From 01685d67d127dfe19a893ee8ffdbf53376bbc208 Mon Sep 17 00:00:00 2001
From: Thomas Nixon <tom@tomn.co.uk>
Date: Tue, 16 Jan 2024 12:12:46 +0000
Subject: [PATCH] NamedType: validate in ++ and --

the mess here is to make sure that the new value is valid without
changing the old value, to make sure that the value stays valid even when
an exception is thrown

fixes #192
---
 include/adm/detail/named_type.hpp | 10 ++++++++--
 tests/named_type_tests.cpp        | 10 ++++++++++
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/include/adm/detail/named_type.hpp b/include/adm/detail/named_type.hpp
index 66384a69..06cb03c0 100644
--- a/include/adm/detail/named_type.hpp
+++ b/include/adm/detail/named_type.hpp
@@ -112,7 +112,10 @@ namespace adm {
       }
 
       NamedType<T, Tag, Validator>& operator++() {
-        ++value_;
+        T tmp = value_;
+        tmp++;
+        Validator::validate(tmp);
+        value_ = std::move(tmp);
         return *this;
       }
 
@@ -123,7 +126,10 @@ namespace adm {
       }
 
       NamedType<T, Tag, Validator>& operator--() {
-        --value_;
+        T tmp = value_;
+        tmp--;
+        Validator::validate(tmp);
+        value_ = std::move(tmp);
         return *this;
       }
 
diff --git a/tests/named_type_tests.cpp b/tests/named_type_tests.cpp
index 7a14d39d..18bb3482 100644
--- a/tests/named_type_tests.cpp
+++ b/tests/named_type_tests.cpp
@@ -52,6 +52,16 @@ TEST_CASE("NamedType_range_check") {
   NamedIntegerRange goodValue(5);
   REQUIRE_THROWS_AS(NamedIntegerRange(12), OutOfRangeError);
   REQUIRE_THROWS_AS(NamedIntegerRange(-1), OutOfRangeError);
+
+  NamedIntegerRange lower_limit(0);
+  REQUIRE_THROWS_AS(lower_limit--, OutOfRangeError);
+  REQUIRE_THROWS_AS(--lower_limit, OutOfRangeError);
+  REQUIRE(lower_limit == 0);
+
+  NamedIntegerRange upper_limit(10);
+  REQUIRE_THROWS_AS(upper_limit++, OutOfRangeError);
+  REQUIRE_THROWS_AS(++upper_limit, OutOfRangeError);
+  REQUIRE(upper_limit == 10);
 }
 
 TEST_CASE("screen_edge_validator") {