Distinguish the random feature and tensor function

Look ahead far enough to choose correctly between the tensor function 'random(tensor-type)'
and the scalar feature 'tensor(literal'"random" feature.

This also relaxes Context to allow arguments (to allow testing).

5 files changed, 23 insertions, 21 deletions

diff --git a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/evaluation/Context.java b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/evaluation/Context.java
index c1720996e9d..785ed78492e 100644
--- a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/evaluation/Context.java
+++ b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/evaluation/Context.java
@@ -2,12 +2,14 @@
 package com.yahoo.searchlib.rankingexpression.evaluation;
 
 import com.yahoo.searchlib.rankingexpression.rule.Arguments;
+import com.yahoo.searchlib.rankingexpression.rule.ExpressionNode;
 import com.yahoo.tensor.evaluation.EvaluationContext;
 
 import java.util.Set;
+import java.util.stream.Collectors;
 
 /**
- * <p>The context providing value bindings for an expression evaluation.</p>
+ * The context providing value bindings for an expression evaluation.
  *
  * @author bratseth
  */
@@ -26,14 +28,12 @@ public abstract class Context implements EvaluationContext {
      * <code>name(argument*)(.output)?</code>, where <i>argument</i> is any
      * string.  This may be used to implement more advanced variables whose
      * values are calculated at runtime from arguments.  Supporting this in a
-     * context is optional. Implementations may choose to throw
-     * UnsupportedOperationException or always return null, or to handle outputs
-     * but not arguments.</p>
-     *
-     * <p>This default implementation does the latter - if arguments is non-null
-     * and non-empty an UnsupportedOperationException is thrown, otherwise
-     * get(name + "." + output) is called (or just get(name)) if output is also
-     * null.</p>
+     * context is optional. 
+     * 
+     * <p>This default implementation generates a name on the form
+     * <code>name(argument1, argument2, ...argumentN).output</code>.
+     * If there are no arguments the parenthesis are omitted.
+     * If there is no output, the dot is omitted.</p>
      *
      * @param name      The name of this variable.
      * @param arguments The parsed arguments as given in the textual expression.
@@ -41,13 +41,12 @@ public abstract class Context implements EvaluationContext {
      *                  calculation to output several), or null to output the
      *                  "main" (or only) value.
      */
-    public Value get(String name, Arguments arguments,String output) {
-        if (arguments!=null && arguments.expressions().size() > 0)
-            throw new UnsupportedOperationException(this + " does not support structured ranking expression variables, attempted to reference '" +
-                                                    name + arguments + "'");
-        if (output==null)
-            return get(name);
-        return get(name + "." + output);
+    public Value get(String name, Arguments arguments, String output) {
+        if (arguments != null && arguments.expressions().size() > 0)
+            name = name + "(" + arguments.expressions().stream().map(ExpressionNode::toString).collect(Collectors.joining(",")) + ")";
+        if (output !=null)
+            name = name + "." + output;
+        return get(name);
     }
 
     /**
diff --git a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/evaluation/MapContext.java b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/evaluation/MapContext.java
index e5e2ebcb5d2..09895a0c2f6 100644
--- a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/evaluation/MapContext.java
+++ b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/evaluation/MapContext.java
@@ -46,8 +46,8 @@ public class MapContext extends Context {
      */
     @Override
     public Value get(String key) {
-        Value value=bindings.get(key);
-        if (value==null) return DoubleValue.zero;
+        Value value = bindings.get(key);
+        if (value == null) return DoubleValue.zero;
         return value;
     }
 
diff --git a/searchlib/src/main/javacc/RankingExpressionParser.jj b/searchlib/src/main/javacc/RankingExpressionParser.jj
index 3c62082e147..c3b9235cc93 100755
--- a/searchlib/src/main/javacc/RankingExpressionParser.jj
+++ b/searchlib/src/main/javacc/RankingExpressionParser.jj
@@ -227,7 +227,7 @@ ExpressionNode value() :
     ( [ LOOKAHEAD(2) <SUB>                                  { neg = true;     }   ]
       (            ret = constantPrimitive()                                      |
                    LOOKAHEAD(2) ret = ifExpression()                              |
-                   LOOKAHEAD(2) ret = function()                                  |
+                   LOOKAHEAD(4) ret = function()                                  |
                    ret = feature()                                                |
                    ret = queryFeature()                                           |
         ( <LBRACE> ret = expression() <RBRACE> { ret = new EmbracedNode(ret); } ) ) )
diff --git a/searchlib/src/test/java/com/yahoo/searchlib/rankingexpression/evaluation/EvaluationTestCase.java b/searchlib/src/test/java/com/yahoo/searchlib/rankingexpression/evaluation/EvaluationTestCase.java
index fea272216c6..5d357777657 100644
--- a/searchlib/src/test/java/com/yahoo/searchlib/rankingexpression/evaluation/EvaluationTestCase.java
+++ b/searchlib/src/test/java/com/yahoo/searchlib/rankingexpression/evaluation/EvaluationTestCase.java
@@ -79,6 +79,10 @@ public class EvaluationTestCase {
         tester.assertEvaluates(0, "sin(0)");
         tester.assertEvaluates(1, "cos(0)");
         tester.assertEvaluates(8, "pow(4/2,min(cos(0)*3,5))");
+        
+        // Random feature (which is also a tensor function) (We expect to be able to parse it and look up a zero)
+        tester.assertEvaluates(0, "random(1)");
+        tester.assertEvaluates(0, "random(foo)");
 
         // Combined
         tester.assertEvaluates(1.25, "5*if(1>=1.1, one_half, if(min(1,2)<max(1,2),if (\"foo\" in [\"foo\",\"bar\"],a_quarter,3000), 0.57345347))");
diff --git a/searchlib/src/test/java/com/yahoo/searchlib/rankingexpression/evaluation/EvaluationTester.java b/searchlib/src/test/java/com/yahoo/searchlib/rankingexpression/evaluation/EvaluationTester.java
index 47ef69b914a..d67c9dfd9dc 100644
--- a/searchlib/src/test/java/com/yahoo/searchlib/rankingexpression/evaluation/EvaluationTester.java
+++ b/searchlib/src/test/java/com/yahoo/searchlib/rankingexpression/evaluation/EvaluationTester.java
@@ -16,11 +16,10 @@ import static org.junit.Assert.assertEquals;
  */
 public class EvaluationTester {
 
-    private double tolerance = 0.000001;
     private MapContext defaultContext;
 
     public EvaluationTester() {
-        Map<String, Value> bindings = new HashMap<String, Value>();
+        Map<String, Value> bindings = new HashMap<>();
         bindings.put("zero", DoubleValue.frozen(0d));
         bindings.put("one", DoubleValue.frozen(1d));
         bindings.put("one_half", DoubleValue.frozen(0.5d));