Made prs-rs an optional module.

Compression will fall back into the JS implementation if program is not built with prs-rs.

package.json

@@ -20,7 +20,7 @@
         "build_prs_rs_browser": "yarn build_prs_rs -t bundler && yarn upgrade prs-rs",
         "build_prs_rs_testing": "yarn build_prs_rs -t nodejs -d 'test/pkg'",
         "build_bundle": "webpack --config webpack.prod.js",
-        "build": "yarn build_prs_rs_browser && yarn build_bundle",
+        "build": "yarn build_bundle",
         "test": "jest",
         "update_generic_data": "ts-node --project=tsconfig-scripts.json assets_generation/update_generic_data.ts",
         "update_ephinea_data": "ts-node --project=tsconfig-scripts.json assets_generation/update_ephinea_data.ts",

src/core/data_formats/compression/prs/compress.ts

@@ -3,16 +3,17 @@ import { Cursor } from "../../cursor/Cursor";
 import { ResizableBufferCursor } from "../../cursor/ResizableBufferCursor";
 import { WritableCursor } from "../../cursor/WritableCursor";
 import { ResizableBuffer } from "../../ResizableBuffer";
-import { ArrayBufferCursor } from "../../cursor/ArrayBufferCursor";
-import * as prs_wasm from "prs-rs";
 import { browser_supports_webassembly } from "../../../util";
+import { get_prs_wasm_module } from "./prs_wasm";
+
+const prs_wasm = get_prs_wasm_module();
 
 /**
  * Automatically picks the best available compression method.
  */
 export function prs_compress(cursor: Cursor): Cursor {
-    if (browser_supports_webassembly()) {
-        return prs_compress_wasm(cursor);
+    if (browser_supports_webassembly() && prs_wasm) {
+        return prs_wasm.prs_compress_wasm(cursor);
     } else {
         return prs_compress_js(cursor);
     }
@@ -149,14 +150,3 @@ class Context {
         }
     }
 }
-
-export function prs_compress_wasm(cursor: Cursor): Cursor {
-    const bytes = new Uint8Array(cursor.array_buffer());
-    const result = prs_wasm.compress(bytes);
-    return new ArrayBufferCursor(
-        result.buffer,
-        Endianness.Little,
-        result.byteOffset,
-        result.length,
-    );
-}

src/core/data_formats/compression/prs/decompress.ts

@@ -3,19 +3,19 @@ import { ResizableBufferCursor } from "../../cursor/ResizableBufferCursor";
 import { WritableCursor } from "../../cursor/WritableCursor";
 import { ResizableBuffer } from "../../ResizableBuffer";
 import { LogManager } from "../../../Logger";
-import * as prs_wasm from "prs-rs";
 import { browser_supports_webassembly } from "../../../util";
-import { ArrayBufferCursor } from "../../cursor/ArrayBufferCursor";
-import { Endianness } from "../../Endianness";
+import { get_prs_wasm_module } from "./prs_wasm";
 
 const logger = LogManager.get("core/data_formats/compression/prs/decompress");
 
+const prs_wasm = get_prs_wasm_module();
+
 /**
  * Automatically picks the best available decompression method.
  */
 export function prs_decompress(cursor: Cursor): Cursor {
-    if (browser_supports_webassembly()) {
-        return prs_decompress_wasm(cursor);
+    if (browser_supports_webassembly() && prs_wasm) {
+        return prs_wasm.prs_decompress_wasm(cursor);
     } else {
         return prs_decompress_js(cursor);
     }
@@ -135,14 +135,3 @@ class Context {
         this.dst.write_cursor(buf.take(length % buf_size));
     }
 }
-
-export function prs_decompress_wasm(cursor: Cursor): Cursor {
-    const bytes = new Uint8Array(cursor.array_buffer());
-    const result = prs_wasm.decompress(bytes);
-    return new ArrayBufferCursor(
-        result.buffer,
-        Endianness.Little,
-        result.byteOffset,
-        result.length,
-    );
-}

src/core/data_formats/compression/prs/index.test.ts

@@ -2,16 +2,41 @@ import { readFileSync } from "fs";
 import { Endianness } from "../../Endianness";
 import { ArrayBufferCursor } from "../../cursor/ArrayBufferCursor";
 import { BufferCursor } from "../../cursor/BufferCursor";
-import { prs_compress_js, prs_compress_wasm } from "./compress";
-import { prs_decompress_js, prs_decompress_wasm } from "./decompress";
+import { prs_compress_js } from "./compress";
+import { prs_decompress_js } from "./decompress";
 import { Cursor } from "../../cursor/Cursor";
+import { get_prs_wasm_module } from "./prs_wasm";
 
 type CompressionFunction = (cursor: Cursor) => Cursor;
 
-type CompressionMethod = readonly [string, CompressionFunction, CompressionFunction];
+type CompressionMethod = [string, CompressionFunction, CompressionFunction];
 
-const prs_js: CompressionMethod = ["JS", prs_compress_js, prs_decompress_js] as const;
-const prs_wasm: CompressionMethod = ["WASM", prs_compress_wasm, prs_decompress_wasm] as const;
+const prs_nop = (cursor: Cursor): Cursor => cursor;
+
+const prs_wasm_module = get_prs_wasm_module();
+
+const should_run_wasm_tests = prs_wasm_module !== undefined;
+
+const prs_compress_wasm = prs_wasm_module
+    ? prs_wasm_module.prs_compress_wasm.bind(prs_wasm_module)
+    : prs_nop;
+const prs_decompress_wasm = prs_wasm_module
+    ? prs_wasm_module.prs_decompress_wasm.bind(prs_wasm_module)
+    : prs_nop;
+
+const prs_js: CompressionMethod = ["JS", prs_compress_js, prs_decompress_js];
+const prs_wasm: CompressionMethod = ["WASM", prs_compress_wasm, prs_decompress_wasm];
+
+/**
+ * Helper function that removes wasm tests if wasm module is not available.
+ */
+function prepare_test_data(js_test_data: any[][], wasm_test_data: any[][]): any[] {
+    if (should_run_wasm_tests) {
+        return [...js_test_data, ...wasm_test_data];
+    } else {
+        return js_test_data;
+    }
+}
 
 function test_with_bytes(
     compress_fn: CompressionFunction,
@@ -40,7 +65,7 @@ function test_with_bytes(
     expect(test_cursor.position).toBe(test_cursor.size);
 }
 
-test.each([[prs_js, 475].flat(), [prs_wasm, 134].flat()])(
+test.each(prepare_test_data([[...prs_js, 475]], [[...prs_wasm, 134]]))(
     "%s PRS compression and decompression, best case",
     (
         _name: string,
@@ -52,7 +77,7 @@ test.each([[prs_js, 475].flat(), [prs_wasm, 134].flat()])(
     },
 );
 
-test.each([[prs_js, 11253].flat(), [prs_wasm, 11250].flat()])(
+test.each(prepare_test_data([[...prs_js, 11253]], [[...prs_wasm, 11250]]))(
     "%s PRS compression and decompression, worst case",
     (
         _name: string,
@@ -70,7 +95,7 @@ test.each([[prs_js, 11253].flat(), [prs_wasm, 11250].flat()])(
     },
 );
 
-test.each([[prs_js, 14924].flat(), [prs_wasm, 12901].flat()])(
+test.each(prepare_test_data([[...prs_js, 14924]], [[...prs_wasm, 12901]]))(
     "%s PRS compression and decompression, typical case",
     (
         _name: string,
@@ -87,16 +112,22 @@ test.each([[prs_js, 14924].flat(), [prs_wasm, 12901].flat()])(
     },
 );
 
-test.each([
-    [prs_js[0], 0, prs_js[1], prs_js[2], [], 3],
-    [prs_js[0], 1, prs_js[1], prs_js[2], [111], 4],
-    [prs_js[0], 2, prs_js[1], prs_js[2], [111, 224], 5],
-    [prs_js[0], 3, prs_js[1], prs_js[2], [56, 237, 158], 6],
-    [prs_wasm[0], 0, prs_wasm[1], prs_wasm[2], [], 3],
-    [prs_wasm[0], 1, prs_wasm[1], prs_wasm[2], [111], 4],
-    [prs_wasm[0], 2, prs_wasm[1], prs_wasm[2], [111, 224], 5],
-    [prs_wasm[0], 3, prs_wasm[1], prs_wasm[2], [56, 237, 158], 6],
-])(
+test.each(
+    prepare_test_data(
+        [
+            [prs_js[0], 0, prs_js[1], prs_js[2], [], 3],
+            [prs_js[0], 1, prs_js[1], prs_js[2], [111], 4],
+            [prs_js[0], 2, prs_js[1], prs_js[2], [111, 224], 5],
+            [prs_js[0], 3, prs_js[1], prs_js[2], [56, 237, 158], 6],
+        ],
+        [
+            [prs_wasm[0], 0, prs_wasm[1], prs_wasm[2], [], 3],
+            [prs_wasm[0], 1, prs_wasm[1], prs_wasm[2], [111], 4],
+            [prs_wasm[0], 2, prs_wasm[1], prs_wasm[2], [111, 224], 5],
+            [prs_wasm[0], 3, prs_wasm[1], prs_wasm[2], [56, 237, 158], 6],
+        ],
+    ),
+)(
     "%s PRS compression and decompression, %d bytes",
     (
         _name: string,
@@ -140,7 +171,7 @@ function test_with_quest(
     expect(matching_bytes).toBe(orig.size);
 }
 
-test.each([prs_js, prs_wasm])(
+test.each(prepare_test_data([prs_js], [prs_wasm]))(
     "%s PRS compression and decompression of quest118_e.bin",
     (_name: string, compress_fn: CompressionFunction, decompress_fn: CompressionFunction) => {
         test_with_quest(compress_fn, decompress_fn, "test/resources/quest118_e.bin");

src/core/data_formats/compression/prs/prs_wasm.ts

@@ -0,0 +1,50 @@
+/**
+ * @file Exposes the WASM PRS functions depending on whether the WASM module is available or not.
+ */
+
+import { browser_supports_webassembly } from "../../../util";
+import { Cursor } from "../../cursor/Cursor";
+import { ArrayBufferCursor } from "../../cursor/ArrayBufferCursor";
+import { Endianness } from "../../Endianness";
+
+type PrsRsModule = typeof import("prs-rs");
+
+class PrsWasm {
+    constructor(private module: PrsRsModule) {}
+
+    public prs_compress_wasm(cursor: Cursor): Cursor {
+        const bytes = new Uint8Array(cursor.array_buffer());
+        const result = this.module.compress(bytes);
+        return new ArrayBufferCursor(
+            result.buffer,
+            Endianness.Little,
+            result.byteOffset,
+            result.length,
+        );
+    }
+
+    public prs_decompress_wasm(cursor: Cursor): Cursor {
+        const bytes = new Uint8Array(cursor.array_buffer());
+        const result = this.module.decompress(bytes);
+        return new ArrayBufferCursor(
+            result.buffer,
+            Endianness.Little,
+            result.byteOffset,
+            result.length,
+        );
+    }
+}
+
+// Load prs-rs if it exists.
+let prs_wasm: PrsWasm | undefined = undefined;
+try {
+    if (browser_supports_webassembly()) {
+        prs_wasm = new PrsWasm(require("prs-rs"));
+    }
+} catch (e) {
+    // Webpack will emit a warning if module is missing.
+}
+
+export function get_prs_wasm_module(): PrsWasm | undefined {
+    return prs_wasm;
+}

typedefs/prs-rs.d.ts

@@ -0,0 +1,16 @@
+/**
+ * @file This file is needed because prs-rs is an optional module and typescript will complain if code refers to an undeclared module.
+ */
+
+declare module "prs-rs" {
+    /**
+     * @param {Uint8Array} data
+     * @returns {Uint8Array}
+     */
+    export function compress(data: Uint8Array): Uint8Array;
+    /**
+     * @param {Uint8Array} data
+     * @returns {Uint8Array}
+     */
+    export function decompress(data: Uint8Array): Uint8Array;
+}