From c8a00b789671d59589bcb5520c1e9d208bcc27f6 Mon Sep 17 00:00:00 2001
From: bculkin2442 <bjculkin@mix.wvu.edu>
Date: Mon, 11 Apr 2016 21:54:44 -0400
Subject: Work on restructing data.

---
 .../java/bjc/utils/data/experimental/LazyPair.java | 317 +++++++++++++++++++++
 1 file changed, 317 insertions(+)
 create mode 100644 BJC-Utils2/src/main/java/bjc/utils/data/experimental/LazyPair.java

(limited to 'BJC-Utils2/src/main/java/bjc/utils/data/experimental/LazyPair.java')

diff --git a/BJC-Utils2/src/main/java/bjc/utils/data/experimental/LazyPair.java b/BJC-Utils2/src/main/java/bjc/utils/data/experimental/LazyPair.java
new file mode 100644
index 0000000..04a4b61
--- /dev/null
+++ b/BJC-Utils2/src/main/java/bjc/utils/data/experimental/LazyPair.java
@@ -0,0 +1,317 @@
+package bjc.utils.data.experimental;
+
+import java.util.function.BiFunction;
+import java.util.function.Function;
+import java.util.function.Supplier;
+
+/**
+ * A lazy implementation of a pair
+ * 
+ * @author ben
+ *
+ * @param <LeftType>
+ *            The type on the left side of the pair
+ * @param <RightType>
+ *            The type on the right side of the pair
+ */
+public class LazyPair<LeftType, RightType>
+		implements IPair<LeftType, RightType> {
+	private static class HalfBoundLazyPair<OldType, NewLeft, NewRight>
+			implements IPair<NewLeft, NewRight> {
+		private Supplier<OldType>							oldSupplier;
+
+		private Function<OldType, IPair<NewLeft, NewRight>>	binder;
+
+		private IPair<NewLeft, NewRight>					boundPair;
+		private boolean										pairBound;
+
+		public HalfBoundLazyPair(Supplier<OldType> oldSupp,
+				Function<OldType, IPair<NewLeft, NewRight>> bindr) {
+			oldSupplier = oldSupp;
+			binder = bindr;
+		}
+
+		@Override
+		public <BoundLeft> IPair<BoundLeft, NewRight> bindLeft(
+				Function<NewLeft, IPair<BoundLeft, NewRight>> leftBinder) {
+			Supplier<NewLeft> leftSupp = () -> {
+				IPair<NewLeft, NewRight> newPair = boundPair;
+
+				if (!pairBound) {
+					newPair = binder.apply(oldSupplier.get());
+				}
+
+				return newPair.getLeft();
+			};
+
+			return new HalfBoundLazyPair<>(leftSupp, leftBinder);
+		}
+
+		@Override
+		public <BoundRight> IPair<NewLeft, BoundRight> bindRight(
+				Function<NewRight, IPair<NewLeft, BoundRight>> rightBinder) {
+			Supplier<NewRight> rightSupp = () -> {
+				IPair<NewLeft, NewRight> newPair = boundPair;
+
+				if (!pairBound) {
+					newPair = binder.apply(oldSupplier.get());
+				}
+
+				return newPair.getRight();
+			};
+
+			return new HalfBoundLazyPair<>(rightSupp, rightBinder);
+		}
+
+		@Override
+		public <BoundLeft, BoundRight> IPair<BoundLeft, BoundRight> bind(
+				BiFunction<NewLeft, NewRight, IPair<BoundLeft, BoundRight>> bindr) {
+			IHolder<IPair<NewLeft, NewRight>> newPair = new Identity<>(
+					boundPair);
+			IHolder<Boolean> newPairMade = new Identity<>(pairBound);
+
+			Supplier<NewLeft> leftSupp = () -> {
+				if (!newPairMade.getValue()) {
+					newPair.replace(binder.apply(oldSupplier.get()));
+					newPairMade.replace(true);
+				}
+
+				return newPair.unwrap((pair) -> pair.getLeft());
+			};
+
+			Supplier<NewRight> rightSupp = () -> {
+				if (!newPairMade.getValue()) {
+					newPair.replace(binder.apply(oldSupplier.get()));
+					newPairMade.replace(true);
+				}
+
+				return newPair.unwrap((pair) -> pair.getRight());
+			};
+
+			return new BoundLazyPair<>(leftSupp, rightSupp, bindr);
+		}
+
+		@Override
+		public <MergedType> MergedType merge(
+				BiFunction<NewLeft, NewRight, MergedType> merger) {
+			if (!pairBound) {
+				boundPair = binder.apply(oldSupplier.get());
+
+				pairBound = true;
+			}
+
+			return boundPair.merge(merger);
+		}
+	}
+
+	private static class BoundLazyPair<OldLeft, OldRight, NewLeft, NewRight>
+			implements IPair<NewLeft, NewRight> {
+		private Supplier<OldLeft>										leftSupplier;
+		private Supplier<OldRight>										rightSupplier;
+
+		private BiFunction<OldLeft, OldRight, IPair<NewLeft, NewRight>>	binder;
+
+		private IPair<NewLeft, NewRight>								boundPair;
+
+		private boolean													pairBound;
+
+		public BoundLazyPair(Supplier<OldLeft> leftSupp,
+				Supplier<OldRight> rightSupp,
+				BiFunction<OldLeft, OldRight, IPair<NewLeft, NewRight>> bindr) {
+			leftSupplier = leftSupp;
+			rightSupplier = rightSupp;
+			binder = bindr;
+		}
+
+		@Override
+		public <BoundLeft> IPair<BoundLeft, NewRight> bindLeft(
+				Function<NewLeft, IPair<BoundLeft, NewRight>> leftBinder) {
+			Supplier<NewLeft> leftSupp = () -> {
+				IPair<NewLeft, NewRight> newPair = boundPair;
+
+				if (!pairBound) {
+					newPair = binder.apply(leftSupplier.get(),
+							rightSupplier.get());
+				}
+
+				return newPair.getLeft();
+			};
+
+			return new HalfBoundLazyPair<>(leftSupp, leftBinder);
+		}
+
+		@Override
+		public <BoundRight> IPair<NewLeft, BoundRight> bindRight(
+				Function<NewRight, IPair<NewLeft, BoundRight>> rightBinder) {
+			Supplier<NewRight> rightSupp = () -> {
+				IPair<NewLeft, NewRight> newPair = boundPair;
+
+				if (!pairBound) {
+					newPair = binder.apply(leftSupplier.get(),
+							rightSupplier.get());
+				}
+
+				return newPair.getRight();
+			};
+
+			return new HalfBoundLazyPair<>(rightSupp, rightBinder);
+		}
+
+		@Override
+		public <BoundLeft, BoundRight> IPair<BoundLeft, BoundRight> bind(
+				BiFunction<NewLeft, NewRight, IPair<BoundLeft, BoundRight>> bindr) {
+			IHolder<IPair<NewLeft, NewRight>> newPair = new Identity<>(
+					boundPair);
+			IHolder<Boolean> newPairMade = new Identity<>(pairBound);
+
+			return new BoundLazyPair<>(() -> {
+				if (!newPairMade.getValue()) {
+					newPair.replace(binder.apply(leftSupplier.get(),
+							rightSupplier.get()));
+
+					newPairMade.replace(false);
+				}
+
+				return newPair.unwrap((pair) -> pair.getLeft());
+			}, () -> {
+				if (!newPairMade.getValue()) {
+					newPair.replace(binder.apply(leftSupplier.get(),
+							rightSupplier.get()));
+
+					newPairMade.replace(false);
+				}
+
+				return newPair.unwrap((pair) -> pair.getRight());
+			}, bindr);
+		}
+
+		@Override
+		public <MergedType> MergedType merge(
+				BiFunction<NewLeft, NewRight, MergedType> merger) {
+			if (!pairBound) {
+				boundPair = binder.apply(leftSupplier.get(),
+						rightSupplier.get());
+
+				pairBound = true;
+			}
+
+			return boundPair.merge(merger);
+		}
+	}
+
+	private LeftType			leftValue;
+	private RightType			rightValue;
+
+	private Supplier<LeftType>	leftSupplier;
+	private Supplier<RightType>	rightSupplier;
+
+	private boolean				leftMaterialized;
+	private boolean				rightMaterialized;
+
+	/**
+	 * Create a new lazy pair, using the set value s
+	 * 
+	 * @param leftVal
+	 *            The value for the left side of the pair
+	 * @param rightVal
+	 *            The value for the right side of the pair
+	 */
+	public LazyPair(LeftType leftVal, RightType rightVal) {
+		leftValue = leftVal;
+		rightValue = rightVal;
+
+		leftMaterialized = true;
+		rightMaterialized = true;
+	}
+
+	/**
+	 * Create a new lazy pair from the given value sources
+	 * 
+	 * @param leftSupp
+	 *            The source for a value on the left side of the pair
+	 * @param rightSupp
+	 *            The source for a value on the right side of the pair
+	 */
+	public LazyPair(Supplier<LeftType> leftSupp,
+			Supplier<RightType> rightSupp) {
+		leftSupplier = leftSupp;
+		rightSupplier = rightSupp;
+
+		leftMaterialized = false;
+		rightMaterialized = false;
+	}
+
+	@Override
+	public <BoundLeft> IPair<BoundLeft, RightType> bindLeft(
+			Function<LeftType, IPair<BoundLeft, RightType>> leftBinder) {
+		Supplier<LeftType> leftSupp = () -> {
+			if (leftMaterialized) {
+				return leftValue;
+			}
+
+			return leftSupplier.get();
+		};
+
+		return new HalfBoundLazyPair<>(leftSupp, leftBinder);
+	}
+
+	@Override
+	public <BoundRight> IPair<LeftType, BoundRight> bindRight(
+			Function<RightType, IPair<LeftType, BoundRight>> rightBinder) {
+		Supplier<RightType> rightSupp = () -> {
+			if (rightMaterialized) {
+				return rightValue;
+			}
+
+			return rightSupplier.get();
+		};
+
+		return new HalfBoundLazyPair<>(rightSupp, rightBinder);
+	}
+
+	@Override
+	public <BoundLeft, BoundRight> IPair<BoundLeft, BoundRight> bind(
+			BiFunction<LeftType, RightType, IPair<BoundLeft, BoundRight>> binder) {
+		return new BoundLazyPair<>(leftSupplier, rightSupplier, binder);
+	}
+
+	@Override
+	public <MergedType> MergedType merge(
+			BiFunction<LeftType, RightType, MergedType> merger) {
+		if (!leftMaterialized) {
+			leftValue = leftSupplier.get();
+
+			leftMaterialized = true;
+		}
+
+		if (!rightMaterialized) {
+			rightValue = rightSupplier.get();
+
+			rightMaterialized = true;
+		}
+
+		return merger.apply(leftValue, rightValue);
+	}
+
+	@Override
+	public LeftType getLeft() {
+		if (!leftMaterialized) {
+			leftValue = leftSupplier.get();
+
+			leftMaterialized = true;
+		}
+
+		return leftValue;
+	}
+
+	@Override
+	public RightType getRight() {
+		if (!rightMaterialized) {
+			rightValue = rightSupplier.get();
+
+			rightMaterialized = true;
+		}
+
+		return rightValue;
+	}
+}
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