/**
* Creates a partial mapping.
*
* <p>Initially, no element is mapped to any other:
*
* <table border="1">
* <caption>Example</caption>
* <tr>
* <th>source</th>
* <td>0</td>
* <td>1</td>
* <td>2</td>
* </tr>
* <tr>
* <th>target</th>
* <td>-1</td>
* <td>-1</td>
* <td>-1</td>
* </tr>
* </table>
*
* <table border="1">
* <caption>Example</caption>
* <tr>
* <th>target</th>
* <td>0</td>
* <td>1</td>
* <td>2</td>
* <td>3</td>
* </tr>
* <tr>
* <th>source</th>
* <td>-1</td>
* <td>-1</td>
* <td>-1</td>
* <td>-1</td>
* </tr>
* </table>
*
* @param sourceCount Number of source elements
* @param targetCount Number of target elements
* @param mappingType Mapping type; must not allow multiple sources per target or multiple
* targets per source
*/
public PartialMapping(int sourceCount, int targetCount, MappingType mappingType) {
this.mappingType = mappingType;
assert mappingType.isSingleSource() : mappingType;
assert mappingType.isSingleTarget() : mappingType;
this.sources = new int[targetCount];
this.targets = new int[sourceCount];
Arrays.fill(sources, -1);
Arrays.fill(targets, -1);
}
/**
* Creates a partial mapping from a list. For example, <code>
* PartialMapping({1, 2, 4}, 6)</code> creates the mapping
*
* <table border="1">
* <caption>Example</caption>
* <tr>
* <th>source</th>
* <td>0</td>
* <td>1</td>
* <td>2</td>
* <td>3</td>
* <td>4</td>
* <td>5</td>
* </tr>
* <tr>
* <th>target</th>
* <td>-1</td>
* <td>0</td>
* <td>1</td>
* <td>-1</td>
* <td>2</td>
* <td>-1</td>
* </tr>
* </table>
*
* @param sourceList List whose i'th element is the source of target #i
* @param sourceCount Number of elements in the source domain
* @param mappingType Mapping type, must be {@link
* org.eigenbase.util.mapping.MappingType#PARTIAL_SURJECTION} or stronger.
*/
public PartialMapping(List<Integer> sourceList, int sourceCount, MappingType mappingType) {
this.mappingType = mappingType;
assert mappingType.isSingleSource();
assert mappingType.isSingleTarget();
int targetCount = sourceList.size();
this.targets = new int[sourceCount];
this.sources = new int[targetCount];
Arrays.fill(sources, -1);
for (int i = 0; i < sourceList.size(); ++i) {
final int source = sourceList.get(i);
sources[i] = source;
if (source >= 0) {
targets[source] = i;
} else {
assert !this.mappingType.isMandatorySource();
}
}
}
public void set(int source, int target) {
if ((target < 0) && mappingType.isMandatorySource()) {
throw new IllegalArgumentException("Target is required");
}
if ((target >= targetCount) && (targetCount >= 0)) {
throw new IllegalArgumentException("Target must be less than target count, " + targetCount);
}
targets[source] = target;
}
public PartialFunctionImpl(int sourceCount, int targetCount, MappingType mappingType) {
super();
if (sourceCount < 0) {
throw new IllegalArgumentException("Sources must be finite");
}
this.sourceCount = sourceCount;
this.targetCount = targetCount;
this.mappingType = mappingType;
if (!mappingType.isSingleTarget()) {
throw new IllegalArgumentException("Must have at most one target");
}
this.targets = new int[sourceCount];
Arrays.fill(targets, -1);
}
/** Creates a mapping with required properties. */
public static Mapping create(MappingType mappingType, int sourceCount, int targetCount) {
switch (mappingType) {
case BIJECTION:
assert sourceCount == targetCount;
return new Permutation(sourceCount);
case INVERSE_SURJECTION:
assert sourceCount >= targetCount;
return new SurjectionWithInverse(sourceCount, targetCount);
case PARTIAL_SURJECTION:
case SURJECTION:
return new Mappings.PartialMapping(sourceCount, targetCount, mappingType);
case PARTIAL_FUNCTION:
case FUNCTION:
return new PartialFunctionImpl(sourceCount, targetCount, mappingType);
case INVERSE_FUNCTION:
case INVERSE_PARTIAL_FUNCTION:
return new InverseMapping(create(mappingType.inverse(), targetCount, sourceCount));
default:
throw Util.needToImplement("no known implementation for mapping type " + mappingType);
}
}
public Mapping inverse() {
return new PartialMapping(targets.clone(), sources.clone(), mappingType.inverse());
}
