/** 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 Iterator<IntPair> iterator() {
throw Util.needToImplement(this);
}
public Variable getConnectionVariable() {
throw Util.needToImplement("getConnectionVariable");
}
public void unparse(
SqlWriter writer, SqlOperator operator, SqlCall call, int leftPrec, int rightPrec) {
// You probably need to override the operator's unparse
// method.
throw Util.needToImplement(this);
}
/**
* Reduces a list of operators and arguments according to the rules of precedence and
* associativity. Returns the ordinal of the node which replaced the expression.
*
* <p>The default implementation throws {@link UnsupportedOperationException}.
*
* @param ordinal indicating the ordinal of the current operator in the list on which a possible
* reduction can be made
* @param list List of alternating {@link org.eigenbase.sql.parser.SqlParserUtil.ToTreeListItem}
* and {@link SqlNode}
* @return ordinal of the node which replaced the expression
*/
public int reduceExpr(int ordinal, List<Object> list) {
throw Util.needToImplement(this);
}
