basetable.java

开源的axion的数据库代码

    public boolean isColumnIndexed(Column column) {
        Iterator indices = _indices.iterator();

        while(indices.hasNext()) {
            Index index = (Index)indices.next();

            if(column.equals(index.getIndexedColumn())) {
                return true;
            }
        }

        return false;
    }

    public RowIterator getMatchingRows(List selectables, List values) throws AxionException {
        if(null == selectables || selectables.isEmpty()) {
            return getRowIterator(true);
        } else {
            // TODO: may be able to optimize this by first checking for for indices or
            //       with a special subclass of AbstractAcceptingRowIterator rather
            //       than creating a WhereNode
            WhereNode root = null;
            Iterator left = selectables.iterator();
            Iterator right = values.iterator();
            while(left.hasNext()) {
                LeafWhereNode leaf = null;
                Object value = right.next();               
                leaf = new LeafWhereNode(
                    (Selectable)left.next(),
                    ComparisonOperator.EQUAL,
                    new Literal(value));
                if(null == root) {
                    root = leaf;
                } else {
                    BinaryBranchWhereNode branch = new BinaryBranchWhereNode();
                    branch.setIsAnd(true);
                    branch.setLeft(root);
                    branch.setRight(leaf);
                    root = branch;
                }
            }
            
            return new FilteringRowIterator(getRowIterator(true),makeRowDecorator(),root);
        }
    }

    public RowIterator getIndexedRows(WhereNode node, boolean readOnly) throws AxionException {
        if(readOnly) {
            return UnmodifiableRowIterator.wrap(getIndexedRows(node));
        } else {
            return getIndexedRows(node);
        }
    }
    
    /**
     * Add the given {@link Column} to this table.
     * This implementation throws an {@link AxionException}
     * if rows have already been added to the table.
     */
    public void addColumn(Column col) throws AxionException {
        if(getRowCount() > 0) {
            throw new AxionException("Cannot add column because table already contains rows.");
        } else {
            // XXX FIX ME XXX
            if(col.getDataType() instanceof LOBType) {
                LOBType lob = (LOBType)(col.getDataType());
                if(null == lob.getLobDir()) {
                    lob.setLobDir(new File(System.getProperty("axiondb.lobdir", "."), col.getName()));
                }
            }
            _cols.add(col);
            _colIndexToColIdMap = null;
            publishEvent(new ColumnEvent(this, col));
        }
    }

    public boolean hasColumn(ColumnIdentifier id) {
        boolean result = false;
        String tableName = id.getTableName();
        if(tableName == null || tableName.equals(getName())) {
            result = (getColumn(id.getName()) != null);
        }
        return result;
    }

    public Column getColumn(int index) {
        return (Column)(_cols.get(index));
    }

    public Column getColumn(String name) {
        for(int i = 0; i < _cols.size(); i++) {
            Column col = (Column)(_cols.get(i));
            if(col.getName().equalsIgnoreCase(name)) {
                return col;
            }
        }
        return null;
    }

    public int getColumnIndex(String name) throws AxionException {
        for(int i = 0; i < _cols.size(); i++) {
            Column col = (Column)(_cols.get(i));
            if(col.getName().equalsIgnoreCase(name)) {
                return i;
            }
        }
        throw new AxionException("Column " + name + " not found.");
    }

    public Iterator getColumnIdentifiers() {
        List result = new ArrayList();
        for(int i=0;i<_cols.size();i++) {
            Column col = (Column)(_cols.get(i));
            result.add(new ColumnIdentifier(new TableIdentifier(getName()),col.getName(),null,col.getDataType()));
        }
        return result.iterator();
    }

    public int getColumnCount() {
        return _cols.size();
    }

    public void drop() throws AxionException {
    }

    public void remount(File dir, boolean datafilesonly) throws AxionException {
    }

    public void checkpoint() throws AxionException {
    }

    public void shutdown() throws AxionException {
    }

    public RowDecorator makeRowDecorator() {
        if(null == _colIndexToColIdMap) {
            Map map = new HashMap();
            int i=0;
            for(Iterator iter = getColumnIdentifiers();iter.hasNext();) {
                map.put(iter.next(),new Integer(i++));
            }
            _colIndexToColIdMap = map;
        }
        return new RowDecorator(_colIndexToColIdMap);
    }
    
    public TransactableTable makeTransactableTable() {
        return new TransactableTableImpl(this);
    }

    public Iterator getIndices() {
        return _indices.iterator();
    }
    
    protected void checkConstraints(RowEvent event) throws AxionException {
        checkConstraints(event,false);
    }
    
    protected void checkConstraints(RowEvent event, boolean deferred) throws AxionException {
        for(Iterator iter = getConstraints();iter.hasNext();) {
            Constraint c = (Constraint)iter.next();
            if(c.isDeferred() == deferred) {
                if(!c.evaluate(event)) {
                    throw new ConstraintViolationException(c);
                }
            }
        }
    }

    protected boolean hasDeferredConstraint() {
        for(Iterator iter = getConstraints();iter.hasNext();) {
            Constraint c = (Constraint)iter.next();
            if(c.isDeferred()) {
                return true;
            }
        }
        return false;
    }

    protected void notifyColumnsOfNewLobDir(File directory) {
        Iterator iter = _cols.iterator();
        while(iter.hasNext()) {
            Column col = (Column)(iter.next());
            if(col.getDataType() instanceof LOBType) {
                LOBType lob = (LOBType)(col.getDataType());
                if(null == lob.getLobDir()) {
                    lob.setLobDir(new File(directory,col.getName()));
                }
            }
        }
    }

    private RowIterator getIndexedRows(WhereNode node) throws AxionException {
        if(node instanceof LeafWhereNode) {
            LeafWhereNode leaf = (LeafWhereNode)node;
            Column column = null;
            Literal literal = null;
            ComparisonOperator op = leaf.getOperator();
            if(leaf.getLeft() instanceof ColumnIdentifier && leaf.getRight() instanceof Literal) {
                column = getColumn(((ColumnIdentifier)leaf.getLeft()).getName());
                literal = (Literal)(leaf.getRight());
            } else if(leaf.getLeft() instanceof Literal && leaf.getRight() instanceof ColumnIdentifier) {
                column = getColumn(((ColumnIdentifier)leaf.getRight()).getName());
                literal = (Literal)(leaf.getLeft());
                op = op.flip();
            } else {
                return null;
            }
            if(!isColumnIndexed(column)) {
                return null;
            } else {
                Index index = getIndexForColumn(column);
                if(!index.supportsOperator(op)) {
                    return null;
                } else if(literal instanceof BindVariable) {
                    return new RebindableIndexedRowIterator(index,this,op,(BindVariable)literal);
                } else {
                    return index.getRowIterator(this,op,literal.evaluate(null));
                }
            }
        } else {
            return null;
        }
    }
    
    private String _name = null;
    private String _type = null;
    private List _cols = new ArrayList();
    private List _indices = new ArrayList();
    private Map _constraints = new HashMap();
    private Map _colIndexToColIdMap = null;
    private static Log _log = LogFactory.getLog(BaseTable.class);   
}