From 60e9ff9cbcacf5faa2ab8ae560e9486cf5772dc7 Mon Sep 17 00:00:00 2001
From: Immanuel Haffner <haffner.immanuel@gmail.com>
Date: Sun, 25 Feb 2024 12:20:39 +0100
Subject: [PATCH] [Util] Add `Pooled::assert_not_none()`.

Converts an optional to a non-optional `Pooled`.  In a debug build,
asserts that a value is indeed present.
---
 include/mutable/util/Pool.hpp | 5 +++++
 unittest/util/PoolTest.cpp    | 2 ++
 2 files changed, 7 insertions(+)

diff --git a/include/mutable/util/Pool.hpp b/include/mutable/util/Pool.hpp
index 38a244e4..16cd0a04 100644
--- a/include/mutable/util/Pool.hpp
+++ b/include/mutable/util/Pool.hpp
@@ -232,6 +232,11 @@ struct Pooled
 
     bool has_value() const requires can_be_none { return ref_ != nullptr; }
 
+    Pooled<T, Pool, false> assert_not_none() const requires can_be_none {
+        M_insist(has_value());
+        return { pool_, ref_ };
+    }
+
     /**
      * Returns the number of references to the pooled object or 0 if
      * this `Pooled` CanBeNone and does *not* hold a reference to an object.
diff --git a/unittest/util/PoolTest.cpp b/unittest/util/PoolTest.cpp
index 7144d693..867b7c4b 100644
--- a/unittest/util/PoolTest.cpp
+++ b/unittest/util/PoolTest.cpp
@@ -151,6 +151,7 @@ TEST_CASE("PooledOptionalString Utilization", "[core][util][pool]")
         PooledOptionalString ps0{ pool("ps0") };
         REQUIRE(pool.size() == 1);
         REQUIRE(ps0.has_value());
+        CHECK(*ps0.assert_not_none() == "ps0"sv);
         REQUIRE(ps0.count() == 1);
 
         // copy constructing a non-empty PooledOptionalString should not affect the pool
@@ -158,6 +159,7 @@ TEST_CASE("PooledOptionalString Utilization", "[core][util][pool]")
         REQUIRE(pool.size() == 1);
         REQUIRE(ps0.has_value());
         REQUIRE(ps1.has_value());
+        CHECK(*ps1.assert_not_none() == "ps0"sv);
         REQUIRE(ps0 == ps1);
         REQUIRE(ps0.count() == 2);
         REQUIRE(ps1.count() == 2);