feat(noir_js): allow providing foreign call handlers in noirJS

tooling/noir_js/src/program.ts

@@ -2,13 +2,13 @@
 import { Backend, CompiledCircuit, ProofData } from '@noir-lang/types';
 import { generateWitness } from './witness_generation.js';
 import initAbi, { abiDecode, InputMap, InputValue } from '@noir-lang/noirc_abi';
-import initACVM, { compressWitness } from '@noir-lang/acvm_js';
+import initACVM, { compressWitness, ForeignCallHandler } from '@noir-lang/acvm_js';
 
 export class Noir {
   constructor(
     private circuit: CompiledCircuit,
     private backend?: Backend,
-  ) {}
+  ) { }
 
   async init(): Promise<void> {
     // If these are available, then we are in the
@@ -29,9 +29,9 @@ export class Noir {
   }
 
   // Initial inputs to your program
-  async execute(inputs: InputMap): Promise<{ witness: Uint8Array; returnValue: InputValue }> {
+  async execute(inputs: InputMap, foreignCallHandler?: ForeignCallHandler): Promise<{ witness: Uint8Array; returnValue: InputValue }> {
     await this.init();
-    const witness = await generateWitness(this.circuit, inputs);
+    const witness = await generateWitness(this.circuit, inputs, foreignCallHandler);
     const { return_value: returnValue } = abiDecode(this.circuit.abi, witness);
     return { witness: compressWitness(witness), returnValue };
   }

tooling/noir_js/src/witness_generation.ts

@@ -1,19 +1,21 @@
 import { abiEncode, InputMap } from '@noir-lang/noirc_abi';
 import { base64Decode } from './base64_decode.js';
-import { executeCircuit, WitnessMap } from '@noir-lang/acvm_js';
+import { executeCircuit, WitnessMap, ForeignCallHandler, ForeignCallInput } from '@noir-lang/acvm_js';
 import { CompiledCircuit } from '@noir-lang/types';
 
+const defaultForeignCallHandler: ForeignCallHandler = (name: string, args: ForeignCallInput[]) => {
+  throw Error(`Unexpected oracle during execution: ${name}(${args.join(', ')})`)
+}
+
 // Generates the witnesses needed to feed into the chosen proving system
-export async function generateWitness(compiledProgram: CompiledCircuit, inputs: InputMap): Promise<WitnessMap> {
+export async function generateWitness(compiledProgram: CompiledCircuit, inputs: InputMap, foreignCallHandler: ForeignCallHandler = defaultForeignCallHandler): Promise<WitnessMap> {
   // Throws on ABI encoding error
   const witnessMap = abiEncode(compiledProgram.abi, inputs);
 
   // Execute the circuit to generate the rest of the witnesses and serialize
   // them into a Uint8Array.
   try {
-    const solvedWitness = await executeCircuit(base64Decode(compiledProgram.bytecode), witnessMap, () => {
-      throw Error('unexpected oracle during execution');
-    });
+    const solvedWitness = await executeCircuit(base64Decode(compiledProgram.bytecode), witnessMap, foreignCallHandler);
     return solvedWitness;
   } catch (err) {
     throw new Error(`Circuit execution failed: ${err}`);