Splice

lolleko · lolleko · commit 19cab94cea02 · 2018-07-19T18:52:09.000+02:00
diff --git a/src/lualib/ArraySplice.ts b/src/lualib/ArraySplice.ts
@@ -0,0 +1,94 @@
+// https://www.ecma-international.org/publications/files/ECMA-ST/Ecma-262.pdf
+function __TS__ArraySplice<T>(list: T[], start: number, deleteCount: number, ...items: T[]) {
+    // 1. 2.
+    const len = list.length;
+
+    let actualStart;
+
+    // 4.
+    if (start <  0) {
+        actualStart = Math.max(len + start, 0);
+    } else {
+        actualStart = Math.min(start, len);
+    }
+
+    // 13.
+    // 14.
+    const itemCount = items.length;
+
+    // 5. - 7.
+    let actualDeleteCount: number;
+
+    if (!start) {
+        actualDeleteCount = 0;
+    } else if (!deleteCount) {
+        actualDeleteCount = len - actualStart;
+    } else {
+        actualDeleteCount = Math.min(Math.max(deleteCount, 0), len - actualStart);
+    }
+
+    // 8. ignored
+
+    // 9.
+    const out: T[] = [];
+
+    // 10.
+    let k = 0;
+
+    // 11.
+    for (k = 0; k < actualDeleteCount; k++) {
+        const from = actualStart + k;
+
+        if (list[from]) {
+            out[k] = list[from];
+        }
+    }
+
+    // 15.
+    if (itemCount < actualDeleteCount) {
+        // a. b.
+        for (k = actualStart; k < len - actualDeleteCount; k++) {
+            const from = k + actualDeleteCount;
+            const to = k + itemCount;
+
+            if (list[from]) {
+                list[to] = list[from];
+            } else {
+                list[to] = undefined;
+            }
+        }
+        // c. d.
+        for (k = len; k > len - actualDeleteCount + itemCount; k--) {
+            list[k] = undefined;
+        }
+    // 16.
+    } else if (itemCount > actualDeleteCount) {
+
+        for (k = len - actualDeleteCount; k > actualStart; k--) {
+            const from = k + actualDeleteCount - 1;
+            const to = k + itemCount - 1;
+
+            if (list[from]) {
+                list[to] = list[from];
+            } else {
+                list[to] = undefined;
+            }
+
+        }
+    }
+
+    // 17.
+    // 18.
+    for (k = actualStart; k < items.length; k++) {
+        const e = items[k];
+        list[k] = e;
+    }
+
+    // 19.
+    for (k = list.length; k > len - actualDeleteCount + itemCount; k--) {
+        list[k] = undefined;
+    }
+
+    // 20.
+    return out;
+}
