| com.hp.hpl.jena.rdf.model.RDFList
All known Subclasses: com.hp.hpl.jena.rdf.model.impl.RDFListImpl,
| RDFList | | public interface RDFList extends Resource(Code) | |
Provides a convenience encapsulation for lists formed from chains of RDF
statements arranged to form a head/tail cons-cell structure. The properties
that form the links between cells, and from cells to values, are specified by
a vocabulary interface, so this abstraction is designed to cope equally well
with DAML lists, RDF lists, and user-defined lists.
A well-formed list has cells that are made up of three statements: one
denoting the rdf:type of the list cell, one denoting the link
to the value of the list at that point, and one pointing to the list tail. If
a list cell is not well-formed, list operations may fail in unpredictable
ways. However, to explicitly check that the list is well-formed at all times
is expensive. Therefore the list operates in two modes: in strict
mode, the well-formedness of the list is checked at the start of each list
operation, and an
InvalidListException is thrown if the list is not
well- formed. This ensures that list operations are safe, but will slow down
processing. In non-strict mode, this checking is switched off, but can
be invoked explicitly by clients by calling
RDFList.isValid . By default, RDF
lists are processed in non-strict mode.
author:
Ian Dickinson, HP Labs
author:
(email)
version:
Release ($Id: RDFList.java,v 1.13 2008/01/02 12:05:46 andy_seaborne Exp $) |
| Inner Class :public static interface ApplyFn | |
| Inner Class :public static interface ReduceFn | |
| Method Summary | |
| public void | add(RDFNode value)
Add the given value to the end of the list. | | public RDFList | append(RDFList list)
Answer a new list that is formed by adding each element of this list to
the head of the given list. | | public RDFList | append(Iterator nodes)
Answer a new list that is formed by adding each element of this list to
the head of the the list formed from the
given nodes. | | public void | apply(ApplyFn fn)
Apply a function to each value in the list in turn. | | public List | asJavaList()
Answer the contents of this RDF list as a Java list of RDFNode values. | | public void | concatenate(RDFList list)
Change the tail of this list to point to the given list, so that this
list becomes the list of the concatenation of the elements of both lists.
This is a side-effecting operation on this list; for a non side-effecting
alternative, see
RDFList.append . | | public void | concatenate(Iterator nodes)
Add the nodes returned by the given iterator to the end of this list. | | public RDFList | cons(RDFNode value)
Return a reference to a new list cell whose head is value
and whose tail is this list. | | public boolean | contains(RDFNode value)
Answer true if the given node appears as the value of a value of any
of the cells of this list. | | public RDFList | copy()
Answer a list that contains all of the elements of this list in the same
order, but is a duplicate copy in the underlying model. | | public RDFNode | get(int i)
Answer the node that is the i'th element of the list, assuming that the
head is item zero. | | public RDFNode | getHead()
Answer the value that is at the head of the list. | | public boolean | getStrict()
Answer true lists are operating in strict mode, in which the
well- formedness of the list is checked at every operation. | | public RDFList | getTail()
Answer the list that is the tail of this list. | | public String | getValidityErrorMessage()
Answer the error message returned by the last failed validity check,
if any. | | public int | indexOf(RDFNode value)
Answer the index of the first occurrence of the given value in the list,
or -1 if the value is not in the list. | | public int | indexOf(RDFNode value, int start)
Answer the index of the first occurrence of the given value in the list
after index start, or -1 if the value is not in the list
after the given start point. | | public boolean | isEmpty()
Answer true if this list is the empty list. | | public boolean | isValid()
Answer true if the list is well-formed, by checking that each node is
correctly typed, and has a head and tail pointer from the correct
vocabulary. | | public ExtendedIterator | iterator()
Answer an iterator over the elements of the list. | | public ExtendedIterator | mapWith(Map1 fn)
| | public Object | reduce(ReduceFn fn, Object initial)
Apply a function to each value in the list in turn, accumulating the
results in an accumulator. | | public RDFList | remove(RDFNode val)
Remove the given value from this list. | | public void | removeAll()
Deprecated. | | public RDFList | removeHead()
Remove the value from the head of the list. | | public void | removeList()
Remove all of the components of this list from the model. | | public RDFNode | replace(int i, RDFNode value)
Replace the value at the i'th position in the list with the given value. | | public boolean | sameListAs(RDFList list)
Answer true if this list has the same elements in the same order as the
given list. | | public RDFNode | setHead(RDFNode value)
Update the head of the list to have the given value, and return the
previous value. | | public void | setStrict(boolean strict)
Set a flag to indicate whether to strictly check the well-formedness of
lists at each operation. | | public RDFList | setTail(RDFList tail)
Update the list cell at the front of the list to have the given list as
tail. | | public int | size()
Answer the number of elements in the list. | | public RDFList | with(RDFNode value)
Answer the list that is this list with the given value added to the end
of the list. |
| add | | public void add(RDFNode value)(Code) | |
Add the given value to the end of the list. This is a side-effecting
operation on the underlying model that is only defined if this is not the
empty list. If this list is the empty (nil) list, we cannot perform a
side-effecting update without changing the URI of this node (from rdf:nilRDFList.with and
RDFList.cons .
Parameters:
value - A value to add to the end of the list
exception:
EmptyListUpdateException - if an attempt is made to add to the empty list. |
| append | | public RDFList append(RDFList list)(Code) | |
Answer a new list that is formed by adding each element of this list to
the head of the given list. This is a non side-effecting
operation on either this list or the given list, but generates a copy
of this list. For a more storage efficient alternative, see
RDFList.concatenate concatenate .
Parameters:
list - The argument list A new RDFList that contains all of this elements of this list,followed by all of the elements of the given list. |
| append | | public RDFList append(Iterator nodes)(Code) | |
Answer a new list that is formed by adding each element of this list to
the head of the the list formed from the
given nodes. This is a non side-effecting
operation on either this list or the given list, but generates a copy
of this list. For a more storage efficient alternative, see
RDFList.concatenate concatenate .
Parameters:
nodes - An iterator whose range is RDFNode A new RDFList that contains all of this elements of this list,followed by all of the elements of the given iterator. |
| apply | | public void apply(ApplyFn fn)(Code) | |
Apply a function to each value in the list in turn.
Parameters:
fn - The function to apply to each list node. |
| asJavaList | | public List asJavaList()(Code) | |
Answer the contents of this RDF list as a Java list of RDFNode values.
The contents of this list as a Java List. |
| concatenate | | public void concatenate(RDFList list)(Code) | |
Change the tail of this list to point to the given list, so that this
list becomes the list of the concatenation of the elements of both lists.
This is a side-effecting operation on this list; for a non side-effecting
alternative, see
RDFList.append . Due to the problem of maintaining
the URI invariant on a node, this operation will throw an exception if an
attempt is made to concatenate onto an empty list. To avoid this, test for
an empty list: if true replace the empty list with the argument list, otherwise
proceed with the concatenate as usual. An alternative solution is to use
RDFList.append and replace the original list with the return value.
Parameters:
list - The argument list to concatenate to this list
exception:
EmptyListUpdateException - if this list is the nil list |
| concatenate | | public void concatenate(Iterator nodes)(Code) | |
Add the nodes returned by the given iterator to the end of this list.
Parameters:
nodes - An iterator whose range is RDFNode
exception:
EmptyListUpdateException - if this list is the nil list
See Also: RDFList.concatenate(RDFList)
See Also: for details on avoiding the empty list update exception. |
| cons | | public RDFList cons(RDFNode value)(Code) | |
Return a reference to a new list cell whose head is value
and whose tail is this list.
Parameters:
value - A new value to add to the head of the list The new list, whose head is value |
| contains | | public boolean contains(RDFNode value)(Code) | |
Answer true if the given node appears as the value of a value of any
of the cells of this list.
Parameters:
value - A value to test for True if the list contains value. |
| copy | | public RDFList copy()(Code) | |
Answer a list that contains all of the elements of this list in the same
order, but is a duplicate copy in the underlying model.
A copy of the current list |
| get | | public RDFNode get(int i)(Code) | |
Answer the node that is the i'th element of the list, assuming that the
head is item zero. If the list is too short to have an i'th element,
throws a
ListIndexException .
Parameters:
i - The index into the list, from 0 The list value at index i, or null
exception:
ListIndexException - if the list has fewer than (i + 1)elements. |
| getHead | | public RDFNode getHead()(Code) | |
Answer the value that is at the head of the list.
The value that is associated with the head of the list.
exception:
EmptyListException - if this list is the empty list |
| getStrict | | public boolean getStrict()(Code) | |
Answer true lists are operating in strict mode, in which the
well- formedness of the list is checked at every operation.
True lists are being strictly checked. |
| getTail | | public RDFList getTail()(Code) | |
Answer the list that is the tail of this list.
The tail of the list, as a list
exception:
EmptyListException - if this list is the empty list |
| getValidityErrorMessage | | public String getValidityErrorMessage()(Code) | |
Answer the error message returned by the last failed validity check,
if any.
The most recent error message, or null.
See Also: RDFList.isValid |
| indexOf | | public int indexOf(RDFNode value)(Code) | |
Answer the index of the first occurrence of the given value in the list,
or -1 if the value is not in the list.
Parameters:
value - The value to search for The index of the first occurrence of value in the list, or-1 if not found. |
| indexOf | | public int indexOf(RDFNode value, int start)(Code) | |
Answer the index of the first occurrence of the given value in the list
after index start, or -1 if the value is not in the list
after the given start point.
Parameters:
value - The value to search for
Parameters:
start - The index into the list to start searching from The index of the first occurrence of value in the list not lessthan start, or -1 if not found.
exception:
ListIndexException - if start is greater than thelength of the list. |
| isEmpty | | public boolean isEmpty()(Code) | | Answer true if this list is the empty list.
True if this is the empty (nil) list, otherwise false. |
| isValid | | public boolean isValid()(Code) | |
Answer true if the list is well-formed, by checking that each node is
correctly typed, and has a head and tail pointer from the correct
vocabulary. If the list is invalid, the reason is available via
RDFList.getValidityErrorMessage .
True if the list is well-formed.
See Also: RDFList.getValidityErrorMessage |
| iterator | | public ExtendedIterator iterator()(Code) | |
Answer an iterator over the elements of the list. Note that this iterator
does not take a snapshot of the list, so changes to the list statements
in the model while iterating will affect the behaviour of the iterator.
To get an iterator that is not affected by model changes, use
RDFList.asJavaList .
A closable iterator over the elements of the list. |
| mapWith | | public ExtendedIterator mapWith(Map1 fn)(Code) | | Answer an iterator of the elements of this list, to each of which
the given map function has been applied.
Parameters:
fn - A Map function The iterator of the elements of this list mapped with the given map function. |
| reduce | | public Object reduce(ReduceFn fn, Object initial)(Code) | |
Apply a function to each value in the list in turn, accumulating the
results in an accumulator. The final value of the accumulator is returned
as the value of reduce().
Parameters:
fn - The reduction function to apply
Parameters:
initial - The initial value for the accumulator The final value of the accumulator. |
| remove | | public RDFList remove(RDFNode val)(Code) | | Remove the given value from this list. If val does not occur in
the list, no action is taken. Since removing the head of the list will invalidate
the list head cell, in general the list must return the list that results from this
operation. However, in many cases the return value will be the same as the object
that this method is invoked on
Parameters:
val - The value to be removed from the list The resulting list, which will be the same as the current list in mostcases, except when val occurs at the head of the list. |
| removeAll | | public void removeAll()(Code) | | Deprecated. Since an RDFList does not behave like a Java container, it is not
the case that the contents of the list can be removed and the container filled with values
again. Therefore, this method name has been deprecated in favour of
RDFList.removeList
RDFList.removeList |
| removeHead | | public RDFList removeHead()(Code) | |
Remove the value from the head of the list. The tail of the list remains
in the model. Note that no changes are made to list cells that point to
this list cell as their tail. Immediately following a
removeHead operation, such lists will be in a non-valid
state.
The remainder of the list after the head is removed (i.e. thepre-removal list tail) |
| removeList | | public void removeList()(Code) | | Remove all of the components of this list from the model. Once this operation
has completed, the
RDFList resource on which it was called will no
longer be a resource in the model, so further methods calls on the list object
(for example,
RDFList.size will fail. Due to restrictions on the encoding
of lists in RDF, it is not possible to perform an operation which empties a list
and then adds further values to that list. Client code wishing to perform
such an operation should do so in two steps: first remove the old list, then
create a new list with the new contents. It is important that RDF statements
that reference the old list (in the object position) be updated to point
to the newly created list.
Note that this
is operation is only removing the list cells themselves, not the resources
referenced by the list - unless being the object of an rdf:first
statement is the only mention of that resource in the model.
|
| replace | | public RDFNode replace(int i, RDFNode value)(Code) | |
Replace the value at the i'th position in the list with the given value.
If the list is too short to have an i'th element, throws a
ListIndexException .
Parameters:
i - The index into the list, from 0
Parameters:
value - The new value to associate with the i'th list element The value that was previously at position i in the list
exception:
ListIndexException - if the list has fewer than (i + 1)elements. |
| sameListAs | | public boolean sameListAs(RDFList list)(Code) | |
Answer true if this list has the same elements in the same order as the
given list. Note that the standard equals test just tests
for equality of two given list cells. While such a test is sufficient
for many purposes, this test provides a broader equality definition, but
is correspondingly more expensive to test.
Parameters:
list - The list to test against True if the given list and this list are the same length, andcontain equal elements in the same order. |
| setHead | | public RDFNode setHead(RDFNode value)(Code) | |
Update the head of the list to have the given value, and return the
previous value.
Parameters:
value - The value that will become the value of the list head
exception:
EmptyListException - if this list is the empty list |
| setStrict | | public void setStrict(boolean strict)(Code) | |
Set a flag to indicate whether to strictly check the well-formedness of
lists at each operation. Default false. Note that the flag that is
manipulated is actually a static: it applies to all lists. However, RDFList
is a Java interface, and Java does not permit static methods in interfaces.
Parameters:
strict - The static flag for whether lists will be checked strictly. |
| setTail | | public RDFList setTail(RDFList tail)(Code) | |
Update the list cell at the front of the list to have the given list as
tail. The old tail is returned, and remains in the model.
Parameters:
tail - The new tail for this list. The old tail. |
| size | | public int size()(Code) | |
Answer the number of elements in the list.
The size of the list as an integer |
| with | | public RDFList with(RDFNode value)(Code) | |
Answer the list that is this list with the given value added to the end
of the list. This operation differs from
RDFList.add in that it will
always work, even on an empty list, but the return value is the updated
list. Specifically, in the case of adding a value to the empty list, the
returned list will not be the same as this list. Client code should
not assume that this is an in-place update, but should ensure that the resulting
list is asserted back into the graph into the appropriate relationships.
Parameters:
value - A value to add to the end of the list The list that results from adding a value to the end of this list |
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