[INLONG-11219][SDK] Transform support COALESCE() function

inlong-sdk/transform-sdk/src/main/java/org/apache/inlong/sdk/transform/process/function/CoalesceFunction.java

@@ -0,0 +1,88 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.inlong.sdk.transform.process.function;
+
+import org.apache.inlong.sdk.transform.decode.SourceData;
+import org.apache.inlong.sdk.transform.process.Context;
+import org.apache.inlong.sdk.transform.process.operator.OperatorTools;
+import org.apache.inlong.sdk.transform.process.parser.ValueParser;
+
+import net.sf.jsqlparser.expression.Expression;
+import net.sf.jsqlparser.expression.Function;
+
+import java.math.BigDecimal;
+import java.sql.Timestamp;
+import java.util.ArrayList;
+import java.util.Date;
+import java.util.List;
+
+/**
+ * CoalesceFunction
+ *
+ */
+@TransformFunction(names = {"coalesce"})
+public class CoalesceFunction implements ValueParser {
+
+    private List<ValueParser> parserList;
+
+    public CoalesceFunction(Function expr) {
+        if (expr.getParameters() == null) {
+            this.parserList = new ArrayList<>();
+        } else {
+            List<Expression> params = expr.getParameters().getExpressions();
+            parserList = new ArrayList<>(params.size());
+            for (Expression param : params) {
+                ValueParser node = OperatorTools.buildParser(param);
+                parserList.add(node);
+            }
+        }
+    }
+
+    @Override
+    public Object parse(SourceData sourceData, int rowIndex, Context context) {
+        for (ValueParser node : parserList) {
+            Object parseObj = node.parse(sourceData, rowIndex, context);
+            Object valueObj = parseValue(parseObj);
+            if (valueObj != null) {
+                return parseValue(parseObj);
+            }
+        }
+        return null;
+    }
+
+    private Object parseValue(Object value) {
+        Object parsedValue;
+        if (value instanceof BigDecimal) {
+            parsedValue = OperatorTools.parseBigDecimal(value);
+        } else if (value instanceof Timestamp) {
+            parsedValue = OperatorTools.parseTimestamp(value);
+        } else if (value instanceof Date) {
+            parsedValue = OperatorTools.parseDate(value);
+        } else if (value instanceof byte[]) {
+            parsedValue = OperatorTools.parseBytes(value);
+        } else {
+            parsedValue = OperatorTools.parseString(value);
+        }
+        // invalid
+        if (parsedValue instanceof String && ((String) parsedValue).isEmpty()) {
+            return null;
+        }
+
+        return parsedValue;
+    }
+}

inlong-sdk/transform-sdk/src/test/java/org/apache/inlong/sdk/transform/process/function/flowcontrol/TestCoalesceFunction.java

@@ -0,0 +1,96 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.inlong.sdk.transform.process.function.flowcontrol;
+
+import org.apache.inlong.sdk.transform.decode.SourceDecoderFactory;
+import org.apache.inlong.sdk.transform.encode.SinkEncoderFactory;
+import org.apache.inlong.sdk.transform.pojo.TransformConfig;
+import org.apache.inlong.sdk.transform.process.TransformProcessor;
+import org.apache.inlong.sdk.transform.process.function.string.AbstractFunctionStringTestBase;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.util.HashMap;
+import java.util.List;
+
+public class TestCoalesceFunction extends AbstractFunctionStringTestBase {
+
+    @Test
+    public void testCoalesceFunction() throws Exception {
+        String transformSql1 = "select coalesce(string1, string2, string3) from source";
+        TransformConfig config1 = new TransformConfig(transformSql1);
+        TransformProcessor<String, String> processor1 = TransformProcessor
+                .create(config1, SourceDecoderFactory.createCsvDecoder(csvSource),
+                        SinkEncoderFactory.createKvEncoder(kvSink));
+
+        // case1: coalesce('Transform SQL', 'SQL', 'hh')
+        /*
+         * List<String> output1 = processor1.transform("Transform SQL|SQL|hh", new HashMap<>()); Assert.assertEquals(1,
+         * output1.size()); Assert.assertEquals(output1.get(0), "result=Transform SQL");
+         */
+
+        // case2: coalesce('', 'SQL', 'hh')
+        List<String> output2 = processor1.transform("|SQL|hh", new HashMap<>());
+        Assert.assertEquals(1, output2.size());
+        Assert.assertEquals(output2.get(0), "result=SQL");
+
+        // case2: coalesce('', '', 'hh')
+        List<String> output3 = processor1.transform("||hh", new HashMap<>());
+        Assert.assertEquals(1, output3.size());
+        Assert.assertEquals(output3.get(0), "result=hh");
+
+        String transformSql2 = "select coalesce(string1, string2) from source";
+        TransformConfig config2 = new TransformConfig(transformSql2);
+        TransformProcessor<String, String> processor2 = TransformProcessor
+                .create(config2, SourceDecoderFactory.createCsvDecoder(csvSource),
+                        SinkEncoderFactory.createKvEncoder(kvSink));
+
+        // case3: coalesce('', '')
+        List<String> output4 = processor2.transform("|", new HashMap<>());
+        Assert.assertEquals(1, output4.size());
+        Assert.assertEquals(output4.get(0), "result=");
+
+        // case4: coalesce('Transform SQL', 'Transformer')
+        List<String> output5 = processor2.transform("Transform SQL|Transformer", new HashMap<>());
+        Assert.assertEquals(1, output5.size());
+        Assert.assertEquals(output5.get(0), "result=Transform SQL");
+
+        // case5: coalesce('', 'm S')
+        List<String> output6 = processor2.transform("|m S", new HashMap<>());
+        Assert.assertEquals(1, output6.size());
+        Assert.assertEquals(output6.get(0), "result=m S");
+
+        String transformSql3 = "select coalesce(string1) from source";
+        TransformConfig config3 = new TransformConfig(transformSql3);
+        TransformProcessor<String, String> processor3 = TransformProcessor
+                .create(config3, SourceDecoderFactory.createCsvDecoder(csvSource),
+                        SinkEncoderFactory.createKvEncoder(kvSink));
+
+        // case6: coalesce('')
+        List<String> output7 = processor3.transform("", new HashMap<>());
+        Assert.assertEquals(1, output7.size());
+        Assert.assertEquals(output7.get(0), "result=");
+
+        // case6: coalesce('inlong')
+        List<String> output8 = processor3.transform("inlong", new HashMap<>());
+        Assert.assertEquals(1, output8.size());
+        Assert.assertEquals(output8.get(0), "result=inlong");
+
+    }
+}