work on sorted list from map

src/observable/BaseObservableCollection.js

@@ -0,0 +1,30 @@
+export default class BaseObservableCollection {
+    constructor() {
+        this._handlers = new Set();
+    }
+
+    onSubscribeFirst() {
+
+    }
+
+    onUnsubscribeLast() {
+
+    }
+
+    subscribe(handler) {
+        this._handlers.add(handler);
+        if (this._handlers.length === 1) {
+            this.onSubscribeFirst();
+        }
+        return () => {
+            if (handler) {
+                this._handlers.delete(this._handler);
+                if (this._handlers.length === 0) {
+                    this.onUnsubscribeLast();
+                }
+                handler = null;
+            }
+            return null;
+        };
+    }
+}

src/observable/list/BaseObservableList.js

@@ -0,0 +1,37 @@
+import BaseObservableCollection from "../BaseObservableCollection.js";
+
+export default class BaseObservableList extends BaseObservableCollection {
+    emitReset() {
+        for(let h of this._handlers) {
+            h.onReset();
+        }
+    }
+    // we need batch events, mostly on index based collection though?
+    // maybe we should get started without?
+    emitAdd(index, value) {
+        for(let h of this._handlers) {
+            h.onAdd(index, value);
+        }
+    }
+
+    emitChange(index, value, params) {
+        for(let h of this._handlers) {
+            h.onChange(index, value, params);
+        }
+    }
+
+    emitRemove(index, value) {
+        for(let h of this._handlers) {
+            h.onRemove(index, value);
+        }
+    }
+
+    // toIdx assumes the item has already
+    // been removed from its fromIdx
+    emitMove(fromIdx, toIdx, value) {
+        for(let h of this._handlers) {
+            h.onMove(fromIdx, toIdx, value);
+        }
+    }
+
+}

src/observable/list/SortOperator.js

@@ -1,4 +1,30 @@
-import Operator from "../Operator.js";
+import BaseObservableList from "../BaseObservableList.js";
+
+
+/*
+
+when a value changes, it sorting order can change. It would still be at the old index prior to firing an onChange event.
+So how do you know where it was before it changed, if not by going over all values?
+
+how to make this fast?
+
+seems hard to solve with an array, because you need to map the key to it's previous location somehow, to efficiently find it,
+and move it.
+
+I wonder if we could do better with a binary search tree (BST).
+The tree has a value with {key, value}. There is a plain Map mapping keys to this tuple,
+for easy lookup. Now how do we find the index of this tuple in the BST?
+
+either we store in every node the amount of nodes on the left and right, or we decend into the part
+of the tree preceding the node we want to know about. Updating the counts upwards would probably be fine as this is log2 of
+the size of the container.
+
+to be able to go from a key to an index, the value would have the have a link with the tree node though
+
+so key -> Map<key,value> -> value -> node -> *parentNode -> rootNode
+with a node containing {value, leftCount, rightCount, leftNode, rightNode, parentNode}
+*/
+
 
 /**
  * @license
@@ -26,44 +52,54 @@ function sortedIndex(array, value, comparator) {
     }
     return high;
 }
-
-// TODO: this should not inherit from an BaseObservableMap, as it's a list
-export default class SortOperator extends Operator {
-    constructor(sourceMap, comparator) {
-        super(sourceMap);
+// no duplicates allowed for now
+export default class SortOperator extends BaseObservableList {
+    constructor(sourceMap, comparator, getKey) {
+        super();
+        this._sourceMap = sourceMap;
         this._comparator = comparator;
+        this._getKey = getKey;
         this._sortedValues = [];
-        this._keyIndex = new Map();
     }
     
     onAdd(key, value) {
         const idx = sortedIndex(this._sortedValues, value, this._comparator);
         this._sortedValues.splice(idx, 0, value);
-        this._keyIndex.set(key, idx);
         this.emitAdd(idx, value);
     }
 
-    onRemove(key, _value) {
+    onRemove(key, value) {
         const idx = sortedIndex(this._sortedValues, value, this._comparator);
-        this._sortedValues.splice(idx, 0, value);
-        this._keyIndex.set(key, idx);
-        this.emitAdd(idx, value);
+        this._sortedValues.splice(idx, 1);
+        this.emitRemove(idx, value);
     }
 
     onChange(key, value, params) {
-        // index could have moved if other items got added in the meantime
-        const oldIdx = this._keyIndex.get(key);
-        this._sortedValues.splice(oldIdx, 1);
-        const idx = sortedIndex(this._sortedValues, value, this._comparator);
+        const idxIfSortUnchanged = sortedIndex(this._sortedValues, value, this._comparator);
+        if (this._getKey(this._sortedValues[idxIfSortUnchanged]) === key) {
+            this.emitChange(idxIfSortUnchanged, value, params);
+        } else {
+            // TODO: slow!? See above for idea with BST to speed this up if we need to
+            const oldIdx = this._sortedValues.find(v => this._getKey(v) === key);
+            this._sortedValues.splice(oldIdx, 1);
+            const newIdx = sortedIndex(this._sortedValues, value, this._comparator);
+            this._sortedValues.splice(newIdx, 0, value);
+            this.emitMove(oldIdx, newIdx, value);
+            this.emitChange(newIdx, value, params);
+        }
+    }
 
+    onReset() {
+        this._sortedValues = [];
+        this.emitReset();
     }
 
     onSubscribeFirst() {
-        this._sortedValues = new Array(this._source.size);
+        this._mapSubscription = this._sourceMap.subscribe(this);
+        this._sortedValues = new Array(this._sourceMap.size);
         let i = 0;
-        for (let [key, value] of this._source) {
+        for (let [, value] of this._sourceMap) {
             this._sortedValues[i] = value;
-            this._keyIndex.set(key, i);
             ++i;
         }
         this._sortedValues.sort(this._comparator);
@@ -73,15 +109,12 @@ export default class SortOperator extends Operator {
     onUnsubscribeLast() {
         super.onUnsubscribeLast();
         this._sortedValues = null;
+        this._mapSubscription = this._mapSubscription();
     }
 
-    onReset() {
-        this._sortedValues = [];
-        this.emitReset();
-    }
 
     get length() {
-        return this._source.size;
+        return this._sourceMap.size;
     }
 
     [Symbol.iterator]() {

src/observable/map/BaseObservableMap.js

@@ -1,11 +1,8 @@
 import MapOperator from "./operators/MapOperator.js";
 import SortOperator from "./operators/SortOperator.js";
+import BaseObservableCollection from "../BaseObservableCollection.js";
 
-export default class BaseObservableMap {
-    constructor() {
-        this._handlers = new Set();
-    }
-
+export default class BaseObservableMap extends BaseObservableCollection {
     emitReset() {
         for(let h of this._handlers) {
             h.onReset();
@@ -31,31 +28,6 @@ export default class BaseObservableMap {
         }
     }
 
-    onSubscribeFirst() {
-
-    }
-
-    onUnsubscribeLast() {
-
-    }
-
-    subscribe(handler) {
-        this._handlers.add(handler);
-        if (this._handlers.length === 1) {
-            this.onSubscribeFirst();
-        }
-        return () => {
-            if (handler) {
-                this._handlers.delete(this._handler);
-                if (this._handlers.length === 0) {
-                    this.onUnsubscribeLast();
-                }
-                handler = null;
-            }
-            return null;
-        };
-    }
-
     map(mapper, updater) {
         return new MapOperator(this, mapper, updater);
     }