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package bjc.utils.data;
import java.util.function.Function;
import java.util.function.UnaryOperator;
/**
* @author ben
*
* @param <ContainedType>
*/
/**
* Simple implementation of IHolder that has no hidden behavior
*
* @author ben
*
* @param <ContainedType>
* The type contained in the holder
*/
public class Identity<ContainedType> implements IHolder<ContainedType> {
private ContainedType heldValue;
/**
* Create a holder holding null
*/
public Identity() {
heldValue = null;
}
/**
* Create a holder holding the specified value
*
* @param value
* The value to hold
*/
public Identity(ContainedType value) {
heldValue = value;
}
@Override
public <BoundType> IHolder<BoundType> bind(Function<ContainedType, IHolder<BoundType>> binder) {
return binder.apply(heldValue);
}
/*
* (non-Javadoc)
*
* @see java.lang.Object#equals(java.lang.Object)
*/
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
else if (obj == null)
return false;
else if (getClass() != obj.getClass()) return false;
Identity<?> other = (Identity<?>) obj;
if (heldValue == null) {
if (other.heldValue != null) return false;
} else if (!heldValue.equals(other.heldValue)) return false;
return true;
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
int fieldHash = heldValue == null ? 0 : heldValue.hashCode();
result = prime * result + fieldHash;
return result;
}
@Override
public <NewType> Function<ContainedType, IHolder<NewType>> lift(Function<ContainedType, NewType> func) {
return (val) -> {
return new Identity<>(func.apply(val));
};
}
@Override
public <MappedType> IHolder<MappedType> map(Function<ContainedType, MappedType> mapper) {
return new Identity<>(mapper.apply(heldValue));
}
@Override
public String toString() {
return "holding[v=" + heldValue + "]";
}
@Override
public IHolder<ContainedType> transform(UnaryOperator<ContainedType> transformer) {
heldValue = transformer.apply(heldValue);
return this;
}
@Override
public <UnwrappedType> UnwrappedType unwrap(Function<ContainedType, UnwrappedType> unwrapper) {
return unwrapper.apply(heldValue);
}
/**
* Create a new identity container.
*
* @param val
* The contained value.
*
* @return A new identity container.
*/
public static <ContainedType> Identity<ContainedType> id(ContainedType val) {
return new Identity<>(val);
}
/**
* Create a new empty identity container.
*
* @return A new empty identity container.
*/
public static <ContainedType> Identity<ContainedType> id() {
return new Identity<>();
}
}
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