implement live query on @orbit/record-cache

packages/@orbit/record-cache/src/async-record-cache.ts

@@ -38,6 +38,7 @@ import {
 } from './record-accessor';
 import { PatchResult } from './patch-result';
 import { QueryResult, QueryResultData } from './query-result';
+import { AsyncLiveQuery } from './live-query/async-live-query';
 
 const { assert } = Orbit;
 
@@ -246,6 +247,24 @@ export abstract class AsyncRecordCache implements Evented, AsyncRecordAccessor {
     return result;
   }
 
+  liveQuery(
+    queryOrExpressions: QueryOrExpressions,
+    options?: object,
+    id?: string
+  ): AsyncLiveQuery {
+    const query = buildQuery(
+      queryOrExpressions,
+      options,
+      id,
+      this.queryBuilder
+    );
+
+    return new AsyncLiveQuery({
+      cache: this,
+      query
+    });
+  }
+
   /////////////////////////////////////////////////////////////////////////////
   // Protected methods
   /////////////////////////////////////////////////////////////////////////////

packages/@orbit/record-cache/src/index.ts

@@ -4,9 +4,11 @@ export * from './record-accessor';
 
 export * from './async-record-cache';
 export * from './async-operation-processor';
+export * from './live-query/async-live-query';
 
 export * from './sync-record-cache';
 export * from './sync-operation-processor';
+export * from './live-query/sync-live-query';
 
 // Operators
 export * from './operators/async-inverse-patch-operators';

packages/@orbit/record-cache/src/live-query/async-live-query.ts

@@ -0,0 +1,57 @@
+import { Schema, Query } from '@orbit/data';
+import { QueryResult } from '../query-result';
+import { AsyncRecordCache } from '../async-record-cache';
+import { LiveQuery, LiveQuerySettings } from './live-query';
+
+export interface AsyncLiveQueryUpdateSettings {
+  cache: AsyncRecordCache;
+  query: Query;
+}
+
+export class AsyncLiveQueryUpdate {
+  private _cache: AsyncRecordCache;
+  private _query: Query;
+
+  constructor(settings: AsyncLiveQueryUpdateSettings) {
+    this._cache = settings.cache;
+    this._query = settings.query;
+  }
+
+  query(): Promise<QueryResult> {
+    return this._cache.query(this._query);
+  }
+}
+
+export interface AsyncLiveQuerySettings extends LiveQuerySettings {
+  cache: AsyncRecordCache;
+}
+
+export class AsyncLiveQuery extends LiveQuery {
+  protected cache: AsyncRecordCache;
+
+  protected get schema(): Schema {
+    return this.cache.schema;
+  }
+
+  private get _update() {
+    return new AsyncLiveQueryUpdate({
+      cache: this.cache,
+      query: this._query
+    });
+  }
+
+  constructor(settings: AsyncLiveQuerySettings) {
+    super(settings);
+    this.cache = settings.cache;
+  }
+
+  async query(): Promise<QueryResult> {
+    return this._update.query();
+  }
+
+  subscribe(cb: (update: AsyncLiveQueryUpdate) => void): () => void {
+    return this._subscribe(() => {
+      cb(this._update);
+    });
+  }
+}

packages/@orbit/record-cache/src/live-query/live-query.ts

@@ -0,0 +1,182 @@
+import Orbit, { Evented } from '@orbit/core';
+import {
+  QueryExpression,
+  FindRecord,
+  FindRecords,
+  FindRelatedRecord,
+  FindRelatedRecords,
+  equalRecordIdentities,
+  Query,
+  Schema,
+  RecordOperation
+} from '@orbit/data';
+
+import { RecordChange, recordOperationChange } from './record-change';
+
+const { assert } = Orbit;
+
+export interface LiveQuerySettings {
+  query: Query;
+}
+
+export abstract class LiveQuery {
+  protected cache: Evented;
+  protected schema: Schema;
+
+  protected _query: Query;
+  protected _subscribe(onNext: () => void): () => void {
+    const execute = onceTick(onNext);
+
+    const unsubscribePatch = this.cache.on(
+      'patch',
+      (operation: RecordOperation) => {
+        if (this.operationRelevantForQuery(operation)) {
+          execute();
+        }
+      }
+    );
+
+    const unsubscribeReset = this.cache.on('reset', () => {
+      execute();
+    });
+
+    function unsubscribe() {
+      cancelTick(execute);
+      unsubscribePatch();
+      unsubscribeReset();
+    }
+
+    return unsubscribe;
+  }
+
+  constructor(settings: LiveQuerySettings) {
+    assert(
+      'Only single expression queries are supported on LiveQuery',
+      settings.query.expressions.length === 1
+    );
+    this._query = settings.query;
+  }
+
+  operationRelevantForQuery(operation: RecordOperation): boolean {
+    const change = recordOperationChange(operation);
+    const expression = this._query.expressions[0];
+    return this.queryExpressionRelevantForChange(expression, change);
+  }
+
+  protected queryExpressionRelevantForChange(
+    expression: QueryExpression,
+    change: RecordChange
+  ): boolean {
+    switch (expression.op) {
+      case 'findRecord':
+        return this.findRecordQueryExpressionRelevantForChange(
+          expression as FindRecord,
+          change
+        );
+      case 'findRecords':
+        return this.findRecordsQueryExpressionRelevantForChange(
+          expression as FindRecords,
+          change
+        );
+      case 'findRelatedRecord':
+        return this.findRelatedRecordQueryExpressionRelevantForChange(
+          expression as FindRelatedRecord,
+          change
+        );
+      case 'findRelatedRecords':
+        return this.findRelatedRecordsQueryExpressionRelevantForChange(
+          expression as FindRelatedRecords,
+          change
+        );
+      default:
+        return true;
+    }
+  }
+
+  protected findRecordQueryExpressionRelevantForChange(
+    expression: FindRecord,
+    change: RecordChange
+  ): boolean {
+    return equalRecordIdentities(expression.record, change);
+  }
+
+  protected findRecordsQueryExpressionRelevantForChange(
+    expression: FindRecords,
+    change: RecordChange
+  ): boolean {
+    if (expression.type) {
+      return expression.type === change.type;
+    } else if (expression.records) {
+      for (let record of expression.records) {
+        if (record.type === change.type) {
+          return true;
+        }
+      }
+      return false;
+    }
+    return true;
+  }
+
+  protected findRelatedRecordQueryExpressionRelevantForChange(
+    expression: FindRelatedRecord,
+    change: RecordChange
+  ): boolean {
+    return (
+      equalRecordIdentities(expression.record, change) &&
+      (change.relationships.includes(expression.relationship) || change.remove)
+    );
+  }
+
+  protected findRelatedRecordsQueryExpressionRelevantForChange(
+    expression: FindRelatedRecords,
+    change: RecordChange
+  ): boolean {
+    const { type } = this.schema.getRelationship(
+      expression.record.type,
+      expression.relationship
+    );
+
+    if (Array.isArray(type) && type.find(type => type === change.type)) {
+      return true;
+    } else if (type === change.type) {
+      return true;
+    }
+
+    return (
+      equalRecordIdentities(expression.record, change) &&
+      (change.relationships.includes(expression.relationship) || change.remove)
+    );
+  }
+}
+
+const isNode =
+  typeof process === 'object' && typeof process.nextTick === 'function';
+let resolvedPromise: Promise<void>;
+const nextTick = isNode
+  ? function(fn: () => void) {
+      if (!resolvedPromise) {
+        resolvedPromise = Promise.resolve();
+      }
+      resolvedPromise.then(() => {
+        process.nextTick(fn);
+      });
+    }
+  : window.setImmediate || setTimeout;
+
+function onceTick(fn: () => void) {
+  return function tick() {
+    if (!ticks.has(tick)) {
+      ticks.add(tick);
+      nextTick(() => {
+        fn();
+        cancelTick(tick);
+      });
+    }
+  };
+}
+
+function cancelTick(tick: () => void) {
+  ticks.delete(tick);
+}
+
+const ticks = new WeakSet();

packages/@orbit/record-cache/src/live-query/record-change.ts

@@ -0,0 +1,68 @@
+import {
+  Record,
+  cloneRecordIdentity,
+  RecordIdentity,
+  RecordOperation
+} from '@orbit/data';
+
+export interface RecordChange extends RecordIdentity {
+  keys: string[];
+  attributes: string[];
+  relationships: string[];
+  meta: string[];
+  links: string[];
+  remove: boolean;
+}
+
+export function recordOperationChange(
+  operation: RecordOperation
+): RecordChange {
+  const record = operation.record as Record;
+  const change: RecordChange = {
+    ...cloneRecordIdentity(record),
+    remove: false,
+    keys: [],
+    attributes: [],
+    relationships: [],
+    meta: [],
+    links: []
+  };
+
+  switch (operation.op) {
+    case 'addRecord':
+    case 'updateRecord':
+      if (record.keys) {
+        change.keys = Object.keys(record.keys);
+      }
+      if (record.attributes) {
+        change.attributes = Object.keys(record.attributes);
+      }
+      if (record.relationships) {
+        change.relationships = Object.keys(record.relationships);
+      }
+      if (record.meta) {
+        change.meta = Object.keys(record.meta);
+      }
+      if (record.links) {
+        change.links = Object.keys(record.links);
+      }
+      break;
+    case 'replaceAttribute':
+      change.attributes = [operation.attribute];
+      break;
+    case 'replaceKey':
+      change.keys = [operation.key];
+      break;
+    case 'replaceRelatedRecord':
+    case 'replaceRelatedRecords':
+    case 'addToRelatedRecords':
+    case 'removeFromRelatedRecords':
+      change.relationships = [operation.relationship];
+      break;
+    case 'removeRecord':
+      change.remove = true;
+      break;
+  }
+
+  return change;
+}