wasm: Provide toWallyMap/fromWallyMap utility functions

Author: shesek

src/wasm_package/exports.js

@@ -1,3 +1,4 @@
 export * from './core.js'
 export * from './const.js'
-export * from './functions.js'
+export * from './functions.js'
+export * from './util.js'

src/wasm_package/index.d.ts

@@ -6,7 +6,7 @@ export * from './core'
 declare const OPAQUE_TAG: unique symbol;
 type OpaqueRef<S> = number & { readonly [OPAQUE_TAG]: S};
 
-export type Ref = OpaqueRef<'unknown'>;
+export type Ref = OpaqueRef<'unknown'> | null;
 export type Ref_words = OpaqueRef<'words'> | null;
 export type Ref_ext_key = OpaqueRef<'ext_key'> | null; // TODO check whether this is nullable anywhere in the C interface
 export type Ref_wally_map = OpaqueRef<'wally_map'> | null;

src/wasm_package/test.js

@@ -5,6 +5,7 @@ import {
     WALLY_NETWORK_BITCOIN_MAINNET, WALLY_ADDRESS_VERSION_WIF_MAINNET, WALLY_WIF_FLAG_COMPRESSED,
     BIP32_FLAG_KEY_PUBLIC, BIP32_INITIAL_HARDENED_CHILD,
 } from './index.js'
+import { toWallyMap, fromWallyMap } from './util.js'
 
 // Test simple invocation, with a return code only and no destination pointer
 wally.hex_verify('00') // should not throw
@@ -77,6 +78,19 @@ const try_scrypt = size => wally.scrypt(Buffer.from("password"), Buffer.from("Na
 assert.equal(try_scrypt(32).toString('hex'), 'fdbabe1c9d3472007856e7190d01e9fe7c6ad7cbc8237830e77376634b373162')
 assert.equal(try_scrypt(64).toString('hex'), 'fdbabe1c9d3472007856e7190d01e9fe7c6ad7cbc8237830e77376634b3731622eaf30d92e22a3886ff109279d9830dac727afb94a83ee6d8360cbdfa2cc0640')
 
+// Test JS<->wally map conversion
+let m1, m2
+const js_map = new Map([
+    [0, Buffer.from('zero')],
+    [1, Buffer.from('one')],
+    ['k1', Buffer.from('v1')],
+    ['k2', Buffer.from('v2')],
+])
+assert.deepEqual(fromWallyMap(m1=toWallyMap(js_map)), js_map)
+// works with plain objects and string values (auto-converted to a Map of Buffer values)
+assert.deepEqual(fromWallyMap(m2=toWallyMap({ 'foo': 'bar' })), new Map([['foo', Buffer.from('bar')]]))
+wally.map_free(m1); wally.map_free(m2)
+
 // Test base58 conversion (depends on a JS length function)
 assert.equal(wally.base58_to_bytes('1EMBaSSyxMQPV2fmUsdB7mMfMoocgfiMNw', 0).toString('hex'), '00926ac8843cbca0ee59aa857188324d6d5b76c1c6f0bcc3b0')
 assert.equal(wally.base58_n_to_bytes('1EMBaSSyxMQPV2fmUsdB7mMfMoocgfiMNw', 34, 0).toString('hex'), '00926ac8843cbca0ee59aa857188324d6d5b76c1c6f0bcc3b0')

src/wasm_package/util.js

@@ -0,0 +1,36 @@
+import { map_get_num_items, map_get_item_key, map_get_item_key_length, map_get_item_integer_key, map_get_item, map_init, map_add, map_add_integer } from "./functions.js"
+
+export function fromWallyMap(wally_map) {
+    const js_map = new Map, map_len = map_get_num_items(wally_map)
+
+    for (let i = 0; i < map_len; i++) {
+        const is_int_key = map_get_item_key_length(wally_map, i) == 0
+            , key = is_int_key ? map_get_item_integer_key(wally_map, i)
+                               : map_get_item_key(wally_map, i).toString()
+        js_map.set(key, map_get_item(wally_map, i))
+    }
+
+    return js_map
+}
+
+export function toWallyMap(js_map) {
+    if (js_map && js_map.constructor == Object) {
+        // Convert plain objects into a Map
+        js_map = new Map(Object.entries(js_map))
+    } else if (!(js_map instanceof Map)) {
+        throw new Error('Invalid map for toWallyMap')
+    }
+
+    const wally_map = map_init(js_map.size, null)
+
+    js_map.forEach((val, key) => {
+        val = Buffer.from(val)
+        if (typeof key == 'number') {
+            map_add_integer(wally_map, key, val)
+        } else {
+            map_add(wally_map, Buffer.from(key), val)
+        }
+    })
+
+    return wally_map
+}