feat: LATERAL VIEW supports multiple alias columns

- fixes #2088

Signed-off-by: Andreas Reichel <[email protected]>

Author: manticore-projects

src/main/java/net/sf/jsqlparser/expression/Alias.java

@@ -65,7 +65,7 @@ public void setAliasColumns(List<AliasColumn> aliasColumns) {
 
     @Override
     public String toString() {
-        String alias = (useAs ? " AS " : " ") + name;
+        String alias = (useAs ? " AS " : " ") + (name != null ? name : "");
 
         if (aliasColumns != null && !aliasColumns.isEmpty()) {
             StringBuilder ac = new StringBuilder();
@@ -75,10 +75,10 @@ public String toString() {
                 }
                 ac.append(col.name);
                 if (col.colDataType != null) {
-                    ac.append(" ").append(col.colDataType.toString());
+                    ac.append(" ").append(col.colDataType);
                 }
             }
-            alias += "(" + ac + ")";
+            alias += name != null ? "(" + ac + ")" : ac;
         }
 
         return alias;
@@ -99,6 +99,16 @@ public Alias withAliasColumns(List<AliasColumn> aliasColumns) {
         return this;
     }
 
+
+    public Alias addAliasColumns(String... columnNames) {
+        List<AliasColumn> collection =
+                Optional.ofNullable(getAliasColumns()).orElseGet(ArrayList::new);
+        for (String columnName : columnNames) {
+            collection.add(new AliasColumn(columnName));
+        }
+        return this.withAliasColumns(collection);
+    }
+
     public Alias addAliasColumns(AliasColumn... aliasColumns) {
         List<AliasColumn> collection =
                 Optional.ofNullable(getAliasColumns()).orElseGet(ArrayList::new);

src/main/jjtree/net/sf/jsqlparser/parser/JSqlParserCC.jjt

@@ -2314,9 +2314,15 @@ LateralView LateralView() #LateralView:
             tableAlias = new Alias(tableName, false);
         }
     ]
-    <K_AS> columnName = RelObjectNameWithoutStart()
+    <K_AS> columnName = RelObjectNameWithoutStart() { columnAlias = new Alias(columnName, true); }
+
+    // Spark SQL supports multiple Alias Columns: https://spark.apache.org/docs/latest/sql-ref-syntax-qry-select-lateral-view.html
+    // we simulate this by setting the alias name to null and then just adding the columns
+    [
+        LOOKAHEAD(2) ","  { columnAlias.setName(null);  columnAlias.addAliasColumns( columnName); }
+        columnName = RelObjectNameWithoutStart() { columnAlias.addAliasColumns( columnName); }
+    ]
     {
-        columnAlias = new Alias(columnName, true);
         return new LateralView(
             useOuter
             , generatorFunction

src/test/java/net/sf/jsqlparser/expression/AliasTest.java

@@ -20,4 +20,12 @@ void testUDTF() throws JSQLParserException {
         String sqlStr = "select udtf_1(words) as (a1, a2) from tab";
         TestUtils.assertSqlCanBeParsedAndDeparsed(sqlStr, true);
     }
+
+    @Test
+    void testLateralViewMultipleColumns() throws JSQLParserException {
+        String sqlStr = "SELECT k, v \n" +
+                "FROM table \n" +
+                "LATERAL VIEW EXPLODE(a) exploded_data AS k, v;";
+        TestUtils.assertSqlCanBeParsedAndDeparsed(sqlStr, true);
+    }
 }