- Tool alias adder implemented

Author: wumpz

src/main/java/net/sf/jsqlparser/util/AddAliasesVisitor.java

@@ -0,0 +1,99 @@
+package net.sf.jsqlparser.util;
+
+import java.util.LinkedList;
+import java.util.List;
+import net.sf.jsqlparser.statement.select.AllColumns;
+import net.sf.jsqlparser.statement.select.AllTableColumns;
+import net.sf.jsqlparser.statement.select.PlainSelect;
+import net.sf.jsqlparser.statement.select.SelectExpressionItem;
+import net.sf.jsqlparser.statement.select.SelectItem;
+import net.sf.jsqlparser.statement.select.SelectItemVisitor;
+import net.sf.jsqlparser.statement.select.SelectVisitor;
+import net.sf.jsqlparser.statement.select.SetOperationList;
+
+/**
+ * Add aliases to every column and expression selected by a
+ * select - statement. Existing aliases are recognized and
+ * preserved. This class standard uses a prefix of A and a counter
+ * to generate new aliases (e.g. A1, A5, ...). This behaviour
+ * can be altered.
+ * 
+ * @author tw
+ */
+public class AddAliasesVisitor implements SelectVisitor, SelectItemVisitor {
+
+	private List<String> aliases = new LinkedList<String>();
+	private boolean firstRun = true;
+	private int counter = 0;
+	private String prefix = "A";
+
+	@Override
+	public void visit(PlainSelect plainSelect) {
+		firstRun = true;
+		counter = 0;
+		aliases.clear();
+		for (SelectItem item : plainSelect.getSelectItems()) {
+			item.accept(this);
+		}
+		firstRun = false;
+		for (SelectItem item : plainSelect.getSelectItems()) {
+			item.accept(this);
+		}
+	}
+
+	@Override
+	public void visit(SetOperationList setOpList) {
+		for (PlainSelect select : setOpList.getPlainSelects()) {
+			select.accept(this);
+		}
+	}
+
+	@Override
+	public void visit(AllColumns allColumns) {
+		throw new UnsupportedOperationException("Not supported yet.");
+	}
+
+	@Override
+	public void visit(AllTableColumns allTableColumns) {
+		throw new UnsupportedOperationException("Not supported yet.");
+	}
+
+	@Override
+	public void visit(SelectExpressionItem selectExpressionItem) {
+		if (firstRun) {
+			if (selectExpressionItem.getAlias() != null) {
+				aliases.add(selectExpressionItem.getAlias().toUpperCase());
+			}
+		} else {
+			if (selectExpressionItem.getAlias() == null) {
+
+				while (true) {
+					String alias = getNextAlias().toUpperCase();
+					if (!aliases.contains(alias)) {
+						aliases.add(alias);
+						selectExpressionItem.setAlias(alias);
+						break;
+					}
+				}
+			}
+		}
+	}
+
+	/**
+	 * Calculate next alias name to use.
+	 * @return 
+	 */
+	protected String getNextAlias() {
+		counter++;
+		return prefix + counter;
+	}
+
+	/**
+	 * Set alias prefix.
+	 *
+	 * @param prefix
+	 */
+	public void setPrefix(String prefix) {
+		this.prefix = prefix;
+	}
+}

src/test/java/net/sf/jsqlparser/util/AddAliasesVisitorTest.java

@@ -0,0 +1,87 @@
+package net.sf.jsqlparser.util;
+
+import java.io.StringReader;
+import net.sf.jsqlparser.JSQLParserException;
+import net.sf.jsqlparser.parser.CCJSqlParserManager;
+import net.sf.jsqlparser.statement.select.Select;
+import net.sf.jsqlparser.statement.select.SetOperationList;
+import org.junit.After;
+import org.junit.AfterClass;
+import org.junit.Before;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import static org.junit.Assert.*;
+
+/**
+ *
+ * @author tw
+ */
+public class AddAliasesVisitorTest {
+	
+	public AddAliasesVisitorTest() {
+	}
+	
+	@BeforeClass
+	public static void setUpClass() {
+	}
+	
+	@AfterClass
+	public static void tearDownClass() {
+	}
+	
+	@Before
+	public void setUp() {
+	}
+	
+	@After
+	public void tearDown() {
+	}
+	
+	CCJSqlParserManager parserManager = new CCJSqlParserManager();
+
+	/**
+	 * Test of visit method, of class AddAliasesVisitor.
+	 */
+	@Test
+	public void testVisit_PlainSelect() throws JSQLParserException {
+		String sql = "select a,b,c from test";
+		Select select = (Select) parserManager.parse( new StringReader(sql));
+		final AddAliasesVisitor instance = new AddAliasesVisitor();
+		select.getSelectBody().accept(instance);
+		
+		assertEquals("SELECT a AS A1, b AS A2, c AS A3 FROM test", select.toString());
+	}
+	
+	@Test
+	public void testVisit_PlainSelect_duplicates() throws JSQLParserException {
+		String sql = "select a,b as a1,c from test";
+		Select select = (Select) parserManager.parse( new StringReader(sql));
+		final AddAliasesVisitor instance = new AddAliasesVisitor();
+		select.getSelectBody().accept(instance);
+		
+		assertEquals("SELECT a AS A2, b AS a1, c AS A3 FROM test", select.toString());
+	}
+	
+	@Test
+	public void testVisit_PlainSelect_expression() throws JSQLParserException {
+		String sql = "select 3+4 from test";
+		Select select = (Select) parserManager.parse( new StringReader(sql));
+		final AddAliasesVisitor instance = new AddAliasesVisitor();
+		select.getSelectBody().accept(instance);
+		
+		assertEquals("SELECT 3 + 4 AS A1 FROM test", select.toString());
+	}
+
+	/**
+	 * Test of visit method, of class AddAliasesVisitor.
+	 */
+	@Test
+	public void testVisit_SetOperationList() throws JSQLParserException {
+		String sql = "select 3+4 from test union select 7+8 from test2";
+		Select setOpList = (Select) parserManager.parse( new StringReader(sql));
+		final AddAliasesVisitor instance = new AddAliasesVisitor();
+		setOpList.getSelectBody().accept(instance);
+		
+		assertEquals("(SELECT 3 + 4 AS A1 FROM test) UNION (SELECT 7 + 8 AS A1 FROM test2)", setOpList.toString());
+	}
+}