From 40f7b6e806140fc2fc741c63c71f5ce97b4bd1d2 Mon Sep 17 00:00:00 2001
From: Adrien Hopkins <ahopk127@my.yorku.ca>
Date: Mon, 18 Apr 2022 17:41:43 -0500
Subject: Implemented one-way conversion, duplicate prefixes can now be hidden

---
 src/main/java/sevenUnits/unit/UnitDatabase.java | 26 +++++++++++++++----------
 1 file changed, 16 insertions(+), 10 deletions(-)

(limited to 'src/main/java/sevenUnits/unit/UnitDatabase.java')

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)));
 	}
 	
 	/**
-- 
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