+
−/*
+
− * 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/.
+
− *
+
− * Copyright 2008-2015 MonetDB B.V.
+
− */
+
−
+
−package nl.cwi.monetdb.embedded;
+
−
+
−import java.io.Closeable;
+
−import java.sql.SQLException;
+
−import java.util.Iterator;
+
−
+
−import nl.cwi.monetdb.embedded.column.Column;
+
−
+
−/**
+
− * Embedded MonetDB query result.
+
− * The query result columns are not eagerly copied from the native code to Java.
+
− * Instead, they are kept around at MonetDB native C-level, materialised in Java 
+
− * on demand and freed on {@code super.close()}.
+
− *
+
− */
+
−public class EmbeddedQueryResult implements Closeable, Iterable<Column<?>> {
+
−	/**
+
−	 * The names of the columns in the query result.
+
−	 */
+
−	protected final String[] columnNames;
+
−	/**
+
−	 * The types of the columns in the query result.
+
−	 */
+
−    protected final String[] columnTypes;
+
−    /**
+
−     * The sizes of the columns in the query result.
+
−     */
+
−    protected final int[] columnSizes;
+
−	/**
+
−	 * The number of columns in the query result.
+
−	 */
+
−    protected final int numberOfColumns;
+
−	/**
+
−	 * The number of rows in the query result.
+
−	 */
+
−    protected final int numberOfRows;
+
−	/**
+
−	 * Pointer to the native result set.
+
−	 * We need to keep it around for getting columns.
+
−	 * The native result set is kept until the {@link super.close()} is called.
+
−	 */
+
−    protected long resultPointer;
+
−	/**
+
−	 * To avoid reconstructing the columns a second time, we will use this cache
+
−	 */
+
−    protected final Column<?>[] columnsCache;
+
−
+
−	public EmbeddedQueryResult(String[] columnNames, String[] columnTypes, int[] columnSizes, int numberOfColumns, int numberOfRows, long resultPointer) {
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−		this.columnNames = columnNames;
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−		this.columnTypes = columnTypes;
+
−        this.columnSizes = columnSizes;
+
−		this.numberOfColumns = numberOfColumns;
+
−		this.numberOfRows = numberOfRows;
+
−		this.resultPointer = resultPointer;
+
−		this.columnsCache = new Column<?>[numberOfColumns];
+
−	}
+
−
+
−	/**
+
−	 * Get the column names as a string array.
+
−	 * 
+
−	 * @return The column names array
+
−	 */
+
−	public String[] getColumnNames() {
+
−		return columnNames;
+
−	}
+
−
+
−	/**
+
−	 * Get the column types as a string array.
+
−	 * 
+
−	 * @return The column types array
+
−	 */
+
−	public String[] getColumnTypes() {
+
−		return columnTypes;
+
−	}
+
−
+
−    /**
+
−     * Get the column sizes as a int array.
+
−     *
+
−     * @return The column sizes array
+
−     */
+
−    public int[] getColumnSizes() {
+
−        return columnSizes;
+
−    }
+
−
+
−	/**
+
−	 * Returns the number of columns in the result set.
+
−	 *
+
−	 * @return Number of columns
+
−	 */
+
−	public int getNumberOfColumns() {
+
−		return numberOfColumns;
+
−	}
+
−
+
−	/**
+
−	 * Returns the number of rows in the result set.
+
−	 *
+
−	 * @return Number of rows
+
−	 */
+
−	public int getNumberOfRows() {
+
−		return numberOfRows;
+
−	}
+
−
+
−	/**
+
−	 * Get a column from the result set by index.
+
−	 *
+
−	 * @param index Column index (starting from 0)
+
−	 * @return The column, {@code null} if index not in bounds
+
−	 */
+
−	public Column<?> getColumn(int index) throws SQLException {
+
−		if (index < 0) {
+
−			throw new ArrayIndexOutOfBoundsException("The index must be larger than 0!");
+
−		} else if (index >= this.numberOfColumns) {
+
−			throw new ArrayIndexOutOfBoundsException("The index must be smaller than the number of columns");
+
−		}
+
−		if(this.columnsCache[index] != null) {
+
−			return this.columnsCache[index];
+
−		}
+
−		if (this.resultPointer == 0) {
+
−			// The object was closed and result was cleaned-up. Calling the can produce a native Segfault (and crash the JVM)
+
−			throw new NullPointerException("The result set has been already cleaned!");
+
−		}
+
−		Column<?> result = this.getColumnWrapper(index, this.resultPointer);
+
−		this.columnsCache[index] = result;
+
−		return result;
+
−	}
+
−
+
−	/**
+
−	 * Get a column from the result set by name.
+
−	 *
+
−	 * @param name Column name
+
−	 * @return The column, {@code null} if not found
+
−	 */
+
−	public Column<?> getColumn(String name) throws SQLException {
+
−		int index = 0;
+
−		for (String columnName : this.columnNames) {
+
−			if (name.equals(columnName)) {
+
−				return this.getColumn(index);
+
−			}
+
−			index++;
+
−		}
+
−		throw new ArrayIndexOutOfBoundsException("The column is not present in the result set!");
+
−	}
+
−
+
−	/**
+
−	 * A native C function that returns a {@code Column} object.
+
−	 *
+
−	 * @param index Column index (starting from 0) 
+
−	 * @return
+
−	 */
+
−	private native Column<?> getColumnWrapper(int index, long resultPointer) throws SQLException;
+
−
+
−	@Override
+
−	public Iterator<Column<?>> iterator() {
+
−		return new Iterator<Column<?>>() {
+
−			private int currentIndex = 0;
+
−
+
−			@Override
+
−			public boolean hasNext() {
+
−				return (currentIndex < getNumberOfColumns());
+
−			}
+
−
+
−			@Override
+
−			public Column<?> next() {
+
−				try {
+
−					return getColumn(currentIndex++);
+
−				} catch (SQLException ex) {
+
−					return null;
+
−				}
+
−			}
+
−		};
+
−	}
+
−
+
−	/**
+
−	 * Get a matrix of objects representing the rows and columns of the query
+
−	 *
+
−	 * @return The rows as {@code  Object[][]}
+
−	 */
+
−	public Object[][] getRows() throws SQLException {
+
−		Object[][] result = new Object[this.numberOfRows][this.numberOfColumns];
+
−		Column<?> column;
+
−		for (int i = 0 ; i < this.numberOfColumns; i++) {
+
−			column = this.getColumn(i);
+
−			for (int j = 0 ; j < this.numberOfRows; j++) {
+
−				result[j][i] = column.getValue(i);
+
−			}
+
−		}
+
−		return result;
+
−	}
+
−
+
−	@Override
+
−	public void close() {
+
−		if(this.resultPointer > 0) {
+
−			this.cleanupResult(this.resultPointer);
+
−			this.resultPointer = 0;
+
−		}
+
−	}
+
−
+
−	/** 
+
−	 * Free the C-level result structure.
+
−	 */
+
−	private native void cleanupResult(long resultPointer);
+
−}