com.github.fge.jsonschema.ref

Class JsonPointer

java.lang.Object

com.github.fge.jsonschema.ref.JsonFragment

com.github.fge.jsonschema.ref.JsonPointer

All Implemented Interfaces:

Comparable<JsonFragment>

public final class JsonPointer
extends JsonFragment

Implementation of IETF JSON Pointer draft, version 9

JSON Pointer is an IETF draft defining a way to address paths within JSON values (including non container values).

An individual entry of a JSON Pointer is called a reference token. For JSON Objects, a reference token is a member name. For arrays, it is an index. Indices start at 0. Note that array indices written with a leading 0 are considered to be failing (ie, 0 is OK but 00 is not).

The general syntax is /reference/tokens/here. A JSON Pointer may be empty, in which case this refers to the JSON value itself.

The difficulty solved by JSON Pointer is that any JSON String is valid as an object member name. These are all valid object member names, and all of them can be addressed by using JSON Pointer:

• "" -- the empty string;
• "/";
• "0";
• "-1";
• ".", "..", "../..".

The latter example is the reason why a JSON Pointer is always absolute.

All instances of this class are immutable (and therefore thread safe).

Field Summary

Fields inherited from class com.github.fge.jsonschema.ref.JsonFragment

asString

Constructor Summary

Constructors

Constructor and Description
JsonPointer(String input) Constructor

Method Summary

Methods

Modifier and Type	Method and Description
JsonPointer	append(int index) Append an array index to this pointer.
JsonPointer	append(JsonPointer other) Append a pointer to the current pointer
JsonPointer	append(String element) Append a reference token as a string to this pointer.
List<JsonPointer>	asElements() Return this pointer as a series of JSON Pointers starting from the beginning
static JsonPointer	empty() Return an empty pointer
boolean	isEmpty() Tell whether this fragment is empty
boolean	isParentOf(JsonPointer other) Return true if this JSON Pointer is "parent" of another one
boolean	isPointer() Tell whether this fragment is a valid JSON Pointer
JsonPointer	relativize(JsonPointer other) Relativize a pointer to the current pointer
JsonNode	resolve(JsonNode node) Apply the pointer to a JSON value and return the result

Methods inherited from class com.github.fge.jsonschema.ref.JsonFragment

compareTo, equals, fromFragment, hashCode, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

JsonPointer

public JsonPointer(String input)
            throws JsonSchemaException

Constructor

Parameters:

input - The input string, guaranteed not to be JSON encoded

Throws:

JsonSchemaException - illegal JSON Pointer

Method Detail

empty

public static JsonPointer empty()

Return an empty pointer

Returns:

a statically created empty JSON Pointer

append

public JsonPointer append(JsonPointer other)

Append a pointer to the current pointer

Parameters:

other - the other pointer

Returns:

a new instance with the pointer appended

append

public JsonPointer append(String element)

Append a reference token as a string to this pointer.

Parameters:

element - the element to append

Returns:

a new instance with the element appended

append

public JsonPointer append(int index)

Append an array index to this pointer.

Note that the index validity is NOT checked for (ie, you can append -1 if you want to -- don't do that)

Parameters:

index - the index to add

Returns:

a new instance with the index appended

resolve

public JsonNode resolve(JsonNode node)

Apply the pointer to a JSON value and return the result

If the pointer fails to look up a value, a MissingNode is returned.

Specified by:

resolve in class JsonFragment

Parameters:

node - the node to apply the pointer to

Returns:

the resulting node

isEmpty

public boolean isEmpty()

Description copied from class: JsonFragment

Tell whether this fragment is empty

Specified by:

isEmpty in class JsonFragment

Returns:

true if this fragment is empty

See Also:

JsonRef.isAbsolute()

isPointer

public boolean isPointer()

Description copied from class: JsonFragment

Tell whether this fragment is a valid JSON Pointer

Specified by:

isPointer in class JsonFragment

Returns:

true if this fragment is an instance of JsonPointer

asElements

public List<JsonPointer> asElements()

Return this pointer as a series of JSON Pointers starting from the beginning

Returns:

an unmodifiable list of JSON Pointers

isParentOf

public boolean isParentOf(JsonPointer other)

Return true if this JSON Pointer is "parent" of another one

That is, its number of reference tokens is less than, or equal to, the other pointer's, and its first reference tokens are the same.

This means that this will also return true if the pointers are equal.

Parameters:

other - the other pointer

Returns:

true if this pointer is the parent of the other

relativize

public JsonPointer relativize(JsonPointer other)

Relativize a pointer to the current pointer

If isParentOf(JsonPointer) returns false, this will return the other pointer.

Otherwise, it will return a pointer containing all reference tokens following this pointer's reference tokens. For instance, relativizing /a/b against /a/b/c gives /c.

If the pointers are the same, it will return an empty pointer.

Parameters:

other - the pointer to relativize this pointer to

Returns:

a relativized pointer