com.unit16.z.indexed.DSL Maven / Gradle / Ivy
package com.unit16.z.indexed;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.function.Function;
import java.util.function.Predicate;
import com.google.common.collect.Iterators;
import com.google.common.collect.Lists;
import com.google.common.collect.UnmodifiableIterator;
public abstract class DSL
implements Indexed, Iterable
{
private static final class ListBacked
extends DSL
{
private final List _list;
ListBacked(List i)
{
_list = i;
}
ListBacked(DSL i)
{
_list = new ArrayList<>(i.size());
for (C c : i) { _list.add(c); }
}
@Override public C get(int i) { return _list.get(i); }
@Override public int size() { return _list.size(); }
@Override public Iterator iterator() { return _list.iterator(); }
}
private static final class IndexedBacked
extends DSL
{
private final Indexed _i;
IndexedBacked(Indexed i) {
_i = i;
}
@Override
public C get(int i) { return _i.get(i); }
@Override
public int size() { return _i.size(); }
@Override
public Iterator iterator() {
return new UnmodifiableIterator() {
private int _j = 0;
@Override
public boolean hasNext() { return _j < size(); }
@Override
public C next() { _j++; return get(_j - 1);}
};
}
}
public static DSL from(List c)
{
return new ListBacked<>(c);
}
public static DSL from(Indexed c)
{
return (c instanceof DSL) ? (DSL) c : new IndexedBacked<>(c);
}
public final DSL map(Function f)
{
return new OnResultOf<>(this, f);
}
public final DSL head(final int max)
{
final Indexed w = this;
return new IndexedBacked<>(new Indexed(){
@Override
public B get(int i) { return w.get(i); }
@Override
public int size() { return max; }});
}
public final DSL tail(final int min)
{
final Indexed w = this;
return new IndexedBacked<>(new Indexed(){
@Override
public B get(int i) { return w.get(i + min); }
@Override
public int size() { return w.size() - min; }});
}
public final DSL filter(Predicate p)
{
if (size() > 0)
{
final Iterator i = Iterators.filter(this.iterator(), x -> p.test(x));
if (i.hasNext())
{
return new ListBacked<>(Lists.newArrayList(i));
}
}
return new Empty<>();
}
public final DSL strict()
{
return new ListBacked<>(this);
}
public final DSL append(Indexed snd)
{
return new Concat<>(this, snd);
}
private static final class Concat
extends DSL
{
private final DSL fst_;
private final DSL snd_;
private final int sf;
private final int ss;
Concat(Indexed fst, Indexed snd) {
fst_ = from(fst);
snd_ = from(snd);
sf = fst_.size();
ss = snd_.size();
}
@Override
public C get(int i) {
return i < sf ? fst_.get(i) : snd_.get(i - sf);
}
@Override
public int size() { return sf + ss; }
@Override
public Iterator iterator() {
return Iterators.concat(fst_.iterator(), snd_.iterator()); }
}
}