TDI-38097:Create conversion for most used functions (#889)

* TDI-38097:Create conversion for most used functions in
Datastage/Informatica

main/plugins/org.talend.librariesmanager/resources/java/routines/TalendStringUtil.java

@@ -0,0 +1,51 @@
+package routines;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class TalendStringUtil<T,Y> {
+	
+	
+	/**
+	 * Searches a port for a value you specify. If the function finds the value, it returns a result value, which you define.
+	 *  You can build an unlimited number of searches within a DECODE function.
+	 * 
+	 * @param value : Passes the values you want to search
+	 * @param defaultValue : The value you want to return if the search does not find a matching value.
+	 * @param search : a Map contains the search-value & result-value.
+	 * @return result-value if the search finds a matching value. Default-value if the search does not find a matching value.
+	 * 
+	 *  PS:You cannot create a DECODE function with both string and numeric return
+	 * values. When you validate the expression above, you receive the following
+	 * mismatching datatypes.
+	 */
+	public Y DECODE(T value, Y defaultValue, Map<T, Y> search) {
+		if (search.containsKey(value)) {
+			return search.get(value);
+		} else {
+			return defaultValue;
+		}
+	}
+	
+	/**
+	 * Searches a port for a value you specify. If the function finds the value, it returns a result value, which you define. 
+	 * You can build an unlimited number of searches within a DECODE function.
+	 * 
+	 * @param value : Passes the values you want to search
+	 * @param defaultValue : The value you want to return if the search does not find a matching value.
+	 * @param search : a Map contains the search-value & result-value.
+	 * @param searchAndResult : pairs of search-value & result-value. You can enter one or more pairs of values.
+	 * @return result-value if the search finds a matching value. Default-value if the search does not find a matching value.
+	 */
+	public Y DECODE(T value, Y defaultValue, T... searchAndResult) {
+		if (searchAndResult.length % 2 != 0) {
+			throw new IllegalArgumentException("Parameter searchAndResult should be in pair.");
+		}
+		Map<T, Y> search = new HashMap<T, Y>();
+		for (int i = 0; i < searchAndResult.length; i += 2) {
+			search.put(searchAndResult[i], (Y) searchAndResult[i + 1]);
+		}
+		return DECODE(value, defaultValue, search);
+	}
+
+}