1 files changed, 87 insertions, 23 deletions
diff --git a/config-model/src/main/java/com/yahoo/searchdefinition/FeatureNames.java b/config-model/src/main/java/com/yahoo/searchdefinition/FeatureNames.java
index dc59d9cb3e5..dd03cb8b2a7 100644
--- a/config-model/src/main/java/com/yahoo/searchdefinition/FeatureNames.java
+++ b/config-model/src/main/java/com/yahoo/searchdefinition/FeatureNames.java
@@ -5,10 +5,11 @@
  */
 package com.yahoo.searchdefinition;
 
-import com.yahoo.searchlib.rankingexpression.Reference;
-
+import java.util.Arrays;
+import java.util.List;
 import java.util.Optional;
 import java.util.regex.Pattern;
+import java.util.stream.Collectors;
 
 /**
  * Utility methods for query, document and constant rank feature names
@@ -19,16 +20,85 @@ public class FeatureNames {
 
     private static final Pattern identifierRegexp = Pattern.compile("[A-Za-z0-9_][A-Za-z0-9_-]*");
 
-    public static Reference asConstantFeature(String constantName) {
-        return Reference.simple("constant", quoteIfNecessary(constantName));
+    /**
+     * <p>Returns the given query, document or constant feature in canonical form.
+     * A feature name consists of a feature type name (query, attribute or constant),
+     * followed by one argument enclosed in quotes.
+     * The argument may be an identifier or any string single or double quoted.</p>
+     *
+     * <p>Argument string values may not contain comma, single quote nor double quote characters.</p>
+     *
+     * <p><i>The canonical form use no quotes for arguments which are identifiers, and double quotes otherwise.</i></p>
+     *
+     * <p>Note that the above definition is not true for features in general, which accept any ranking expression
+     * as argument.</p>
+     *
+     * @throws IllegalArgumentException if the feature name is not valid
+     */
+    // Note that this implementation is more general than what is described above:
+    // It accepts any number of arguments and an optional output
+    public static String canonicalize(String feature) {
+        return canonicalizeIfValid(feature).orElseThrow(() ->
+            new IllegalArgumentException("A feature name must be on the form query(name), attribute(name) or " +
+                                         "constant(name), but was '" + feature + "'"
+        ));
+    }
+
+    /**
+     * Canonicalizes the given argument as in canonicalize, but returns empty instead of throwing an exception if
+     * the argument is not a valid feature
+     */
+    public static Optional<String> canonicalizeIfValid(String feature) {
+        int startParenthesis = feature.indexOf('(');
+        if (startParenthesis < 0)
+            return Optional.empty();
+        int endParenthesis = feature.lastIndexOf(')');
+        String featureType = feature.substring(0, startParenthesis);
+        if ( ! ( featureType.equals("query") || featureType.equals("attribute") || featureType.equals("constant")))
+            return Optional.empty();
+        if (startParenthesis < 1) return Optional.of(feature); // No arguments
+        if (endParenthesis < startParenthesis)
+            return Optional.empty();
+        String argumentString = feature.substring(startParenthesis + 1, endParenthesis);
+        List<String> canonicalizedArguments =
+                Arrays.stream(argumentString.split(","))
+                        .map(FeatureNames::canonicalizeArgument)
+                        .collect(Collectors.toList());
+        return Optional.of(featureType + "(" +
+                           canonicalizedArguments.stream().collect(Collectors.joining(",")) +
+                           feature.substring(endParenthesis));
+    }
+
+    /** Canomicalizes a single argument */
+    private static String canonicalizeArgument(String argument) {
+        if (argument.startsWith("'")) {
+            if ( ! argument.endsWith("'"))
+                throw new IllegalArgumentException("Feature arguments starting by a single quote " +
+                                                   "must end by a single quote, but was \"" + argument + "\"");
+            argument = argument.substring(1, argument.length() - 1);
+        }
+        if (argument.startsWith("\"")) {
+            if ( ! argument.endsWith("\""))
+                throw new IllegalArgumentException("Feature arguments starting by a double quote " +
+                                                   "must end by a double quote, but was '" + argument + "'");
+            argument = argument.substring(1, argument.length() - 1);
+        }
+        if (identifierRegexp.matcher(argument).matches())
+            return argument;
+        else
+            return "\"" + argument + "\"";
+    }
+
+    public static String asConstantFeature(String constantName) {
+        return canonicalize("constant(\"" + constantName + "\")");
     }
 
-    public static Reference asAttributeFeature(String attributeName) {
-        return Reference.simple("attribute", quoteIfNecessary(attributeName));
+    public static String asAttributeFeature(String attributeName) {
+        return canonicalize("attribute(\"" + attributeName + "\")");
     }
 
-    public static Reference asQueryFeature(String propertyName) {
-        return Reference.simple("query", quoteIfNecessary(propertyName));
+    public static String asQueryFeature(String propertyName) {
+        return canonicalize("query(\"" + propertyName + "\")");
     }
 
     /**
@@ -36,21 +106,15 @@ public class FeatureNames {
      * or empty if it is not a valid query, attribute or constant feature name
      */
     public static Optional<String> argumentOf(String feature) {
-        Optional<Reference> reference = Reference.simple(feature);
-        if ( ! reference.isPresent()) return Optional.empty();
-        if ( ! ( reference.get().name().equals("attribute") ||
-                 reference.get().name().equals("constant") ||
-                 reference.get().name().equals("query")))
-            return Optional.empty();
-
-        return Optional.of(reference.get().arguments().expressions().get(0).toString());
-    }
-
-    private static String quoteIfNecessary(String s) {
-        if (identifierRegexp.matcher(s).matches())
-            return s;
-        else
-            return "\"" + s + "\"";
+        return canonicalizeIfValid(feature).map(f -> {
+            int startParenthesis = f.indexOf("(");
+            int endParenthesis = f.indexOf(")");
+            String possiblyQuotedArgument = f.substring(startParenthesis + 1, endParenthesis);
+            if (possiblyQuotedArgument.startsWith("\""))
+                return possiblyQuotedArgument.substring(1, possiblyQuotedArgument.length() - 1);
+            else
+                return possiblyQuotedArgument;
+        });
     }
 
 }