Add replacement for System.Double.IsNormal

fable-compiler · Sep 2, 2021 · 9d854bf · 9d854bf
1 parent 9d3a2e2
commit 9d854bf
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diff --git a/src/Fable.Transforms/Replacements.fs b/src/Fable.Transforms/Replacements.fs
@@ -2121,6 +2121,8 @@ let parseNum (com: ICompiler) (ctx: Context) r t (i: CallInfo) (thisArg: Expr op
         Helper.GlobalCall("Number", t, args, memb="isNaN", ?loc=r) |> Some
     | "IsInfinity", [_] when isFloat ->
         Helper.LibCall(com, "Double", "isInfinity", t, args, i.SignatureArgTypes, ?loc=r) |> Some
+    | "IsNormal", [_] when isFloat ->
+        Helper.LibCall(com, "Double", "isNormal", t, args, i.SignatureArgTypes, ?loc=r) |> Some
     | ("Parse" | "TryParse") as meth,
             str::Value(EnumConstant(Value(NumberConstant(style, _),_),_),_)::_ ->
         let style = int style

diff --git a/src/fable-library/Double.ts b/src/fable-library/Double.ts
@@ -1,4 +1,6 @@
 import { FSharpRef } from "./Types.js";
+import { doubleToInt64Bits } from './BitConverter.js';
+import * as LongLib from "./lib/long.js";
 
 export function tryParse(str: string, defValue: FSharpRef<number>): boolean {
   // TODO: test if value is valid and in range
@@ -25,3 +27,10 @@ export function parse(str: string): number {
 export function isInfinity(x: number) {
   return x === Number.POSITIVE_INFINITY || x === Number.NEGATIVE_INFINITY;
 }
+
+// https://github.com/dotnet/runtime/blob/6ff32877f6ae0ddf48218477c7acc78de12f7fbf/src/libraries/System.Private.CoreLib/src/System/Double.cs#L122-L130
+export function isNormal(d: number) {
+  let bits = doubleToInt64Bits(d);
+  bits = LongLib.and(bits, 0x7FFFFFFFFFFFFFFF);
+  return LongLib.lessThan(bits, 0x7FF0000000000000) && (bits !== LongLib.ZERO) && (LongLib.and(bits, 0x7FF0000000000000) !== LongLib.ZERO);
+}
diff --git a/tests/Main/ArithmeticTests.fs b/tests/Main/ArithmeticTests.fs
@@ -687,4 +687,27 @@ let tests =
         formatEuro 0.020M |> equal "0,02 €"
         formatEuro 0.20M |> equal "0,20 €"
         formatEuro 2.0M |> equal "2,00 €"
+
+    testList "Double.IsNormal works" [
+        let testData = [
+            // https://github.com/dotnet/runtime/blob/6ff32877f6ae0ddf48218477c7acc78de12f7fbf/src/libraries/System.Runtime/tests/System/DoubleTests.cs#L687-L704
+            Double.NegativeInfinity, false
+            Double.MinValue, true
+            -2.2250738585072014E-308, true
+            -2.2250738585072009E-308, false
+            -4.94065645841247E-324, false
+            -0.0, false
+            Double.NaN, false
+            0.0, false
+            4.94065645841247E-324, false
+            2.2250738585072009E-308, false
+            2.2250738585072014E-308, true
+            Double.MaxValue, true
+            Double.PositiveInfinity, false
+        ]
+
+        for v, e in testData ->
+            testCase $"Double.IsNormal({v}) should be {e}" <| fun _ ->
+                Double.IsNormal v |> equal e
+    ]
 ]