- All Implemented Interfaces:
Operation
Namespace
of
an object. E.g. a property getter would be described as
Operation propertyGetter = new NamespaceOperation( StandardOperation.GET, StandardNamespace.PROPERTY);They are often combined with
NamedOperation
, e.g. to express a
property getter for a property named "color", you would construct:
Operation colorPropertyGetter = new NamedOperation( new NamespaceOperation( StandardOperation.GET, StandardNamespace.PROPERTY), "color");
While NamespaceOperation
can be constructed directly, it is often convenient
to use the Operation.withNamespace(Namespace)
and Operation.withNamespaces(Namespace...)
factory
methods instead, e.g.:
Operation getElementOrPropertyEmpty = StandardOperation.GET .withNamespace(StandardNamespace.PROPERTY) .named("color");
Operations on multiple namespaces
If multiple namespaces are specified, the namespaces are treated as alternatives to each other in order of preference. The semantics of such operation is "first applicable". That is, a composite ofGET:PROPERTY|ELEMENT:color
should be
interpreted as get the property named "color" on the object, but if the
property does not exist, then get the collection element named "color"
instead.
Operations with multiple namespaces are helpful in implementation of languages that
don't distinguish between one or more of the namespaces, or when expressing operations
against objects that can be considered both ordinary objects and collections, e.g. Java
Map
objects. A GET:PROPERTY|ELEMENT:empty
operation
against a Java map will always match
the Map.isEmpty()
property, but
GET:ELEMENT|PROPERTY:empty
will actually match a map element with
key "empty"
if the map contains that key, and only fall back to the
isEmpty()
property getter if the map does not contain the key. If
the source language mandates this semantics, it can be easily achieved using
operations on multiple namespaces.
Even if the language itself doesn't distinguish between some of the
namespaces, it can be helpful to map different syntaxes to different namespace orderings.
E.g. the source expression obj.color
could map to
GET:PROPERTY|ELEMENT|METHOD:color
, but a different source
expression that looks like collection element access obj[key]
could
be expressed instead as GET:ELEMENT|PROPERTY|METHOD
in order to favor the
element semantics. Finally, if the retrieved value is subsequently called, then it makes sense
to bring METHOD
to the front of the namespace list: the getter part of the
source expression obj.color()
could be
GET:METHOD|PROPERTY|ELEMENT:color
and the one for
obj[key]()
could be GET:METHOD|ELEMENT|PROPERTY
.
The base operation of a namespace operation can not itself be a namespace or named
operation, but rather one of simple operations such are elements of
StandardOperation
. A namespace operation itself can serve as the base
operation of a named operation, though; a typical way to construct e.g. the
GET:ELEMENT|PROPERTY:empty
from above would be:
Operation getElementOrPropertyEmpty = StandardOperation.GET .withNamespaces( StandardNamespace.ELEMENT, StandardNamespace.PROPERTY) .named("empty");
-
Constructor Summary
ConstructorDescriptionNamespaceOperation
(Operation baseOperation, Namespace... namespaces) Constructs a new namespace operation. -
Method Summary
Modifier and TypeMethodDescriptionboolean
Returns true if this namespace operation contains a namespace equal to the specified namespace.static boolean
Returns true if the specified operation is aNamespaceOperation
and its base operation is equal to the specified operation, and it contains the specified namespace.boolean
Returns true if the other object is also a namespace operation and their base operation and namespaces are equal.Returns the base operation of this named operation.static Operation
If the passed operation is a namespace operation, returns itsgetBaseOperation()
, otherwise returns the operation as is.getNamespace
(int i) Returns the i-th namespace in this namespace operation.int
Returns the number of namespaces in this namespace operation.Returns the namespaces in this namespace operation.static Namespace[]
If the passed operation is a namespace operation, returns itsgetNamespaces()
, otherwise returns an empty array.int
hashCode()
Returns the hash code of this namespace operation.toString()
Returns the string representation of this namespace operation.Methods declared in class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
Methods declared in interface jdk.dynalink.Operation
named, withNamespace, withNamespaces
-
Constructor Details
-
NamespaceOperation
Constructs a new namespace operation.- Parameters:
baseOperation
- the base operation that operates on one or more namespaces.namespaces
- one or more namespaces this operation operates on.- Throws:
IllegalArgumentException
- if less than one namespace is specified, or the base operation is itself aNamespaceOperation
or aNamedOperation
.NullPointerException
- if either thenamespaces
array or any of its elements arenull
, or ifbaseOperation
isnull
.
-
-
Method Details
-
getBaseOperation
Returns the base operation of this named operation.- Returns:
- the base operation of this named operation.
-
getNamespaces
Returns the namespaces in this namespace operation. The returned array is a copy and changes to it don't have effect on this object.- Returns:
- the namespaces in this namespace operation.
-
getNamespaceCount
public int getNamespaceCount()Returns the number of namespaces in this namespace operation.- Returns:
- the number of namespaces in this namespace operation.
-
getNamespace
Returns the i-th namespace in this namespace operation.- Parameters:
i
- the namespace index- Returns:
- the i-th namespace in this namespace operation.
- Throws:
IndexOutOfBoundsException
- if the index is out of range.
-
contains
Returns true if this namespace operation contains a namespace equal to the specified namespace.- Parameters:
namespace
- the namespace being searched for. Must not be null.- Returns:
- true if the if this namespace operation contains a namespace equal to the specified namespace.
-
equals
Returns true if the other object is also a namespace operation and their base operation and namespaces are equal. -
hashCode
public int hashCode()Returns the hash code of this namespace operation. Defined to be equal tobaseOperation.hashCode() + 31 * Arrays.hashCode(namespaces)
. -
toString
Returns the string representation of this namespace operation. Defined to be thetoString
of its base operation, followed by a colon character, followed with the list of its namespaces separated with the vertical line character (e.g."GET:PROPERTY|ELEMENT"
). -
getBaseOperation
If the passed operation is a namespace operation, returns itsgetBaseOperation()
, otherwise returns the operation as is.- Parameters:
op
- the operation- Returns:
- the base operation of the passed operation.
-
getNamespaces
If the passed operation is a namespace operation, returns itsgetNamespaces()
, otherwise returns an empty array.- Parameters:
op
- the operation- Returns:
- the namespaces of the passed operation.
-
contains
Returns true if the specified operation is aNamespaceOperation
and its base operation is equal to the specified operation, and it contains the specified namespace. If it is not aNamespaceOperation
, then it returns false.- Parameters:
op
- the operation. Must not be null.baseOperation
- the base operation being searched for. Must not be null.namespace
- the namespace being searched for. Must not be null.- Returns:
- true if the if the passed operation is a
NamespaceOperation
, its base operation equals the searched base operation, and contains a namespace equal to the searched namespace.
-