package com.fasterxml.jackson.databind;

import java.io.IOException;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.*;

import com.fasterxml.jackson.core.*;
import com.fasterxml.jackson.databind.node.JsonNodeType;
import com.fasterxml.jackson.databind.node.MissingNode;
import 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.

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 ObjectNode
and ArrayNode).
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).
 Actual concrete sub-classes can be found from package node. 
 Note that it is possible to "read" from nodes, using method TreeNode.traverse(ObjectCodec), which will result in a JsonParser being constructed. This can be used for (relatively) efficient conversations between different representations; and it is what core databind uses for methods like ObjectMapper.treeToValue(TreeNode, Class<Object>) and ObjectMapper.treeAsTokens(TreeNode) /**
 * 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 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.

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
Returns:
Node that is either a copy of this node (and all non-leaf
   children); or, for immutable leaf nodes, node itself./**
     * 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; }

    @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.

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
node.size(), null is returned; no exception is
thrown for any index.

NOTE: if the element value has been explicitly set as null (which is different from removal!), a NullNode will be returned, not null. 
Returns:
Node that represent value of the specified element,
  if this node is an array and has specified element.
  Null otherwise./**
     * 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 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.

NOTE: if the property value has been explicitly set as null (which is different from removal!), a NullNode will be returned, not null. 
Returns:
Node that represent value of the specified field,
  if this node is an object and has value for the specified
  field. Null otherwise./**
     * 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 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 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 isMissingNode) will be returned. This allows for convenient and safe chained access via path calls. /**
     * 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 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 isMissingNode) will be returned. This allows for convenient and safe chained access via path calls. /**
     * 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 isMissingNode() returns true. 
Returns:
Node that matches given JSON Pointer: if no match exists, will return a node for which isMissingNode() returns true.
Since:
2.3/**
     * 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:
  return at(JsonPointer.valueOf(jsonPointerExpression));

 Note that if the same expression is used often, it is preferable to construct JsonPointer instance once and reuse it: this method will not perform any caching of compiled expressions. 
Params:
jsonPtrExpr – Expression to compile as a JsonPointer instance
Returns:
Node that matches given JSON Pointer: if no match exists, will return a node for which TreeNode.isMissingNode() returns true.
Since:
2.3/**
     * 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));
    }

    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
Returns:
the node type as a JsonNodeType enum value
Since:
2.2/**
     * 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 POJONode.
Returns:
True if this node wraps a POJO/**
     * 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;
    }

    
Returns:
True if this node represents a numeric JSON value/**
     * @return True if this node represents a numeric JSON value
     */
    public final boolean isNumber() {
        return getNodeType() == JsonNodeType.NUMBER;
    }

    
Returns:
True if this node represents an integral (integer)
  numeric JSON value/**
     * 
     * @return True if this node represents an integral (integer)
     *   numeric JSON value
     */
    public boolean isIntegralNumber() { return false; }

    
Returns:
True if this node represents a non-integral
  numeric JSON value/**
     * @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 short. 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 canConvertToInt() instead. 
Returns:
True if the value contained by this node is stored as Java short/**
     * 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 int. 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 canConvertToInt() instead. 
Returns:
True if the value contained by this node is stored as Java int/**
     * 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 long. 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 canConvertToInt() instead. 
Returns:
True if the value contained by this node is stored as Java long/**
     * 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 #canConvertToInt()} 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/**
     * @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.
/**
     * 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").
/**
     * 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.
/**
     * 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, isTextual will return false if this method returns true. 
Returns:
True if this node represents base64 encoded binary data/**
     * 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 (isNumber would return true) AND its value fits within Java's 32-bit signed integer type, int.
Note that floating-point numbers are convertible if the integral
part fits without overflow (as per standard Java coercion rules)
 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 asInt could still succeed if node is a JSON String representing integral number, or boolean. 
Since:
2.0/**
     * 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 (isNumber would return true) AND its value fits within Java's 64-bit signed integer type, long.
Note that floating-point numbers are convertible if the integral
part fits without overflow (as per standard Java coercion rules)
 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 asLong could still succeed if node is a JSON String representing integral number, or boolean. 
Since:
2.0/**
     * 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; }
    
    /*
    /**********************************************************
    /* Public API, straight value access
    /**********************************************************
     */

    
Method to use for accessing String values.
Does NOT do any conversions for non-String value nodes; for non-String values (ones for which isTextual returns false) null will be returned. For String values, null is never returned (but empty Strings may be) 
Returns:
Textual value this node contains, iff it is a textual
  JSON node (comes from JSON String value entry)/**
     * 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 isBinary returns true); or for Text Nodes (ones for which textValue returns non-null value), to read decoded base64 data. For other types of nodes, returns null. 
Returns:
Binary data this node contains, iff it is a binary
  node; null otherwise/**
     * 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.
Returns:
Textual value this node contains, iff it is a textual
  json node (comes from JSON String value entry)/**
     * 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, if and only if this node is numeric (isNumber returns true); otherwise returns null 
Returns:
Number value this node contains, if any (null for non-number
  nodes)./**
     * 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, if and only if this node is numeric (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. 
Returns:
Short value this node contains, if any; 0 for non-number
  nodes./**
     * 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, if and only if this node is numeric (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. 
Returns:
Integer value this node contains, if any; 0 for non-number
  nodes./**
     * 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, if and only if this node is numeric (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. 
Returns:
Long value this node contains, if any; 0 for non-number
  nodes./**
     * 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, if and only if this node is numeric (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 
Returns:
32-bit float value this node contains, if any; 0.0 for non-number nodes.
Since:
2.2/**
     * 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, if and only if this node is numeric (isNumber returns true). For other types returns 0.0. For integer values, conversion is done using coercion; this may result in overflows with BigInteger values. 
Returns:
64-bit double value this node contains, if any; 0.0 for non-number nodes.
Since:
2.2/**
     * 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 BigDecimal), if and only if this node is numeric (isNumber returns true). For other types returns BigDecimal.ZERO.
Returns:
BigDecimal value this node contains, if numeric node; BigDecimal.ZERO for non-number nodes./**
     * 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 BigDecimal), if and only if this node is numeric (isNumber returns true). For other types returns BigInteger.ZERO.
Returns:
BigInteger value this node contains, if numeric node; BigInteger.ZERO for non-number nodes./**
     * 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 isValueNode returns true), otherwise empty String. /**
     * 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 asText(), except that it will return defaultValue 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/**
     * 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 int.
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.

If representation cannot be converted to an int (including structured types
like Objects and Arrays),
default value of 0 will be returned; no exceptions are thrown.
/**
     * 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 int.
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.

If representation cannot be converted to an int (including structured types
like Objects and Arrays),
specified defaultValue will be returned; no exceptions are thrown.
/**
     * 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 long.
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.

If representation cannot be converted to an long (including structured types
like Objects and Arrays),
default value of 0 will be returned; no exceptions are thrown.
/**
     * 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 an 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 long.
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.

If representation cannot be converted to an long (including structured types
like Objects and Arrays),
specified defaultValue will be returned; no exceptions are thrown.
/**
     * 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 an 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 double.
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.

If representation cannot be converted to an int (including structured types
like Objects and Arrays),
default value of 0.0 will be returned; no exceptions are thrown.
/**
     * 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 double.
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.

If representation cannot be converted to an int (including structured types
like Objects and Arrays),
specified defaultValue will be returned; no exceptions are thrown.
/**
     * 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 boolean.
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.

If representation cannot be converted to a boolean value (including structured types
like Objects and Arrays),
default value of false will be returned; no exceptions are thrown.
/**
     * 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 boolean.
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.

If representation cannot be converted to a boolean value (including structured types
like Objects and Arrays),
specified defaultValue will be returned; no exceptions are thrown.
/**
     * 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, 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.

This method is equivalent to:
  node.get(fieldName) != null

(since return value of get() is node, not value node contains)

NOTE: when explicit null values are added, this
method will return true for such properties.
Params:
fieldName – Name of element to check
Returns:
True if this node is a JSON Object node, and has a property
  entry with specified name (with any value, including null value)/**
     * 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.

Note: array element indexes are 0-based.

This method is equivalent to:
  node.get(index) != null


NOTE: this method will return true for explicitly added
null values.
Params:
index – Index to check
Returns:
True if this node is a JSON Object node, and has a property
  entry with specified name (with any value, including null value)/**
     * 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 has(String), but that will return false for explicitly added nulls.

This method is functionally equivalent to:
  node.get(fieldName) != null << !node.get(fieldName).isNull()

Since:
2.1/**
     * 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 &lt;&lt; !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 has(int), but that will return false for explicitly added nulls.

This method is equivalent to:
  node.get(index) != null << !node.get(index).isNull()

Since:
2.1/**
     * 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 &lt;&lt; !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 elements; implemented so that convenience "for-each" loop can be used for looping over elements of JSON Array constructs. /**
     * 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.
/**
     * 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();
    }

    
Returns:
Iterator that can be used to traverse all key/value pairs for
  object nodes; empty iterator (no contents) for other types/**
     * @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.
Params:
fieldName – Name of field to look for
Returns:
Value of first matching node found, if any; null if none/**
     * 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 not included.
If no matching fields are found in this node or its descendants, returns
an empty List.
Params:
fieldName – Name of field to look for/**
     * 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 findValues, but will additionally convert values into Strings, calling asText. /**
     * 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 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 isMissingNode returns true; and all value access methods return empty or missing value. 
Params:
fieldName – Name of field to look for
Returns:
Value of first matching node found; or if not found, a
   "missing node" (non-null instance that has no value)/**
     * 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.
Params:
fieldName – Name of field to look for
Returns:
Value of first matching node found, if any; null if none/**
     * 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.
Params:
fieldName – Name of field to look for
Returns:
Value of first matching node found, if any; null if none/**
     * 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, UnsupportedOperationException is thrown /**
     * 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
     */
    public JsonNode 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 Array 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, UnsupportedOperationException is thrown /**
     * 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
     */
    public JsonNode 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 Comparator object. Nodes will handle traversal of structured types (arrays, objects), but defer to comparator for scalar value comparisons. If a "natural" Comparator is passed -- one that simply calls equals() on one of arguments, passing the other
-- implementation is the same as directly calling equals()
on node.

Default implementation simply delegates to passed in comparator,
with this as the first argument, and other as
the second argument.
Params:
comparator – Object called to compare two scalar JsonNode instances, and return either 0 (are equals) or non-zero (not equal)
Since:
2.6/**
     * 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 developer-readable representation of the
node; which may or may not be as valid JSON. If you want valid JSON output (or output formatted using one of other Jackson supported data formats) make sure to use ObjectMapper or ObjectWriter to serialize an instance, for example: 
  String json = objectMapper.writeValueAsString(rootNode);

 Note: method defined as abstract to ensure all implementation classes explicitly implement method, instead of relying on Object.toString() definition. /**
     * Method that will produce developer-readable representation of the
     * node; which may <b>or may not</b> be as valid JSON.
     * If you want valid 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();

    
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.
 Note: marked as abstract to ensure all implementation classes define it properly and not rely on definition from Object. /**
     * 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);
}