Add yield expression to cypher QB

Author: CarsonF

src/core/database/query-augmentation/index.ts

@@ -11,3 +11,4 @@ import './map';
 import './pattern-formatting';
 import './subquery';
 import './summary';
+import './yield';

src/core/database/query-augmentation/yield.ts

@@ -0,0 +1,23 @@
+import { Many } from '@seedcompany/common';
+import { Clause, Query } from 'cypher-query-builder';
+
+declare module 'cypher-query-builder/dist/typings/query' {
+  interface Query {
+    yield(...terms: Array<Many<string>>): this;
+  }
+}
+
+Query.prototype.yield = function (this: Query, ...terms: Array<Many<string>>) {
+  const flattened = terms.flat();
+  if (flattened.length === 0) return this;
+  return this.continueChainClause(new Yield(flattened));
+};
+
+class Yield extends Clause {
+  constructor(public terms: readonly string[]) {
+    super();
+  }
+  build() {
+    return `YIELD ${this.terms.join(', ')}`;
+  }
+}