diff --git a/src/tree/vieter_tree.c b/src/tree/vieter_tree.c index 792ad30..b066af1 100644 --- a/src/tree/vieter_tree.c +++ b/src/tree/vieter_tree.c @@ -16,7 +16,7 @@ vieter_tree_error vieter_tree_insert(vieter_tree *tree, uint64_t key, tree->root = vieter_tree_node_init(); tree->root->key = key; tree->root->data = data; - vieter_tree_node_set(tree->root, vieter_node_black); + vieter_tree_node_set(tree->root, vieter_tree_node_black, true); tree->size = 1; return vieter_tree_ok; @@ -80,13 +80,13 @@ void vieter_tree_free(vieter_tree *tree) { stack = realloc(stack, capacity * sizeof(vieter_tree_node *)); } - if (node->left != NULL) { - stack[size] = node->left; + if (node->children[0] != NULL) { + stack[size] = node->children[0]; size++; } - if (node->right != NULL) { - stack[size] = node->right; + if (node->children[1] != NULL) { + stack[size] = node->children[1]; size++; } @@ -99,9 +99,9 @@ end: free(tree); } -int vieter_tree_validate(vieter_tree *tree) { +bool vieter_tree_validate(vieter_tree *tree) { if (tree->size == 0) { - return 0; + return true; } // DFS to get expected black nodes @@ -109,12 +109,13 @@ int vieter_tree_validate(vieter_tree *tree) { vieter_tree_node *node = tree->root; while (node != NULL) { - if (vieter_tree_node_get(node, vieter_node_black)) { + if (vieter_tree_node_get(node, vieter_tree_node_black)) { expected_black_nodes++; } - node = node->left; + node = node->children[0]; } - return vieter_tree_node_validate(tree->root, 0, expected_black_nodes); + return vieter_tree_node_get(tree->root, vieter_tree_node_black) && + vieter_tree_node_validate(tree->root, 0, expected_black_nodes); } diff --git a/src/tree/vieter_tree_balancing.c b/src/tree/vieter_tree_balancing.c index 70c52e0..b160563 100644 --- a/src/tree/vieter_tree_balancing.c +++ b/src/tree/vieter_tree_balancing.c @@ -1,150 +1,127 @@ #include "vieter_tree_balancing.h" +#include -int vieter_tree_node_validate(vieter_tree_node *node, - uint64_t passed_black_nodes, - uint64_t expected_black_nodes) { - if (vieter_tree_node_get(node, vieter_node_black)) { +bool vieter_tree_node_validate(vieter_tree_node *node, + uint64_t passed_black_nodes, + uint64_t expected_black_nodes) { + // Path to NULL children should contain the same amount of black nodes + if (node == NULL) { + return passed_black_nodes == expected_black_nodes; + } + + if (vieter_tree_node_get(node, vieter_tree_node_black)) { passed_black_nodes++; - } else { - // A red node should have black child nodes - if ((node->left != NULL && - !vieter_tree_node_get(node->left, vieter_node_black)) || - (node->right != NULL && - !vieter_tree_node_get(node->right, vieter_node_black))) { - return 1; - } } - // All paths to a NULL child should have the same amount of black nodes - if ((node->left == NULL || node->right == NULL) && - passed_black_nodes != expected_black_nodes) { - return 1; - } + // Either the node itself is black, or its children are both either NULL or + // black. + bool correctly_colored_children = + vieter_tree_node_get(node, vieter_tree_node_black) || + ((node->children[0] == NULL || + vieter_tree_node_get(node->children[0], vieter_tree_node_black)) && + (node->children[1] == NULL || + vieter_tree_node_get(node->children[1], vieter_tree_node_black))); - if (node->left != NULL) { - if (vieter_tree_node_validate(node->left, passed_black_nodes, - expected_black_nodes) != 0) { - return 1; - } - } - - if (node->right != NULL) { - if (vieter_tree_node_validate(node->right, passed_black_nodes, - expected_black_nodes) != 0) { - return 1; - } - } - - return 0; + return correctly_colored_children && + vieter_tree_node_validate(node->children[0], passed_black_nodes, + expected_black_nodes) && + vieter_tree_node_validate(node->children[1], passed_black_nodes, + expected_black_nodes); } vieter_tree_node *vieter_tree_node_balance(vieter_tree_node *node) { vieter_tree_node *parent = node->parent; vieter_tree_node *grand_parent = parent->parent; vieter_tree_node *root = grand_parent; - vieter_tree_node *left, *right; - vieter_tree_node *children[4]; + vieter_tree_node *children[2]; + vieter_tree_node *grand_children[4]; uint64_t key_root = root->key; void *data_root = root->data; - if (node->key < parent->key && parent->key < grand_parent->key) { - root->key = parent->key; - root->data = parent->data; + if (vieter_tree_node_get(node, vieter_tree_node_right)) { + children[0] = parent; + children[1] = node; - parent->key = key_root; - parent->data = data_root; + if (vieter_tree_node_get(parent, vieter_tree_node_right)) { + root->key = parent->key; + root->data = parent->data; - left = node; - right = parent; + parent->key = key_root; + parent->data = data_root; - children[0] = node->left; - children[1] = node->right; - children[2] = parent->right; - children[3] = grand_parent->right; - } else if (node->key < parent->key && parent->key > grand_parent->key) { - root->key = node->key; - root->data = node->data; + grand_children[0] = grand_parent->children[0]; + grand_children[1] = parent->children[0]; + grand_children[2] = node->children[0]; + grand_children[3] = node->children[1]; + } else { + root->key = node->key; + root->data = node->data; - node->key = key_root; - node->data = data_root; + node->key = key_root; + node->data = data_root; - left = node; - right = parent; - - children[0] = grand_parent->left; - children[1] = node->left; - children[2] = node->right; - children[3] = parent->right; - } else if (node->key > parent->key && parent->key < grand_parent->key) { - root->key = node->key; - root->data = node->data; - - node->key = key_root; - node->data = data_root; - - left = parent; - right = node; - - children[0] = parent->left; - children[1] = node->left; - children[2] = node->right; - children[3] = grand_parent->right; + grand_children[0] = parent->children[0]; + grand_children[1] = node->children[0]; + grand_children[2] = node->children[1]; + grand_children[3] = grand_parent->children[1]; + } } else { - root->key = parent->key; - root->data = parent->data; + children[0] = node; + children[1] = parent; - parent->key = key_root; - parent->data = data_root; + if (vieter_tree_node_get(parent, vieter_tree_node_right)) { + root->key = node->key; + root->data = node->data; - left = parent; - right = node; + node->key = key_root; + node->data = data_root; - children[0] = grand_parent->left; - children[1] = parent->left; - children[2] = node->left; - children[3] = node->right; + grand_children[0] = grand_parent->children[0]; + grand_children[1] = node->children[0]; + grand_children[2] = node->children[1]; + grand_children[3] = parent->children[1]; + } else { + root->key = parent->key; + root->data = parent->data; + + parent->key = key_root; + parent->data = data_root; + + grand_children[0] = node->children[0]; + grand_children[1] = node->children[1]; + grand_children[2] = parent->children[1]; + grand_children[3] = grand_parent->children[1]; + } } - vieter_tree_node_set(left, vieter_node_black); - vieter_tree_node_set(right, vieter_node_black); - vieter_tree_node_unset(root, vieter_node_black); + vieter_tree_node_set( + root, vieter_tree_node_right, + vieter_tree_node_get(grand_parent, vieter_tree_node_right)); - left->left = children[0]; - left->right = children[1]; + vieter_tree_node_set(children[0], vieter_tree_node_black, true); + vieter_tree_node_set(children[1], vieter_tree_node_black, true); - if (children[0] != NULL) - children[0]->parent = left; + vieter_tree_node_set(root, vieter_tree_node_black, false); - if (children[1] != NULL) - children[1]->parent = left; - - right->left = children[2]; - right->right = children[3]; - - if (children[2] != NULL) - children[2]->parent = right; - - if (children[3] != NULL) - children[3]->parent = right; - - root->left = left; - root->right = right; - left->parent = root; - right->parent = root; + vieter_tree_node_set_children(children[0], grand_children); + vieter_tree_node_set_children(children[1], grand_children + 2); + vieter_tree_node_set_children(root, children); return root; } void vieter_tree_node_balance_after_insert(vieter_tree_node *node) { - while (!vieter_tree_node_get(node, vieter_node_black) && + while (!vieter_tree_node_get(node, vieter_tree_node_black) && node->parent != NULL && - !vieter_tree_node_get(node->parent, vieter_node_black)) { + !vieter_tree_node_get(node->parent, vieter_tree_node_black)) { node = vieter_tree_node_balance(node); } // The root must always be black if (node->parent == NULL) { - vieter_tree_node_set(node, vieter_node_black); + vieter_tree_node_set(node, vieter_tree_node_black, true); } } + +void vieter_tree_node_remove_balanced(vieter_tree_node *node) {} diff --git a/src/tree/vieter_tree_balancing.h b/src/tree/vieter_tree_balancing.h index 4492588..007af34 100644 --- a/src/tree/vieter_tree_balancing.h +++ b/src/tree/vieter_tree_balancing.h @@ -3,6 +3,17 @@ #include "vieter_tree_node.h" +/* + * Ensure the tree remains a valid red-black tree after having inserting the + * node. + */ void vieter_tree_node_balance_after_insert(vieter_tree_node *node); +/* + * Remove the given node, ensuring the tree remains a valid red-black tree. + * + * @param node node to remove. This node should have at least one NULL child. + */ +void vieter_tree_node_remove_balanced(vieter_tree_node *node); + #endif diff --git a/src/tree/vieter_tree_internal.h b/src/tree/vieter_tree_internal.h index dc4ee81..670d45b 100644 --- a/src/tree/vieter_tree_internal.h +++ b/src/tree/vieter_tree_internal.h @@ -1,8 +1,10 @@ #include "vieter_tree.h" +#include + /* * Inspect whether the tree is still a valid red-black-tree. * - * @return 0 if correct, 1 if not. + * @return true if valid, false otherwise. */ -int vieter_tree_validate(vieter_tree *tree); +bool vieter_tree_validate(vieter_tree *tree); diff --git a/src/tree/vieter_tree_node.c b/src/tree/vieter_tree_node.c index 40407a3..2f45b82 100644 --- a/src/tree/vieter_tree_node.c +++ b/src/tree/vieter_tree_node.c @@ -1,6 +1,8 @@ #include "vieter_tree_node.h" #include "vieter_tree_balancing.h" +#include + vieter_tree_node *vieter_tree_node_init() { return calloc(1, sizeof(vieter_tree_node)); } @@ -13,14 +15,24 @@ void vieter_tree_node_add_child(vieter_tree_node *parent, uint64_t key, return; } - if (key < parent->key) { - parent->left = child; - } else { - parent->right = child; - } + bool side = key > parent->key; + parent->children[side] = child; if (child != NULL) { child->parent = parent; + vieter_tree_node_set(child, vieter_tree_node_right, side); + } +} + +void vieter_tree_node_set_children(vieter_tree_node *parent, + vieter_tree_node **children) { + memcpy(parent->children, children, 2 * sizeof(vieter_tree_node *)); + + for (uint8_t i = 0; i < 2; i++) { + if (parent->children[i] != NULL) { + parent->children[i]->parent = parent; + vieter_tree_node_set(parent->children[i], vieter_tree_node_right, i); + } } } @@ -28,14 +40,7 @@ void vieter_tree_node_replace_with_child(vieter_tree_node *to_replace, vieter_tree_node *replacement) { to_replace->key = replacement->key; to_replace->data = replacement->data; - to_replace->left = replacement->left; - to_replace->right = replacement->right; - - if (to_replace->left != NULL) - to_replace->left->parent = to_replace; - - if (to_replace->right != NULL) - to_replace->right->parent = to_replace; + vieter_tree_node_set_children(to_replace, replacement->children); } vieter_tree_error vieter_tree_node_insert(vieter_tree_node *root, uint64_t key, @@ -49,12 +54,7 @@ vieter_tree_error vieter_tree_node_insert(vieter_tree_node *root, uint64_t key, } parent = node; - - if (key < parent->key) { - node = parent->left; - } else { - node = parent->right; - } + node = node->children[key > parent->key]; } vieter_tree_node *new_node = vieter_tree_node_init(); @@ -79,11 +79,7 @@ vieter_tree_error vieter_tree_node_search_node(vieter_tree_node **out, return vieter_tree_ok; } - if (key < node->key) { - node = node->left; - } else { - node = node->right; - } + node = node->children[key > node->key]; } return vieter_tree_not_present; @@ -114,13 +110,13 @@ vieter_tree_error vieter_tree_node_remove(void **out, vieter_tree_node *root, *out = target->data; - if (target->left == NULL && target->right == NULL) { + if (target->children[0] == NULL && target->children[1] == NULL) { vieter_tree_node_add_child(target->parent, target->key, NULL); vieter_tree_node_free(target); - } else if ((target->left == NULL) ^ (target->right == NULL)) { + } else if ((target->children[0] == NULL) ^ (target->children[1] == NULL)) { vieter_tree_node *child = - target->left != NULL ? target->left : target->right; + target->children[0] != NULL ? target->children[0] : target->children[1]; if (target->parent != NULL) { vieter_tree_node_add_child(target->parent, child->key, child); @@ -131,10 +127,10 @@ vieter_tree_error vieter_tree_node_remove(void **out, vieter_tree_node *root, } } else { - vieter_tree_node *replacement = target->right; + vieter_tree_node *replacement = target->children[1]; - while (replacement->left != NULL) { - replacement = replacement->left; + while (replacement->children[0] != NULL) { + replacement = replacement->children[0]; } // We use replacement->key here because the right child can be NULL, so @@ -142,7 +138,7 @@ vieter_tree_error vieter_tree_node_remove(void **out, vieter_tree_node *root, // will still get placed into the right location because of how binary // trees work. vieter_tree_node_add_child(replacement->parent, replacement->key, - replacement->right); + replacement->children[1]); target->key = replacement->key; target->data = replacement->data; @@ -153,14 +149,15 @@ vieter_tree_error vieter_tree_node_remove(void **out, vieter_tree_node *root, return vieter_tree_ok; } -void vieter_tree_node_set(vieter_tree_node *node, vieter_node_flag flag) { - node->flags |= flag; +void vieter_tree_node_set(vieter_tree_node *node, vieter_tree_node_flag flag, + bool set) { + if (set) { + node->flags |= flag; + } else { + node->flags &= ~flag; + } } -void vieter_tree_node_unset(vieter_tree_node *node, vieter_node_flag flag) { - node->flags &= ~flag; -} - -bool vieter_tree_node_get(vieter_tree_node *node, vieter_node_flag flag) { +bool vieter_tree_node_get(vieter_tree_node *node, vieter_tree_node_flag flag) { return (node->flags & flag) != 0; } diff --git a/src/tree/vieter_tree_node.h b/src/tree/vieter_tree_node.h index 1c88159..1ebb15a 100644 --- a/src/tree/vieter_tree_node.h +++ b/src/tree/vieter_tree_node.h @@ -5,18 +5,18 @@ #include #include -#define VIETER_NODE_BLACK ((uint8_t)1) - -typedef enum vieter_node_flag { - vieter_node_black = ((uint8_t)1) << 0 -} vieter_node_flag; +typedef enum vieter_tree_node_flag { + vieter_tree_node_black = ((uint8_t)1) << 0, + // This flag is used to index the children array. If this flag isn't set, + // it'll evaluate to false, or index 0 in the children array. + vieter_tree_node_right = ((uint8_t)1) << 1 +} vieter_tree_node_flag; typedef struct vieter_tree_node { uint64_t key; void *data; struct vieter_tree_node *parent; - struct vieter_tree_node *left; - struct vieter_tree_node *right; + struct vieter_tree_node *children[2]; uint8_t flags; } vieter_tree_node; @@ -26,20 +26,24 @@ void vieter_tree_node_free(vieter_tree_node *node); vieter_tree_error vieter_tree_node_insert(vieter_tree_node *root, uint64_t key, void *data); +/* + * Return the node representing the requested value. + */ vieter_tree_error vieter_tree_node_search_node(vieter_tree_node **out, vieter_tree_node *root, uint64_t key); + vieter_tree_error vieter_tree_node_search(void **out, vieter_tree_node *root, uint64_t key); vieter_tree_error vieter_tree_node_remove(void **out, vieter_tree_node *root, uint64_t key); -void vieter_tree_node_replace(vieter_tree_node *to_replace, vieter_tree_node *replacement); +void vieter_tree_node_replace_with_child(vieter_tree_node *to_replace, vieter_tree_node *replacement); -void vieter_tree_node_set(vieter_tree_node *node, vieter_node_flag flag); -void vieter_tree_node_unset(vieter_tree_node *node, vieter_node_flag flag); -bool vieter_tree_node_get(vieter_tree_node *node, vieter_node_flag flag); +void vieter_tree_node_set(vieter_tree_node *node, vieter_tree_node_flag flag, bool value); +bool vieter_tree_node_get(vieter_tree_node *node, vieter_tree_node_flag flag); void vieter_tree_node_add_child(vieter_tree_node *parent, uint64_t key, vieter_tree_node *child); +void vieter_tree_node_set_children(vieter_tree_node *parent, vieter_tree_node **children); -int vieter_tree_node_validate(vieter_tree_node *node, uint64_t passed_black_nodes, uint64_t expected_black_nodes); +bool vieter_tree_node_validate(vieter_tree_node *node, uint64_t passed_black_nodes, uint64_t expected_black_nodes); #endif diff --git a/test/tree/test_tree.c b/test/tree/test_tree.c index c875137..257ec66 100644 --- a/test/tree/test_tree.c +++ b/test/tree/test_tree.c @@ -18,7 +18,7 @@ void test_insert() { for (uint64_t i = 0; i < 250; i++) { TEST_CHECK(vieter_tree_insert(tree, i, NULL) == vieter_tree_ok); TEST_SIZE(tree, i + 1); - TEST_CHECK(vieter_tree_validate(tree) == 0); + TEST_CHECK(vieter_tree_validate(tree)); } void *out; @@ -37,7 +37,7 @@ void test_remove() { for (uint64_t i = 0; i < 250; i++) { TEST_CHECK(vieter_tree_insert(tree, i, NULL) == vieter_tree_ok); - TEST_CHECK(vieter_tree_validate(tree) == 0); + TEST_CHECK(vieter_tree_validate(tree)); } void *out; @@ -45,7 +45,7 @@ void test_remove() { for (uint64_t i = 0; i < 25; i++) { TEST_CHECK(vieter_tree_search(&out, tree, i) == vieter_tree_ok); TEST_CHECK(vieter_tree_remove(&out, tree, i) == vieter_tree_ok); - TEST_CHECK(vieter_tree_validate(tree) == 0); + TEST_CHECK(vieter_tree_validate(tree)); TEST_CHECK(vieter_tree_search(&out, tree, i) == vieter_tree_not_present); TEST_SIZE(tree, 250 - i - 1); }