Rough demo for how calendar enumerator will work.

This is an example of how multiple enumerators can be combined
into an EventCollator. The collator does the minimum amount
of work to keep searching for one event at a time, while always
emitting them in chronological order.

demo/nodejs/calendar/calendar.ts

@@ -5,12 +5,101 @@
     interesting events for a calendar.
 */
 
-import { AstroTime } from "./astronomy";
+import { AstroTime, Observer, Body, SearchRiseSet, Search } from "./astronomy";
+
+class AstroEvent {
+    constructor(
+        public time: AstroTime,
+        public title: string,
+        public creator: AstroEventEnumerator)
+        {}
+}
+
+interface AstroEventEnumerator {
+    FindFirst(startTime: AstroTime): AstroEvent | null;
+    FindNext(): AstroEvent | null;
+}
+
+
+class EventCollator implements AstroEventEnumerator {
+    private eventQueue: AstroEvent[];
+
+    constructor(private enumeratorList: AstroEventEnumerator[]) {
+    }
+
+    Append(enumerator: AstroEventEnumerator) {
+        this.enumeratorList.push(enumerator);
+    }
+
+    FindFirst(startTime: AstroTime): AstroEvent | null {
+        this.eventQueue = [];
+        for (let enumerator of this.enumeratorList)
+            this.InsertEvent(enumerator.FindFirst(startTime));
+        return this.FindNext();
+    }
+
+    FindNext(): AstroEvent | null {
+        if (this.eventQueue.length === 0)
+            return null;
+
+        const evt = this.eventQueue.shift();
+        const another = evt.creator.FindNext();
+        this.InsertEvent(another);
+        return evt;
+    }
+
+    InsertEvent(evt: AstroEvent | null): void {
+        if (evt !== null) {
+            // Insert the event in time order -- after anything that happens before it.
+
+            let i = 0;
+            while (i < this.eventQueue.length && this.eventQueue[i].time.tt < evt.time.tt)
+                ++i;
+
+            this.eventQueue.splice(i, 0, evt);
+        }
+    }
+}
+
+
+class RiseSetEnumerator implements AstroEventEnumerator {
+    private nextSearchTime: AstroTime;
+
+    constructor(private observer: Observer, private body: Body, private direction: number, private title: string) {
+    }
+
+    FindFirst(startTime: AstroTime): AstroEvent | null {
+        this.nextSearchTime = SearchRiseSet(this.body, this.observer, this.direction, startTime, 366.0);
+        if (this.nextSearchTime)
+            return new AstroEvent(this.nextSearchTime, this.title, this);
+        return null;
+    }
+
+    FindNext(): AstroEvent | null {
+        if (this.nextSearchTime) {
+            const startTime = this.nextSearchTime.AddDays(0.01);
+            return this.FindFirst(startTime);
+        }
+        return null;
+    }
+}
 
 
 function RunTest(): void {
-    const now = new AstroTime(new Date());
-    console.log(now);
+    const startTime = new AstroTime(new Date('2022-01-01T00:00:00Z'));
+    const observer = new Observer(28.6, -81.2, 10.0);
+    const collator = new EventCollator([
+        new RiseSetEnumerator(observer, Body.Sun, +1, 'sunrise'),
+        new RiseSetEnumerator(observer, Body.Sun, -1, 'sunset'),
+        new RiseSetEnumerator(observer, Body.Moon, +1, 'moonrise'),
+        new RiseSetEnumerator(observer, Body.Moon, -1, 'moonset')
+    ]);
+
+    let evt:AstroEvent = collator.FindFirst(startTime);
+    while (evt !== null && evt.time.date.getUTCFullYear() === startTime.date.getUTCFullYear()) {
+        console.log(`${evt.time} ${evt.title}`);
+        evt = collator.FindNext();
+    }
 }
 
 

demo/nodejs/calendar/package.json

@@ -4,7 +4,7 @@
   "description": "Demo of enumerating interesting astronomy events for a calendar.",
   "main": "index.js",
   "scripts": {
-    "test": "tsc && node dist/calendar.js"
+    "test": "tsc && node dist/calendar.js > test/calendar.txt && diff test/calendar_correct.txt test/calendar.txt"
   },
   "author": "Don Cross <cosinekitty@gmail.com>",
   "license": "MIT",

demo/nodejs/calendar/test/.gitignore

@@ -0,0 +1 @@
+calendar.txt