Reusable gaps (#364)

src/util/prepared-query.ts

@@ -1,6 +1,7 @@
 import {
 	Encoded,
 	type Fill,
+	Gap,
 	type PartiallyEncoded,
 	Writer,
 	encode,
@@ -47,9 +48,22 @@ export class PreparedQuery {
 	): PreparedQuery {
 		const base = this.length;
 		this.length += values.length;
-		const mapped_bindings = values.map(
-			(v, i) => [`bind___${base + i}`, v] as const,
-		);
+
+		let reused = 0;
+		const gaps = new Map<Gap, number>();
+		const mapped_bindings = values.map((v, i) => {
+			if (v instanceof Gap) {
+				const index = gaps.get(v);
+				if (index !== undefined) {
+					reused++;
+					return [`bind___${index}`, v] as const;
+				}
+
+				gaps.set(v, i - reused);
+			}
+
+			return [`bind___${base + i - reused}`, v] as const;
+		});
 
 		for (const [k, v] of mapped_bindings) {
 			this._bindings[k] = encode(v, {

src/util/tagged-template.ts

@@ -1,10 +1,26 @@
+import { Gap } from "../cbor/gap.ts";
 import { PreparedQuery } from "./prepared-query.ts";
 
 export function surrealql(
 	query_raw: string[] | TemplateStringsArray,
 	...values: unknown[]
 ): PreparedQuery {
-	const mapped_bindings = values.map((v, i) => [`bind___${i}`, v] as const);
+	let reused = 0;
+	const gaps = new Map<Gap, number>();
+	const mapped_bindings = values.map((v, i) => {
+		if (v instanceof Gap) {
+			const index = gaps.get(v);
+			if (index !== undefined) {
+				reused++;
+				return [`bind___${index}`, v] as const;
+			}
+
+			gaps.set(v, i - reused);
+		}
+
+		return [`bind___${i - reused}`, v] as const;
+	});
+
 	const bindings = mapped_bindings.reduce<Record<`bind___${number}`, unknown>>(
 		(prev, [k, v]) => {
 			prev[k] = v;

tests/integration/tests/querying.test.ts

@@ -437,6 +437,39 @@ describe("template literal", async () => {
 			},
 		]);
 	});
+
+	test("reused gap", async () => {
+		const foo = new Gap();
+		const bar = new Gap();
+		const query = surql`RETURN [${foo}, ${bar}, ${1}, ${foo}, ${bar}, ${2}]`;
+		expect(Object.keys(query.bindings)).toStrictEqual([
+			"bind___0",
+			"bind___1",
+			"bind___2",
+			"bind___3",
+		]);
+
+		// Ensure appended segments also re-use
+		query.append`; RETURN [${foo}, ${bar}, ${1}, ${foo}, ${bar}, ${2}]`;
+		expect(Object.keys(query.bindings)).toStrictEqual([
+			"bind___0",
+			"bind___1",
+			"bind___2",
+			"bind___3",
+			"bind___4",
+			"bind___5",
+			"bind___6",
+			"bind___7",
+		]);
+
+		// Check result
+		const res = await surreal.query(query, [foo.fill("a"), bar.fill("b")]);
+
+		expect(res).toStrictEqual([
+			["a", "b", 1, "a", "b", 2],
+			["a", "b", 1, "a", "b", 2],
+		]);
+	});
 });
 
 test("query", async () => {