Add .unaryValue to ExecutionValue (#2324)

Author: benjie

.changeset/fast-phones-change.md

@@ -0,0 +1,8 @@
+---
+"grafast": patch
+---
+
+🚨 ExecutionValue no longer exposes .value and .entries (you need to narrow to
+access these). Added new `.unaryValue()` that can be used to assert the value is
+unary and retrieve its value - this should be used instead of `.at(0)` in
+general.

grafast/grafast/__tests__/unaryDeps-test.ts

@@ -86,8 +86,9 @@ class GetRecordsStep<T extends Record<string, any>> extends ExecutableStep {
     indexMap,
     values,
   }: ExecutionDetails): Promise<GrafastResultsList<any>> {
-    const db = values[this.dbDepId].value as sqlite3.Database;
-    const first = this.firstUDI != null ? values[this.firstUDI].value : null;
+    const db = values[this.dbDepId].unaryValue() as sqlite3.Database;
+    const first =
+      this.firstUDI != null ? values[this.firstUDI].unaryValue() : null;
 
     const identifierCols = Object.keys(this.depIdByIdentifier);
 

grafast/grafast/src/engine/executeBucket.ts

@@ -1246,6 +1246,12 @@ export function bucketToString(this: Bucket) {
   return `Bucket<${this.layerPlan}>`;
 }
 
+function throwNotUnary(): never {
+  throw new Error(
+    `This is not a unary value so we cannot get the single value - there may be more than one!`,
+  );
+}
+
 // TODO: memoize?
 export function batchExecutionValue<TData>(
   entries: TData[],
@@ -1256,6 +1262,7 @@ export function batchExecutionValue<TData>(
     at: batchEntriesAt,
     isBatch: true,
     entries,
+    unaryValue: throwNotUnary,
     _flags,
     _flagsAt: batchFlagsAt,
     _getStateUnion() {
@@ -1313,6 +1320,7 @@ export function unaryExecutionValue<TData>(
     at: unaryAt,
     isBatch: false,
     value,
+    unaryValue: () => value,
     _entryFlags,
     _flagsAt: unaryFlagsAt,
     _getStateUnion: unaryGetStateUnion,

grafast/grafast/src/interfaces.ts

@@ -849,6 +849,8 @@ export type ExecutionValue<TData = any> =
 interface ExecutionValueBase<TData = any> {
   at(i: number): TData;
   isBatch: boolean;
+  /** Returns this.value for a unary execution value; throws if non-unary */
+  unaryValue(): TData;
   /** @internal */
   _flagsAt(i: number): ExecutionEntryFlags;
   /** bitwise OR of all the entry states @internal */
@@ -866,15 +868,17 @@ export interface BatchExecutionValue<TData = any>
   extends ExecutionValueBase<TData> {
   isBatch: true;
   entries: ReadonlyArray<TData>;
-  value?: never;
+  /** Always throws, since this should only be called on unary execution values */
+  unaryValue(): never;
   /** @internal */
   readonly _flags: Array<ExecutionEntryFlags>;
 }
 export interface UnaryExecutionValue<TData = any>
   extends ExecutionValueBase<TData> {
   isBatch: false;
   value: TData;
-  entries?: never;
+  /** Same as getting .value */
+  unaryValue(): TData;
   /** @internal */
   _entryFlags: ExecutionEntryFlags;
 }

grafast/grafast/src/steps/applyTransforms.ts

@@ -105,7 +105,7 @@ export class ApplyTransformsStep extends ExecutableStep {
       );
     }
     if (itemStep._isUnary) {
-      store.set(itemStepId, unaryExecutionValue(values0.at(0)));
+      store.set(itemStepId, unaryExecutionValue(values0.unaryValue()));
     } else {
       store.set(itemStepId, batchExecutionValue([]));
     }

grafast/grafast/src/steps/listTransform.ts

@@ -231,7 +231,7 @@ export class __ListTransformStep<
     const listStepValue = values[this.listStepDepId];
 
     if (itemStep._isUnary) {
-      const list = listStepValue.at(0);
+      const list = listStepValue.unaryValue();
       store.set(
         itemStepId,
         unaryExecutionValue(Array.isArray(list) ? list[0] : list),