CMIS: Normalisation of scores in 0..1 range (due to standard statements) (#377)

src/main/java/org/alfresco/opencmis/search/CMISResultSetColumn.java

@@ -37,8 +37,14 @@ import org.apache.chemistry.opencmis.commons.enums.PropertyType;
 public class CMISResultSetColumn implements ResultSetColumn
 {
 
+    // Constant used at alfresco-data-model > org.alfresco.opencmis.search.CMISQueryParser.buildColumns()
+    public static final String SCORE_SELECTOR_ID = "SEARCH_SCORE";
+    public static final String SCORE_SELECTOR_FUNCTION = "Score";
+
     private String name;
     
+    private String functionName;
+
     private PropertyDefinitionWrapper propertyDefinition;
 
     private PropertyType dataType;
@@ -47,10 +53,11 @@ public class CMISResultSetColumn implements ResultSetColumn
 
     private QName alfrescoDataTypeQName;
 
-    CMISResultSetColumn(String name, PropertyDefinitionWrapper propertyDefinition, PropertyType dataType,
+    CMISResultSetColumn(String name, String functionName, PropertyDefinitionWrapper propertyDefinition, PropertyType dataType,
             QName alfrescoPropertyQName, QName alfrescoDataTypeQName)
     {
         this.name = name;
+        this.functionName = functionName;
         this.propertyDefinition = propertyDefinition;
         this.dataType = dataType;
         this.alfrescoPropertyQName = alfrescoPropertyQName;
@@ -62,6 +69,11 @@ public class CMISResultSetColumn implements ResultSetColumn
         return name;
     }
     
+    public String getFunctionName()
+    {
+        return functionName;
+    }
+
     public PropertyDefinitionWrapper getCMISPropertyDefinition()
     {
         return propertyDefinition;
@@ -81,4 +93,5 @@ public class CMISResultSetColumn implements ResultSetColumn
     {
         return alfrescoPropertyQName;
     }
+
 }

src/main/java/org/alfresco/opencmis/search/CMISResultSetMetaData.java

@@ -106,7 +106,8 @@ public class CMISResultSetMetaData implements ResultSetMetaData
             {
                 alfrescoDataTypeQName = cmisDictionaryService.findAlfrescoDataType(type);
             }
-            CMISResultSetColumn cmd = new CMISResultSetColumn(column.getAlias(), propertyDefinition, type,
+            CMISResultSetColumn cmd = new CMISResultSetColumn(column.getAlias(), column.getFunction().getName(), 
+                    propertyDefinition, type,
                     alfrescoPropertyQName, alfrescoDataTypeQName);
             columnMetaData.put(cmd.getName(), cmd);
         }

src/main/java/org/alfresco/opencmis/search/CMISResultSetRow.java

@@ -176,7 +176,14 @@ public class CMISResultSetRow implements ResultSetRow
         context.setScore(getScore());
         for (Column column : query.getColumns())
         {
-            if (column.getAlias().equals(columnName))
+            
+            // When an SCORE selector is included, score must be adapted to range 0..1 due to CMIS specification
+            if (column.getAlias().equals(CMISResultSetColumn.SCORE_SELECTOR_ID) ||
+                column.getFunction().getName().equals(CMISResultSetColumn.SCORE_SELECTOR_FUNCTION))
+            {
+                return getNormalisedScore();
+            }
+            else if (column.getAlias().equals(columnName))
             {
                 return column.getFunction().getValue(column.getFunctionArguments(), context);
             }
@@ -222,6 +229,17 @@ public class CMISResultSetRow implements ResultSetRow
         return null;
     }
     
+    /**
+    /**
+     * CMIS Specification states that scoring results must be in a 0..1 range
+     * This function re-adapt the scores when any scoring field or expression is requested by the query. 
+     * It's a safe approach, as includes negative numbers and also paged requests.
+     * @return
+     */
+    private float getNormalisedScore() {
+        return (float) (Math.atan(getScore()) / Math.PI) + 0.5f;  
+    }
+
     /*
      * (non-Javadoc)
      *