Decimal: Added integralDigitPlaces and fractionDigitPlaces prop…

…erties
orchetect · Nov 21, 2023 · 7e44c39 · 7e44c39
1 parent 98217c7
commit 7e44c39
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diff --git a/Sources/OTCore/Extensions/Foundation/Decimal.swift b/Sources/OTCore/Extensions/Foundation/Decimal.swift
@@ -269,4 +269,28 @@ extension Decimal {
     }
 }
 
+// MARK: - Digit Places
+
+extension Decimal {
+    /// **OTCore:**
+    /// Returns the number of digit places of the ``integral`` portion (left of the decimal).
+    @inlinable @_disfavoredOverload
+    public var integralDigitPlaces: Int {
+        // this works but may be brittle.
+        // not sure if some locales will localize the number differently than expected.
+        // on English systems the `significand` string interpolation produces
+        // a string of digits with no thousands separators or other characters.
+
+        if abs(self) <= 1 { return 0 }
+        return "\(abs(significand))".count + exponent
+    }
+
+    /// **OTCore:**
+    /// Returns the number of digit places of the ``fraction`` portion (right of the decimal).
+    @inlinable @_disfavoredOverload
+    public var fractionDigitPlaces: Int {
+        return max(-exponent, 0)
+    }
+}
+
 #endif
diff --git a/Tests/OTCoreTests/Extensions/Foundation/Decimal Tests.swift b/Tests/OTCoreTests/Extensions/Foundation/Decimal Tests.swift
@@ -191,6 +191,46 @@ class Extensions_Foundation_Decimal_Tests: XCTestCase {
         XCTAssertEqual(Decimal(string: "17.5")!.integral, Decimal(string: "17")!)
         XCTAssertEqual(Decimal(string: "17.5")!.fraction, Decimal(string: "0.5")!)
     }
+
+    func testIntegralDigitPlaces_and_fractionDigitPlaces() {
+        // we'll cast the number literals as Double to see if Decimal converts them and results are
+        // still as expected
+
+        XCTAssertEqual(Decimal(0.05 as Double).integralDigitPlaces, 0)
+        XCTAssertEqual(Decimal(0.05 as Double).fractionDigitPlaces, 2)
+        XCTAssertEqual(Decimal(-0.05 as Double).integralDigitPlaces, 0)
+        XCTAssertEqual(Decimal(-0.05 as Double).fractionDigitPlaces, 2)
+
+        XCTAssertEqual(Decimal(10.0 as Double).integralDigitPlaces, 2)
+        XCTAssertEqual(Decimal(10.0 as Double).fractionDigitPlaces, 0)
+        XCTAssertEqual(Decimal(-10.0 as Double).integralDigitPlaces, 2)
+        XCTAssertEqual(Decimal(-10.0 as Double).fractionDigitPlaces, 0)
+
+        XCTAssertEqual(Decimal(10.123 as Double).integralDigitPlaces, 2)
+        XCTAssertEqual(Decimal(10.123 as Double).fractionDigitPlaces, 3)
+        XCTAssertEqual(Decimal(-10.123 as Double).integralDigitPlaces, 2)
+        XCTAssertEqual(Decimal(-10.123 as Double).fractionDigitPlaces, 3)
+
+        XCTAssertEqual(Decimal(10_000.123 as Double).integralDigitPlaces, 5)
+        XCTAssertEqual(Decimal(10_000.123 as Double).fractionDigitPlaces, 3)
+        XCTAssertEqual(Decimal(-10_000.123 as Double).integralDigitPlaces, 5)
+        XCTAssertEqual(Decimal(-10_000.123 as Double).fractionDigitPlaces, 3)
+
+        XCTAssertEqual(Decimal(10_000.0 as Double).integralDigitPlaces, 5)
+        XCTAssertEqual(Decimal(10_000.0 as Double).fractionDigitPlaces, 0)
+        XCTAssertEqual(Decimal(-10_000.0 as Double).integralDigitPlaces, 5)
+        XCTAssertEqual(Decimal(-10_000.0 as Double).fractionDigitPlaces, 0)
+
+        XCTAssertEqual(Decimal(12_345.0 as Double).integralDigitPlaces, 5)
+        XCTAssertEqual(Decimal(12_345.0 as Double).fractionDigitPlaces, 0)
+        XCTAssertEqual(Decimal(-12_345.0 as Double).integralDigitPlaces, 5)
+        XCTAssertEqual(Decimal(-12_345.0 as Double).fractionDigitPlaces, 0)
+
+        XCTAssertEqual(Decimal(12_345.67 as Double).integralDigitPlaces, 5)
+        XCTAssertEqual(Decimal(12_345.67 as Double).fractionDigitPlaces, 2)
+        XCTAssertEqual(Decimal(-12_345.67 as Double).integralDigitPlaces, 5)
+        XCTAssertEqual(Decimal(-12_345.67 as Double).fractionDigitPlaces, 2)
+    }
 }
 
 #endif