com.saxonica.ee.optim

Class SearchableValue

java.lang.Object

com.saxonica.ee.optim.SearchableValue

All Implemented Interfaces:

GroundedValue, Sequence

Direct Known Subclasses:

IndexedValue

public abstract class SearchableValue
extends java.lang.Object
implements GroundedValue

A sequence that is held in a form that permits rapid searching, typically by use of indexes. This is an abstract class with several implementations

Field Summary

Fields

Modifier and Type	Field and Description
protected int	end
protected Item[]	value

Constructor Summary

Constructors

Constructor and Description
SearchableValue()

Method Summary

Modifier and Type	Method and Description
boolean	effectiveBooleanValue() Get the effective boolean value of this sequence
abstract SequenceIterator	findItems(Expression use, SequenceIterator values, boolean convertUntypedToOther, boolean firstOnly, AtomicComparer comparer, XPathContext context) Retrieve items that match a given index value
int	getLength() Get the length of the sequence
java.lang.String	getStringValue() Get the string value of this sequence, as an instance of String.
UnicodeString	getUnicodeStringValue() Get the string value of this sequence, as an instance of UnicodeString.
Item	head() Get the first item in the sequence.
Item	itemAt(int n) Get the n'th item in the sequence (starting from 0).
SequenceIterator	iterate() Return an Iterator to iterate over the values of a sequence.
static SearchableValue	makeSearchableValue(SequenceIterator iter)
GroundedValue	reduce() Reduce the sequence to its simplest form.
GroundedValue	subsequence(int start, int length) Get a subsequence of the value

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface net.sf.saxon.om.GroundedValue

asIterable, concatenate, containsNode, materialize, toShortString

Methods inherited from interface net.sf.saxon.om.Sequence

makeRepeatable

Field Detail

value

protected Item[] value

end

protected int end

Constructor Detail

SearchableValue

public SearchableValue()

Method Detail

makeSearchableValue

public static SearchableValue makeSearchableValue(SequenceIterator iter)
                                           throws XPathException

Throws:

XPathException

iterate

public SequenceIterator iterate()

Return an Iterator to iterate over the values of a sequence. The value of every expression can be regarded as a sequence, so this method is supported for all expressions. This default implementation handles iteration for expressions that return singleton values: for non-singleton expressions, the subclass must provide its own implementation.

Specified by:

iterate in interface GroundedValue

Specified by:

iterate in interface Sequence

Returns:

a SequenceIterator that can be used to iterate over the result of the expression

itemAt

public Item itemAt(int n)

Get the n'th item in the sequence (starting from 0). This is defined for all Values, but its real benefits come for a sequence Value stored extensionally (or for a MemoClosure, once all the values have been read)

Specified by:

itemAt in interface GroundedValue

Parameters:

n - position of the required item, counting from zero.

Returns:

the n'th item in the sequence, where the first item in the sequence is numbered zero. If n is negative or >= the length of the sequence, returns null.

getLength

public int getLength()

Get the length of the sequence

Specified by:

getLength in interface GroundedValue

Returns:

the number of items in the sequence. Note that for a single item, including a map or array, the result is always 1 (one).

findItems

public abstract SequenceIterator findItems(Expression use,
                                           SequenceIterator values,
                                           boolean convertUntypedToOther,
                                           boolean firstOnly,
                                           AtomicComparer comparer,
                                           XPathContext context)
                                    throws XPathException

Retrieve items that match a given index value

Parameters:

use - the expression whose value is to be matched

values - the set of values to be found

convertUntypedToOther - true if untypedAtomic values are to be converted to the type of the other operand

firstOnly - true if only the first matching item is required

comparer - AtomicComparer used to compare values for equality (encapsulates a collation if necessary)

context - the dynamic evaluation context @return an iterator over the items that match the specified values

Returns:

an iterator over the items that matched

Throws:

XPathException - if an error occurs

subsequence

public GroundedValue subsequence(int start,
                                 int length)

Get a subsequence of the value

Specified by:

subsequence in interface GroundedValue

Parameters:

start - the index of the first item to be included in the result, counting from zero. A negative value is taken as zero. If the value is beyond the end of the sequence, an empty sequence is returned

length - the number of items to be included in the result. Specify Integer.MAX_VALUE to get the subsequence up to the end of the base sequence. If the value is negative, an empty sequence is returned. If the value goes off the end of the sequence, the result returns items up to the end of the sequence

Returns:

the required subsequence. If min is

effectiveBooleanValue

public boolean effectiveBooleanValue()
                              throws XPathException

Description copied from interface: GroundedValue

Get the effective boolean value of this sequence

Specified by:

effectiveBooleanValue in interface GroundedValue

Returns:

the effective boolean value

Throws:

XPathException - if the sequence has no effective boolean value (for example a sequence of two integers)

getUnicodeStringValue

public UnicodeString getUnicodeStringValue()
                                    throws XPathException

Description copied from interface: GroundedValue

Get the string value of this sequence, as an instance of UnicodeString. The string value of an item is the result of applying the XPath string() function. The string value of a sequence is the space-separated result of applying the string-join() function using a single space as the separator

The result of this method is always equivalent to the result of the GroundedValue.getStringValue() method. Use this method in preference either (a) if you need to use the value in a context where a UnicodeString is required, or (b) if the underlying value is held as a UnicodeString, or in a form that is readily converted to a UnicodeString. This is typically the case (i) when the value is a text or element node in a TinyTree, and (ii) when the value is a StringItem: that is, an atomic value of type xs:string.

Specified by:

getUnicodeStringValue in interface GroundedValue

Returns:

the string value of the sequence.

Throws:

XPathException - if the sequence contains items that have no string value (for example, function items)

getStringValue

public java.lang.String getStringValue()
                                throws XPathException

Description copied from interface: GroundedValue

Get the string value of this sequence, as an instance of String. The string value of an item is the result of applying the XPath string() function. The string value of a sequence is the space-separated result of applying the string-join() function using a single space as the separator.

The result of this method is always equivalent to the result of the GroundedValue.getUnicodeStringValue() method. Use this method in preference either (a) if you need to use the value in a context where a String is required, or (b) if the underlying value is held as a String, or in a form that is readily converted to a String. This is typically the case (i) when the value is an attribute node in a TinyTree, or (ii) any kind of node in a third-party tree model such as DOM.

Specified by:

getStringValue in interface GroundedValue

Returns:

the string value of the sequence.

Throws:

XPathException - if the sequence contains items that have no string value (for example, function items)

head

public Item head()

Get the first item in the sequence.

Specified by:

head in interface GroundedValue

Specified by:

head in interface Sequence

Returns:

the first item in the sequence if there is one, or null if the sequence is empty

reduce

public GroundedValue reduce()

Reduce the sequence to its simplest form. If the value is an empty sequence, the result will be EmptySequence.getInstance(). If the value is a single atomic value, the result will be an instance of AtomicValue. If the value is a single item of any other kind, the result will be an instance of SingletonItem. Otherwise, the result will typically be unchanged.

Specified by:

reduce in interface GroundedValue

Returns:

the simplified sequence