feat: Add functions to convert between compressed witnesses and `JSWi…

…tnessMap` (noir-lang/acvm-simulator#42)

acvm_js/src/compression.rs

@@ -0,0 +1,26 @@
+use acvm::acir::native_types::WitnessMap;
+use js_sys::JsString;
+use wasm_bindgen::prelude::wasm_bindgen;
+
+use crate::JsWitnessMap;
+
+#[wasm_bindgen(js_name = compressWitness)]
+pub fn compress_witness(witness_map: JsWitnessMap) -> Result<Vec<u8>, JsString> {
+    console_error_panic_hook::set_once();
+
+    let witness_map = WitnessMap::from(witness_map);
+    let compressed_witness_map: Vec<u8> =
+        Vec::<u8>::try_from(witness_map).map_err(|err| err.to_string())?;
+
+    Ok(compressed_witness_map)
+}
+
+#[wasm_bindgen(js_name = decompressWitness)]
+pub fn decompress_witness(compressed_witness: Vec<u8>) -> Result<JsWitnessMap, JsString> {
+    console_error_panic_hook::set_once();
+
+    let witness_map =
+        WitnessMap::try_from(compressed_witness.as_slice()).map_err(|err| err.to_string())?;
+
+    Ok(witness_map.into())
+}

acvm_js/src/lib.rs

@@ -10,11 +10,13 @@ use wasm_bindgen::prelude::*;
 
 mod abi;
 mod barretenberg;
+mod compression;
 mod execute;
 mod js_transforms;
 mod public_witness;
 
 pub use abi::{abi_decode, abi_encode};
+pub use compression::{compress_witness, decompress_witness};
 pub use execute::execute_circuit;
 pub use public_witness::{get_public_parameters_witness, get_public_witness, get_return_witness};
 

acvm_js/test/browser/witness_conversion.test.ts

@@ -0,0 +1,25 @@
+import { expect } from "@esm-bundle/chai";
+import initACVMSimulator, {
+  compressWitness,
+  decompressWitness,
+} from "../../result/";
+import {
+  expectedCompressedWitnessMap,
+  expectedWitnessMap,
+} from "../shared/witness_compression";
+
+it("successfully compresses the witness", async () => {
+  await initACVMSimulator();
+
+  const compressedWitnessMap = compressWitness(expectedWitnessMap);
+
+  expect(compressedWitnessMap).to.be.deep.eq(expectedCompressedWitnessMap);
+});
+
+it("successfully decompresses the witness", async () => {
+  await initACVMSimulator();
+
+  const witnessMap = decompressWitness(expectedCompressedWitnessMap);
+
+  expect(witnessMap).to.be.deep.eq(expectedWitnessMap);
+});

acvm_js/test/node/witness_conversion.test.ts

@@ -0,0 +1,18 @@
+import { expect } from "chai";
+import { compressWitness, decompressWitness } from "../../result/";
+import {
+  expectedCompressedWitnessMap,
+  expectedWitnessMap,
+} from "../shared/witness_compression";
+
+it("successfully compresses the witness", () => {
+  const compressedWitnessMap = compressWitness(expectedWitnessMap);
+
+  expect(compressedWitnessMap).to.be.deep.eq(expectedCompressedWitnessMap);
+});
+
+it("successfully decompresses the witness", () => {
+  const witnessMap = decompressWitness(expectedCompressedWitnessMap);
+
+  expect(witnessMap).to.be.deep.eq(expectedWitnessMap);
+});

acvm_js/test/shared/witness_compression.ts

@@ -0,0 +1,23 @@
+// Solved witness for noir program (x = 1, y = 2)
+//
+// fn main(x : Field, y : pub Field) -> pub Field {
+//   assert(x != y);
+//   x + y
+// }
+
+export const expectedCompressedWitnessMap = Uint8Array.from([
+  0xa5, 0xd0, 0x39, 0x11, 0xc0, 0x30, 0x0c, 0x00, 0xc1, 0xc9, 0xc7, 0x47, 0xaf,
+  0x2d, 0x75, 0xa6, 0x12, 0x4d, 0x64, 0x26, 0x01, 0x69, 0x36, 0x69, 0xc2, 0x40,
+  0x07, 0x60, 0x8b, 0x7b, 0xb7, 0x35, 0xa0, 0x16, 0xee, 0x65, 0x82, 0x8e, 0x35,
+  0x18, 0x9a, 0x48, 0x76, 0x4a, 0x64, 0xbc, 0x81, 0x3c, 0x4c, 0x41, 0x34, 0x9a,
+  0xa1, 0xa1, 0x9a, 0x3e, 0x64, 0xcc, 0x69, 0x62, 0xdd, 0xc3, 0x3b, 0x38, 0x0a,
+  0x27, 0x4e, 0x75, 0x9e, 0xbf, 0x71, 0xd6, 0x89, 0xab, 0xfe, 0xe2, 0x03,
+]);
+
+export const expectedWitnessMap = new Map([
+  [1, "0x0000000000000000000000000000000000000000000000000000000000000001"],
+  [2, "0x0000000000000000000000000000000000000000000000000000000000000002"],
+  [3, "0x30644e72e131a029b85045b68181585d2833e84879b9709143e1f593f0000000"],
+  [4, "0x30644e72e131a029b85045b68181585d2833e84879b9709143e1f593f0000000"],
+  [5, "0x0000000000000000000000000000000000000000000000000000000000000001"],
+]);