added a demo how to use functions from external APIs

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1408205 13f79535-47bb-0310-9956-ffa450edef68

src/examples/src/org/apache/poi/ss/examples/formula/SettingExternalFunction.java

@@ -0,0 +1,93 @@
+/*
+ *  ====================================================================
+ *    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.poi.ss.examples.formula;
+
+import org.apache.poi.ss.formula.OperationEvaluationContext;
+import org.apache.poi.ss.formula.eval.ErrorEval;
+import org.apache.poi.ss.formula.eval.ValueEval;
+import org.apache.poi.ss.formula.functions.FreeRefFunction;
+import org.apache.poi.ss.formula.udf.UDFFinder;
+import org.apache.poi.ss.usermodel.Row;
+import org.apache.poi.ss.usermodel.Sheet;
+import org.apache.poi.ss.usermodel.Workbook;
+import org.apache.poi.xssf.usermodel.XSSFWorkbook;
+
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * Demonstrates how to use functions provided by third-party add-ins, e.g. Bloomberg Excel Add-in.
+ *
+ * There can be situations when you are not interested in formula evaluation,
+ * you just need to set the formula  and the workbook will be evaluation by the client.
+ *
+ * @author Yegor Kozlov
+ */
+public class SettingExternalFunction {
+
+    /**
+     * wrap external functions in a plugin
+     */
+    public static class BloombergAddIn implements UDFFinder {
+        private final Map<String, FreeRefFunction> _functionsByName;
+
+        public BloombergAddIn() {
+            // dummy function that returns NA
+            // don't care about the implementation, we are not interested in evaluation
+            // and this method will never be called
+            FreeRefFunction NA = new FreeRefFunction() {
+                public ValueEval evaluate(ValueEval[] args, OperationEvaluationContext ec) {
+                    return ErrorEval.NA;
+                }
+            };
+            _functionsByName = new HashMap<String, FreeRefFunction>();
+            _functionsByName.put("BDP", NA);
+            _functionsByName.put("BDH", NA);
+            _functionsByName.put("BDS", NA);
+        }
+
+        public FreeRefFunction findFunction(String name) {
+            return _functionsByName.get(name.toUpperCase());
+        }
+
+    }
+
+    public static void main( String[] args ) throws IOException {
+
+        Workbook wb = new XSSFWorkbook();  // or new HSSFWorkbook()
+
+        // register the add-in
+        wb.addToolPack(new BloombergAddIn());
+
+        Sheet sheet = wb.createSheet();
+        Row row = sheet.createRow(0);
+        row.createCell(0).setCellFormula("BDP(\"GOOG Equity\",\"CHG_PCT_YTD\")/100");
+        row.createCell(1).setCellFormula("BDH(\"goog us equity\",\"EBIT\",\"1/1/2005\",\"12/31/2009\",\"per=cy\",\"curr=USD\") ");
+        row.createCell(2).setCellFormula("BDS(\"goog us equity\",\"top_20_holders_public_filings\") ");
+
+        FileOutputStream out = new FileOutputStream("bloomberg-demo.xlsx");
+        wb.write(out);
+        out.close();
+
+    }
+
+}