * it is possible that {@link #asInt} could still succeed
      * if node is a JSON String representing integral number, or boolean.
      * 
      * @since 2.0
      */
     public boolean canConvertToInt() { return false; }
 
     /**
      * Method that can be used to check whether this node is a numeric
      * node ({@link #isNumber} would return true) AND its value fits
      * within Java's 64-bit signed integer type, <code>long</code>.
      * Note that floating-point numbers are convertible if the integral
      * part fits without overflow (as per standard Java coercion rules)
      *<p>
      * NOTE: this method does not consider possible value type conversion
      * from JSON String into Number; so even if this method returns false,
      * it is possible that {@link #asLong} could still succeed
      * if node is a JSON String representing integral number, or boolean.
      * 
      * @since 2.0
      */
     public boolean canConvertToLong() { return false; }
 
     /**
      * Method that can be used to check whether contained value
      * is numeric (returns true for {@link #isNumber()}) and
      * can be losslessly converted to integral number (specifically,
      * {@link BigInteger} but potentially others, see
      * {@link #canConvertToInt} and {@link #canConvertToInt}).
      * Latter part allows floating-point numbers
      * (for which {@link #isFloatingPointNumber()} returns {@code true})
      * that do not have fractional part.
      * Note that "not-a-number" values of {@code double} and {@code float}
      * will return {@code false} as they can not be converted to matching
      * integral representations.
      *
      * @return True if the value is an actual number with no fractional
      *    part; false for non-numeric types, NaN representations of floating-point
      *    numbers, and floating-point numbers with fractional part.
      *
      * @since 2.12
      */
     public boolean canConvertToExactIntegral() {
         return isIntegralNumber();
     }
 
     /*
     /**********************************************************
     /* Public API, straight value access
     /**********************************************************
      */
 
     /**
      * Method to use for accessing String values.
      * Does <b>NOT</b> do any conversions for non-String value nodes;
      * for non-String values (ones for which {@link #isTextual} returns
      * false) null will be returned.
      * For String values, null is never returned (but empty Strings may be)
      *
      * @return Textual value this node contains, iff it is a textual
      *   JSON node (comes from JSON String value entry)
      */
     public String textValue() { return null; }
 
     /**
      * Method to use for accessing binary content of binary nodes (nodes
      * for which {@link #isBinary} returns true); or for Text Nodes
      * (ones for which {@link #textValue} returns non-null value),
      * to read decoded base64 data.
      * For other types of nodes, returns null.
      *
      * @return Binary data this node contains, iff it is a binary
      *   node; null otherwise
      */
     public byte[] binaryValue() throws IOException {
         return null;
     }
 
     /**
      * Method to use for accessing JSON boolean values (value
      * literals 'true' and 'false').
      * For other types, always returns false.
      *
      * @return Textual value this node contains, iff it is a textual
      *   json node (comes from JSON String value entry)
      */
     public boolean booleanValue() { return false; }
 
     /**
      * Returns numeric value for this node, <b>if and only if</b>
      * this node is numeric ({@link #isNumber} returns true); otherwise
      * returns null
      *
      * @return Number value this node contains, if any (null for non-number
      *   nodes).
      */
     public Number numberValue() { return null; }
 
     /**
      * Returns 16-bit short value for this node, <b>if and only if</b>
      * this node is numeric ({@link #isNumber} returns true). For other
      * types returns 0.
      * For floating-point numbers, value is truncated using default
      * Java coercion, similar to how cast from double to short operates.
      *
      * @return Short value this node contains, if any; 0 for non-number
      *   nodes.
      */
     public short shortValue() { return 0; }
 
     /**
      * Returns integer value for this node, <b>if and only if</b>
      * this node is numeric ({@link #isNumber} returns true). For other
      * types returns 0.
      * For floating-point numbers, value is truncated using default
      * Java coercion, similar to how cast from double to int operates.
      *
      * @return Integer value this node contains, if any; 0 for non-number
      *   nodes.
      */
     public int intValue() { return 0; }
 
     /**
      * Returns 64-bit long value for this node, <b>if and only if</b>
      * this node is numeric ({@link #isNumber} returns true). For other
      * types returns 0.
      * For floating-point numbers, value is truncated using default
      * Java coercion, similar to how cast from double to long operates.
      *
      * @return Long value this node contains, if any; 0 for non-number
      *   nodes.
      */
     public long longValue() { return 0L; }
 
     /**
      * Returns 32-bit floating value for this node, <b>if and only if</b>
      * this node is numeric ({@link #isNumber} returns true). For other
      * types returns 0.0.
      * For integer values, conversion is done using coercion; this means
      * that an overflow is possible for `long` values
      *
      * @return 32-bit float value this node contains, if any; 0.0 for non-number nodes.
      *
      * @since 2.2
      */
     public float floatValue() { return 0.0f; }
 
     /**
      * Returns 64-bit floating point (double) value for this node, <b>if and only if</b>
      * this node is numeric ({@link #isNumber} returns true). For other
      * types returns 0.0.
      * For integer values, conversion is done using coercion; this may result
      * in overflows with {@link BigInteger} values.
      *
      * @return 64-bit double value this node contains, if any; 0.0 for non-number nodes.
      *
      * @since 2.2
      */
     public double doubleValue() { return 0.0; }
 
     /**
      * Returns floating point value for this node (as {@link BigDecimal}), <b>if and only if</b>
      * this node is numeric ({@link #isNumber} returns true). For other
      * types returns <code>BigDecimal.ZERO</code>.
      *
      * @return {@link BigDecimal} value this node contains, if numeric node; <code>BigDecimal.ZERO</code> for non-number nodes.
      */
     public BigDecimal decimalValue() { return BigDecimal.ZERO; }
 
     /**
      * Returns integer value for this node (as {@link BigDecimal}), <b>if and only if</b>
      * this node is numeric ({@link #isNumber} returns true). For other
      * types returns <code>BigInteger.ZERO</code>.
      *
      * @return {@link BigInteger} value this node contains, if numeric node; <code>BigInteger.ZERO</code> for non-number nodes.
      */
     public BigInteger bigIntegerValue() { return BigInteger.ZERO; }
 
     /*
     /**********************************************************
     /* Public API, value access with conversion(s)/coercion(s)
     /**********************************************************
      */
 
     /**
      * Method that will return a valid String representation of
      * the container value, if the node is a value node
      * (method {@link #isValueNode} returns true),
      * otherwise empty String.
      */
     public abstract String asText();
 
     /**
      * Method similar to {@link #asText()}, except that it will return
      * <code>defaultValue</code> in cases where null value would be returned;
      * either for missing nodes (trying to access missing property, or element
      * at invalid item for array) or explicit nulls.
      * 
      * @since 2.4
      */
     public String asText(String defaultValue) {
         String str = asText();
         return (str == null) ? defaultValue : str;
     }
     
     /**
      * Method that will try to convert value of this node to a Java <b>int</b>.
      * Numbers are coerced using default Java rules; booleans convert to 0 (false)
      * and 1 (true), and Strings are parsed using default Java language integer
      * parsing rules.
      *<p>
      * If representation cannot be converted to an int (including structured types
      * like Objects and Arrays),
      * default value of <b>0</b> will be returned; no exceptions are thrown.
      */
     public int asInt() {
         return asInt(0);
     }
 
     /**
      * Method that will try to convert value of this node to a Java <b>int</b>.
      * Numbers are coerced using default Java rules; booleans convert to 0 (false)
      * and 1 (true), and Strings are parsed using default Java language integer
      * parsing rules.
      *<p>
      * If representation cannot be converted to an int (including structured types
      * like Objects and Arrays),
      * specified <b>defaultValue</b> will be returned; no exceptions are thrown.
      */
     public int asInt(int defaultValue) {
         return defaultValue;
     }
 
     /**
      * Method that will try to convert value of this node to a Java <b>long</b>.
      * Numbers are coerced using default Java rules; booleans convert to 0 (false)
      * and 1 (true), and Strings are parsed using default Java language integer
      * parsing rules.
      *<p>
      * If representation cannot be converted to a long (including structured types
      * like Objects and Arrays),
      * default value of <b>0</b> will be returned; no exceptions are thrown.
      */
     public long asLong() {
         return asLong(0L);
     }
     
     /**
      * Method that will try to convert value of this node to a Java <b>long</b>.
      * Numbers are coerced using default Java rules; booleans convert to 0 (false)
      * and 1 (true), and Strings are parsed using default Java language integer
      * parsing rules.
      *<p>
      * If representation cannot be converted to a long (including structured types
      * like Objects and Arrays),
      * specified <b>defaultValue</b> will be returned; no exceptions are thrown.
      */
     public long asLong(long defaultValue) {
         return defaultValue;
     }
     
     /**
      * Method that will try to convert value of this node to a Java <b>double</b>.
      * Numbers are coerced using default Java rules; booleans convert to 0.0 (false)
      * and 1.0 (true), and Strings are parsed using default Java language integer
      * parsing rules.
      *<p>
      * If representation cannot be converted to an int (including structured types
      * like Objects and Arrays),
      * default value of <b>0.0</b> will be returned; no exceptions are thrown.
      */
     public double asDouble() {
         return asDouble(0.0);
     }
     
     /**
      * Method that will try to convert value of this node to a Java <b>double</b>.
      * Numbers are coerced using default Java rules; booleans convert to 0.0 (false)
      * and 1.0 (true), and Strings are parsed using default Java language integer
      * parsing rules.
      *<p>
      * If representation cannot be converted to an int (including structured types
      * like Objects and Arrays),
      * specified <b>defaultValue</b> will be returned; no exceptions are thrown.
      */
     public double asDouble(double defaultValue) {
         return defaultValue;
     }
 
     /**
      * Method that will try to convert value of this node to a Java <b>boolean</b>.
      * JSON booleans map naturally; integer numbers other than 0 map to true, and
      * 0 maps to false
      * and Strings 'true' and 'false' map to corresponding values.
      *<p>
      * If representation cannot be converted to a boolean value (including structured types
      * like Objects and Arrays),
      * default value of <b>false</b> will be returned; no exceptions are thrown.
      */
     public boolean asBoolean() {
         return asBoolean(false);
     }
     
     /**
      * Method that will try to convert value of this node to a Java <b>boolean</b>.
      * JSON booleans map naturally; integer numbers other than 0 map to true, and
      * 0 maps to false
      * and Strings 'true' and 'false' map to corresponding values.
      *<p>
      * If representation cannot be converted to a boolean value (including structured types
      * like Objects and Arrays),
      * specified <b>defaultValue</b> will be returned; no exceptions are thrown.
      */
     public boolean asBoolean(boolean defaultValue) {
         return defaultValue;
     }
 
     /*
     /**********************************************************************
     /* Public API, extended traversal (2.10) with "required()"
     /**********************************************************************
      */
 
     /**
      * Method that may be called to verify that {@code this} node is NOT so-called
      * "missing node": that is, one for which {@link #isMissingNode()} returns {@code true}.
      * If not missing node, {@code this} is returned to allow chaining; otherwise
      * {@link IllegalArgumentException} is thrown.
      *
      * @return {@code this} node to allow chaining
      *
      * @throws IllegalArgumentException if this node is "missing node"
      *
      * @since 2.10
      */
     public <T extends JsonNode> T require() throws IllegalArgumentException {
         return _this();
     }
 
     /**
      * Method that may be called to verify that {@code this} node is neither so-called
      * "missing node" (that is, one for which {@link #isMissingNode()} returns {@code true})
      * nor "null node" (one for which {@link #isNull()} returns {@code true}).
      * If non-null non-missing node, {@code this} is returned to allow chaining; otherwise
      * {@link IllegalArgumentException} is thrown.
      *
      * @return {@code this} node to allow chaining
      *
      * @throws IllegalArgumentException if this node is either "missing node" or "null node"
      *
      * @since 2.10
      */
     public <T extends JsonNode> T requireNonNull() throws IllegalArgumentException {
         return _this();
     }
 
     /**
      * Method is functionally equivalent to
      *{@code
      *   path(fieldName).required()
      *}
      * and can be used to check that this node is an {@code ObjectNode} (that is, represents
      * JSON Object value) and has value for specified property with key {@code fieldName}
      * (but note that value may be explicit JSON null value).
      * If this node is Object Node and has value for specified property, matching value
      * is returned; otherwise {@link IllegalArgumentException} is thrown.
      *
      * @param propertyName Name of property to access
      *
      * @return Value of the specified property of this Object node
      *
      * @throws IllegalArgumentException if this node is not an Object node or if it does not
      *   have value for specified property
      *
      * @since 2.10
      */
     public JsonNode required(String propertyName) throws IllegalArgumentException {
         return _reportRequiredViolation("Node of type `%s` has no fields", getClass().getName());
     }
 
     /**
      * Method is functionally equivalent to
      *{@code
      *   path(index).required()
      *}
      * and can be used to check that this node is an {@code ArrayNode} (that is, represents
      * JSON Array value) and has value for specified {@code index}
      * (but note that value may be explicit JSON null value).
      * If this node is Array Node and has value for specified index, value at index
      * is returned; otherwise {@link IllegalArgumentException} is thrown.
      *
      * @param index Index of the value of this Array node to access
      *
      * @return Value at specified index of this Array node
      *
      * @throws IllegalArgumentException if this node is not an Array node or if it does not
      *   have value for specified index
      *
      * @since 2.10
      */
     public JsonNode required(int index) throws IllegalArgumentException {
         return _reportRequiredViolation("Node of type `%s` has no indexed values", getClass().getName());
     }
 
     /**
      * Method is functionally equivalent to
      *{@code
      *   at(pathExpr).required()
      *}
      * and can be used to check that there is an actual value node at specified {@link JsonPointer}
      * starting from {@code this} node
      * (but note that value may be explicit JSON null value).
      * If such value node exists it is returned;
      * otherwise {@link IllegalArgumentException} is thrown.
      *
      * @param pathExpr {@link JsonPointer} expression (as String) to use for finding value node
      *
      * @return Matching value node for given expression
      *
      * @throws IllegalArgumentException if no value node exists at given {@code JSON Pointer} path
      *
      * @since 2.10
      */
     public JsonNode requiredAt(String pathExpr) throws IllegalArgumentException {
         return requiredAt(JsonPointer.compile(pathExpr));
     }
 
     /**
      * Method is functionally equivalent to
      *{@code
      *   at(path).required()
      *}
      * and can be used to check that there is an actual value node at specified {@link JsonPointer}
      * starting from {@code this} node
      * (but note that value may be explicit JSON null value).
      * If such value node exists it is returned;
      * otherwise {@link IllegalArgumentException} is thrown.
      *
      * @param path {@link JsonPointer} expression to use for finding value node
      *
      * @return Matching value node for given expression
      *
      * @throws IllegalArgumentException if no value node exists at given {@code JSON Pointer} path
      *
      * @since 2.10
      */
     public final JsonNode requiredAt(final JsonPointer path) throws IllegalArgumentException {
         JsonPointer currentExpr = path;
         JsonNode curr = this;
 
         // Note: copied from `at()`
         while (true) {
             if (currentExpr.matches()) {
                 return curr;
             }
             curr = curr._at(currentExpr); // lgtm [java/dereferenced-value-may-be-null]
             if (curr == null) {
                 _reportRequiredViolation("No node at '%s' (unmatched part: '%s')",
                         path, currentExpr);
             }
             currentExpr = currentExpr.tail();
         }
     }
 
     /*
     /**********************************************************
     /* Public API, value find / existence check methods
     /**********************************************************
      */
 
     /**
      * Method that allows checking whether this node is JSON Object node
      * and contains value for specified property. If this is the case
      * (including properties with explicit null values), returns true;
      * otherwise returns false.
      *<p>
      * This method is equivalent to:
      *<pre>
      *   node.get(fieldName) != null
      *</pre>
      * (since return value of get() is node, not value node contains)
      *<p>
      * NOTE: when explicit <code>null</code> values are added, this
      * method will return <code>true</code> for such properties.
      *
      * @param fieldName Name of element to check
      * 
      * @return True if this node is a JSON Object node, and has a property
      *   entry with specified name (with any value, including null value)
      */
     public boolean has(String fieldName) {
         return get(fieldName) != null;
     }
 
     /**
      * Method that allows checking whether this node is JSON Array node
      * and contains a value for specified index
      * If this is the case
      * (including case of specified indexing having null as value), returns true;
      * otherwise returns false.
      *<p>
      * Note: array element indexes are 0-based.
      *<p>
      * This method is equivalent to:
      *<pre>
      *   node.get(index) != null
      *</pre>
      *<p>
      * NOTE: this method will return <code>true</code> for explicitly added
      * null values.
      *
      * @param index Index to check
      * 
      * @return True if this node is a JSON Object node, and has a property
      *   entry with specified name (with any value, including null value)
      */
     public boolean has(int index) {
         return get(index) != null;
     }
 
     /**
      * Method that is similar to {@link #has(String)}, but that will
      * return <code>false</code> for explicitly added nulls.
      *<p>
      * This method is functionally equivalent to:
      *<pre>
      *   node.get(fieldName) != null &amp;&amp; !node.get(fieldName).isNull()
      *</pre>
      * 
      * @since 2.1
      */
     public boolean hasNonNull(String fieldName) {
         JsonNode n = get(fieldName);
         return (n != null) && !n.isNull();
     }
 
     /**
      * Method that is similar to {@link #has(int)}, but that will
      * return <code>false</code> for explicitly added nulls.
      *<p>
      * This method is equivalent to:
      *<pre>
      *   node.get(index) != null &amp;&amp; !node.get(index).isNull()
      *</pre>
      * 
      * @since 2.1
      */
     public boolean hasNonNull(int index) {
         JsonNode n = get(index);
         return (n != null) && !n.isNull();
     }
 
     /*
     /**********************************************************
     /* Public API, container access
     /**********************************************************
      */
 
     /**
      * Same as calling {@link #elements}; implemented so that
      * convenience "for-each" loop can be used for looping over elements
      * of JSON Array constructs.
      */
     @Override
     public final Iterator<JsonNode> iterator() { return elements(); }
 
     /**
      * Method for accessing all value nodes of this Node, iff
      * this node is a JSON Array or Object node. In case of Object node,
      * field names (keys) are not included, only values.
      * For other types of nodes, returns empty iterator.
      */
     public Iterator<JsonNode> elements() {
         return ClassUtil.emptyIterator();
     }
 
     /**
      * @return Iterator that can be used to traverse all key/value pairs for
      *   object nodes; empty iterator (no contents) for other types
      */
     public Iterator<Map.Entry<String, JsonNode>> fields() {
         return ClassUtil.emptyIterator();
     }
 
     /*
     /**********************************************************
     /* Public API, find methods
     /**********************************************************
      */
 
     /**
      * Method for finding a JSON Object field with specified name in this
      * node or its child nodes, and returning value it has.
      * If no matching field is found in this node or its descendants, returns null.
      * 
      * @param fieldName Name of field to look for
      * 
      * @return Value of first matching node found, if any; null if none
      */
     public abstract JsonNode findValue(String fieldName);
 
     /**
      * Method for finding JSON Object fields with specified name, and returning
      * found ones as a List. Note that sub-tree search ends if a field is found,
      * so possible children of result nodes are <b>not</b> included.
      * If no matching fields are found in this node or its descendants, returns
      * an empty List.
      * 
      * @param fieldName Name of field to look for
      */
     public final List<JsonNode> findValues(String fieldName)
     {
         List<JsonNode> result = findValues(fieldName, null);
         if (result == null) {
             return Collections.emptyList();
         }
         return result;
     }
 
     /**
      * Similar to {@link #findValues}, but will additionally convert
      * values into Strings, calling {@link #asText}.
      */
     public final List<String> findValuesAsText(String fieldName)
     {
         List<String> result = findValuesAsText(fieldName, null);
         if (result == null) {
             return Collections.emptyList();
         }
         return result;
     }
     
     /**
      * Method similar to {@link #findValue}, but that will return a
      * "missing node" instead of null if no field is found. Missing node
      * is a specific kind of node for which {@link #isMissingNode}
      * returns true; and all value access methods return empty or
      * missing value.
      * 
      * @param fieldName Name of field to look for
      * 
      * @return Value of first matching node found; or if not found, a
      *    "missing node" (non-null instance that has no value)
      */
     public abstract JsonNode findPath(String fieldName);
     
     /**
      * Method for finding a JSON Object that contains specified field,
      * within this node or its descendants.
      * If no matching field is found in this node or its descendants, returns null.
      * 
      * @param fieldName Name of field to look for
      * 
      * @return Value of first matching node found, if any; null if none
      */
     public abstract JsonNode findParent(String fieldName);
 
     /**
      * Method for finding a JSON Object that contains specified field,
      * within this node or its descendants.
      * If no matching field is found in this node or its descendants, returns null.
      * 
      * @param fieldName Name of field to look for
      * 
      * @return Value of first matching node found, if any; null if none
      */
     public final List<JsonNode> findParents(String fieldName)
     {
         List<JsonNode> result = findParents(fieldName, null);
         if (result == null) {
             return Collections.emptyList();
         }
         return result;
     }
 
     public abstract List<JsonNode> findValues(String fieldName, List<JsonNode> foundSoFar);
     public abstract List<String> findValuesAsText(String fieldName, List<String> foundSoFar);
     public abstract List<JsonNode> findParents(String fieldName, List<JsonNode> foundSoFar);
 
     /*
     /**********************************************************
     /* Public API, path handling
     /**********************************************************
      */
 
     /**
      * Method that can be called on Object nodes, to access a property
      * that has Object value; or if no such property exists, to create,
      * add and return such Object node.
      * If the node method is called on is not Object node,
      * or if property exists and has value that is not Object node,
      * {@link UnsupportedOperationException} is thrown
      *<p>
      * NOTE: since 2.10 has had co-variant return type
      */
     public <T extends JsonNode> T with(String propertyName) {
         throw new UnsupportedOperationException("JsonNode not of type ObjectNode (but "
                 +getClass().getName()+"), cannot call with() on it");
     }
 
     /**
      * Method that can be called on Object nodes, to access a property
      * that has <code>Array</code> value; or if no such property exists, to create,
      * add and return such Array node.
      * If the node method is called on is not Object node,
      * or if property exists and has value that is not Array node,
      * {@link UnsupportedOperationException} is thrown
      *<p>
      * NOTE: since 2.10 has had co-variant return type
      */
     public <T extends JsonNode> T withArray(String propertyName) {
         throw new UnsupportedOperationException("JsonNode not of type ObjectNode (but "
                 +getClass().getName()+"), cannot call withArray() on it");
     }
 
     /*
     /**********************************************************
     /* Public API, comparison
     /**********************************************************
      */
 
     /**
      * Entry method for invoking customizable comparison, using passed-in
      * {@link Comparator} object. Nodes will handle traversal of structured
      * types (arrays, objects), but defer to comparator for scalar value
      * comparisons. If a "natural" {@link Comparator} is passed -- one that
      * simply calls <code>equals()</code> on one of arguments, passing the other
      * -- implementation is the same as directly calling <code>equals()</code>
      * on node.
      *<p>
      * Default implementation simply delegates to passed in <code>comparator</code>,
      * with <code>this</code> as the first argument, and <code>other</code> as
      * the second argument.
      * 
      * @param comparator Object called to compare two scalar {@link JsonNode} 
      *   instances, and return either 0 (are equals) or non-zero (not equal)
      *
      * @since 2.6
      */
     public boolean equals(Comparator<JsonNode> comparator, JsonNode other) {
         return comparator.compare(this, other) == 0;
     }
     
     /*
     /**********************************************************
     /* Overridden standard methods
     /**********************************************************
      */
     
     /**
      * Method that will produce (as of Jackson 2.10) valid JSON using
      * default settings of databind, as String.
      * If you want other kinds of JSON output (or output formatted using one of
      * other Jackson-supported data formats) make sure to use
      * {@link ObjectMapper} or {@link ObjectWriter} to serialize an
      * instance, for example:
      *<pre>
      *   String json = objectMapper.writeValueAsString(rootNode);
      *</pre>
      *<p>
      * Note: method defined as abstract to ensure all implementation
      * classes explicitly implement method, instead of relying
      * on {@link Object#toString()} definition.
      */
     @Override
     public abstract String toString();
 
     /**
      * Alternative to {@link #toString} that will serialize this node using
      * Jackson default pretty-printer.
      *
      * @since 2.10
      */
     public String toPrettyString() {
         return toString();
     }
     
     /**
      * Equality for node objects is defined as full (deep) value
      * equality. This means that it is possible to compare complete
      * JSON trees for equality by comparing equality of root nodes.
      *<p>
      * Note: marked as abstract to ensure all implementation
      * classes define it properly and not rely on definition
      * from {@link java.lang.Object}.
      */
     @Override
     public abstract boolean equals(Object o);
 
     /*
     /**********************************************************************
     /* Helper methods,  for sub-classes
     /**********************************************************************
      */
 
     // @since 2.10
     @SuppressWarnings("unchecked")
     protected <T extends JsonNode> T _this() {
         return (T) this;
     }
 
     /**
      * Helper method that throws {@link IllegalArgumentException} as a result of
      * violating "required-constraint" for this node (for {@link #required} or related
      * methods).
      */
     protected <T> T _reportRequiredViolation(String msgTemplate, Object...args) {
         throw new IllegalArgumentException(String.format(msgTemplate, args));
     }
 }