Retrieve execution value explicitly by '_'

2 files changed, 62 insertions, 0 deletions

diff --git a/indexinglanguage/src/main/java/com/yahoo/vespa/indexinglanguage/expressions/ExecutionValueExpression.java b/indexinglanguage/src/main/java/com/yahoo/vespa/indexinglanguage/expressions/ExecutionValueExpression.java
new file mode 100644
index 00000000000..a4c430125a4
--- /dev/null
+++ b/indexinglanguage/src/main/java/com/yahoo/vespa/indexinglanguage/expressions/ExecutionValueExpression.java
@@ -0,0 +1,54 @@
+package com.yahoo.vespa.indexinglanguage.expressions;
+
+import com.yahoo.document.DataType;
+import com.yahoo.document.DocumentType;
+import com.yahoo.document.FieldPath;
+import com.yahoo.vespa.objects.ObjectOperation;
+import com.yahoo.vespa.objects.ObjectPredicate;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Objects;
+
+/**
+ * Returns the current execution value, that is the value passed to this expression.
+ * Referring to this explicitly is useful e.g to concatenate it to some other string:
+ * ... | input foo . " " . _ | ...
+ *
+ * @author bratseth
+ */
+public final class ExecutionValueExpression extends Expression {
+
+    public ExecutionValueExpression() {
+        super(null);
+    }
+
+    @Override
+    protected void doExecute(ExecutionContext context) {
+        // Noop: Set the output execution value to the current execution value
+    }
+
+    @Override
+    protected void doVerify(VerificationContext context) {}
+
+    @Override
+    public DataType createdOutputType() {
+        return UnresolvedDataType.INSTANCE;
+    }
+
+    @Override
+    public String toString() {
+        return "_";
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        return obj instanceof ExecutionValueExpression;
+    }
+
+    @Override
+    public int hashCode() {
+        return 9875876;
+    }
+
+}
diff --git a/indexinglanguage/src/main/javacc/IndexingParser.jj b/indexinglanguage/src/main/javacc/IndexingParser.jj
index 9f0b4733119..a039ad137ee 100644
--- a/indexinglanguage/src/main/javacc/IndexingParser.jj
+++ b/indexinglanguage/src/main/javacc/IndexingParser.jj
@@ -205,6 +205,7 @@ TOKEN :
     <ZCURVE: "zcurve"> |
     <TRUE: "true" > |
     <FALSE: "false" > |
+    <UNDERSCORE: "_"> |
     <IDENTIFIER: ["a"-"z","A"-"Z", "_"] (["a"-"z","A"-"Z","0"-"9","_","-"])*>
 }
 
@@ -343,6 +344,7 @@ Expression value() :
       val = trimExp()               |
       val = literalBoolExp()        |
       val = zcurveExp()             |
+      val = executionValueExp()     |
       ( <LPAREN> val = statement() <RPAREN> { val = new ParenthesisExpression(val); } ) )
     { return val; }
 }
@@ -752,6 +754,12 @@ Expression zcurveExp() : { }
     { return new ZCurveExpression(); }
 }
 
+Expression executionValueExp() : { }
+{
+    ( <UNDERSCORE> )
+    { return new ExecutionValueExpression(); }
+}
+
 String identifier() :
 {
     String val;