♻️ Make the namespacing independent of the branding.

frontend/src/app/util/range_tree.js

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+/*
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * This Source Code Form is "Incompatible With Secondary Licenses", as
+ * defined by the Mozilla Public License, v. 2.0.
+ *
+ * Copyright (c) 2020 UXBOX Labs SL
+ */
+
+/*
+ * Balanced Binary Search Tree based on the red-black BST
+ * described at "Algorithms" by Robert Sedwick & Kevin Wayne
+ */
+"use strict";
+
+goog.provide("app.util.range_tree");
+goog.require("cljs.core")
+
+goog.scope(function() {
+    const eq = cljs.core._EQ_;
+    const vec = cljs.core.vec;
+    const nil = cljs.core.nil;
+
+    const Color = {
+        RED: 1,
+        BLACK: 2
+    }
+
+    class Node {
+        constructor(value, data) {
+            this.value = value;
+            this.data = [ data ];
+            this.left = null;
+            this.right = null;
+            this.color = Color.BLACK;
+        }
+    }
+
+    // Will store a map from key to list of data
+    //   value => [ data ]
+    // The values can be queried in range and the data stored will be retrived whole
+    // but can be removed/updated individually using clojurescript equality
+    class RangeTree {
+        constructor() {
+            this.root = null;
+        }
+
+        insert(value, data) {
+            this.root = recInsert(this.root, value, data);
+            this.root.color = Color.BLACK;
+            return this;
+        }
+
+        remove(value, data) {
+            if (!this.root) {
+                return this;
+            }
+
+            this.root = recRemoveData(this.root, value, data);
+
+            const newData = recGet(this.root, value);
+
+            if (newData && newData.length === 0) {
+                if (!isRed(this.root.left) && !isRed(this.root.right)) {
+                    this.root.color = Color.RED;
+                }
+
+                this.root = recRemoveNode(this.root, value);
+
+                if (this.root) {
+                    this.root.color = Color.BLACK;
+                }
+            }
+
+            return this;
+        }
+
+        update (value, oldData, newData) {
+            this.root = recUpdate(this.root, value, oldData, newData);
+            return this;
+        }
+
+        get(value) {
+            return recGet(this.root, value);
+        }
+
+        rangeQuery (fromValue, toValue) {
+            return recRangeQuery(this.root, fromValue, toValue, []);
+        }
+
+        height() {
+            return recHeight(this.root);
+        }
+
+        isEmpty() {
+            return this.root === null;
+        }
+
+        toString() {
+            const result = [];
+            recToString(this.root, result);
+            return result.join(", ");
+        }
+
+        asMap() {
+            const result = {};
+            recTreeAsMap(this.root, result);
+            return result;
+        }
+    }
+
+    // Tree implementation functions
+
+    function isRed(branch) {
+        return branch !== null && branch.color === Color.RED;
+    }
+
+    // Insert recursively in the tree
+    function recInsert (branch, value, data) {
+        if (branch === null) {
+            const ret = new Node(value, data);
+            ret.color = Color.RED;
+            return ret;
+        } else if (branch.value === value) {
+            // Find node we'll add to the end of the list
+            branch.data.push(data);
+        } else if (branch.value > value) {
+            // Target value is less than the current value we go left
+            branch.left = recInsert(branch.left, value, data);
+        } else if (branch.value < value) {
+            branch.right = recInsert(branch.right, value, data);
+        }
+
+        if (isRed(branch.right) && !isRed(branch.left)) {
+            branch = rotateLeft(branch);
+        }
+        if (isRed(branch.left) && isRed(branch.left.left)) {
+            branch = rotateRight(branch);
+        }
+        if (isRed(branch.left) && isRed(branch.right)) {
+            flipColors(branch);
+        }
+        return branch;
+    }
+
+    // Search for the min node
+    function searchMin(branch) {
+        if (branch.left === null) {
+            return branch;
+        } else {
+            return searchMin(branch.left);
+        }
+    }
+
+    // Remove the lefmost node of the current branch
+    function recRemoveMin(branch) {
+        if (branch.left === null) {
+            return null;
+        }
+
+        if (!isRed(branch.left) && !isRed(branch.left.left)) {
+            branch = moveRedLeft(branch);
+        }
+        branch.left = recRemoveMin(branch.left);
+        return balance(branch);
+    }
+
+    // Remove the data element for the value given
+    // this will not remove the node, we have to remove the empty node afterwards
+    function recRemoveData(branch, value, data) {
+        if (branch === null) {
+            // Not found
+            return branch;
+        } else if (branch.value === value) {
+            // Node found, we remove the data
+            branch.data = branch.data.filter ((it) => !eq(it, data));
+            return branch;
+        } else if (branch.value > value) {
+            branch.left = recRemoveData (branch.left, value, data);
+            return branch;
+        } else if (branch.value < value) {
+            branch.right = recRemoveData(branch.right, value, data);
+            return branch;
+        }
+    }
+
+    function recRemoveNode(branch, value) {
+        if (value < branch.value) {
+            if (!isRed(branch.left) && !isRed(branch.left.left)) {
+                branch = moveRedLeft(branch);
+            }
+            branch.left = recRemoveNode(branch.left, value);
+        } else {
+            if (isRed(branch.left)) {
+                branch = rotateRight(branch);
+            }
+            if (value === branch.value && branch.right === null) {
+                return null;
+            }
+            if (!isRed(branch.right) && !isRed(branch.right.left)) {
+                branch = moveRedRight(branch);
+            }
+
+            if (value === branch.value) {
+                const x = searchMin(branch.right);
+                branch.value = x.value;
+                branch.data = x.data;
+                branch.right = recRemoveMin(branch.right);
+            } else {
+                branch.right = recRemoveNode(branch.right, value);
+            }
+        }
+        return balance(branch);
+    }
+
+    // Retrieve all the data related to value
+    function recGet(branch, value) {
+        if (branch === null) {
+            return null;
+        } else if (branch.value === value) {
+            return branch.data;
+        } else if (branch.value > value) {
+            return recGet(branch.left, value);
+        } else if (branch.value < value) {
+            return recGet(branch.right, value);
+        }
+    }
+
+    function recUpdate(branch, value, oldData, newData) {
+        if (branch === null) {
+            return branch;
+        } else if (branch.value === value) {
+            branch.data = branch.data.map((it) => (eq(it, oldData)) ? newData : it);
+            return branch;
+        } else if (branch.value > value) {
+            return recUpdate(branch.left, value, oldData, newData);
+        } else if (branch.value < value) {
+            return recUpdate(branch.right, value, oldData, newData);
+        }
+    }
+
+    function recRangeQuery(branch, fromValue, toValue, result) {
+        if (branch === null) {
+            return result;
+        }
+        if (fromValue < branch.value) {
+            recRangeQuery(branch.left, fromValue, toValue, result);
+        }
+        if (fromValue <= branch.value && toValue >= branch.value) {
+            result.push(vec([branch.value, vec(branch.data)]))
+        }
+        if (toValue > branch.value) {
+            recRangeQuery(branch.right, fromValue, toValue, result);
+        }
+        return result;
+    }
+
+    function rotateLeft(branch) {
+        const x = branch.right;
+        branch.right = x.left;
+        x.left = branch;
+        x.color = x.left.color;
+        x.left.color = Color.RED;
+        return x;
+    }
+
+    function rotateRight(branch) {
+        const x = branch.left;
+        branch.left = x.right;
+        x.right = branch;
+        x.color = x.right.color;
+        x.right.color = Color.RED;
+        return x;
+    }
+
+    function balance(branch) {
+        if (isRed(branch.right)) {
+            branch = rotateLeft(branch);
+        }
+        if (isRed(branch.left) && isRed(branch.left.left)) {
+            branch = rotateRight(branch);
+        }
+        if (isRed(branch.left) && isRed(branch.right)) {
+            flipColors(branch);
+        }
+        return branch;
+    }
+
+    function moveRedLeft(branch) {
+        flipColors(branch);
+        if (isRed(branch.right.left)) {
+            branch.right = rotateRight(branch.right);
+            branch = rotateLeft(branch);
+            flipColors(branch);
+        }
+        return branch;
+    }
+
+    function moveRedRight(branch) {
+        flipColors(branch);
+        if (branch.left && isRed(branch.left.left)) {
+            branch = rotateRight(branch);
+            flipColors(branch);
+        }
+        return branch;
+    }
+
+    function flip(color) {
+        return color === Color.RED ? Color.BLACK : Color.RED;
+    }
+
+    function flipColors(branch) {
+        branch.color = flip(branch.color);
+        if (branch.left) {
+            branch.left.color = flip(branch.left.color);
+        }
+        if (branch.right) {
+            branch.right.color = flip(branch.right.color);
+        }
+    }
+
+    function recHeight(branch) {
+        let curHeight = 0;
+        if (branch !== null) {
+            curHeight = Math.max(recHeight(branch.left), recHeight(branch.right))
+        }
+        return 1 + curHeight;
+    }
+
+    // This will return the string representation. We don't care about internal structure
+    // only the data
+    function recToString(branch, result) {
+        if (branch === null) {
+            return;
+        }
+
+        recToString(branch.left, result);
+        result.push(`${branch.value}: [${branch.data.join(", ")}]`)
+        recToString(branch.right, result);
+    }
+
+    // This function prints the tree structure, not the data
+    function printTree(tree) {
+        if (!tree) {
+            return "";
+        }
+        const val = tree.color[0] + "(" + tree.value + ")";
+        return "[" + printTree(tree.left) + " " + val + " " + printTree(tree.right) + "]";
+    }
+
+    function recTreeAsMap(branch, result) {
+        if (!branch) {
+            return result;
+        }
+        recTreeAsMap(branch.left, result);
+        result[branch.value] = branch.data;
+        recTreeAsMap(branch.right, result);
+        return result;
+    }
+
+    // External API to CLJS
+    const self = app.util.range_tree;
+    self.make_tree = () => new RangeTree();
+    self.insert = (tree, value, data) => tree.insert(value, data);
+    self.remove = (tree, value, data) => tree.remove(value, data);
+    self.update = (tree, value, oldData, newData) => tree.update(value, oldData, newData);
+    self.get = (tree, value) => {
+        const result = tree.get(value);
+        if (!result) {
+            return nil;
+        }
+        return vec(result);
+    };
+    self.range_query = (tree, from_value, to_value) => {
+        if (!tree) {
+            return vec();
+        }
+        return vec(tree.rangeQuery(from_value, to_value))
+    };
+    self.empty_QMARK_ = (tree) => tree.isEmpty();
+    self.height = (tree) => tree.height();
+    self.print = (tree) => printTree(tree.root);
+    self.as_map = (tree) => tree.asMap();
+});
+