JarCastingsmt-building
A library that can be used to simplify creating builders and fluent API's.
Maven
<dependencies>
<dependency>
<groupId>com.github.shiver-me-timbers</groupId>
<artifactId>smt-building</artifactId>
<version>1.2</version>
</dependency>
</dependencies>
Usage
This library provides an API for creating Builders by populating them with code Blocks. All Blocks are evaluated when the build() method is called. They will be evaluated in the order dictated by the Builder implementation.
final Block<Integer> increment = new Block<Integer>() {
public Integer build(Integer number) {
return number + 1;
}
};
final Builder<Integer> builder = new CollectionBuilder<>(new ArrayList<Block<Integer>>(), 0);
builder.add(increment).add(increment).add(increment);
final Integer result = builder.build();
System.out.println(result); // 3
Three builder implementations have been provided, each one evaluates it's code Blocks in a different order.
QueueBuilder
This builder will evaluate all it's code Blocks in FIFO order.
StackBuilder
This builder will evaluate all it's code Blocks in LIFO order.
CollectionBuilder
This builder will evaluate it's code Blocks in the order specified by it's supplied Collection implementation. This also allows the Blocks to be sorted and/or unique.
// All Blocks will be ordered by their input.
abstract class OrderedBlock implements Block<Integer>, Comparable<Ordered> {
private final Integer number;
Ordered(Integer number) {
this.number = number;
}
public int compareTo(Ordered that) {
return number.compareTo(that.number);
}
}
class Addition extends OrderedBlock {
private final Integer number;
Addition(Integer number) {
super(number);
this.number = number;
}
public Integer build(Integer number) {
return this.number + number;
}
}
class Multiplication extends OrderedBlock {
private final Integer number;
Multiplication(Integer number) {
super(number);
this.number = number;
}
public Integer build(Integer number) {
return this.number * number;
}
}
// Using TreeSet so that the Blocks will be unique and sorted.
final Builder<Integer> builder = new CollectionBuilder<>(new TreeSet<Block<Integer>>(), 0);
builder.add(new Addition(3)).add(new Addition(3)).add(new Multiplication(2));
final Integer result = builder.build();
// Builder.blocks = {new Multiplication(2), new Addition(3)}
System.out.println(result); // (0 * 2) + 3 = 3
Iteration
The Builder implements Iterable so can be used within a for loop.
for (Integer result : builder) {
System.out.println(result);
}
If used in this way each result produced by the iterator will be the result of each individual Block as it is called. The Blocks will be iterated over in the order dictated by the Builder or internal collection implementation.
Specified Iteration
It is also possible to state how many iterations should be run over the Builder. Any number of iterations can be requested, be it less than or greater than the number of Blocks in the Builder.
final Builder<Integer> builder = new CollectionBuilder<>(new ArrayList<Block<Integer>>(), 0);
builder.add(new Addition(3)).add(new Addition(3)).add(new Multiplication(2));
for (Integer result : builder.iterable(2)) {
System.out.println(result);
}
// 3
// 6
As would be expected if you set the number of iterations to be less than the number of Blocks then only that number of will be iterated over. Though, if you set a number iterations that is greater than the number of Blocks then when the iterator has run to the end it will start back at the beginning taking the final result and feeding that back into the top of the Blocks. This will be repeated until the requested number of iterations has been completed.
for (Integer result : builder.iterable(5)) {
System.out.println(result);
}
// 3
// 6
// 12
// 15
// 18