feat(jslib): add variables to jslib query builder

tools/upend_js/query.ts

@@ -2,7 +2,13 @@ import type { Address } from "./types";
 import { isAddress } from "./types";
 
 export const Any = "?";
-type QueryPart<T> = T | T[] | typeof Any;
+class Var {
+  constructor(public readonly name: string) {}
+}
+export function Variable(name: string): Var {
+  return new Var(name);
+}
+type QueryPart<T> = T | T[] | typeof Any | Var;
 
 export class Query {
   private _query: string | undefined;
@@ -17,6 +23,8 @@ export class Query {
     let entityStr;
     if (entity === Any) {
       entityStr = "?";
+    } else if (entity instanceof Var) {
+      entityStr = `?${entity.name}`;
     } else {
       entityStr = Array.isArray(entity) ? `(in ${entity.join(" ")})` : entity;
     }
@@ -24,6 +32,8 @@ export class Query {
     let attributeStr;
     if (attribute === Any) {
       attributeStr = "?";
+    } else if (attribute instanceof Var) {
+      attributeStr = `?${attribute.name}`;
     } else {
       attributeStr = Array.isArray(attribute)
         ? `(in ${attribute.map((a) => `"${a}"`).join(" ")})`
@@ -33,6 +43,8 @@ export class Query {
     let valueStr;
     if (value === Any) {
       valueStr = "?";
+    } else if (value instanceof Var) {
+      valueStr = `?${value.name}`;
     } else {
       valueStr = (Array.isArray(value) ? value : [value])
         .map((v) => {

tools/upend_js/test.ts

@@ -1,5 +1,5 @@
 import test from "ava";
-import { Any, Query } from "./query";
+import { Any, Query, Variable } from "./query";
 
 test("query matches simple", (t) => {
   const query = Query.matches("entity", "attribute", "value");
@@ -31,3 +31,8 @@ test("query matches numbers", (t) => {
   const query = Query.matches("entity", "attribute", [1, 2]);
   t.is(query.toString(), '(matches entity "attribute" (in 1 2))');
 });
+
+test("query matches variables", (t) => {
+  const query = Query.matches("entity", "attribute", Variable("a"));
+  t.is(query.toString(), '(matches entity "attribute" ?a)');
+});