ValueVector (Jess - the Rule Engine for the Java Platform v70b7)

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jess
Class ValueVector

java.lang.Object
  jess.ValueVector

All Implemented Interfaces:: java.lang.Cloneable, java.io.Serializable

Direct Known Subclasses:: Fact, Funcall

public class ValueVector
extends java.lang.Object
implements java.lang.Cloneable, java.io.Serializable

A self-extending array that only holds Value objects. The ValueVector class is Jess's internal representation of a Lisp list, and therefore has a central role in programming with Jess in Java. The ValueVector class itself is used to represent generic lists, while specialized subclasses are used as function calls (Funcall and facts (Fact).

Working with ValueVector itself is simple. Its API is similar to the List interface. ValueVector is a self-extending array: when new elements are added, the ValueVector grows in size to accomodate them. Here is a bit of example Java code in which we create the Jess list (a b c).

ValueVector vv = new ValueVector();
vv.add("a");
vv.add("b");
vv.add("c");

// Prints "(a b c)"
System.out.println(vv.toStringWithParens());

To pass a ValueVector from Java to Jess, you should enclose it in a Value object of type RU.LIST.

Value myList = new Value(vv, RU.LIST);

ValueVector is not synchronized, so you must be careful of multithreading issues.

See Also:: Value, Serialized Form

Field Summary
`protected int`	`m_ptr` The current number of elements.
`protected Value[]`	`m_v` The elements themselves.

Constructor Summary
`ValueVector()` Construct a ValueVector of the default capacity (10).
`ValueVector(int size)` Construct a ValueVector of the given capacity.

Method Summary
`ValueVector`	`add(boolean val)` Add a new element to the end of this ValueVector.
`ValueVector`	`add(double val)` Add a new element to the end of this ValueVector.
`ValueVector`	`add(int val)` Add a new element to the end of this ValueVector.
`ValueVector`	`add(long val)` Add a new element to the end of this ValueVector.
`ValueVector`	`add(java.lang.Object val)` Add a new element to the end of this ValueVector.
`ValueVector`	`add(java.lang.String val)` Add a new element to the end of this ValueVector.
`ValueVector`	`add(Value val)` Add a new element to the end of this ValueVector.
`void`	`addAll(java.util.Collection list)` Add all the members of the collection to this ValueVector.
`ValueVector`	`addAll(ValueVector vv)` Appends all Values in the argument ValueVector.
`java.lang.Object`	`clone()` Create a shallow copy of this ValueVector.
`ValueVector`	`cloneInto(ValueVector vv)` Make the parameter into a copy of this ValueVector.
`static void`	`copy(ValueVector src, int srcPos, ValueVector dest, int destPos, int length)` System.arraycopy DeLuxe for ValueVectors.
`boolean`	`equals(java.lang.Object o)` Compare this ValueVector to another object.
`Value`	`get(int i)` Returns the entry at position i in this ValueVector.
`ValueVector`	`remove(int i)` Remove the item at index i from the ValueVector; move all the higher-numbered elements down.
`ValueVector`	`set(Value val, int i)` Set the element at position i to the given value.
`ValueVector`	`setLength(int i)` Set the length of this ValueVector.
`int`	`size()` Returns the size of this ValueVector.
`java.lang.String`	`toString()` Return a String version of this ValueVector, without parentheses.
`java.lang.String`	`toStringWithParens()` Return a String version of this ValueVector, with parentheses around all ValueVectors.

Methods inherited from class java.lang.Object

finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

m_v

protected Value[] m_v

The elements themselves. Should never be null.

m_ptr

protected int m_ptr

The current number of elements. Should always be nonnegative.

Constructor Detail

ValueVector

public ValueVector()

Construct a ValueVector of the default capacity (10).

ValueVector

public ValueVector(int size)

Construct a ValueVector of the given capacity.
Parameters:: size - The number of Values this vector can hold at creation

Method Detail

size

public final int size()

Returns the size of this ValueVector.

Returns:: the size of this ValueVector

clone

public java.lang.Object clone()

Create a shallow copy of this ValueVector.

Returns:: the copy

cloneInto

public ValueVector cloneInto(ValueVector vv)

Make the parameter into a copy of this ValueVector.

Parameters:: vv - a ValueVector, whose contents are erased.
Returns:: the parameter

get

public Value get(int i)
          throws JessException

Returns the entry at position i in this ValueVector.

Parameters:: i - the 0-based index of the Value to fetch
Returns:: the Value
Throws:: JessException

setLength

public ValueVector setLength(int i)

Set the length of this ValueVector. If necessary the storage will be extended. This can leave some of the elements in the ValueVector with null contents.

Parameters:: i - The new length (>= 0)
Returns:: this object, so methods can be chained.

set

public final ValueVector set(Value val,
                             int i)
                      throws JessException

Set the element at position i to the given value. The argument must be >= 0 and < the return value of size().

Parameters:: val - the new value; i - the index at which to place it.
Returns:: this object, so methods can be chained.
Throws:: JessException

add

public final ValueVector add(Value val)

Add a new element to the end of this ValueVector. The storage will be extended if necessary. This method returns the ValueVector object itself, so that add() calls can be chained together for convenience:

ValueVector vv = new ValueVector();
vv.add(new Value("a", RU.SYMBOL)).add(new Value("b", RU.SYMBOL)).add(new Value("c", RU.SYMBOL));

// Prints "(a b c)"
System.out.println(vv.toStringWithParens());

Parameters:: val - the value to add.
Returns:: this object, so methods can be chained.