address various PR comments

packages/xpath/src/functions/xforms/node-set.ts

@@ -1,4 +1,4 @@
-import sha256 from 'crypto-js/sha256';
+import { SHA256 } from 'crypto-js';
 
 import type { XPathNode } from '../../adapter/interface/XPathNode.ts';
 import type { XPathDOMProvider } from '../../adapter/xpathDOMProvider.ts';
@@ -410,17 +410,18 @@ export const randomize = new NodeSetFunction(
 );
 
 const toBigIntHash = (text: string): bigint => {
-	// hash text with sha256, and interpret the first 64 bits of output
+	// Hash text with sha256, and interpret the first 64 bits of output
 	// (the first and second int32s ("words") of CryptoJS digest output)
-	// as a BigInt. Thus the entropy of the hash is reduced to 64 bits, which
+	// as an int64 (in JS represented in a BigInt).
+	// Thus the entropy of the hash is reduced to 64 bits, which
 	// for some applications is sufficient.
 	// The underlying representations are big-endian regardless of the endianness
 	// of the machine this runs on, as is the equivalent JavaRosa implementation
 	// at https://github.com/getodk/javarosa/blob/ab0e8f4da6ad8180ac7ede5bc939f3f261c16edf/src/main/java/org/javarosa/xpath/expr/XPathFuncExpr.java#L718-L726
 	const buffer = new ArrayBuffer(8);
 	const dataview = new DataView(buffer);
-	sha256(text)
+	SHA256(text)
 		.words.slice(0, 2)
-		.forEach((val, ix) => dataview.setInt32(ix * 4, val));
+		.forEach((val, ix) => dataview.setInt32(ix * Int32Array.BYTES_PER_ELEMENT, val));
 	return dataview.getBigInt64(0);
-}
+};

packages/xpath/src/lib/collections/sort.ts

@@ -14,8 +14,7 @@ class UnseededPseudoRandomNumberGenerator implements PseudoRandomNumberGenerator
 	}
 }
 
-class SeededPseudoRandomNumberGenerator implements PseudoRandomNumberGenerator {
-	// Park-Miller PRNG
+class ParkMillerPRNG implements PseudoRandomNumberGenerator {
 	protected seed: number;
 
 	constructor(seed: Int | bigint) {
@@ -45,32 +44,38 @@ class SeededPseudoRandomNumberGenerator implements PseudoRandomNumberGenerator {
 	}
 }
 
-export const seededRandomize = <T>(values: readonly T[], seed?: number | bigint): T[] => {
-	let generator: PseudoRandomNumberGenerator;
+class JavaRosaPRNG extends ParkMillerPRNG {
+	// Per issue #49 (https://github.com/getodk/web-forms/issues/49) this is intended to be "bug-or-feature-compatible"
+	// with JavaRosa's implementation; org.javarosa.core.model.ItemsetBinding.resolveRandomSeed takes the .longValue() of
+	// the double produced by randomSeedPathExpr.eval() — see https://github.com/getodk/javarosa/blob/6ce13527c/src/main/java/org/javarosa/core/model/ItemsetBinding.java#L311:L317 .
+	// That results in a 0L when the double is NaN, which happens (for instance) when there
+	// is a string that does not look like a number (which is a problem in itself, as any non-numeric
+	// looking string will then result in the same seed of 0 — see https://github.com/getodk/javarosa/issues/800).
+	// We'll emulate Java's Double -> Long conversion here (for NaN and some other double values)
+	// so that we produce the same randomization as JR.
 
-	if (seed == null) {
-		generator = new UnseededPseudoRandomNumberGenerator();
-	} else {
+	constructor(seed: Int | bigint) {
 		let finalSeed: number | bigint;
-		// Per issue #49 (https://github.com/getodk/web-forms/issues/49) this is intended to be "bug-or-feature-compatible"
-		// with JavaRosa's implementation; org.javarosa.core.model.ItemsetBinding.resolveRandomSeed takes the .longValue() of
-		// the double produced by randomSeedPathExpr.eval() — see https://github.com/getodk/javarosa/blob/6ce13527c/src/main/java/org/javarosa/core/model/ItemsetBinding.java#L311:L317 .
-		// That results in a 0L when the double is NaN, which happens (for instance) when there
-		// is a string that does not look like a number (which is a problem in itself, as any non-numeric
-		// looking string will then result in the same seed of 0 — see https://github.com/getodk/javarosa/issues/800).
-		// We'll emulate Java's Double -> Long conversion here (for NaN and some other double values)
-		// so that we produce the same randomization as JR.
-
 		// In Java, a NaN double's .longValue is 0
 		if (Number.isNaN(seed)) finalSeed = 0;
 		// In Java, an Infinity double's .longValue() is 2**63 -1, which is larger than Number.MAX_SAFE_INTEGER, thus we'll need a BigInt.
 		else if (seed === Infinity) finalSeed = 2n ** 63n - 1n;
 		// Analogous with the above conversion, but for -Infinity
 		else if (seed === -Infinity) finalSeed = -(2n ** 63n);
-		// A Java double's .longValue drops the fractional part.
+		// A Java Double's .longValue drops the fractional part.
 		else if (typeof seed === 'number' && !Number.isInteger(seed)) finalSeed = Math.trunc(seed);
 		else finalSeed = seed;
-		generator = new SeededPseudoRandomNumberGenerator(finalSeed);
+		super(finalSeed);
+	}
+}
+
+export const seededRandomize = <T>(values: readonly T[], seed?: number | bigint): T[] => {
+	let generator: PseudoRandomNumberGenerator;
+
+	if (seed == null) {
+		generator = new UnseededPseudoRandomNumberGenerator();
+	} else {
+		generator = new JavaRosaPRNG(seed);
 	}
 
 	const { length } = values;

packages/xpath/test/xforms/randomize.test.ts

@@ -19,7 +19,7 @@ describe('randomize()', () => {
 
 	const SELECTOR = '//xhtml:div[@id="FunctionRandomize"]/xhtml:div';
 	const MIRROR = 'mirror';
-	const MIRROR_HASH_VALUE = 5989458117437254; // in Python: "from struct import unpack; from hashlib import sha256; unpack('>Q', sha256(b'mirror').digest()[:8])[0]"
+	const MIRROR_HASH_VALUE = 5989458117437254;
 	const MIRROR_HASH_SORT_ORDER = 'ACBEDF';
 
 	describe('shuffles nodesets', () => {