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import { test, it, describe, expect } from "bun:test";
import { withoutAggressiveGC } from "gc";
import * as _ from "lodash";
function rebase(str, inBase, outBase) {
const mapBase = (b) => (b === 2 ? 32 : b === 16 ? 8 : null);
const stride = mapBase(inBase);
const pad = mapBase(outBase);
if (!stride) throw new Error(`Bad inBase ${inBase}`);
if (!pad) throw new Error(`Bad outBase ${outBase}`);
if (str.length % stride) throw new Error(`Bad string length ${str.length}`);
const out = [];
for (let i = 0; i < str.length; i += stride)
out.push(
parseInt(str.slice(i, i + stride), inBase)
.toString(outBase)
.padStart(pad, "0"),
);
return out.join("");
}
function expectDeepEqual(a, b) {
expect(a).toEqual(b);
}
class HashMaker {
constructor(length) {
this.length = length;
this._dist = {};
}
length: number;
_dist: any;
binToHex(binHash) {
if (binHash.length !== this.length)
throw new Error(
`Hash length mismatch ${this.length} != ${binHash.length}`,
);
return rebase(binHash, 2, 16);
}
makeBits() {
const bits = [];
for (let i = 0; i < this.length; i++) bits.push(i);
return _.shuffle(bits);
}
makeRandom() {
const bits = [];
for (let i = 0; i < this.length; i++)
bits.push(Math.random() < 0.5 ? 1 : 0);
return bits;
}
get keySet() {
return (this._set = this._set || new Set(this.data));
}
randomKey() {
while (true) {
const hash = this.binToHex(this.makeRandom().join(""));
if (!this.keySet.has(hash)) return hash;
}
}
get data() {
return (this._data =
this._data ||
(() => {
const bits = this.makeBits();
const base = this.makeRandom();
const data = [];
for (let stride = 0; bits.length; stride++) {
const flip = bits.splice(0, stride);
for (const bit of flip) base[bit] = 1 - base[bit];
data.push(this.binToHex(base.join("")));
}
return data;
})());
}
get random() {
const d = this.data;
return d[Math.floor(Math.random() * d.length)];
}
distance(a, b) {
const bitCount = (n) => {
n = n - ((n >> 1) & 0x55555555);
n = (n & 0x33333333) + ((n >> 2) & 0x33333333);
return (((n + (n >> 4)) & 0xf0f0f0f) * 0x1010101) >> 24;
};
if (a === b) return 0;
if (a > b) return this.distance(b, a);
const hash = a + "-" + b;
return (this._dist[hash] =
this._dist[hash] ||
(() => {
let dist = 0;
for (let i = 0; i < a.length; i += 8) {
const va = parseInt(a.slice(i, i + 8), 16);
const vb = parseInt(b.slice(i, i + 8), 16);
dist += bitCount(va ^ vb);
}
return dist;
})());
}
query(baseKey, maxDist) {
const out = [];
for (const key of this.data) {
const distance = this.distance(key, baseKey);
if (distance <= maxDist) out.push({ key, distance });
}
return out.sort((a, b) => a.distance - b.distance);
}
}
const treeClass = require("bktree-fast/native");
withoutAggressiveGC(() => {
// this test is too slow
for (let keyLen = 64; keyLen <= 64; keyLen += 64) {
// for (let keyLen = 64; keyLen <= 512; keyLen += 64) {
const hm = new HashMaker(keyLen);
describe(`Key length: ${keyLen}`, () => {
it("should compute distance", () => {
const tree = new treeClass(keyLen);
for (const a of hm.data)
for (const b of hm.data)
expect(tree.distance(a, b)).toBe(hm.distance(a, b));
});
it("should know which keys it has", () => {
const tree = new treeClass(keyLen).add(hm.data);
expectDeepEqual(
hm.data.map((hash) => tree.has(hash)),
hm.data.map(() => true),
);
// Not interested in the hash
for (const hash of hm.data)
expect(tree.has(hm.randomKey())).toBe(false);
});
it("should know the tree size", () => {
const tree = new treeClass(keyLen, { foo: 1 });
expect(tree.size).toBe(0);
tree.add(hm.data);
expect(tree.size).toBe(hm.data.length);
tree.add(hm.data);
expect(tree.size).toBe(hm.data.length);
});
it("should walk the tree", () => {
const tree = new treeClass(keyLen).add(hm.data);
const got = [];
tree.walk((hash, depth) => got.push(hash));
expectDeepEqual(got.sort(), hm.data.slice(0).sort());
});
it("should query", () => {
((treeClass, expectDeepEqual) => {
const tree = new treeClass(keyLen).add(hm.data);
for (let dist = 0; dist <= hm.length; dist++) {
for (const baseKey of [hm.random, hm.data[0]]) {
const baseKey = hm.random;
const got = [];
tree.query(baseKey, dist, (key, distance) =>
got.push({ key, distance }),
);
const want = hm.query(baseKey, dist);
expectDeepEqual(
got.sort((a, b) => a.distance - b.distance),
want,
);
expectDeepEqual(tree.find(baseKey, dist), want);
}
}
})(treeClass, expectDeepEqual);
});
});
}
describe("Misc functions", () => {
it("should pad keys", () => {
const tree = new treeClass(64);
expect(tree.padKey("1")).toBe("0000000000000001");
tree.add(["1", "2", "3"]);
const got = [];
tree.query("2", 3, (hash, distance) => got.push({ hash, distance }));
const res = got.sort((a, b) => a.distance - b.distance);
const want = [
{ hash: "0000000000000002", distance: 0 },
{ hash: "0000000000000003", distance: 1 },
{ hash: "0000000000000001", distance: 2 },
];
expectDeepEqual(res, want);
});
});
});
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