Implemented one-way conversion, duplicate prefixes can now be hidden

3 files changed, 41 insertions, 11 deletions

diff --git a/src/main/java/sevenUnits/unit/BritishImperial.java b/src/main/java/sevenUnits/unit/BritishImperial.java
index c6e65fb..0ecba6d 100644
--- a/src/main/java/sevenUnits/unit/BritishImperial.java
+++ b/src/main/java/sevenUnits/unit/BritishImperial.java
@@ -121,5 +121,5 @@ public final class BritishImperial {
 	public static final Unit FAHRENHEIT = Unit
 			.fromConversionFunctions(Metric.KELVIN.getBase(),
 					tempK -> tempK * 1.8 - 459.67, tempF -> (tempF + 459.67) / 1.8)
-			.withName(NameSymbol.of("degrees Fahrenheit", "\u00B0F"));
+			.withName(NameSymbol.of("degree Fahrenheit", "\u00B0F"));
 }
diff --git a/src/main/java/sevenUnits/unit/UnitDatabase.java b/src/main/java/sevenUnits/unit/UnitDatabase.java
index a4f0c44..71676a1 100644
--- a/src/main/java/sevenUnits/unit/UnitDatabase.java
+++ b/src/main/java/sevenUnits/unit/UnitDatabase.java
@@ -1160,16 +1160,16 @@ public final class UnitDatabase {
 	}
 	
 	/**
-	 * @return true if entry represents a removable duplicate entry of unitMap.
+	 * @return true if entry represents a removable duplicate entry of map.
 	 * @since 2021-05-22
 	 */
-	static boolean isRemovableDuplicate(Map<String, Unit> unitMap,
-			Entry<String, Unit> entry) {
-		for (final Entry<String, Unit> e : unitMap.entrySet()) {
+	static <T> boolean isRemovableDuplicate(Map<String, T> map,
+			Entry<String, T> entry) {
+		for (final Entry<String, T> e : map.entrySet()) {
 			final String name = e.getKey();
-			final Unit value = e.getValue();
+			final T value = e.getValue();
 			if (lengthFirstComparator.compare(entry.getKey(), name) < 0
-					&& Objects.equals(unitMap.get(entry.getKey()), value))
+					&& Objects.equals(map.get(entry.getKey()), value))
 				return true;
 		}
 		return false;
@@ -2010,12 +2010,18 @@ public final class UnitDatabase {
 	}
 	
 	/**
+	 * @param includeDuplicates if false, duplicates are removed from the map
 	 * @return a map mapping prefix names to prefixes
-	 * @since 2019-04-13
-	 * @since v0.2.0
+	 * @since 2022-04-18
+	 * @since v0.4.0
 	 */
-	public Map<String, UnitPrefix> prefixMap() {
-		return Collections.unmodifiableMap(this.prefixes);
+	public Map<String, UnitPrefix> prefixMap(boolean includeDuplicates) {
+		if (includeDuplicates)
+			return Collections.unmodifiableMap(this.prefixes);
+		else
+			return Collections.unmodifiableMap(ConditionalExistenceCollections
+					.conditionalExistenceMap(this.prefixes,
+							entry -> !isRemovableDuplicate(this.prefixes, entry)));
 	}
 	
 	/**
diff --git a/src/main/java/sevenUnits/unit/UnitType.java b/src/main/java/sevenUnits/unit/UnitType.java
index a13051a..7cebf2d 100644
--- a/src/main/java/sevenUnits/unit/UnitType.java
+++ b/src/main/java/sevenUnits/unit/UnitType.java
@@ -16,6 +16,8 @@
  */
 package sevenUnits.unit;
 
+import java.util.function.Predicate;
+
 /**
  * A type of unit, as chosen by the type of system it is in.
  * <ul>
@@ -31,4 +33,26 @@ package sevenUnits.unit;
  */
 public enum UnitType {
 	METRIC, SEMI_METRIC, NON_METRIC;
+	
+	/**
+	 * Determines which type a unit is. The type will be:
+	 * <ul>
+	 * <li>{@code SEMI_METRIC} if the unit passes the provided predicate
+	 * <li>{@code METRIC} if it fails the predicate but is metric
+	 * <li>{@code NON_METRIC} if it fails the predicate and is not metric
+	 * </ul>
+	 *
+	 * @param u            unit to test
+	 * @param isSemiMetric predicate to determine if a unit is semi-metric
+	 * @return type of unit
+	 * @since 2022-04-18
+	 */
+	public static final UnitType getType(Unit u, Predicate<Unit> isSemiMetric) {
+		if (isSemiMetric.test(u))
+			return SEMI_METRIC;
+		else if (u.isMetric())
+			return METRIC;
+		else
+			return NON_METRIC;
+	}
 }