Added comments to the module AddOneHoprProertyPath and unit test for …

…AST2Text sindice#3

recommendation-servlet/src/main/java/org/sindice/analytics/queryProcessor/AST2TextTranslator.java

@@ -564,11 +564,9 @@ public Object visit(ASTVar node, Object data)
     throws VisitorException {
       final StringBuilder sb = (StringBuilder) data;
 
-//      if (node.getName().startsWith("?")) { // only the POF can start with '?'
-//        sb.append(node.getName()).append("< ");
-//      }
-      if (node.getName().equals("?POF"))
-        sb.append(node.getName()).append(' ');
+      if (node.getName().startsWith("?")) { // only the POF can start with '?'
+        sb.append("< ");
+      }
       else
         sb.append('?').append(node.getName()).append(' ');
       return data;

recommendation-servlet/src/main/java/org/sindice/analytics/queryProcessor/AddOneHopPropertyPath.java

@@ -38,7 +38,8 @@
 import org.slf4j.LoggerFactory;
 
 /**
- * 
+ * This module keeps on adding a property path between two nodes until either
+ * the maximum limit is reached or a valid recommendation is obtained.
  * @author bibhas [Jul 9, 2012]
  * @email bibhas.das@deri.org
  * 
@@ -54,6 +55,10 @@ public AddOneHopPropertyPath(SparqlTranslationProcessor sparql2dgs) {
     this.sparql2dgs = sparql2dgs;
   }
 
+  /* The type of object to be sent to the visitor method.
+   * It stores the path length from one node to another(hops).
+   * It also stores all the variables to be projected for recommendation (varsToProject).
+   * */
   private class HopsVarsPair {
     int hops;
     final ArrayList<String> varsToProject = new ArrayList<String>();
@@ -76,6 +81,10 @@ public PipelineObject process(PipelineObject po)
     final HopsVarsPair hopsVars = new HopsVarsPair();
     while (hops <= po.getMAX_HOPS()) {
       po = sparql2dgs.process(po);
+
+      /* convert the DGS query to an ASK query to check if recommendations
+       * are obtained with the current property paths.
+       */
       ASTQueryContainer ast = selectToAsk.convert(po.getAst());
       QueryIterator<Label, Context> qit = po.getBackend().submit(
           AST2TextTranslator.translate(ast));
@@ -88,6 +97,7 @@ public PipelineObject process(PipelineObject po)
         break;
       hopsVars.reset(hops);
       po.setAst(SyntaxTreeBuilder.parseQuery(query));
+      // add another hop to the existing query
       obj.visit(po.getAst(), hopsVars);
       query = AST2TextTranslator.translate(po.getAst());
       po.getVarsToProject().addAll(hopsVars.varsToProject);
@@ -96,6 +106,10 @@ public PipelineObject process(PipelineObject po)
     return po;
   }
 
+  /*The visitor searches for the triple pattern containing the POF
+   *and adds the requisite number of triples(as mentioned by hops)
+   *after the found triple.
+   * */
   public class AddHopVisitor extends ASTVisitorBase {
     public Object visit(ASTBasicGraphPattern node, Object data)
         throws VisitorException {
@@ -121,6 +135,7 @@ public Object visit(ASTBasicGraphPattern node, Object data)
         bgpDGS.jjtAppendChild(triple);
       }
 
+      // add hops number of triples after the triple containing POF
       if (foundPOF) {
         for (int i = 2; i < hops; i++) {
           bgpDGS.jjtAppendChild(triple);

recommendation-servlet/src/test/java/org/sindice/analytics/queryProcessor/TestAST2TextTranslator.java

@@ -0,0 +1,79 @@
+/*******************************************************************************
+ * Copyright (c) 2012 National University of Ireland, Galway. All Rights Reserved.
+ *
+ *
+ * This project is a free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version.
+ *
+ * This project is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public
+ * License along with this project. If not, see <http://www.gnu.org/licenses/>.
+ *******************************************************************************/
+package org.sindice.analytics.queryProcessor;
+
+
+import static org.junit.Assert.assertEquals;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.openrdf.sindice.query.parser.sparql.ast.ASTQueryContainer;
+import org.openrdf.sindice.query.parser.sparql.ast.SyntaxTreeBuilder;
+
+/**
+ * @author bibhas [Jul 19, 2012]
+ * @email bibhas.das@deri.org
+ *
+ */
+public class TestAST2TextTranslator {
+
+  private ASTQueryContainer ast;
+  /**
+   * @throws java.lang.Exception
+   */
+  @Before
+  public void setUp() throws Exception {
+  }
+
+  /**
+   * @throws java.lang.Exception
+   */
+  @After
+  public void tearDown() throws Exception {
+  }
+
+  @Test
+  public void testPOF() 
+   throws Exception {
+    final String query = "SELECT * WHERE { ?s < ?o .}";
+    ast = SyntaxTreeBuilder.parseQuery(query);
+    String translatedQuery = AST2TextTranslator.translate(ast);
+    String expected = "SELECT *\n" +
+                      "WHERE {\n" +
+                      "  ?s < ?o .\n" +
+                      "}\n";
+    assertEquals(expected, translatedQuery);
+  }
+
+  @Test
+  public void testGraphPOF()
+   throws Exception {
+    final String query = "SELECT * { GRAPH < { ?s ?p ?o .}}";
+    ast = SyntaxTreeBuilder.parseQuery(query);
+    String translatedQuery = AST2TextTranslator.translate(ast);
+    String expected = "SELECT *\n" +
+                      "WHERE {\n" +
+                      "GRAPH < {\n" +
+                      "  ?s ?p ?o .\n" +
+                      "}\n" +
+                      "}\n";
+    assertEquals(expected, translatedQuery);
+  }
+
+}