From 65cbe11757b4aa6061c4228d6bc4f44b59e27beb Mon Sep 17 00:00:00 2001
From: Jonah Scheinerman <jonah@scheinerman.net>
Date: Thu, 16 May 2024 23:33:03 -0400
Subject: [PATCH] Add valueIn method (#185)

---
 src/measure/__test__/numberMeasureTests.ts  | 6 ++++++
 src/measure/genericMeasure.ts               | 8 ++++++++
 src/measure/genericMeasureClass.ts          | 4 ++++
 test/{exponents.ts => exponentTypeTests.ts} | 0
 test/{measures.ts => measureTypeTests.ts}   | 6 ++++++
 test/{units.ts => unitTypeTests.ts}         | 0
 6 files changed, 24 insertions(+)
 rename test/{exponents.ts => exponentTypeTests.ts} (100%)
 rename test/{measures.ts => measureTypeTests.ts} (91%)
 rename test/{units.ts => unitTypeTests.ts} (100%)

diff --git a/src/measure/__test__/numberMeasureTests.ts b/src/measure/__test__/numberMeasureTests.ts
index 173586b..d7d8aa6 100644
--- a/src/measure/__test__/numberMeasureTests.ts
+++ b/src/measure/__test__/numberMeasureTests.ts
@@ -287,6 +287,12 @@ describe("Number measures", () => {
             expect(Measure.of(1000, meters).in(kilometers)).toBe("1000 m");
         });
 
+        it("should get value in another unit", () => {
+            const kilometers = Measure.of(1000, meters);
+            expect(Measure.of(2000, meters).valueIn(kilometers)).toBe(2);
+            expect(Measure.of(500, meters).valueIn(kilometers)).toBe(0.5);
+        });
+
         it("should use base unit symbols to format when available", () => {
             const m = Measure.dimension("test-length", "meter");
             const s = Measure.dimension("test-time", "second");
diff --git a/src/measure/genericMeasure.ts b/src/measure/genericMeasure.ts
index aeb38ae..9a4aa13 100644
--- a/src/measure/genericMeasure.ts
+++ b/src/measure/genericMeasure.ts
@@ -193,6 +193,14 @@ export interface GenericMeasure<N, U extends Unit> {
      */
     in(unit: GenericMeasure<N, U>, formatter?: MeasureFormatter<N>): string;
 
+    /**
+     * Returns the value of this measure as a product of another unit. This can be used to quickly convert a measure to
+     * that unit and extract its underlying value.
+     * @param unit a measure of the same unit to convert this measure into
+     * @returns the numeric value of this unit expressed in the given unit
+     */
+    valueIn(unit: GenericMeasure<N, U>): N;
+
     /**
      * Adds a symbol to this measure.
      * @param symbol the symbol of the unit represented by this measure
diff --git a/src/measure/genericMeasureClass.ts b/src/measure/genericMeasureClass.ts
index 3982a07..337cd27 100644
--- a/src/measure/genericMeasureClass.ts
+++ b/src/measure/genericMeasureClass.ts
@@ -147,6 +147,10 @@ export function createMeasureClass<N>(num: NumericOperations<N>): GenericMeasure
             return `${value} ${unit.symbol}`;
         }
 
+        public valueIn(unit: GenericMeasure<N, U>): N {
+            return num.div(this.value, unit.value);
+        }
+
         public withSymbol(symbol: string | undefined): GenericMeasure<N, U> {
             return new Measure(this.value, this.unit, symbol);
         }
diff --git a/test/exponents.ts b/test/exponentTypeTests.ts
similarity index 100%
rename from test/exponents.ts
rename to test/exponentTypeTests.ts
diff --git a/test/measures.ts b/test/measureTypeTests.ts
similarity index 91%
rename from test/measures.ts
rename to test/measureTypeTests.ts
index 9b4f7b4..786cdbf 100644
--- a/test/measures.ts
+++ b/test/measureTypeTests.ts
@@ -58,3 +58,9 @@ area.minus(volume);
 
 // TODO(jscheinerman): This should be an error but is not because of structural typing
 length.plus(velocity);
+
+// TODO(jscheinerman): This should be an error but is not because of structural typing
+length.valueIn(velocity);
+
+// TODO(jscheinerman): This should be an error but is not because of structural typing
+export const test: Length = velocity;
diff --git a/test/units.ts b/test/unitTypeTests.ts
similarity index 100%
rename from test/units.ts
rename to test/unitTypeTests.ts