Add named unit sets to unit converter

1 files changed, 301 insertions, 226 deletions

diff --git a/src/main/java/sevenUnits/unit/UnitDatabase.java b/src/main/java/sevenUnits/unit/UnitDatabase.java
index 0120067..58c5cac 100644
--- a/src/main/java/sevenUnits/unit/UnitDatabase.java
+++ b/src/main/java/sevenUnits/unit/UnitDatabase.java
@@ -123,7 +123,7 @@ public final class UnitDatabase {
 					implements Entry<String, Unit> {
 				private final String key;
 				private final Unit value;
-
+				
 				/**
 				 * Creates the {@code PrefixedUnitEntry}.
 				 * 
@@ -136,7 +136,7 @@ public final class UnitDatabase {
 					this.key = key;
 					this.value = value;
 				}
-
+				
 				/**
 				 * @since 2019-05-03
 				 */
@@ -148,17 +148,17 @@ public final class UnitDatabase {
 					return Objects.equals(this.getKey(), other.getKey())
 							&& Objects.equals(this.getValue(), other.getValue());
 				}
-
+				
 				@Override
 				public String getKey() {
 					return this.key;
 				}
-
+				
 				@Override
 				public Unit getValue() {
 					return this.value;
 				}
-
+				
 				/**
 				 * @since 2019-05-03
 				 */
@@ -168,13 +168,13 @@ public final class UnitDatabase {
 							^ (this.getValue() == null ? 0
 									: this.getValue().hashCode());
 				}
-
+				
 				@Override
 				public Unit setValue(final Unit value) {
 					throw new UnsupportedOperationException(
 							"Cannot set value in an immutable entry");
 				}
-
+				
 				/**
 				 * Returns a string representation of the entry. The format of the
 				 * string is the string representation of the key, then the equals
@@ -188,7 +188,7 @@ public final class UnitDatabase {
 					return this.getKey() + "=" + this.getValue();
 				}
 			}
-
+			
 			/**
 			 * An iterator that iterates over the units of a
 			 * {@code PrefixedUnitNameSet}.
@@ -203,12 +203,12 @@ public final class UnitDatabase {
 				private int unitNamePosition = 0;
 				// the indices of the prefixes attached to the current unit
 				private final List<Integer> prefixCoordinates = new ArrayList<>();
-
+				
 				// values from the unit entry set
 				private final Map<String, Unit> map;
 				private transient final List<String> unitNames;
 				private transient final List<String> prefixNames;
-
+				
 				/**
 				 * Creates the
 				 * {@code UnitsDatabase.PrefixedUnitMap.PrefixedUnitNameSet.PrefixedUnitNameIterator}.
@@ -221,7 +221,7 @@ public final class UnitDatabase {
 					this.unitNames = new ArrayList<>(map.units.keySet());
 					this.prefixNames = new ArrayList<>(map.prefixes.keySet());
 				}
-
+				
 				/**
 				 * @return current unit name
 				 * @since 2019-04-14
@@ -233,10 +233,10 @@ public final class UnitDatabase {
 						unitName.append(this.prefixNames.get(i));
 					}
 					unitName.append(this.unitNames.get(this.unitNamePosition));
-
+					
 					return unitName.toString();
 				}
-
+				
 				@Override
 				public boolean hasNext() {
 					if (this.unitNames.isEmpty())
@@ -249,7 +249,7 @@ public final class UnitDatabase {
 							return true;
 					}
 				}
-
+				
 				/**
 				 * Changes this iterator's position to the next available one.
 				 * 
@@ -258,11 +258,11 @@ public final class UnitDatabase {
 				 */
 				private void incrementPosition() {
 					this.unitNamePosition++;
-
+					
 					if (this.unitNamePosition >= this.unitNames.size()) {
 						// we have used all of our units, go to a different prefix
 						this.unitNamePosition = 0;
-
+						
 						// if the prefix coordinates are empty, then set it to [0]
 						if (this.prefixCoordinates.isEmpty()) {
 							this.prefixCoordinates.add(0, 0);
@@ -271,7 +271,7 @@ public final class UnitDatabase {
 							int i = this.prefixCoordinates.size() - 1;
 							this.prefixCoordinates.set(i,
 									this.prefixCoordinates.get(i) + 1);
-
+							
 							// fix any carrying errors
 							while (i >= 0 && this.prefixCoordinates
 									.get(i) >= this.prefixNames.size()) {
@@ -279,7 +279,7 @@ public final class UnitDatabase {
 								this.prefixCoordinates.set(i--, 0); // null and
 																				// decrement at the
 																				// same time
-
+								
 								if (i < 0) { // we need to add a new coordinate
 									this.prefixCoordinates.add(0, 0);
 								} else { // increment an existing one
@@ -290,18 +290,18 @@ public final class UnitDatabase {
 						}
 					}
 				}
-
+				
 				@Override
 				public Entry<String, Unit> next() {
 					// get next element
 					final Entry<String, Unit> nextEntry = this.peek();
-
+					
 					// iterate to next position
 					this.incrementPosition();
-
+					
 					return nextEntry;
 				}
-
+				
 				/**
 				 * @return the next element in the iterator, without iterating over
 				 *         it
@@ -310,7 +310,7 @@ public final class UnitDatabase {
 				private Entry<String, Unit> peek() {
 					if (!this.hasNext())
 						throw new NoSuchElementException("No units left!");
-
+						
 					// if I have prefixes, ensure I'm not using a nonlinear unit
 					// since all of the unprefixed stuff is done, just remove
 					// nonlinear units
@@ -321,12 +321,12 @@ public final class UnitDatabase {
 							this.unitNames.remove(this.unitNamePosition);
 						}
 					}
-
+					
 					final String nextName = this.getCurrentUnitName();
-
+					
 					return new PrefixedUnitEntry(nextName, this.map.get(nextName));
 				}
-
+				
 				/**
 				 * Returns a string representation of the object. The exact details
 				 * of the representation are unspecified and subject to change.
@@ -340,10 +340,10 @@ public final class UnitDatabase {
 							this.peek());
 				}
 			}
-
+			
 			// the map that created this set
 			private final PrefixedUnitMap map;
-
+			
 			/**
 			 * Creates the {@code PrefixedUnitNameSet}.
 			 * 
@@ -354,31 +354,31 @@ public final class UnitDatabase {
 			public PrefixedUnitEntrySet(final PrefixedUnitMap map) {
 				this.map = map;
 			}
-
+			
 			@Override
 			public boolean add(final Map.Entry<String, Unit> e) {
 				throw new UnsupportedOperationException(
 						"Cannot add to an immutable set");
 			}
-
+			
 			@Override
 			public boolean addAll(
 					final Collection<? extends Map.Entry<String, Unit>> c) {
 				throw new UnsupportedOperationException(
 						"Cannot add to an immutable set");
 			}
-
+			
 			@Override
 			public void clear() {
 				throw new UnsupportedOperationException(
 						"Cannot clear an immutable set");
 			}
-
+			
 			@Override
 			public boolean contains(final Object o) {
 				// get the entry
 				final Entry<String, Unit> entry;
-
+				
 				try {
 					// This is OK because I'm in a try-catch block, catching the
 					// exact exception that would be thrown.
@@ -389,11 +389,11 @@ public final class UnitDatabase {
 					throw new IllegalArgumentException(
 							"Attempted to test for an entry using a non-entry.");
 				}
-
+				
 				return this.map.containsKey(entry.getKey())
 						&& this.map.get(entry.getKey()).equals(entry.getValue());
 			}
-
+			
 			@Override
 			public boolean containsAll(final Collection<?> c) {
 				for (final Object o : c)
@@ -401,42 +401,42 @@ public final class UnitDatabase {
 						return false;
 				return true;
 			}
-
+			
 			@Override
 			public boolean isEmpty() {
 				return this.map.isEmpty();
 			}
-
+			
 			@Override
 			public Iterator<Entry<String, Unit>> iterator() {
 				return new PrefixedUnitEntryIterator(this.map);
 			}
-
+			
 			@Override
 			public boolean remove(final Object o) {
 				throw new UnsupportedOperationException(
 						"Cannot remove from an immutable set");
 			}
-
+			
 			@Override
 			public boolean removeAll(final Collection<?> c) {
 				throw new UnsupportedOperationException(
 						"Cannot remove from an immutable set");
 			}
-
+			
 			@Override
 			public boolean removeIf(
 					final Predicate<? super Entry<String, Unit>> filter) {
 				throw new UnsupportedOperationException(
 						"Cannot remove from an immutable set");
 			}
-
+			
 			@Override
 			public boolean retainAll(final Collection<?> c) {
 				throw new UnsupportedOperationException(
 						"Cannot remove from an immutable set");
 			}
-
+			
 			@Override
 			public int size() {
 				if (this.map.units.isEmpty())
@@ -449,7 +449,7 @@ public final class UnitDatabase {
 						return Integer.MAX_VALUE;
 				}
 			}
-
+			
 			/**
 			 * @throws IllegalStateException if the set is infinite in size
 			 */
@@ -462,7 +462,7 @@ public final class UnitDatabase {
 					throw new IllegalStateException(
 							"Cannot make an infinite set into an array.");
 			}
-
+			
 			/**
 			 * @throws IllegalStateException if the set is infinite in size
 			 */
@@ -475,7 +475,7 @@ public final class UnitDatabase {
 					throw new IllegalStateException(
 							"Cannot make an infinite set into an array.");
 			}
-
+			
 			@Override
 			public String toString() {
 				if (this.map.units.isEmpty() || this.map.prefixes.isEmpty())
@@ -486,7 +486,7 @@ public final class UnitDatabase {
 							this.map.units, this.map.prefixes);
 			}
 		}
-
+		
 		/**
 		 * The class used for unit name sets.
 		 * 
@@ -518,12 +518,12 @@ public final class UnitDatabase {
 				private int unitNamePosition = 0;
 				// the indices of the prefixes attached to the current unit
 				private final List<Integer> prefixCoordinates = new ArrayList<>();
-
+				
 				// values from the unit name set
 				private final Map<String, Unit> map;
 				private transient final List<String> unitNames;
 				private transient final List<String> prefixNames;
-
+				
 				/**
 				 * Creates the
 				 * {@code UnitsDatabase.PrefixedUnitMap.PrefixedUnitNameSet.PrefixedUnitNameIterator}.
@@ -536,7 +536,7 @@ public final class UnitDatabase {
 					this.unitNames = new ArrayList<>(map.units.keySet());
 					this.prefixNames = new ArrayList<>(map.prefixes.keySet());
 				}
-
+				
 				/**
 				 * @return current unit name
 				 * @since 2019-04-14
@@ -548,10 +548,10 @@ public final class UnitDatabase {
 						unitName.append(this.prefixNames.get(i));
 					}
 					unitName.append(this.unitNames.get(this.unitNamePosition));
-
+					
 					return unitName.toString();
 				}
-
+				
 				@Override
 				public boolean hasNext() {
 					if (this.unitNames.isEmpty())
@@ -564,7 +564,7 @@ public final class UnitDatabase {
 							return true;
 					}
 				}
-
+				
 				/**
 				 * Changes this iterator's position to the next available one.
 				 * 
@@ -573,11 +573,11 @@ public final class UnitDatabase {
 				 */
 				private void incrementPosition() {
 					this.unitNamePosition++;
-
+					
 					if (this.unitNamePosition >= this.unitNames.size()) {
 						// we have used all of our units, go to a different prefix
 						this.unitNamePosition = 0;
-
+						
 						// if the prefix coordinates are empty, then set it to [0]
 						if (this.prefixCoordinates.isEmpty()) {
 							this.prefixCoordinates.add(0, 0);
@@ -586,7 +586,7 @@ public final class UnitDatabase {
 							int i = this.prefixCoordinates.size() - 1;
 							this.prefixCoordinates.set(i,
 									this.prefixCoordinates.get(i) + 1);
-
+							
 							// fix any carrying errors
 							while (i >= 0 && this.prefixCoordinates
 									.get(i) >= this.prefixNames.size()) {
@@ -594,7 +594,7 @@ public final class UnitDatabase {
 								this.prefixCoordinates.set(i--, 0); // null and
 																				// decrement at the
 																				// same time
-
+								
 								if (i < 0) { // we need to add a new coordinate
 									this.prefixCoordinates.add(0, 0);
 								} else { // increment an existing one
@@ -605,16 +605,16 @@ public final class UnitDatabase {
 						}
 					}
 				}
-
+				
 				@Override
 				public String next() {
 					final String nextName = this.peek();
-
+					
 					this.incrementPosition();
-
+					
 					return nextName;
 				}
-
+				
 				/**
 				 * @return the next element in the iterator, without iterating over
 				 *         it
@@ -633,10 +633,10 @@ public final class UnitDatabase {
 							this.unitNames.remove(this.unitNamePosition);
 						}
 					}
-
+					
 					return this.getCurrentUnitName();
 				}
-
+				
 				/**
 				 * Returns a string representation of the object. The exact details
 				 * of the representation are unspecified and subject to change.
@@ -650,10 +650,10 @@ public final class UnitDatabase {
 							this.peek());
 				}
 			}
-
+			
 			// the map that created this set
 			private final PrefixedUnitMap map;
-
+			
 			/**
 			 * Creates the {@code PrefixedUnitNameSet}.
 			 * 
@@ -664,30 +664,30 @@ public final class UnitDatabase {
 			public PrefixedUnitNameSet(final PrefixedUnitMap map) {
 				this.map = map;
 			}
-
+			
 			@Override
 			public boolean add(final String e) {
 				throw new UnsupportedOperationException(
 						"Cannot add to an immutable set");
 			}
-
+			
 			@Override
 			public boolean addAll(final Collection<? extends String> c) {
 				throw new UnsupportedOperationException(
 						"Cannot add to an immutable set");
 			}
-
+			
 			@Override
 			public void clear() {
 				throw new UnsupportedOperationException(
 						"Cannot clear an immutable set");
 			}
-
+			
 			@Override
 			public boolean contains(final Object o) {
 				return this.map.containsKey(o);
 			}
-
+			
 			@Override
 			public boolean containsAll(final Collection<?> c) {
 				for (final Object o : c)
@@ -695,41 +695,41 @@ public final class UnitDatabase {
 						return false;
 				return true;
 			}
-
+			
 			@Override
 			public boolean isEmpty() {
 				return this.map.isEmpty();
 			}
-
+			
 			@Override
 			public Iterator<String> iterator() {
 				return new PrefixedUnitNameIterator(this.map);
 			}
-
+			
 			@Override
 			public boolean remove(final Object o) {
 				throw new UnsupportedOperationException(
 						"Cannot remove from an immutable set");
 			}
-
+			
 			@Override
 			public boolean removeAll(final Collection<?> c) {
 				throw new UnsupportedOperationException(
 						"Cannot remove from an immutable set");
 			}
-
+			
 			@Override
 			public boolean removeIf(final Predicate<? super String> filter) {
 				throw new UnsupportedOperationException(
 						"Cannot remove from an immutable set");
 			}
-
+			
 			@Override
 			public boolean retainAll(final Collection<?> c) {
 				throw new UnsupportedOperationException(
 						"Cannot remove from an immutable set");
 			}
-
+			
 			@Override
 			public int size() {
 				if (this.map.units.isEmpty())
@@ -742,7 +742,7 @@ public final class UnitDatabase {
 						return Integer.MAX_VALUE;
 				}
 			}
-
+			
 			/**
 			 * @throws IllegalStateException if the set is infinite in size
 			 */
@@ -754,9 +754,9 @@ public final class UnitDatabase {
 					// infinite set
 					throw new IllegalStateException(
 							"Cannot make an infinite set into an array.");
-
+				
 			}
-
+			
 			/**
 			 * @throws IllegalStateException if the set is infinite in size
 			 */
@@ -769,7 +769,7 @@ public final class UnitDatabase {
 					throw new IllegalStateException(
 							"Cannot make an infinite set into an array.");
 			}
-
+			
 			@Override
 			public String toString() {
 				if (this.map.units.isEmpty() || this.map.prefixes.isEmpty())
@@ -780,7 +780,7 @@ public final class UnitDatabase {
 							this.map.units, this.map.prefixes);
 			}
 		}
-
+		
 		/**
 		 * The units stored in this collection, without prefixes.
 		 * 
@@ -788,7 +788,7 @@ public final class UnitDatabase {
 		 * @since v0.2.0
 		 */
 		private final Map<String, Unit> units;
-
+		
 		/**
 		 * The available prefixes for use.
 		 * 
@@ -796,12 +796,12 @@ public final class UnitDatabase {
 		 * @since v0.2.0
 		 */
 		private final Map<String, UnitPrefix> prefixes;
-
+		
 		// caches
 		private transient Collection<Unit> values = null;
 		private transient Set<String> keySet = null;
 		private transient Set<Entry<String, Unit>> entrySet = null;
-
+		
 		/**
 		 * Creates the {@code PrefixedUnitMap}.
 		 * 
@@ -817,50 +817,50 @@ public final class UnitDatabase {
 			this.units = Collections.unmodifiableMap(units);
 			this.prefixes = Collections.unmodifiableMap(prefixes);
 		}
-
+		
 		@Override
 		public void clear() {
 			throw new UnsupportedOperationException(
 					"Cannot clear an immutable map");
 		}
-
+		
 		@Override
 		public Unit compute(final String key,
 				final BiFunction<? super String, ? super Unit, ? extends Unit> remappingFunction) {
 			throw new UnsupportedOperationException(
 					"Cannot edit an immutable map");
 		}
-
+		
 		@Override
 		public Unit computeIfAbsent(final String key,
 				final Function<? super String, ? extends Unit> mappingFunction) {
 			throw new UnsupportedOperationException(
 					"Cannot edit an immutable map");
 		}
-
+		
 		@Override
 		public Unit computeIfPresent(final String key,
 				final BiFunction<? super String, ? super Unit, ? extends Unit> remappingFunction) {
 			throw new UnsupportedOperationException(
 					"Cannot edit an immutable map");
 		}
-
+		
 		@Override
 		public boolean containsKey(final Object key) {
 			// First, test if there is a unit with the key
 			if (this.units.containsKey(key))
 				return true;
-
+			
 			// Next, try to cast it to String
 			if (!(key instanceof String))
 				throw new IllegalArgumentException(
 						"Attempted to test for a unit using a non-string name.");
 			final String unitName = (String) key;
-
+			
 			// Then, look for the longest prefix that is attached to a valid unit
 			String longestPrefix = null;
 			int longestLength = 0;
-
+			
 			for (final String prefixName : this.prefixes.keySet()) {
 				// a prefix name is valid if:
 				// - it is prefixed (i.e. the unit name starts with it)
@@ -879,10 +879,10 @@ public final class UnitDatabase {
 					}
 				}
 			}
-
+			
 			return longestPrefix != null;
 		}
-
+		
 		/**
 		 * {@inheritDoc}
 		 * 
@@ -895,7 +895,7 @@ public final class UnitDatabase {
 		public boolean containsValue(final Object value) {
 			return this.units.containsValue(value);
 		}
-
+		
 		@Override
 		public Set<Entry<String, Unit>> entrySet() {
 			if (this.entrySet == null) {
@@ -903,23 +903,23 @@ public final class UnitDatabase {
 			}
 			return this.entrySet;
 		}
-
+		
 		@Override
 		public Unit get(final Object key) {
 			// First, test if there is a unit with the key
 			if (this.units.containsKey(key))
 				return this.units.get(key);
-
+			
 			// Next, try to cast it to String
 			if (!(key instanceof String))
 				throw new IllegalArgumentException(
 						"Attempted to obtain a unit using a non-string name.");
 			final String unitName = (String) key;
-
+			
 			// Then, look for the longest prefix that is attached to a valid unit
 			String longestPrefix = null;
 			int longestLength = 0;
-
+			
 			for (final String prefixName : this.prefixes.keySet()) {
 				// a prefix name is valid if:
 				// - it is prefixed (i.e. the unit name starts with it)
@@ -938,7 +938,7 @@ public final class UnitDatabase {
 					}
 				}
 			}
-
+			
 			// if none found, returns null
 			if (longestPrefix == null)
 				return null;
@@ -949,16 +949,16 @@ public final class UnitDatabase {
 				// before selecting this prefix
 				final LinearUnit unit = (LinearUnit) this.get(rest);
 				final UnitPrefix prefix = this.prefixes.get(longestPrefix);
-
+				
 				return unit.withPrefix(prefix);
 			}
 		}
-
+		
 		@Override
 		public boolean isEmpty() {
 			return this.units.isEmpty();
 		}
-
+		
 		@Override
 		public Set<String> keySet() {
 			if (this.keySet == null) {
@@ -966,64 +966,64 @@ public final class UnitDatabase {
 			}
 			return this.keySet;
 		}
-
+		
 		@Override
 		public Unit merge(final String key, final Unit value,
 				final BiFunction<? super Unit, ? super Unit, ? extends Unit> remappingFunction) {
 			throw new UnsupportedOperationException(
 					"Cannot merge into an immutable map");
 		}
-
+		
 		@Override
 		public Unit put(final String key, final Unit value) {
 			throw new UnsupportedOperationException(
 					"Cannot add entries to an immutable map");
 		}
-
+		
 		@Override
 		public void putAll(final Map<? extends String, ? extends Unit> m) {
 			throw new UnsupportedOperationException(
 					"Cannot add entries to an immutable map");
 		}
-
+		
 		@Override
 		public Unit putIfAbsent(final String key, final Unit value) {
 			throw new UnsupportedOperationException(
 					"Cannot add entries to an immutable map");
 		}
-
+		
 		@Override
 		public Unit remove(final Object key) {
 			throw new UnsupportedOperationException(
 					"Cannot remove entries from an immutable map");
 		}
-
+		
 		@Override
 		public boolean remove(final Object key, final Object value) {
 			throw new UnsupportedOperationException(
 					"Cannot remove entries from an immutable map");
 		}
-
+		
 		@Override
 		public Unit replace(final String key, final Unit value) {
 			throw new UnsupportedOperationException(
 					"Cannot replace entries in an immutable map");
 		}
-
+		
 		@Override
 		public boolean replace(final String key, final Unit oldValue,
 				final Unit newValue) {
 			throw new UnsupportedOperationException(
 					"Cannot replace entries in an immutable map");
 		}
-
+		
 		@Override
 		public void replaceAll(
 				final BiFunction<? super String, ? super Unit, ? extends Unit> function) {
 			throw new UnsupportedOperationException(
 					"Cannot replace entries in an immutable map");
 		}
-
+		
 		@Override
 		public int size() {
 			if (this.units.isEmpty())
@@ -1036,7 +1036,7 @@ public final class UnitDatabase {
 					return Integer.MAX_VALUE;
 			}
 		}
-
+		
 		@Override
 		public String toString() {
 			if (this.units.isEmpty() || this.prefixes.isEmpty())
@@ -1046,7 +1046,7 @@ public final class UnitDatabase {
 						"Infinite map of name-unit entries created from units %s and prefixes %s",
 						this.units, this.prefixes);
 		}
-
+		
 		/**
 		 * {@inheritDoc}
 		 * 
@@ -1064,12 +1064,12 @@ public final class UnitDatabase {
 			return this.values;
 		}
 	}
-
+	
 	/**
 	 * Replacements done to *all* expression types
 	 */
 	private static final Map<Pattern, String> EXPRESSION_REPLACEMENTS = new HashMap<>();
-
+	
 	// add data to expression replacements
 	static {
 		// add spaces around operators
@@ -1077,7 +1077,7 @@ public final class UnitDatabase {
 			EXPRESSION_REPLACEMENTS.put(Pattern.compile(operator),
 					" " + operator + " ");
 		}
-
+		
 		// replace multiple spaces with a single space
 		EXPRESSION_REPLACEMENTS.put(Pattern.compile(" +"), " ");
 		// place brackets around any expression of the form "number unit", with or
@@ -1092,20 +1092,20 @@ public final class UnitDatabase {
 									// "1e3")
 		), "\\($1 $2\\)");
 	}
-
+	
 	/**
 	 * A regular expression that separates names and expressions in unit files.
 	 */
 	private static final Pattern NAME_EXPRESSION = Pattern
 			.compile("(\\S+)\\s+(\\S.*)");
-
+	
 	/**
 	 * Like normal string comparisons, but shorter strings are always less than
 	 * longer strings.
 	 */
 	private static final Comparator<String> lengthFirstComparator = Comparator
 			.comparingInt(String::length).thenComparing(Comparator.naturalOrder());
-
+	
 	/**
 	 * The exponent operator
 	 * 
@@ -1132,7 +1132,7 @@ public final class UnitDatabase {
 			// not a number
 			throw new IllegalArgumentException("Exponents must be numbers.");
 	}
-
+	
 	/**
 	 * The exponent operator
 	 * 
@@ -1158,7 +1158,7 @@ public final class UnitDatabase {
 			// not a number
 			throw new IllegalArgumentException("Exponents must be numbers.");
 	}
-
+	
 	/**
 	 * @return true if entry represents a removable duplicate entry of map.
 	 * @since 2021-05-22
@@ -1174,7 +1174,7 @@ public final class UnitDatabase {
 		}
 		return false;
 	}
-
+	
 	/**
 	 * The units in this system, excluding prefixes.
 	 * 
@@ -1182,7 +1182,7 @@ public final class UnitDatabase {
 	 * @since v0.1.0
 	 */
 	private final Map<String, Unit> prefixlessUnits;
-
+	
 	/**
 	 * The unit prefixes in this system.
 	 * 
@@ -1190,7 +1190,7 @@ public final class UnitDatabase {
 	 * @since v0.1.0
 	 */
 	private final Map<String, UnitPrefix> prefixes;
-
+	
 	/**
 	 * The dimensions in this system.
 	 * 
@@ -1198,7 +1198,7 @@ public final class UnitDatabase {
 	 * @since v0.2.0
 	 */
 	private final Map<String, ObjectProduct<BaseDimension>> dimensions;
-
+	
 	/**
 	 * A map mapping strings to units (including prefixes)
 	 * 
@@ -1206,7 +1206,15 @@ public final class UnitDatabase {
 	 * @since v0.2.0
 	 */
 	private final Map<String, Unit> units;
-
+	
+	/**
+	 * A map mapping strings to unit sets
+	 * 
+	 * @since 2024-08-16
+	 * @since v1.0.0
+	 */
+	private final Map<String, List<LinearUnit>> unitSets;
+	
 	/**
 	 * The rule that specifies when prefix repetition is allowed. It takes in one
 	 * argument: a list of the prefixes being applied to the unit
@@ -1218,7 +1226,7 @@ public final class UnitDatabase {
 	 * {@code prefixRepetitionRule.test(Arrays.asList(giga, mega, kilo))}
 	 */
 	private Predicate<List<UnitPrefix>> prefixRepetitionRule;
-
+	
 	/**
 	 * A parser that can parse unit expressions.
 	 * 
@@ -1227,13 +1235,14 @@ public final class UnitDatabase {
 	 */
 	private final ExpressionParser<LinearUnit> unitExpressionParser = new ExpressionParser.Builder<>(
 			this::getLinearUnit).addBinaryOperator("+", (o1, o2) -> o1.plus(o2), 0)
-			.addBinaryOperator("-", (o1, o2) -> o1.minus(o2), 0)
-			.addBinaryOperator("*", (o1, o2) -> o1.times(o2), 1)
-			.addSpaceFunction("*")
-			.addBinaryOperator("/", (o1, o2) -> o1.dividedBy(o2), 1)
-			.addBinaryOperator("|", (o1, o2) -> o1.dividedBy(o2), 3)
-			.addBinaryOperator("^", UnitDatabase::exponentiateUnits, 2).build();
-
+					.addBinaryOperator("-", (o1, o2) -> o1.minus(o2), 0)
+					.addBinaryOperator("*", (o1, o2) -> o1.times(o2), 1)
+					.addSpaceFunction("*")
+					.addBinaryOperator("/", (o1, o2) -> o1.dividedBy(o2), 1)
+					.addBinaryOperator("|", (o1, o2) -> o1.dividedBy(o2), 3)
+					.addBinaryOperator("^", UnitDatabase::exponentiateUnits, 2)
+					.build();
+	
 	/**
 	 * A parser that can parse unit value expressions.
 	 * 
@@ -1241,15 +1250,15 @@ public final class UnitDatabase {
 	 */
 	private final ExpressionParser<LinearUnitValue> unitValueExpressionParser = new ExpressionParser.Builder<>(
 			this::getLinearUnitValue)
-			.addBinaryOperator("+", (o1, o2) -> o1.plus(o2), 0)
-			.addBinaryOperator("-", (o1, o2) -> o1.minus(o2), 0)
-			.addBinaryOperator("*", (o1, o2) -> o1.times(o2), 1)
-			.addSpaceFunction("*")
-			.addBinaryOperator("/", (o1, o2) -> o1.dividedBy(o2), 1)
-			.addBinaryOperator("|", (o1, o2) -> o1.dividedBy(o2), 3)
-			.addBinaryOperator("^", UnitDatabase::exponentiateUnitValues, 2)
-			.build();
-
+					.addBinaryOperator("+", (o1, o2) -> o1.plus(o2), 0)
+					.addBinaryOperator("-", (o1, o2) -> o1.minus(o2), 0)
+					.addBinaryOperator("*", (o1, o2) -> o1.times(o2), 1)
+					.addSpaceFunction("*")
+					.addBinaryOperator("/", (o1, o2) -> o1.dividedBy(o2), 1)
+					.addBinaryOperator("|", (o1, o2) -> o1.dividedBy(o2), 3)
+					.addBinaryOperator("^", UnitDatabase::exponentiateUnitValues, 2)
+					.build();
+	
 	/**
 	 * A parser that can parse unit prefix expressions
 	 * 
@@ -1258,15 +1267,15 @@ public final class UnitDatabase {
 	 */
 	private final ExpressionParser<UnitPrefix> prefixExpressionParser = new ExpressionParser.Builder<>(
 			this::getPrefix).addBinaryOperator("+", (o1, o2) -> o1.plus(o2), 0)
-			.addBinaryOperator("-", (o1, o2) -> o1.minus(o2), 0)
-			.addBinaryOperator("*", (o1, o2) -> o1.times(o2), 1)
-			.addSpaceFunction("*")
-			.addBinaryOperator("/", (o1, o2) -> o1.dividedBy(o2), 1)
-			.addBinaryOperator("|", (o1, o2) -> o1.dividedBy(o2), 3)
-			.addBinaryOperator("^", (o1, o2) -> o1.toExponent(o2.getMultiplier()),
-					2)
-			.build();
-
+					.addBinaryOperator("-", (o1, o2) -> o1.minus(o2), 0)
+					.addBinaryOperator("*", (o1, o2) -> o1.times(o2), 1)
+					.addSpaceFunction("*")
+					.addBinaryOperator("/", (o1, o2) -> o1.dividedBy(o2), 1)
+					.addBinaryOperator("|", (o1, o2) -> o1.dividedBy(o2), 3)
+					.addBinaryOperator("^",
+							(o1, o2) -> o1.toExponent(o2.getMultiplier()), 2)
+					.build();
+	
 	/**
 	 * A parser that can parse unit dimension expressions.
 	 * 
@@ -1275,14 +1284,14 @@ public final class UnitDatabase {
 	 */
 	private final ExpressionParser<ObjectProduct<BaseDimension>> unitDimensionParser = new ExpressionParser.Builder<>(
 			this::getDimension).addBinaryOperator("*", (o1, o2) -> o1.times(o2), 0)
-			.addSpaceFunction("*")
-			.addBinaryOperator("/", (o1, o2) -> o1.dividedBy(o2), 0)
-			.addBinaryOperator("|", (o1, o2) -> o1.dividedBy(o2), 2)
-			.addNumericOperator("^", (o1, o2) -> {
-				int exponent = (int) Math.round(o2.value());
-				return o1.toExponent(exponent);
-			}, 1).build();
-
+					.addSpaceFunction("*")
+					.addBinaryOperator("/", (o1, o2) -> o1.dividedBy(o2), 0)
+					.addBinaryOperator("|", (o1, o2) -> o1.dividedBy(o2), 2)
+					.addNumericOperator("^", (o1, o2) -> {
+						final int exponent = (int) Math.round(o2.value());
+						return o1.toExponent(exponent);
+					}, 1).build();
+	
 	/**
 	 * Creates the {@code UnitsDatabase}.
 	 * 
@@ -1292,7 +1301,7 @@ public final class UnitDatabase {
 	public UnitDatabase() {
 		this(prefixes -> true);
 	}
-
+	
 	/**
 	 * Creates the {@code UnitsDatabase}
 	 * 
@@ -1309,8 +1318,9 @@ public final class UnitDatabase {
 				new PrefixedUnitMap(this.prefixlessUnits, this.prefixes),
 				entry -> this.prefixRepetitionRule
 						.test(this.getPrefixesFromName(entry.getKey())));
+		this.unitSets = new HashMap<>();
 	}
-
+	
 	/**
 	 * Adds a unit dimension to the database.
 	 * 
@@ -1328,7 +1338,7 @@ public final class UnitDatabase {
 				.withName(dimension.getNameSymbol().withExtraName(name));
 		this.dimensions.put(name, namedDimension);
 	}
-
+	
 	/**
 	 * Adds to the list from a line in a unit dimension file.
 	 * 
@@ -1347,7 +1357,7 @@ public final class UnitDatabase {
 					lineCounter);
 			return;
 		}
-
+		
 		// divide line into name and expression
 		final Matcher lineMatcher = NAME_EXPRESSION.matcher(line);
 		if (!lineMatcher.matches())
@@ -1356,12 +1366,12 @@ public final class UnitDatabase {
 					lineCounter));
 		final String name = lineMatcher.group(1);
 		final String expression = lineMatcher.group(2);
-
+		
 		// if (name.endsWith(" ")) {
 		// System.err.printf("Warning - line %d's dimension name ends in a space",
 		// lineCounter);
 		// }
-
+		
 		// if expression is "!", search for an existing dimension
 		// if no unit found, throw an error
 		if (expression.equals("!")) {
@@ -1377,11 +1387,11 @@ public final class UnitDatabase {
 				System.err.printf("Parsing error on line %d:%n", lineCounter);
 				throw e;
 			}
-
+			
 			this.addDimension(name, dimension);
 		}
 	}
-
+	
 	/**
 	 * Adds a unit prefix to the database.
 	 * 
@@ -1398,7 +1408,7 @@ public final class UnitDatabase {
 		this.prefixes.put(Objects.requireNonNull(name, "name must not be null."),
 				namedPrefix);
 	}
-
+	
 	/**
 	 * Adds a unit to the database.
 	 * 
@@ -1415,7 +1425,7 @@ public final class UnitDatabase {
 		this.prefixlessUnits.put(
 				Objects.requireNonNull(name, "name must not be null."), namedUnit);
 	}
-
+	
 	/**
 	 * Adds to the list from a line in a unit file.
 	 * 
@@ -1434,7 +1444,7 @@ public final class UnitDatabase {
 					lineCounter);
 			return;
 		}
-
+		
 		// divide line into name and expression
 		final Matcher lineMatcher = NAME_EXPRESSION.matcher(line);
 		if (!lineMatcher.matches())
@@ -1442,15 +1452,15 @@ public final class UnitDatabase {
 					"Error at line %d: Lines of a unit file must consist of a unit name, then spaces or tabs, then a unit expression.",
 					lineCounter));
 		final String name = lineMatcher.group(1);
-
+		
 		final String expression = lineMatcher.group(2);
-
+		
 		// this code should never occur
 		// if (name.endsWith(" ")) {
 		// System.err.printf("Warning - line %d's unit name ends in a space",
 		// lineCounter);
 		// }
-
+		
 		// if expression is "!", search for an existing unit
 		// if no unit found, throw an error
 		if (expression.equals("!")) {
@@ -1469,6 +1479,29 @@ public final class UnitDatabase {
 				}
 				final String prefixName = name.substring(0, name.length() - 1);
 				this.addPrefix(prefixName, prefix);
+			} else if (expression.contains(";")) {
+				// it's a multi-unit
+				final String[] parts = expression.split(";");
+				final List<LinearUnit> units = new ArrayList<>(parts.length);
+				for (final String unitName : parts) {
+					final Unit unit;
+					try {
+						unit = this.getUnitFromExpression(unitName.trim());
+					} catch (final NoSuchElementException e) {
+						System.err.printf("Parsing error on line %d:%n", lineCounter);
+						throw e;
+					}
+					
+					if (unit instanceof LinearUnit) {
+						units.add((LinearUnit) unit);
+					} else {
+						System.err.printf("Parsing error on line %d:%n", lineCounter);
+						throw new IllegalArgumentException(String.format(
+								"Unit '%s' is in a unit-set expression, but is not linear.",
+								unitName));
+					}
+				}
+				this.addUnitSet(name, units);
 			} else {
 				// it's a unit, get the unit
 				final Unit unit;
@@ -1483,9 +1516,20 @@ public final class UnitDatabase {
 			}
 		}
 	}
-
+	
 	/**
-	 * Removes all units, prefixes and dimensions from this database.
+	 * Add a unit set to the database.
+	 *
+	 * @param name  name of unit set
+	 * @param value unit set to add
+	 * @since 2024-08-16
+	 */
+	public void addUnitSet(String name, List<LinearUnit> value) {
+		this.unitSets.put(name, value);
+	}
+	
+	/**
+	 * Removes all units, unit sets, prefixes and dimensions from this database.
 	 * 
 	 * @since 2022-02-26
 	 */
@@ -1493,8 +1537,9 @@ public final class UnitDatabase {
 		this.dimensions.clear();
 		this.prefixes.clear();
 		this.prefixlessUnits.clear();
+		this.unitSets.clear();
 	}
-
+	
 	/**
 	 * Tests if the database has a unit dimension with this name.
 	 * 
@@ -1506,7 +1551,7 @@ public final class UnitDatabase {
 	public boolean containsDimensionName(final String name) {
 		return this.dimensions.containsKey(name);
 	}
-
+	
 	/**
 	 * Tests if the database has a unit prefix with this name.
 	 * 
@@ -1518,7 +1563,7 @@ public final class UnitDatabase {
 	public boolean containsPrefixName(final String name) {
 		return this.prefixes.containsKey(name);
 	}
-
+	
 	/**
 	 * Tests if the database has a unit with this name, taking prefixes into
 	 * consideration
@@ -1531,7 +1576,16 @@ public final class UnitDatabase {
 	public boolean containsUnitName(final String name) {
 		return this.units.containsKey(name);
 	}
-
+	
+	/**
+	 * Returns true iff there is a unit set with this name.
+	 *
+	 * @since 2024-08-16
+	 */
+	public boolean containsUnitSetName(String name) {
+		return this.unitSets.containsKey(name);
+	}
+	
 	/**
 	 * @return a map mapping dimension names to dimensions
 	 * @since 2019-04-13
@@ -1540,7 +1594,7 @@ public final class UnitDatabase {
 	public Map<String, ObjectProduct<BaseDimension>> dimensionMap() {
 		return Collections.unmodifiableMap(this.dimensions);
 	}
-
+	
 	/**
 	 * Evaluates a unit expression, following the same rules as
 	 * {@link #getUnitFromExpression}.
@@ -1551,23 +1605,23 @@ public final class UnitDatabase {
 	 */
 	public LinearUnitValue evaluateUnitExpression(final String expression) {
 		Objects.requireNonNull(expression, "expression must not be null.");
-
+		
 		// attempt to get a unit as an alias, or a number with precision first
 		if (this.containsUnitName(expression))
 			return this.getLinearUnitValue(expression);
-
+		
 		// force operators to have spaces
 		String modifiedExpression = expression;
 		modifiedExpression = modifiedExpression.replaceAll("\\+", " \\+ ");
 		modifiedExpression = modifiedExpression.replaceAll("-", " - ");
-
+		
 		// format expression
 		for (final Entry<Pattern, String> replacement : EXPRESSION_REPLACEMENTS
 				.entrySet()) {
 			modifiedExpression = replacement.getKey().matcher(modifiedExpression)
 					.replaceAll(replacement.getValue());
 		}
-
+		
 		// the previous operation breaks negative numbers, fix them!
 		// (i.e. -2 becomes - 2)
 		// FIXME the previous operaton also breaks stuff like "1e-5"
@@ -1580,10 +1634,10 @@ public final class UnitDatabase {
 						+ modifiedExpression.substring(i + 2);
 			}
 		}
-
+		
 		return this.unitValueExpressionParser.parseExpression(modifiedExpression);
 	}
-
+	
 	/**
 	 * Gets a unit dimension from the database using its name.
 	 * 
@@ -1601,7 +1655,7 @@ public final class UnitDatabase {
 		else
 			return dimension;
 	}
-
+	
 	/**
 	 * Uses the database's data to parse an expression into a unit dimension
 	 * <p>
@@ -1624,24 +1678,24 @@ public final class UnitDatabase {
 	public ObjectProduct<BaseDimension> getDimensionFromExpression(
 			final String expression) {
 		Objects.requireNonNull(expression, "expression must not be null.");
-
+		
 		// attempt to get a dimension as an alias first
 		if (this.containsDimensionName(expression))
 			return this.getDimension(expression);
-
+		
 		// force operators to have spaces
 		String modifiedExpression = expression;
-
+		
 		// format expression
 		for (final Entry<Pattern, String> replacement : EXPRESSION_REPLACEMENTS
 				.entrySet()) {
 			modifiedExpression = replacement.getKey().matcher(modifiedExpression)
 					.replaceAll(replacement.getValue());
 		}
-
+		
 		return this.unitDimensionParser.parseExpression(modifiedExpression);
 	}
-
+	
 	/**
 	 * Gets a unit. If it is linear, cast it to a LinearUnit and return it.
 	 * Otherwise, throw an {@code IllegalArgumentException}.
@@ -1660,7 +1714,7 @@ public final class UnitDatabase {
 			if (parts.size() != 2)
 				throw new IllegalArgumentException(
 						"Format nonlinear units like: unit(value).");
-
+			
 			// solve the function
 			final Unit unit = this.getUnit(parts.get(0));
 			final double value = Double.parseDouble(
@@ -1669,7 +1723,7 @@ public final class UnitDatabase {
 		} else {
 			// get a linear unit
 			final Unit unit = this.getUnit(name);
-
+			
 			if (unit instanceof LinearUnit)
 				return (LinearUnit) unit;
 			else
@@ -1677,7 +1731,7 @@ public final class UnitDatabase {
 						String.format("%s is not a linear unit.", name));
 		}
 	}
-
+	
 	/**
 	 * Gets a {@code LinearUnitValue} from a unit name. Nonlinear units will be
 	 * converted to their base units.
@@ -1695,7 +1749,7 @@ public final class UnitDatabase {
 			return LinearUnitValue.getExact(this.getLinearUnit(name), 1);
 		}
 	}
-
+	
 	/**
 	 * Gets a unit prefix from the database from its name
 	 * 
@@ -1716,7 +1770,7 @@ public final class UnitDatabase {
 				return prefix;
 		}
 	}
-
+	
 	/**
 	 * Gets all of the prefixes that are on a unit name, in application order.
 	 * 
@@ -1727,12 +1781,12 @@ public final class UnitDatabase {
 	List<UnitPrefix> getPrefixesFromName(final String unitName) {
 		final List<UnitPrefix> prefixes = new ArrayList<>();
 		String name = unitName;
-
+		
 		while (!this.prefixlessUnits.containsKey(name)) {
 			// find the longest prefix
 			String longestPrefixName = null;
 			int longestLength = name.length();
-
+			
 			while (longestPrefixName == null) {
 				longestLength--;
 				if (longestLength <= 0)
@@ -1742,7 +1796,7 @@ public final class UnitDatabase {
 					longestPrefixName = name.substring(0, longestLength);
 				}
 			}
-
+			
 			// longest prefix found!
 			final UnitPrefix prefix = this.getPrefix(longestPrefixName);
 			prefixes.add(0, prefix);
@@ -1750,7 +1804,7 @@ public final class UnitDatabase {
 		}
 		return prefixes;
 	}
-
+	
 	/**
 	 * Gets a unit prefix from a prefix expression
 	 * <p>
@@ -1767,24 +1821,24 @@ public final class UnitDatabase {
 	 */
 	public UnitPrefix getPrefixFromExpression(final String expression) {
 		Objects.requireNonNull(expression, "expression must not be null.");
-
+		
 		// attempt to get a unit as an alias first
 		if (this.containsUnitName(expression))
 			return this.getPrefix(expression);
-
+		
 		// force operators to have spaces
 		String modifiedExpression = expression;
-
+		
 		// format expression
 		for (final Entry<Pattern, String> replacement : EXPRESSION_REPLACEMENTS
 				.entrySet()) {
 			modifiedExpression = replacement.getKey().matcher(modifiedExpression)
 					.replaceAll(replacement.getValue());
 		}
-
+		
 		return this.prefixExpressionParser.parseExpression(modifiedExpression);
 	}
-
+	
 	/**
 	 * @return the prefixRepetitionRule
 	 * @since 2020-08-26
@@ -1792,7 +1846,7 @@ public final class UnitDatabase {
 	public final Predicate<List<UnitPrefix>> getPrefixRepetitionRule() {
 		return this.prefixRepetitionRule;
 	}
-
+	
 	/**
 	 * Gets a unit from the database from its name, looking for prefixes.
 	 * 
@@ -1825,9 +1879,9 @@ public final class UnitDatabase {
 			} else
 				return unit;
 		}
-
+		
 	}
-
+	
 	/**
 	 * Uses the database's unit data to parse an expression into a unit
 	 * <p>
@@ -1851,23 +1905,23 @@ public final class UnitDatabase {
 	 */
 	public Unit getUnitFromExpression(final String expression) {
 		Objects.requireNonNull(expression, "expression must not be null.");
-
+		
 		// attempt to get a unit as an alias first
 		if (this.containsUnitName(expression))
 			return this.getUnit(expression);
-
+		
 		// force operators to have spaces
 		String modifiedExpression = expression;
 		modifiedExpression = modifiedExpression.replaceAll("\\+", " \\+ ");
 		modifiedExpression = modifiedExpression.replaceAll("-", " - ");
-
+		
 		// format expression
 		for (final Entry<Pattern, String> replacement : EXPRESSION_REPLACEMENTS
 				.entrySet()) {
 			modifiedExpression = replacement.getKey().matcher(modifiedExpression)
 					.replaceAll(replacement.getValue());
 		}
-
+		
 		// the previous operation breaks negative numbers, fix them!
 		// (i.e. -2 becomes - 2)
 		for (int i = 0; i < modifiedExpression.length(); i++) {
@@ -1879,10 +1933,23 @@ public final class UnitDatabase {
 						+ modifiedExpression.substring(i + 2);
 			}
 		}
-
+		
 		return this.unitExpressionParser.parseExpression(modifiedExpression);
 	}
-
+	
+	/**
+	 * Get a unit set from its name, throwing a {@link NoSuchElementException} if
+	 * there is none.
+	 *
+	 * @since 2024-08-16
+	 */
+	public List<LinearUnit> getUnitSet(String name) {
+		final List<LinearUnit> unitSet = this.unitSets.get(name);
+		if (unitSet == null)
+			throw new NoSuchElementException("No unit set with name " + name);
+		return unitSet;
+	}
+	
 	/**
 	 * Adds all dimensions from a file, using data from the database to parse
 	 * them.
@@ -1922,7 +1989,7 @@ public final class UnitDatabase {
 			throw new IllegalArgumentException("Could not read file " + file, e);
 		}
 	}
-
+	
 	/**
 	 * Adds all dimensions from a {@code InputStream}. Otherwise, works like
 	 * {@link #loadDimensionFile}.
@@ -1938,7 +2005,7 @@ public final class UnitDatabase {
 			}
 		}
 	}
-
+	
 	/**
 	 * Adds all units from a file, using data from the database to parse them.
 	 * <p>
@@ -1977,7 +2044,7 @@ public final class UnitDatabase {
 			throw new IllegalArgumentException("Could not read file " + file, e);
 		}
 	}
-
+	
 	/**
 	 * Adds all units from a {@code InputStream}. Otherwise, works like
 	 * {@link #loadUnitsFile}.
@@ -1993,7 +2060,7 @@ public final class UnitDatabase {
 			}
 		}
 	}
-
+	
 	/**
 	 * @param includeDuplicates if false, duplicates are removed from the map
 	 * @return a map mapping prefix names to prefixes
@@ -2008,7 +2075,7 @@ public final class UnitDatabase {
 					.conditionalExistenceMap(this.prefixes,
 							entry -> !isRemovableDuplicate(this.prefixes, entry)));
 	}
-
+	
 	/**
 	 * @param prefixRepetitionRule the prefixRepetitionRule to set
 	 * @since 2020-08-26
@@ -2017,7 +2084,7 @@ public final class UnitDatabase {
 			Predicate<List<UnitPrefix>> prefixRepetitionRule) {
 		this.prefixRepetitionRule = prefixRepetitionRule;
 	}
-
+	
 	/**
 	 * @return a string stating the number of units, prefixes and dimensions in
 	 *         the database
@@ -2029,7 +2096,7 @@ public final class UnitDatabase {
 				this.prefixlessUnits.size(), this.prefixes.size(),
 				this.dimensions.size());
 	}
-
+	
 	/**
 	 * Returns a map mapping unit names to units, including units with prefixes.
 	 * <p>
@@ -2061,7 +2128,7 @@ public final class UnitDatabase {
 		return this.units; // PrefixedUnitMap is immutable so I don't need to make
 									// an unmodifiable map.
 	}
-
+	
 	/**
 	 * @param includeDuplicates if true, duplicate units will all exist in the
 	 *                          map; if false, only one of each unit will exist,
@@ -2079,4 +2146,12 @@ public final class UnitDatabase {
 							entry -> !isRemovableDuplicate(this.prefixlessUnits,
 									entry)));
 	}
+	
+	/**
+	 * @return an unmodifiable map mapping names to unit sets
+	 * @since 2024-08-16
+	 */
+	public Map<String, List<LinearUnit>> unitSetMap() {
+		return Collections.unmodifiableMap(this.unitSets);
+	}
 }