ttree.cpp

一个功能强大的内存数据库源代码,c++编写,有详细的注释

	} else { 
	    oid_t childId = rightId;
	    bool grow = insert(db, childId, recordId, key, type, sizeofType, comparator, offs);
	    if (childId != rightId) { 
		((dbTtreeNode*)db->put(nodeId))->right = rightId = childId;
	    }
	    if (!grow) return false;
	}
	node = (dbTtreeNode*)db->put(nodeId);
	if (node->balance < 0) { 
	    node->balance = 0;
	    return false;
	} else if (node->balance == 0) { 
	    node->balance = 1;
	    return true;
	} else { 
	    dbTtreeNode* right = (dbTtreeNode*)db->put(rightId);
	    node = (dbTtreeNode*)db->get(nodeId);
	    if (right->balance > 0) { // single RR turn
		node->right = right->left;
		right->left = nodeId;
		node->balance = 0;
		right->balance = 0;
		nodeId = rightId;
	    } else { // double RL turn
		oid_t leftId = right->left;
		dbTtreeNode* left = (dbTtreeNode*)db->put(leftId);
		right = (dbTtreeNode*)db->get(rightId);
		node = (dbTtreeNode*)db->get(nodeId);
		right->left = left->right;
		left->right = rightId;
		node->right = left->left;
		left->left = nodeId;
		node->balance = (left->balance > 0) ? -1 : 0;
		right->balance = (left->balance < 0) ? 1 : 0;
		left->balance = 0;
		nodeId = leftId;
	    }
	    return false;
	}
    }
    int l = 1, r = n-1;
    if (type == dbField::tpString) { 
	while (l < r)  {
	    int i = (l+r) >> 1;
	    rec = (char*)db->getRow(node->item[i]);
	    diff = strcmp((char*)key, rec + ((dbVarying*)(rec+offs))->offs);
	    if (diff > 0) { 
		l = i + 1;
	    } else { 
		r = i;
		if (diff == 0) { 
		    break;
		}
	    }
	}
    } else { 
	while (l < r)  {
	    int i = (l+r) >> 1;
	    rec = (char*)db->getRow(node->item[i]);
	    diff = keycmp(key, rec+offs, type, sizeofType, comparator);
	    if (diff > 0) { 
		l = i + 1;
	    } else { 
		r = i;
		if (diff == 0) { 
		    break;
		}
	    }
	}
    }
    // Insert before item[r]
    node = (dbTtreeNode*)db->put(nodeId);
    if (n != pageSize) {
	for (int i = n; i > r; i--) node->item[i] = node->item[i-1]; 
	node->item[r] = recordId;
	node->nItems += 1;
	return false;
    } else { 
	oid_t reinsertId;
	if (node->balance >= 0) { 
	    reinsertId = node->item[0];
	    for (int i = 1; i < r; i++) node->item[i-1] = node->item[i]; 
	    node->item[r-1] = recordId;
	} else { 
	    reinsertId = node->item[n-1];
	    for (int i = n-1; i > r; i--) node->item[i] = node->item[i-1]; 
	    node->item[r] = recordId;
	}
	rec = (char*)db->getRow(reinsertId);
	key = rec + offs;
	if (type == dbField::tpString) { 
	    key = rec + ((dbVarying*)key)->offs;
	}
	return insert(db, nodeId, reinsertId, key, type, sizeofType, comparator, offs);
    }
}

inline int dbTtreeNode::balanceLeftBranch(dbDatabase* db, oid_t& nodeId)
{
    dbTtreeNode* node = (dbTtreeNode*)db->put(nodeId);
    if (node->balance < 0) { 
	node->balance = 0;
	return 1;
    } else if (node->balance == 0) { 
	node->balance = 1;
	return 0;
    } else { 
	oid_t rightId = node->right;
	dbTtreeNode* right = (dbTtreeNode*)db->put(rightId);
	node = (dbTtreeNode*)db->get(nodeId);
	if (right->balance >= 0) { // single RR turn
	    node->right = right->left;
	    right->left = nodeId;
	    if (right->balance == 0) { 
		node->balance = 1;
		right->balance = -1;
		nodeId = rightId;
		return 0;
	    } else { 
		node->balance = 0;
		right->balance = 0;
		nodeId = rightId;
		return 1;
	    }
	} else { // double RL turn
	    oid_t leftId = right->left;
	    dbTtreeNode* left = (dbTtreeNode*)db->put(leftId);
	    node = (dbTtreeNode*)db->get(nodeId);
	    right = (dbTtreeNode*)db->get(rightId);
	    right->left = left->right;
	    left->right = rightId;
	    node->right = left->left;
	    left->left = nodeId;
	    node->balance = left->balance > 0 ? -1 : 0;
	    right->balance = left->balance < 0 ? 1 : 0;
	    left->balance = 0;
	    nodeId = leftId;
	    return 1;
	}
    }
}


inline int dbTtreeNode::balanceRightBranch(dbDatabase* db, oid_t& nodeId)
{
    dbTtreeNode* node = (dbTtreeNode*)db->put(nodeId);
    if (node->balance > 0) { 
	node->balance = 0;
	return 1;
    } else if (node->balance == 0) { 
	node->balance = -1;
	return 0;
    } else { 
	oid_t leftId = node->left;
	dbTtreeNode* left = (dbTtreeNode*)db->put(leftId);
	node = (dbTtreeNode*)db->get(nodeId);
	if (left->balance <= 0) { // single LL turn
	    node->left = left->right;
	    left->right = nodeId;
	    if (left->balance == 0) { 
		node->balance = -1;
		left->balance = 1;
		nodeId = leftId;
		return 0;
	    } else { 
		node->balance = 0;
		left->balance = 0;
		nodeId = leftId;
		return 1;
	    }
	} else { // double LR turn
	    oid_t rightId = left->right;
	    dbTtreeNode* right = (dbTtreeNode*)db->put(rightId);
	    node = (dbTtreeNode*)db->get(nodeId);
	    left = (dbTtreeNode*)db->get(leftId);
	    left->right = right->left;
	    right->left = leftId;
	    node->left = right->right;
	    right->right = nodeId;
	    node->balance = right->balance < 0 ? 1 : 0;
	    left->balance = right->balance > 0 ? -1 : 0;
	    right->balance = 0;
	    nodeId = rightId;
	    return 1;
	}
    }
}

int dbTtreeNode::remove(dbDatabase* db, oid_t& nodeId, oid_t recordId, 
			void* key, int type, int sizeofType, dbUDTComparator comparator, int offs)
{
    dbTtreeNode* node = (dbTtreeNode*)db->get(nodeId);
    char* rec = (char*)db->getRow(node->item[0]);
    int n = node->nItems;
    int diff = (type == dbField::tpString)
	     ? strcmp((char*)key, rec + ((dbVarying*)(rec+offs))->offs)
	     : keycmp(key, rec+offs, type, sizeofType, comparator);
    if (diff <= 0) { 
	oid_t leftId = node->left;
	if (leftId != 0) { 
	    oid_t childId = leftId;
	    int h = remove(db, childId, recordId, key, type, sizeofType, comparator, offs);
	    if (childId != leftId) { 
		((dbTtreeNode*)db->put(nodeId))->left = childId;
	    }
	    if (h > 0) { 
		return balanceLeftBranch(db, nodeId);
	    } else if (h == 0) { 
		return 0;
	    }
	}
	assert (diff == 0);
    }
    rec = (char*)db->getRow(node->item[n-1]);
    diff = (type == dbField::tpString)
	? strcmp((char*)key, rec + ((dbVarying*)(rec+offs))->offs)
	: keycmp(key, rec+offs, type, sizeofType, comparator);
    if (diff <= 0) {	    
	for (int i = 0; i < n; i++) { 
	    if (node->item[i] == recordId) { 
		if (n == 1) { 
		    if (node->right == 0) { 
			db->freeObject(nodeId);
			nodeId = node->left;
			return 1;
		    } else if (node->left == 0) { 
			db->freeObject(nodeId);
			nodeId = node->right;
			return 1;
		    } 
		} 
		node = (dbTtreeNode*)db->put(nodeId);
		oid_t leftId = node->left, rightId = node->right;
		if (n <= minItems) { 
		    if (leftId != 0 && node->balance <= 0) {  
			dbTtreeNode* left = (dbTtreeNode*)db->get(leftId);
			while (left->right != 0) { 
			    left = (dbTtreeNode*)db->get(left->right);
			}
			while (--i >= 0) { 
			    node->item[i+1] = node->item[i];
			}
			node->item[0] = left->item[left->nItems-1];
			rec = (char*)db->getRow(node->item[0]);
			key = rec + offs;
			if (type == dbField::tpString) { 
			    key = rec + ((dbVarying*)key)->offs;
			}
			oid_t childId = leftId;
			int h = remove(db, childId, node->item[0], 
				       key, type, sizeofType, comparator, offs);
			if (childId != leftId) { 
			    ((dbTtreeNode*)db->get(nodeId))->left = childId;
			}
			if (h > 0) {
			    h = balanceLeftBranch(db, nodeId);
			}
			return h;
		    } else if (node->right != 0) { 
			dbTtreeNode* right = (dbTtreeNode*)db->get(rightId);
			while (right->left != 0) { 
			    right = (dbTtreeNode*)db->get(right->left);
			}
			while (++i < n) { 
			    node->item[i-1] = node->item[i];
			}
			node->item[n-1] = right->item[0];
			rec = (char*)db->getRow(node->item[n-1]);
			key = rec + offs;
			if (type == dbField::tpString) { 
			    key = rec + ((dbVarying*)key)->offs;
			}
			oid_t childId = rightId;
			int h = remove(db, childId, node->item[n-1], 
				       key, type, sizeofType, comparator, offs);
			if (childId != rightId) { 
			    ((dbTtreeNode*)db->get(nodeId))->right = childId;
			}
			if (h > 0) {
			    h = balanceRightBranch(db, nodeId);
			}
			return h;
		    }
		}
		while (++i < n) { 
		    node->item[i-1] = node->item[i];
		}
		node->nItems -= 1;
		return 0;
	    }
	}
    }
    oid_t rightId = node->right;
    if (rightId != 0) { 
	oid_t childId = rightId;
	int h = remove(db, childId, recordId, key, type, sizeofType, comparator, offs);
	if (childId != rightId) { 
	    ((dbTtreeNode*)db->put(nodeId))->right = childId;
	}
	if (h > 0) { 
	    return balanceRightBranch(db, nodeId);
	} else { 
	    return h;
	}
    }
    return -1;
}

void dbTtreeNode::purge(dbDatabase* db, oid_t nodeId)
{
    if (nodeId != 0) { 
	dbTtreeNode* node = (dbTtreeNode*)db->get(nodeId);
	oid_t leftId = node->left;
	oid_t rightId = node->right;
	db->freeObject(nodeId);
	purge(db, leftId);
	purge(db, rightId);
    }    
}

bool dbTtreeNode::traverseForward(dbDatabase* db, dbAnyCursor* cursor)
{
    if (left != 0) { 
	if (!((dbTtreeNode*)db->get(left))->traverseForward(db, cursor)) {
	    return false;
	}
    }
    for (int i = 0, n = nItems; i < n; i++) { 
	if (!cursor->add(item[i])) { 
	    return false;
	}
    }
    if (right != 0) { 
	return ((dbTtreeNode*)db->get(right))->traverseForward(db, cursor);
    }
    return true;
}

bool dbTtreeNode::traverseBackward(dbDatabase* db, dbAnyCursor* cursor)
{
    if (right != 0) { 
	if (!((dbTtreeNode*)db->get(right))->traverseBackward(db, cursor)) {
	    return false;
	}
    }
    for (int i = nItems; --i >= 0;) { 
	if (!cursor->add(item[i])) { 
	    return false;
	}
    }
    if (left != 0) { 
	return ((dbTtreeNode*)db->get(left))->traverseBackward(db, cursor);
    }
    return true;
}

bool dbTtreeNode::traverseForward(dbDatabase* db, dbAnyCursor* cursor,
				  dbExprNode* condition)
{
    if (left != 0) { 
	if (!((dbTtreeNode*)db->get(left))->traverseForward(db, cursor, 
							    condition)) 
	{
	    return false;
	}
    }
    dbTable* table = (dbTable*)db->getRow(cursor->table->tableId);
    for (int i = 0, n = nItems; i < n; i++) { 
	if (db->evaluate(condition, item[i], table, cursor)) { 
	    if (!cursor->add(item[i])) { 
		return false;
	    }
	}
    }
    if (right != 0) { 
	return ((dbTtreeNode*)db->get(right))->traverseForward(db, cursor, 
							       condition);
    }
    return true;
}

bool dbTtreeNode::traverseBackward(dbDatabase* db, dbAnyCursor* cursor,
				   dbExprNode* condition)
{
    if (right != 0) { 
	if (!((dbTtreeNode*)db->get(right))->traverseBackward(db, cursor,
							     condition)) 
        {
	    return false;
	}
    }
    dbTable* table = (dbTable*)db->getRow(cursor->table->tableId);
    for (int i = nItems; --i >= 0;) { 
	if (db->evaluate(condition, item[i], table, cursor)) { 
	    if (!cursor->add(item[i])) { 
		return false;
	    }
	}
    }
    if (left != 0) { 
	return ((dbTtreeNode*)db->get(left))->traverseBackward(db, cursor,
							      condition);
    }
    return true;
}