Trim down search::multivalue::Value and search::multivalue::WeightedValue.

Use traits to check for presence of a weight and to extract inner type.

2 files changed, 42 insertions, 10 deletions

diff --git a/searchcommon/src/vespa/searchcommon/attribute/multi_value_traits.h b/searchcommon/src/vespa/searchcommon/attribute/multi_value_traits.h
new file mode 100644
index 00000000000..fcb3f1bd33a
--- /dev/null
+++ b/searchcommon/src/vespa/searchcommon/attribute/multi_value_traits.h
@@ -0,0 +1,42 @@
+// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+
+#pragma once
+
+#include <type_traits>
+
+namespace search::multivalue {
+
+template <typename T> class Value;
+template <typename T> class WeightedValue;
+
+/*
+ * Check for the presence of a weight.
+ */
+template <typename T>
+struct is_WeightedValue;
+
+template <typename T>
+struct is_WeightedValue<Value<T>> : std::false_type {};
+
+template <typename T>
+struct is_WeightedValue<WeightedValue<T>> : std::true_type {};
+
+template <typename T>
+inline constexpr bool is_WeightedValue_v = is_WeightedValue<T>::value;
+
+/*
+ * Extract inner type.
+ */
+template <typename T>
+struct ValueType;
+
+template <typename T>
+struct ValueType<Value<T>> { using type = T; };
+
+template <typename T>
+struct ValueType<WeightedValue<T>> { using type = T; };
+
+template <typename T>
+using ValueType_t = typename ValueType<T>::type;
+
+}
diff --git a/searchcommon/src/vespa/searchcommon/attribute/multivalue.h b/searchcommon/src/vespa/searchcommon/attribute/multivalue.h
index 780e8627b91..0783338c6f6 100644
--- a/searchcommon/src/vespa/searchcommon/attribute/multivalue.h
+++ b/searchcommon/src/vespa/searchcommon/attribute/multivalue.h
@@ -9,7 +9,6 @@ namespace search::multivalue {
 template <typename T>
 class Value {
 public:
-    typedef T ValueType;
     Value() noexcept : _v() {}
     Value(T v) noexcept : _v(v) { }
     Value(T v, int32_t w) noexcept : _v(v) { (void) w; }
@@ -20,13 +19,9 @@ public:
     operator T & ()           { return _v; }
     int32_t weight()    const { return 1; }
     void setWeight(int32_t w) { (void) w; }
-    void incWeight(int32_t w) { (void) w; }
     bool operator ==(const Value<T> & rhs) const { return _v == rhs._v; }
     bool operator <(const Value<T> & rhs) const { return _v < rhs._v; }
     bool operator >(const Value<T> & rhs) const { return _v > rhs._v; }
-    static bool hasWeight() { return false; }
-
-    static constexpr bool _hasWeight = false;
 private:
     T _v;
 };
@@ -34,7 +29,6 @@ private:
 template <typename T>
 class WeightedValue {
 public:
-    typedef T ValueType;
     WeightedValue() noexcept : _v(), _w(1) { }
     WeightedValue(T v, int32_t w) noexcept : _v(v), _w(w) { }
     T value()             const { return _v; }
@@ -44,14 +38,10 @@ public:
     operator T & ()             { return _v; }
     int32_t weight()      const { return _w; }
     void setWeight(int32_t w)   { _w = w; }
-    void incWeight(int32_t w)   { _w += w; }
 
     bool operator==(const WeightedValue<T> & rhs) const { return _v == rhs._v; }
     bool operator <(const WeightedValue<T> & rhs) const { return _v < rhs._v; }
     bool operator >(const WeightedValue<T> & rhs) const { return _v > rhs._v; }
-    static bool hasWeight() { return true; }
-
-    static constexpr bool _hasWeight = true;
 private:
     T       _v;
     int32_t _w;