fix: implement slices.Grow

Signed-off-by: Christian Stewart <christian@aperture.us>

Author: paralin

compliance/tests/slices_grow/expected.log

@@ -0,0 +1,3 @@
+Before Grow: len= 3 cap= 3
+After Grow: len= 3 cap= 8
+slices.Grow test finished

compliance/tests/slices_grow/index.ts

@@ -0,0 +1,11 @@
+package main
+
+import "slices"
+
+func main() {
+	s := []int{1, 2, 3}
+	println("Before Grow: len=", len(s), "cap=", cap(s))
+	s = slices.Grow(s, 5)
+	println("After Grow: len=", len(s), "cap=", cap(s))
+	println("slices.Grow test finished")
+}

compliance/tests/slices_grow/slices_grow.go

@@ -0,0 +1,15 @@
+// Generated file based on slices_grow.go
+// Updated when compliance tests are re-run, DO NOT EDIT!
+
+import * as $ from "@goscript/builtin/index.js"
+
+import * as slices from "@goscript/slices/index.js"
+
+export async function main(): Promise<void> {
+	let s = $.arrayToSlice<number>([1, 2, 3])
+	console.log("Before Grow: len=", $.len(s), "cap=", $.cap(s))
+	s = slices.Grow(s, 5)
+	console.log("After Grow: len=", $.len(s), "cap=", $.cap(s))
+	console.log("slices.Grow test finished")
+}
+

compliance/tests/slices_grow/slices_grow.gs.ts

@@ -0,0 +1,32 @@
+{
+  "compilerOptions": {
+    "allowImportingTsExtensions": true,
+    "lib": [
+      "es2022",
+      "esnext.disposable",
+      "dom"
+    ],
+    "module": "nodenext",
+    "moduleResolution": "nodenext",
+    "noEmit": true,
+    "paths": {
+      "*": [
+        "./*"
+      ],
+      "@goscript/*": [
+        "../../../gs/*",
+        "../../../compliance/deps/*"
+      ],
+      "@goscript/github.com/aperturerobotics/goscript/compliance/tests/slices_grow/*": [
+        "./*"
+      ]
+    },
+    "sourceMap": true,
+    "target": "es2022"
+  },
+  "extends": "../../../tsconfig.json",
+  "include": [
+    "index.ts",
+    "slices_grow.gs.ts"
+  ]
+}

compliance/tests/slices_grow/tsconfig.json

@@ -62,6 +62,43 @@ export function Delete<T>(s: $.Slice<T>, i: number, j: number): $.Slice<T> {
   return $.goSlice(s, 0, length - deleteCount) as $.Slice<T>
 }
 
+/**
+ * Grow increases the slice's capacity, if necessary, to guarantee space for
+ * another n elements. After Grow(n), at least n elements can be appended
+ * to the slice without another allocation. If n is negative or too large to
+ * allocate the memory, Grow panics.
+ * This is equivalent to Go's slices.Grow function.
+ * @param s The slice to grow
+ * @param n The number of additional elements to guarantee space for
+ * @returns The slice with increased capacity
+ */
+export function Grow<T>(s: $.Slice<T>, n: number): $.Slice<T> {
+  if (n < 0) {
+    throw new Error(`slices.Grow: negative n: ${n}`)
+  }
+  const currentLen = $.len(s)
+  const currentCap = $.cap(s)
+  const neededCap = currentLen + n
+
+  if (neededCap <= currentCap) {
+    return s
+  }
+
+  // Create new slice with increased capacity
+  // Go's growth strategy typically doubles capacity when needed
+  let newCap = currentCap * 2
+  if (newCap < neededCap) {
+    newCap = neededCap
+  }
+
+  const newSlice = $.makeSlice<T>(currentLen, newCap)
+  for (let i = 0; i < currentLen; i++) {
+    ;(newSlice as any)[i] = (s as any)[i]
+  }
+
+  return newSlice
+}
+
 /**
  * BinarySearchFunc works like BinarySearch, but uses a custom comparison function.
  * The slice must be sorted in increasing order, where "increasing" is defined by cmp.