feat: add lenPrefixedWrapper to support WrapperOpaque and `Wrappe…

…rKeepOpaque` types (#288)

codegen/codecVisitor.ts

@@ -14,7 +14,10 @@ export function createCodecVisitor(
   files.set("codecs.ts", {
     getContent: () => [
       "\n",
-      ["import { ChainError, BitSequence, Era, $, $era, $null } from", S.string(importSource)],
+      [
+        "import { ChainError, BitSequence, Era, $, $era, $null, $lenPrefixed } from",
+        S.string(importSource),
+      ],
       [`import type * as t from "./mod.ts"`],
       ...codecs,
       [
@@ -51,6 +54,7 @@ export function createCodecVisitor(
     },
     compact: () => null,
     bitSequence: () => null,
+    lenPrefixedWrapper: () => null,
     circular: () => null,
   });
 
@@ -164,6 +168,9 @@ export function createCodecVisitor(
     era(ty) {
       return addCodecDecl(ty, "$era");
     },
+    lenPrefixedWrapper(ty, inner) {
+      return addCodecDecl(ty, ["$lenPrefixed(", this.visit(inner), ")"]);
+    },
     circular(ty) {
       return ["$.deferred(() =>", getName(getRawCodecPath(ty)), ")"];
     },

codegen/genMetadata.ts

@@ -21,6 +21,7 @@ export function genMetadata(metadata: M.Metadata, decls: Decl[]) {
     primitive: () => false,
     compact: () => false,
     bitSequence: () => false,
+    lenPrefixedWrapper: () => false,
     circular: () => false,
   });
 

codegen/typeVisitor.ts

@@ -113,6 +113,9 @@ export function createTypeVisitor(tys: M.Ty[], decls: Decl[]) {
     era() {
       return "Era";
     },
+    lenPrefixedWrapper(_ty, inner) {
+      return this.visit(inner);
+    },
     circular(ty) {
       return getPath(tys, ty) || this._visit(ty);
     },

frame_metadata/Codec.ts

@@ -1,4 +1,5 @@
 import * as $ from "../deps/scale.ts";
+import { $lenPrefixed } from "../util/$lenPrefixed.ts";
 import { $era } from "./Era.ts";
 import type * as M from "./mod.ts";
 import { TyVisitor } from "./TyVisitor.ts";
@@ -102,6 +103,9 @@ export function DeriveCodec(tys: M.Ty[]): DeriveCodec {
     era() {
       return $era;
     },
+    lenPrefixedWrapper(_ty, inner) {
+      return $lenPrefixed(this.visit(inner));
+    },
     circular(ty) {
       return $.deferred(() => this.cache[ty.id]!);
     },

frame_metadata/Extrinsic.ts

@@ -2,6 +2,7 @@ import * as $ from "../deps/scale.ts";
 import { assert } from "../deps/std/testing/asserts.ts";
 import * as H from "../hashers/mod.ts";
 import * as ss58 from "../ss58/mod.ts";
+import { $lenPrefixed } from "../util/$lenPrefixed.ts";
 import { hex } from "../util/mod.ts";
 import { $null, DeriveCodec } from "./Codec.ts";
 import { Metadata } from "./Metadata.ts";
@@ -165,25 +166,7 @@ export function $extrinsic(props: ExtrinsicCodecProps): $.Codec<Extrinsic> {
     },
   });
 
-  return $.createCodec({
-    _metadata: [$extrinsic, props],
-    _staticSize: $.compactU32._staticSize + $baseExtrinsic._staticSize,
-    _encode(buffer, extrinsic) {
-      const lengthCursor = buffer.createCursor($.compactU32._staticSize);
-      const contentCursor = buffer.createCursor($baseExtrinsic._staticSize);
-      $baseExtrinsic._encode(contentCursor, extrinsic);
-      buffer.waitForBuffer(contentCursor, () => {
-        const length = contentCursor.finishedSize + contentCursor.index;
-        $.compactU32._encode(lengthCursor, length);
-        lengthCursor.close();
-        contentCursor.close();
-      });
-    },
-    _decode(buffer) {
-      const length = $.compactU32._decode(buffer);
-      return $baseExtrinsic.decode(buffer.array.subarray(buffer.index, buffer.index += length));
-    },
-  });
+  return $lenPrefixed($baseExtrinsic);
 
   function findExtrinsicTypeParam(name: string) {
     return metadata.extrinsic.ty.params.find((x) => x.name === name)?.ty;

frame_metadata/TyVisitor.ts

@@ -37,6 +37,8 @@ export interface TyVisitorMethods<T> {
 
   era?(ty: Ty & UnionTyDef): T;
 
+  lenPrefixedWrapper(ty: Ty & StructTyDef, inner: Ty): T;
+
   circular(ty: Ty): T;
 }
 
@@ -74,6 +76,8 @@ export class TyVisitor<T> {
         return this.map(ty, ty.params[0]!.ty!, ty.params[1]!.ty!);
       } else if (this.set && ty.path[0] === "BTreeSet") {
         return this.set(ty, ty.params[0]!.ty!);
+      } else if (ty.path.at(-1) === "WrapperOpaque" || ty.path.at(-1) === "WrapperKeepOpaque") {
+        return this.lenPrefixedWrapper(ty, ty.params[0]!.ty!);
       } else if (ty.fields.length === 0) {
         return this.unitStruct(ty);
       } else if (ty.fields[0]!.name === undefined) {

mod.ts

@@ -6,6 +6,7 @@ export * as M from "./frame_metadata/mod.ts";
 export { $era, $null, ChainError, type Era } from "./frame_metadata/mod.ts";
 export { kusama, moonbeam, polkadot, rococo, westend } from "./known/mod.ts"; // TODO: get rid of this!
 export {
+  $lenPrefixed,
   type CreateWatchHandler,
   hex,
   mapCreateWatchHandler,

util/$lenPrefixed.ts

@@ -0,0 +1,23 @@
+import * as $ from "../deps/scale.ts";
+
+export function $lenPrefixed<T>($inner: $.Codec<T>): $.Codec<T> {
+  return $.createCodec({
+    _metadata: [$lenPrefixed, $inner],
+    _staticSize: $.compactU32._staticSize + $inner._staticSize,
+    _encode(buffer, extrinsic) {
+      const lengthCursor = buffer.createCursor($.compactU32._staticSize);
+      const contentCursor = buffer.createCursor($inner._staticSize);
+      $inner._encode(contentCursor, extrinsic);
+      buffer.waitForBuffer(contentCursor, () => {
+        const length = contentCursor.finishedSize + contentCursor.index;
+        $.compactU32._encode(lengthCursor, length);
+        lengthCursor.close();
+        contentCursor.close();
+      });
+    },
+    _decode(buffer) {
+      const length = $.compactU32._decode(buffer);
+      return $inner.decode(buffer.array.subarray(buffer.index, buffer.index += length));
+    },
+  });
+}

util/mod.ts

@@ -1,3 +1,4 @@
+export * from "./$lenPrefixed.ts";
 export * from "./branded.ts";
 export * from "./error.ts";
 export * as hex from "./hex.ts";