NPath skeleton

Author: hbutani

windowing/src/main/java/com/sap/hadoop/windowing/functions2/table/npath/NPath.java

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+package com.sap.hadoop.windowing.functions2.table.npath;
+
+import com.sap.hadoop.windowing.WindowingException;
+import com.sap.hadoop.windowing.functions2.TableFunctionEvaluator;
+import com.sap.hadoop.windowing.runtime2.Partition;
+
+/**
+ * return rows that meet a specified pattern. Use symbols to specify a list of expressions to match. 
+ * Pattern is used to specify a Path. The results list can contain expressions based on the input columns 
+ * and also the matched Path.
+ * <ol>
+ * <li><b>pattern:</b> pattern for the Path. Path is 'dot' separated list of symbols. 
+ * Each element is treated as a symbol. Elements that end in '*' or '+' are interpreted with the 
+ * usual meaning of zero or more, one or more respectively. For e.g. "LATE.EARLY*.ONTIMEOREARLY" implies a sequence of flights 
+ * where the first occurrence was LATE, followed by zero or more EARLY flights, followed by a ONTIME or EARLY flight.
+ * <li><b>symbols</b> specify a list of name, expression pairs. For e.g.
+ * 'LATE', arrival_delay > 0, 'EARLY', arrival_delay < 0 , 'ONTIME', arrival_delay == 0.
+ * These symbols can be used in the Pattern defined above.
+ * <li><b>resultSelectList</b> specified as a select list. 
+ * The expressions in the selectList are evaluated in the context where all the input columns are available, plus the attribute 
+ * "tpath" is available. Path is a collection of rows that represents the matching Path. 
+ * </ol>
+ */
+public class NPath extends TableFunctionEvaluator
+{
+	/**
+	 * <ul>
+	 * <li> check structure of Arguments:
+	 * <ol>
+	 * <li> First arg should be a String
+	 * <li> then there should be an even number of Arguments: String, expression; expression should be Convertible to Boolean.
+	 * <li> finally there should be a String.
+	 * </ol>
+	 * <li> convert pattern into a NNode chain.
+	 * <li> convert symbol args into a Symbol Map.
+	 * <li> parse selectList into SelectList struct. The inputOI used to translate these expressions should be based on the 
+	 * columns in the Input, the 'path.attr'
+	 * </ul>
+	 */
+	@Override
+	public void setupOI() throws WindowingException
+	{
+		
+	}
+	
+	@Override
+	public void execute(Partition iPart, Partition outP) throws WindowingException
+	{
+		
+	}
+}