Add lualib support for Math.trunc (#1564)

lolleko · web-flow · commit 5ba1facbebdd · 2024-07-09T17:33:31.000+02:00
Also includes a small fix that makes `Math.sign` ECMA compliant Closes #1550
diff --git a/src/LuaLib.ts b/src/LuaLib.ts
@@ -63,6 +63,7 @@ export enum LuaLibFeature {
     MathAtan2 = "MathAtan2",
     MathModf = "MathModf",
     MathSign = "MathSign",
+    MathTrunc = "MathTrunc",
     New = "New",
     Number = "Number",
     NumberIsFinite = "NumberIsFinite",
diff --git a/src/lualib/MathSign.ts b/src/lualib/MathSign.ts
@@ -1,9 +1,15 @@
+// https://tc39.es/ecma262/multipage/numbers-and-dates.html#sec-math.sign
+
+import { __TS__NumberIsNaN } from "./NumberIsNaN";
+
 export function __TS__MathSign(this: void, val: number) {
-    if (val > 0) {
-        return 1;
-    } else if (val < 0) {
+    if (__TS__NumberIsNaN(val) || val === 0) {
+        return val;
+    }
+
+    if (val < 0) {
         return -1;
     }
 
-    return 0;
+    return 1;
 }
diff --git a/src/lualib/MathTrunc.ts b/src/lualib/MathTrunc.ts
@@ -0,0 +1,10 @@
+// https://tc39.es/ecma262/multipage/numbers-and-dates.html#sec-math.trunc
+
+import { __TS__NumberIsFinite } from "./NumberIsFinite";
+export function __TS__MathTrunc(this: void, val: number) {
+    if (!__TS__NumberIsFinite(val) || val === 0) {
+        return val;
+    }
+
+    return val > 0 ? math.floor(val) : math.ceil(val);
+}
diff --git a/src/transformation/builtins/math.ts b/src/transformation/builtins/math.ts
@@ -100,6 +100,10 @@ export function transformMathCall(
             return transformLuaLibFunction(context, LuaLibFeature.MathSign, node, ...params);
         }
 
+        case "trunc": {
+            return transformLuaLibFunction(context, LuaLibFeature.MathTrunc, node, ...params);
+        }
+
         case "abs":
         case "acos":
         case "asin":
diff --git a/test/unit/builtins/math.spec.ts b/test/unit/builtins/math.spec.ts
@@ -51,6 +51,12 @@ test.each([
     // sqrt
     "Math.sqrt(2)",
     "Math.sqrt(-2)",
+    // trunc
+    "Math.trunc(42.42)",
+    "Math.trunc(-42.42)",
+    "Math.trunc(0)",
+    "Math.trunc(Infinity)",
+    "Math.trunc(-Infinity)",
 ])("%s", code => {
     util.testExpression(code).expectToMatchJsResult();
 });
@@ -65,7 +71,14 @@ test.each(["E", "LN10", "LN2", "LOG10E", "LOG2E", "SQRT1_2", "SQRT2"])("Math.%s"
 });
 
 // LuaLib MathSign
-test.each(["Math.sign(-42)", "Math.sign(42)", "Math.sign(-4.2)", "Math.sign(4.2)", "Math.sign(0)"])("%s", code => {
+test.each([
+    "Math.sign(-42)",
+    "Math.sign(42)",
+    "Math.sign(-4.2)",
+    "Math.sign(4.2)",
+    "Math.sign(0)",
+    "Math.sign(-Infinity)",
+])("%s", code => {
     util.testExpression(code).expectToMatchJsResult();
 });
 
