Module jdk.dynalink
Package jdk.dynalink

Class NamedOperation

  • All Implemented Interfaces:
    Operation
    public final class NamedOperation
extends Object
implements Operation
    Operation that associates a name with another operation. Typically used with operations that normally take a name or an index to bind them to a fixed name. E.g. 
         new NamedOperation(
         new NamespaceOperation(
             StandardOperation.GET,
             StandardNamespace.PROPERTY),
         "color")
    will be a named operation for getting the property named "color" on the object it is applied to, and 
         new NamedOperation(
         new NamespaceOperation(
             StandardOperation.GET,
             StandardNamespace.ELEMENT),
         3)
    will be a named operation for getting the element at index 3 from the collection it is applied to ("name" in this context is akin to "address" and encompasses both textual names, numeric indices, or any other kinds of addressing that linkers can understand). In these cases, the expected signature of the call site for the operation will change to no longer include the name parameter. Specifically, the documentation for all StandardOperation members describes how they are affected by being incorporated into a named operation.

    While NamedOperation can be constructed directly, it is often convenient to use the Operation.named(Object) factory method instead, e.g.: 

        StandardOperation.GET
        .withNamespace(StandardNamespace.ELEMENT),
        .named(3)
     )

    Even though NamedOperation is most often used with NamespaceOperation as its base, it can have other operations as its base too (except another named operation). Specifically, StandardOperation.CALL as well as StandardOperation.NEW can both be used with NamedOperation directly. The contract for these operations is such that when they are used as named operations, their name is only used for diagnostic messages, usually containing the textual representation of the source expression that retrieved the callee, e.g. StandardOperation.CALL.named("window.open").

    • Constructor Detail

      • NamedOperation

        public NamedOperation​(Operation baseOperation,
                      Object name)
        Creates a new named operation.
        Parameters:
        baseOperation - the base operation that is associated with a name.
        name - the name associated with the base operation. Note that the name is not necessarily a string, but can be an arbitrary object. As the name is used for addressing, it can be an Integer when meant to be used as an index into an array or list etc.
        Throws:
        NullPointerException - if either baseOperation or name is null.
        IllegalArgumentException - if baseOperation is itself a NamedOperation.

    • Method Detail

      • getBaseOperation

        public Operation getBaseOperation()
        Returns the base operation of this named operation.
        Returns:
        the base operation of this named operation.

      • getName

        public Object getName()
        Returns the name of this named operation.
        Returns:
        the name of this named operation.

      • changeName

        public final NamedOperation changeName​(String newName)
        Finds or creates a named operation that differs from this one only in the name.
        Parameters:
        newName - the new name to replace the old name with.
        Returns:
        a named operation with the changed name.
        Throws:
        NullPointerException - if the name is null.

      • equals

        public boolean equals​(Object obj)
        Compares this named operation to another object. Returns true if the other object is also a named operation, and both their base operations and name are equal.
        Overrides:
        equals in class Object
        Parameters:
        obj - the reference object with which to compare.
        Returns:
        true if this object is the same as the obj argument; false otherwise.
        See Also:
        Object.hashCode(), HashMap

      • toString

        public String toString()
        Returns the string representation of this named operation. It is defined to be equal to baseOperation.toString() + ":" + name.toString().
        Overrides:
        toString in class Object
        Returns:
        a string representation of the object.

      • getBaseOperation

        public static Operation getBaseOperation​(Operation op)
        If the passed operation is a named operation, returns its getBaseOperation(), otherwise returns the operation as is.
        Parameters:
        op - the operation
        Returns:
        the base operation of the passed operation.

      • getName

        public static Object getName​(Operation op)
        If the passed operation is a named operation, returns its getName(), otherwise returns null. Note that a named operation object can never have a null name, therefore returning null is indicative that the passed operation is not, in fact, a named operation.
        Parameters:
        op - the operation
        Returns:
        the name in the passed operation, or null if it is not a named operation.