feat: add formatNode utility for descriptor and miniscript ASTs

packages/wasm-miniscript/js/ast/formatNode.ts

@@ -0,0 +1,94 @@
+/*
+
+This file contains type definitions for building an Abstract Syntax Tree for
+Bitcoin Descriptors and Miniscript expressions.
+
+Currently, the types do not encode any validity or soundness checks, so it is
+possible to construct invalid descriptors.
+
+*/
+type Key = string;
+
+// https://bitcoin.sipa.be/miniscript/
+// r is for custom bitgo extension OP_DROP
+type Identities = "a" | "s" | "c" | "t" | "d" | "v" | "j" | "n" | "l" | "u" | "r";
+
+// Union of all possible prefixes: { f: T } => { 'a:f': T } | { 's:f': T } | ...
+type PrefixWith<T, P extends string> = {
+  [K in keyof T & string as `${P}:${K}`]: T[K];
+};
+type PrefixIdUnion<T> = { [P in Identities]: PrefixWith<T, P> }[Identities];
+
+// Wrap a type with a union of all possible prefixes
+type Wrap<T> = T | PrefixIdUnion<T>;
+
+type Miniscript =
+  | Wrap<{ pk: Key }>
+  | Wrap<{ pkh: Key }>
+  | Wrap<{ wpkh: Key }>
+  | Wrap<{ multi: [number, ...Key[]] }>
+  | Wrap<{ sortedmulti: [number, ...Key[]] }>
+  | Wrap<{ multi_a: [number, ...Key[]] }>
+  | Wrap<{ sortedmulti_a: [number, ...Key[]] }>
+  | Wrap<{ tr: Key | [Key, Miniscript] }>
+  | Wrap<{ sh: Miniscript }>
+  | Wrap<{ wsh: Miniscript }>
+  | Wrap<{ and_v: [Miniscript, Miniscript] }>
+  | Wrap<{ and_b: [Miniscript, Miniscript] }>
+  | Wrap<{ andor: [Miniscript, Miniscript, Miniscript] }>
+  | Wrap<{ or_b: [Miniscript, Miniscript] }>
+  | Wrap<{ or_c: [Miniscript, Miniscript] }>
+  | Wrap<{ or_d: [Miniscript, Miniscript] }>
+  | Wrap<{ or_i: [Miniscript, Miniscript] }>
+  | Wrap<{ thresh: [number, ...Miniscript[]] }>
+  | Wrap<{ sha256: string }>
+  | Wrap<{ ripemd160: string }>
+  | Wrap<{ hash256: string }>
+  | Wrap<{ hash160: string }>
+  | Wrap<{ older: number }>
+  | Wrap<{ after: number }>;
+
+// Top level descriptor expressions
+// https://github.com/bitcoin/bitcoin/blob/master/doc/descriptors.md#reference
+type Descriptor =
+  | { sh: Miniscript | { wsh: Miniscript } }
+  | { wsh: Miniscript }
+  | { pk: Key }
+  | { pkh: Key }
+  | { wpkh: Key }
+  | { combo: Key }
+  | { tr: [Key, Miniscript] }
+  | { addr: string }
+  | { raw: string }
+  | { rawtr: string };
+
+type Node = Miniscript | Descriptor | number | string;
+
+function formatN(n: Node | Node[]): string {
+  if (typeof n === "string") {
+    return n;
+  }
+  if (typeof n === "number") {
+    return String(n);
+  }
+  if (Array.isArray(n)) {
+    return n.map(formatN).join(",");
+  }
+  if (n && typeof n === "object") {
+    const entries = Object.entries(n);
+    if (entries.length !== 1) {
+      throw new Error(`Invalid node: ${n}`);
+    }
+    const [name, value] = entries[0];
+    return `${name}(${formatN(value)})`;
+  }
+  throw new Error(`Invalid node: ${n}`);
+}
+
+export type MiniscriptNode = Miniscript;
+export type DescriptorNode = Descriptor;
+
+/** Format a Miniscript or Descriptor node as a descriptor string (without checksum) */
+export function formatNode(n: MiniscriptNode | DescriptorNode): string {
+  return formatN(n);
+}

packages/wasm-miniscript/js/ast/fromWasmNode.ts

@@ -0,0 +1,130 @@
+import { DescriptorNode, MiniscriptNode } from "./formatNode";
+import { Descriptor, Miniscript } from "../index";
+
+function getSingleEntry(v: unknown): [string, unknown] {
+  if (typeof v === "object" && v) {
+    const entries = Object.entries(v);
+    if (entries.length === 1) {
+      return entries[0];
+    }
+  }
+
+  throw new Error("Expected single entry object");
+}
+
+function node(type: string, value: unknown): MiniscriptNode | DescriptorNode {
+  return { [type]: fromUnknown(value) } as MiniscriptNode | DescriptorNode;
+}
+
+function wrap(type: string, value: unknown): MiniscriptNode {
+  const n = fromWasmNode(value);
+  const [name, inner] = getSingleEntry(n);
+  return { [`${type}:${name}`]: inner } as MiniscriptNode;
+}
+
+type Node = DescriptorNode | MiniscriptNode | string | number;
+
+function fromUnknown(v: unknown): Node | Node[] {
+  if (typeof v === "number" || typeof v === "string") {
+    return v;
+  }
+  if (Array.isArray(v)) {
+    return v.map(fromUnknown) as Node[];
+  }
+  if (typeof v === "object" && v) {
+    const [type, value] = getSingleEntry(v);
+    switch (type) {
+      case "Bare":
+      case "Single":
+      case "Ms":
+      case "XPub":
+      case "relLockTime":
+      case "absLockTime":
+        return fromUnknown(value);
+      case "Sh":
+      case "Wsh":
+      case "Tr":
+      case "Pk":
+      case "Pkh":
+      case "PkH":
+      case "Wpkh":
+      case "Combo":
+      case "SortedMulti":
+      case "Addr":
+      case "Raw":
+      case "RawTr":
+      case "After":
+      case "Older":
+      case "Sha256":
+      case "Hash256":
+      case "Ripemd160":
+      case "Hash160":
+        return node(type.toLocaleLowerCase(), value);
+      case "PkK":
+        return node("pk", value);
+      case "RawPkH":
+        return node("raw_pkh", value);
+
+      // Wrappers
+      case "Alt":
+        return wrap("a", value);
+      case "Swap":
+        return wrap("s", value);
+      case "Check":
+        return fromUnknown(value);
+      case "DupIf":
+        return wrap("d", value);
+      case "Verify":
+        return wrap("v", value);
+      case "ZeroNotEqual":
+        return wrap("n", value);
+
+      // Conjunctions
+      case "AndV":
+        return node("and_v", value);
+      case "AndB":
+        return node("and_b", value);
+      case "AndOr":
+        if (!Array.isArray(value)) {
+          throw new Error(`Invalid AndOr node: ${JSON.stringify(value)}`);
+        }
+        const [cond, success, failure] = value;
+        if (failure === false) {
+          return node("and_n", [cond, success]);
+        }
+        return node("andor", [cond, success, failure]);
+
+      // Disjunctions
+      case "OrB":
+        return node("or_b", value);
+      case "OrD":
+        return node("or_d", value);
+      case "OrC":
+        return node("or_c", value);
+      case "OrI":
+        return node("or_i", value);
+
+      // Thresholds
+      case "Thresh":
+        return node("thresh", value);
+      case "Multi":
+        return node("multi", value);
+      case "MultiA":
+        return node("multi_a", value);
+    }
+  }
+
+  throw new Error(`Unknown node ${JSON.stringify(v)}`);
+}
+
+function fromWasmNode(v: unknown): DescriptorNode | MiniscriptNode {
+  return fromUnknown(v) as DescriptorNode | MiniscriptNode;
+}
+
+export function fromDescriptor(d: Descriptor): DescriptorNode {
+  return fromWasmNode(d.node()) as DescriptorNode;
+}
+
+export function fromMiniscript(m: Miniscript): MiniscriptNode {
+  return fromWasmNode(m.node()) as MiniscriptNode;
+}

packages/wasm-miniscript/js/ast/index.ts

@@ -0,0 +1,2 @@
+export * from "./formatNode";
+export * from "./fromWasmNode";

packages/wasm-miniscript/js/index.ts

@@ -10,6 +10,7 @@ export type ScriptContext = "tap" | "segwitv0" | "legacy";
 
 declare module "./wasm/wasm_miniscript" {
   interface WrapDescriptor {
+    /** These are not the same types of nodes as in the ast module */
     node(): unknown;
   }
 
@@ -18,6 +19,7 @@ declare module "./wasm/wasm_miniscript" {
   }
 
   interface WrapMiniscript {
+    /** These are not the same types of nodes as in the ast module */
     node(): unknown;
   }
 
@@ -30,3 +32,5 @@ declare module "./wasm/wasm_miniscript" {
 export { WrapDescriptor as Descriptor } from "./wasm/wasm_miniscript";
 export { WrapMiniscript as Miniscript } from "./wasm/wasm_miniscript";
 export { WrapPsbt as Psbt } from "./wasm/wasm_miniscript";
+
+export * as ast from "./ast";

packages/wasm-miniscript/package.json

@@ -12,8 +12,8 @@
     "dist/*/js/wasm/wasm_miniscript_bg.js",
     "dist/*/js/wasm/wasm_miniscript_bg.wasm",
     "dist/*/js/wasm/wasm_miniscript_bg.wasm.d.ts",
-    "dist/*/js/index.d.ts",
-    "dist/*/js/index.js"
+    "dist/*/js/ast/*",
+    "dist/*/js/index.*"
   ],
   "main": "dist/node/js/index.js",
   "types": "dist/node/js/index.d.ts",

packages/wasm-miniscript/src/try_into_js_value.rs

@@ -92,7 +92,7 @@ impl TryIntoJsValue for AbsLockTime {
 
 impl TryIntoJsValue for RelLockTime {
     fn try_to_js_value(&self) -> Result<JsValue, JsError> {
-        Ok(JsValue::from_str(&self.to_string()))
+        Ok(JsValue::from_f64(self.to_consensus_u32() as f64))
     }
 }
 

packages/wasm-miniscript/test/ast/formatNode.ts

@@ -0,0 +1,14 @@
+import * as assert from "assert";
+
+import { formatNode } from "../../js/ast";
+
+describe("formatNode", function () {
+  it("formats simple nodes", function () {
+    assert.strictEqual(formatNode({ pk: "lol" }), "pk(lol)");
+    assert.strictEqual(formatNode({ after: 1 }), "after(1)");
+    assert.strictEqual(
+      formatNode({ and_v: [{ after: 1 }, { after: 1 }] }),
+      "and_v(after(1),after(1))",
+    );
+  });
+});

packages/wasm-miniscript/test/descriptorUtil.ts

@@ -2,6 +2,7 @@ import * as fs from "fs/promises";
 import * as utxolib from "@bitgo/utxo-lib";
 import { Descriptor } from "../js";
 import * as assert from "node:assert";
+import { DescriptorNode, MiniscriptNode } from "../js/ast";
 
 async function assertEqualJSON(path: string, value: unknown): Promise<void> {
   try {
@@ -16,8 +17,15 @@ async function assertEqualJSON(path: string, value: unknown): Promise<void> {
   }
 }
 
-export async function assertEqualAst(path: string, descriptor: Descriptor): Promise<void> {
-  await assertEqualJSON(path, { descriptor: descriptor.toString(), ast: descriptor.node() });
+export async function assertEqualFixture(
+  path: string,
+  content: {
+    descriptor: string;
+    wasmNode: unknown;
+    ast: DescriptorNode | MiniscriptNode;
+  },
+): Promise<void> {
+  await assertEqualJSON(path, content);
 }
 
 /** Expand a template with the given root wallet keys and chain code */

packages/wasm-miniscript/test/fixtures/0.json

@@ -1,12 +1,15 @@
 {
   "descriptor": "pk(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd)#9pcxlpvx",
-  "ast": {
+  "wasmNode": {
     "Bare": {
       "Check": {
         "PkK": {
           "Single": "03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd"
         }
       }
     }
+  },
+  "ast": {
+    "pk": "03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd"
   }
 }

packages/wasm-miniscript/test/fixtures/1.json

@@ -1,12 +1,15 @@
 {
   "descriptor": "pk(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd)#9pcxlpvx",
-  "ast": {
+  "wasmNode": {
     "Bare": {
       "Check": {
         "PkK": {
           "Single": "03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd"
         }
       }
     }
+  },
+  "ast": {
+    "pk": "03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd"
   }
 }

packages/wasm-miniscript/test/fixtures/10.json

@@ -1,8 +1,11 @@
 {
   "descriptor": "pkh(04a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd5b8dec5235a0fa8722476c7709c02559e3aa73aa03918ba2d492eea75abea235)#9907vvwz",
-  "ast": {
+  "wasmNode": {
     "Pkh": {
       "Single": "04a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd5b8dec5235a0fa8722476c7709c02559e3aa73aa03918ba2d492eea75abea235"
     }
+  },
+  "ast": {
+    "pkh": "04a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd5b8dec5235a0fa8722476c7709c02559e3aa73aa03918ba2d492eea75abea235"
   }
 }

packages/wasm-miniscript/test/fixtures/11.json

@@ -1,8 +1,11 @@
 {
   "descriptor": "pkh(04a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd5b8dec5235a0fa8722476c7709c02559e3aa73aa03918ba2d492eea75abea235)#9907vvwz",
-  "ast": {
+  "wasmNode": {
     "Pkh": {
       "Single": "04a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd5b8dec5235a0fa8722476c7709c02559e3aa73aa03918ba2d492eea75abea235"
     }
+  },
+  "ast": {
+    "pkh": "04a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd5b8dec5235a0fa8722476c7709c02559e3aa73aa03918ba2d492eea75abea235"
   }
 }

packages/wasm-miniscript/test/fixtures/12.json

@@ -1,6 +1,6 @@
 {
   "descriptor": "sh(pk(03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd))#s53ls94y",
-  "ast": {
+  "wasmNode": {
     "Sh": {
       "Ms": {
         "Check": {
@@ -10,5 +10,10 @@
         }
       }
     }
+  },
+  "ast": {
+    "sh": {
+      "pk": "03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd"
+    }
   }
 }