ci: add pre-commit

Signed-off-by: Matej Focko <mfocko@redhat.com>

.gitlab-ci.yml

@@ -0,0 +1,21 @@
+pages:
+  script:
+    - mkdir .public
+    - cp -r * .public
+    - mv .public public
+  artifacts:
+    paths:
+      - public
+  only:
+    - main
+
+pre-commit:
+  variables:
+    PRE_COMMIT_HOME: ${CI_PROJECT_DIR}/.cache/pre-commit
+  cache:
+    paths:
+      - ${PRE_COMMIT_HOME}
+  image: registry.gitlab.com/yesolutions/docker-pre-commit
+  script:
+    - pip install pre-commit
+    - pre-commit run --all-files

avl.js

@@ -33,30 +33,24 @@ class AVLTree extends RankedTree {
         );
     }
 
-    fix0Child(x, y, z, rotatingAroundRoot, rotateLeft, rotateRight) {
+    fix0Child(x, y, z, rotateLeft, rotateRight) {
         let newRoot = x.parent;
 
         if (!y || nodeDifference(y) == 2) {
-            newRoot = rotateRight(z);
-            if (rotatingAroundRoot) {
-                this.root = newRoot;
-            }
+            newRoot = rotateRight(this, z);
             this.record("Fixing 0-child by single rotation: by z", z, newRoot);
 
             z.demote();
             this.record("Fixing 0-child by single rotation: demoting z", z);
         } else if (nodeDifference(y) == 1) {
-            let intermediateRoot = rotateLeft(x);
+            let intermediateRoot = rotateLeft(this, x);
             this.record(
                 "Fixing 0-child by double-rotation: first rotation by x",
                 x,
                 intermediateRoot
             );
 
-            newRoot = rotateRight(z);
-            if (rotatingAroundRoot) {
-                this.root = newRoot;
-            }
+            newRoot = rotateRight(this, z);
             this.record(
                 "Fixing 0-child by double-rotation: second rotation by z",
                 z,
@@ -91,8 +85,6 @@ class AVLTree extends RankedTree {
             return;
         }
 
-        let rotatingAroundRoot = x.parent.parent == null;
-
         let rankDifference = nodeDifference(x);
         if (rankDifference != 0) {
             return;
@@ -101,49 +93,32 @@ class AVLTree extends RankedTree {
         let xParent = x.parent;
 
         if (rankDifference == 0 && x.parent.left === x) {
-            this.fix0Child(
-                x,
-                x.right,
-                xParent,
-                rotatingAroundRoot,
-                rotateLeft,
-                rotateRight
-            );
+            this.fix0Child(x, x.right, xParent, rotateLeft, rotateRight);
         } else if (rankDifference == 0 && x.parent.right === x) {
-            this.fix0Child(
-                x,
-                x.left,
-                xParent,
-                rotatingAroundRoot,
-                rotateRight,
-                rotateLeft
-            );
+            this.fix0Child(x, x.left, xParent, rotateRight, rotateLeft);
         }
     }
 
-    deleteRotate(x, y, leaning, rotatingAroundRoot, rotateLeft, rotateRight) {
+    deleteRotate(x, y, leaning, rotateLeft, rotateRight) {
         let newRoot = x;
 
         let factor = balanceFactor(y);
         switch (factor) {
             case 0:
             case leaning:
-                newRoot = rotateLeft(x);
+                newRoot = rotateLeft(this, x);
                 break;
             default:
-                let intermediateRoot = rotateRight(y);
+                let intermediateRoot = rotateRight(this, y);
                 this.record(
                     "AVL deletion, fixing by double-rotation: by y",
                     y,
                     intermediateRoot
                 );
 
-                newRoot = rotateLeft(x);
+                newRoot = rotateLeft(this, x);
                 break;
         }
-        if (rotatingAroundRoot) {
-            this.root = newRoot;
-        }
         this.record("AVL deletion, fixing by rotation by x", x, newRoot);
 
         [newRoot.left, newRoot.right, newRoot]
@@ -172,7 +147,6 @@ class AVLTree extends RankedTree {
                 return false;
         }
 
-        let rotatingAroundRoot = x.parent == null;
         let [z, leaning, toLeft, toRight] = [
             x.left,
             -1,
@@ -188,14 +162,7 @@ class AVLTree extends RankedTree {
             ];
         }
 
-        return this.deleteRotate(
-            x,
-            z,
-            leaning,
-            rotatingAroundRoot,
-            toLeft,
-            toRight
-        );
+        return this.deleteRotate(x, z, leaning, toLeft, toRight);
     }
 
     deleteRebalance(node, parent) {

comparator.html

@@ -148,6 +148,18 @@
             <label class="btn btn-outline-primary" for="lRavlTreeBtn"
               >rAVL</label
             >
+
+            <input
+              type="radio"
+              class="btn-check"
+              name="leftTreeSelection"
+              id="lRbTreeBtn"
+              autocomplete="off"
+              onclick="switchTree(RBTree, 'left')"
+            />
+            <label class="btn btn-outline-primary" for="lRbTreeBtn"
+              >Red-Black</label
+            >
           </div>
         </div>
       </div>
@@ -190,6 +202,18 @@
             <label class="btn btn-outline-primary" for="rRavlTreeBtn"
               >rAVL</label
             >
+
+            <input
+              type="radio"
+              class="btn-check"
+              name="rightTreeSelection"
+              id="rRbTreeBtn"
+              autocomplete="off"
+              onclick="switchTree(RBTree, 'right')"
+            />
+            <label class="btn btn-outline-primary" for="rRbTreeBtn"
+              >Red-Black</label
+            >
           </div>
         </div>
       </div>
@@ -211,6 +235,7 @@
   <script src="avl.js"></script>
   <script src="wavl.js"></script>
   <script src="ravl.js"></script>
+  <script src="rbt.js"></script>
 
   <script src="recorder.js"></script>
 

index.html

@@ -115,6 +115,18 @@
             <label class="btn btn-outline-primary" for="ravlTreeBtn"
               >rAVL</label
             >
+
+            <input
+              type="radio"
+              class="btn-check"
+              name="treeSelection"
+              id="rbTreeBtn"
+              autocomplete="off"
+              onclick="switchTree(RBTree)"
+            />
+            <label class="btn btn-outline-primary" for="rbTreeBtn"
+              >Red-Black</label
+            >
           </div>
         </div>
       </div>
@@ -186,6 +198,7 @@
   <script src="avl.js"></script>
   <script src="wavl.js"></script>
   <script src="ravl.js"></script>
+  <script src="rbt.js"></script>
 
   <script src="recorder.js"></script>
 

node.js

@@ -36,7 +36,7 @@ function nodeDifferences(node) {
     return [r - nodeRank(left), r - nodeRank(right)];
 }
 
-function rotateRight(x) {
+function rotateRight(t, x) {
     let parent = x.parent;
     let y = x.left;
     // let z = x.right;
@@ -47,6 +47,8 @@ function rotateRight(x) {
         } else {
             parent.right = y;
         }
+    } else if (t) {
+        t.root = y;
     }
 
     x.left = y.right;
@@ -61,7 +63,7 @@ function rotateRight(x) {
     return y;
 }
 
-function rotateLeft(x) {
+function rotateLeft(t, x) {
     let parent = x.parent;
     // let y = x.left;
     let z = x.right;
@@ -72,6 +74,8 @@ function rotateLeft(x) {
         } else {
             parent.right = z;
         }
+    } else if (t) {
+        t.root = z;
     }
 
     x.right = z.left;

ranked_tree.js

@@ -37,10 +37,12 @@ class RankedTree {
 
         edges.forEach((vertices) => {
             let [u, v] = vertices;
+            let diff = nodeDifference(v);
+
             result.push(
                 `\t"Node(${u.value})" -> "Node(${
                     v.value
-                })" [label="${nodeDifference(v)}"];\n`
+                })" [label="${diff}"${this.styleEdge(diff)}];\n`
             );
         });
 
@@ -176,4 +178,8 @@ class RankedTree {
     deleteRebalance(node, parent) {
         throw "not implemented!";
     }
+
+    styleEdge(rankDifference) {
+        return "";
+    }
 }

rbt.js

@@ -0,0 +1,173 @@
+const RED = 0;
+const BLACK = 1;
+
+function isDoubleBlack(x) {
+    return x && nodeDifferences(x).indexOf(2) != -1;
+}
+
+class RBTree extends RankedTree {
+    isCorrectNode(node, recursive) {
+        if (!node) {
+            return true;
+        }
+
+        let [left, right] = nodeDifferences(node);
+        if ([RED, BLACK].indexOf(left) == -1) {
+            // left subtree has invalid difference
+            return false;
+        } else if ([RED, BLACK].indexOf(right) == -1) {
+            // right subtree has invalid difference
+            return false;
+        }
+
+        if (nodeDifference(node) == RED && (left == RED || right == RED)) {
+            // two consecutive red nodes
+            return false;
+        }
+
+        recursive = recursive ?? true;
+        return (
+            !recursive ||
+            (this.isCorrectNode(node.left) && this.isCorrectNode(node.right))
+        );
+    }
+
+    insertRebalanceStep(z, y, rightChild, rotateLeft, rotateRight) {
+        let [p, pp] = [z.parent, z.parent.parent];
+
+        if (y && nodeDifference(y) == RED) {
+            // Case 1
+            // ======
+            // z’s uncle y is red
+            pp.rank++;
+            this.record("Insertion case #1: recoloring uncle", pp);
+            z = pp;
+        } else if (z === rightChild) {
+            // Case 2
+            // ======
+            // z’s uncle y is black and z is a right child
+            z = p;
+            rotateLeft(this, p);
+            this.record("Insertion case #2: rotating by parent");
+        } else {
+            // Case 3
+            // ======
+            // z’s uncle y is black and z is a left child
+            rotateRight(this, pp);
+            this.record("Insertion case #3: rotating by grandparent");
+        }
+
+        return z;
+    }
+
+    insertRebalance(z) {
+        while (z.parent && nodeDifference(z.parent) == RED) {
+            let [p, pp] = [z.parent, z.parent.parent];
+
+            if (p === pp.left) {
+                z = this.insertRebalanceStep(
+                    z,
+                    pp.right,
+                    p.right,
+                    rotateLeft,
+                    rotateRight
+                );
+            } else {
+                z = this.insertRebalanceStep(
+                    z,
+                    pp.left,
+                    p.left,
+                    rotateRight,
+                    rotateLeft
+                );
+            }
+        }
+    }
+
+    deleteRebalanceStep(x, w, parent, right, rotateLeft, rotateRight) {
+        if (nodeDifference(w) == RED) {
+            // Case 1
+            // ======
+            // x’s sibling w is red
+            rotateLeft(this, parent);
+            this.record("Deletion case #1: rotating by parent", parent);
+            w = right(parent);
+        }
+
+        if (nodeDifferences(w).equals([BLACK, BLACK])) {
+            // Case 2
+            // ======
+            // x’s sibling w is black, and both of w’s children are black
+            parent.rank--;
+            this.record("Deletion case #2: recoloring sibling", w);
+            x = parent;
+        } else {
+            // Case 3
+            // ======
+            // x’s sibling w is black,
+            // w’s left child is red, and w’s right child is black
+            if (nodeDifference(right(w), w) == BLACK) {
+                rotateRight(this, w);
+                this.record("Deletion case #3: rotating by w", w);
+                w = right(parent);
+            }
+
+            // Case 4
+            // ======
+            // x’s sibling w is black, and w’s right child is red
+            parent.rank--;
+            this.record(
+                "Deletion case #4: moving double black to parent",
+                parent
+            );
+            w.rank++;
+            this.record("Deletion case #4: coloring w's child", w);
+            rotateLeft(this, parent);
+            this.record("Deletion case #4: rotating by parent", parent);
+
+            x = this.root;
+        }
+
+        return [x, x ? x.parent : null];
+    }
+
+    deleteRebalance(node, parent) {
+        if (!node && !parent) {
+            return;
+        }
+
+        while (node !== this.root && isDoubleBlack(parent)) {
+            if (node === parent.left) {
+                [node, parent] = this.deleteRebalanceStep(
+                    node,
+                    parent.right,
+                    parent,
+                    (x) => x.right,
+                    rotateLeft,
+                    rotateRight
+                );
+            } else {
+                [node, parent] = this.deleteRebalanceStep(
+                    node,
+                    parent.left,
+                    parent,
+                    (x) => x.left,
+                    rotateRight,
+                    rotateLeft
+                );
+            }
+        }
+    }
+
+    styleEdge(rankDifference) {
+        switch (rankDifference) {
+            case 2:
+                return " penwidth=2";
+            case 0:
+                return ', color="red"';
+            case 1:
+            default:
+                return "";
+        }
+    }
+}

wavl.js

@@ -21,7 +21,7 @@ class WAVLTree extends AVLTree {
         );
     }
 
-    fixDelete(x, y, z, reversed, rotatingAroundRoot, rotateLeft, rotateRight) {
+    fixDelete(x, y, z, reversed, rotateLeft, rotateRight) {
         let newRoot = x;
         let [v, w] = [y.left, y.right];
 
@@ -30,13 +30,9 @@ class WAVLTree extends AVLTree {
         }
 
         let wDiff = nodeDifference(w, y);
-
         if (wDiff == 1 && y.parent) {
             let oldRoot = y.parent;
-            newRoot = rotateLeft(y.parent);
-            if (rotatingAroundRoot) {
-                this.root = newRoot;
-            }
+            newRoot = rotateLeft(this, y.parent);
             this.record(
                 "Final step of deletion rebalance: single rotation by parent of y",
                 oldRoot,
@@ -58,7 +54,7 @@ class WAVLTree extends AVLTree {
             }
         } else if (wDiff == 2 && v && v.parent) {
             let oldRoot = v.parent;
-            let intermediateRoot = rotateRight(v.parent);
+            let intermediateRoot = rotateRight(this, v.parent);
             this.record(
                 "Final step of deletion rebalance: first of double rotation by parent of v",
                 oldRoot,
@@ -66,10 +62,7 @@ class WAVLTree extends AVLTree {
             );
 
             oldRoot = v.parent;
-            newRoot = rotateLeft(v.parent);
-            if (rotatingAroundRoot) {
-                this.root = newRoot;
-            }
+            newRoot = rotateLeft(this, v.parent);
             this.record(
                 "Final step of deletion rebalance: second of double rotation by parent of v",
                 oldRoot,
@@ -132,8 +125,6 @@ class WAVLTree extends AVLTree {
             return;
         }
 
-        let rotatingAroundRoot = parent.parent == null;
-
         let parentNodeDiffs = nodeDifferences(parent);
         if (parentNodeDiffs.sort().equals([1, 3])) {
             if (parent.left === x) {
@@ -142,7 +133,6 @@ class WAVLTree extends AVLTree {
                     parent.right,
                     parent,
                     false,
-                    rotatingAroundRoot,
                     rotateLeft,
                     rotateRight
                 );
@@ -152,7 +142,6 @@ class WAVLTree extends AVLTree {
                     parent.left,
                     parent,
                     true,
-                    rotatingAroundRoot,
                     rotateRight,
                     rotateLeft
                 );