From 0459599b1d7e0778373e26672d9b4e002371edd3 Mon Sep 17 00:00:00 2001
From: Michele Caini <michele.caini@gmail.com>
Date: Wed, 7 Mar 2018 08:31:03 +0100
Subject: [PATCH] added estimated number of entities for multi component
 standard view

---
 README.md                 | 5 +++--
 src/entt/entity/view.hpp  | 8 ++++++++
 test/entt/entity/view.cpp | 2 ++
 3 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/README.md b/README.md
index 95dec0d17..07c994157 100644
--- a/README.md
+++ b/README.md
@@ -769,8 +769,9 @@ components in their bags. During construction, these views look at the number
 of entities available for each component and pick up a reference to the smallest
 set of candidates in order to speed up iterations.<br/>
 They offer fewer functionalities than their companion views for single
-component, the most important of which can be used to reset the view and refresh
-the reference to the set of candidate entities to iterate.<br/>
+component. In particular, a multi component standard view exposes utility
+functions to reset its internal state (optimization purposes) and to get the
+estimated number of entities it is going to return.<br/>
 Refer to the [official documentation](https://skypjack.github.io/entt/) for all
 the details.
 
diff --git a/src/entt/entity/view.hpp b/src/entt/entity/view.hpp
index c4ae7487c..09ce9d423 100644
--- a/src/entt/entity/view.hpp
+++ b/src/entt/entity/view.hpp
@@ -428,6 +428,14 @@ public:
     /*! @brief Unsigned integer type. */
     using size_type = typename view_type::size_type;
 
+    /**
+     * @brief Estimates the number of entities that have the given components.
+     * @return Estimated number of entities that have the given components.
+     */
+    size_type size() const noexcept {
+        return view->size();
+    }
+
     /**
      * @brief Returns an iterator to the first entity that has the given
      * components.
diff --git a/test/entt/entity/view.cpp b/test/entt/entity/view.cpp
index 89850b0e7..ffe2b0bcf 100644
--- a/test/entt/entity/view.cpp
+++ b/test/entt/entity/view.cpp
@@ -93,6 +93,8 @@ TEST(View, MultipleComponent) {
     auto view = registry.view<int, char>();
 
     ASSERT_NE(view.begin(), view.end());
+    ASSERT_EQ(view.begin()+1, view.end());
+    ASSERT_EQ(view.size(), decltype(view.size()){1});
 
     view.get<char>(e0) = '1';
     view.get<char>(e1) = '2';