commit f6321fb: [Minor] Add a simple utility to find a value in a map like stuff as an optional

[Vsevolod Stakhov]

Author: Vsevolod Stakhov
Date: 2021-06-18 12:56:50 +0100
URL: https://github.com/rspamd/rspamd/commit/f6321fbd323034d9763e53a56af014872a8a625a (HEAD -> master)

[Minor] Add a simple utility to find a value in a map like stuff as an optional

---
 src/libserver/css/css_property.cxx  |  7 ++++---
 src/libserver/css/css_tokeniser.cxx |  6 +++---
 src/libutil/cxx/util.hxx            | 15 +++++++++++++++
 3 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/src/libserver/css/css_property.cxx b/src/libserver/css/css_property.cxx
index 2a463f8da..1dd73026d 100644
--- a/src/libserver/css/css_property.cxx
+++ b/src/libserver/css/css_property.cxx
@@ -17,6 +17,7 @@
 #include "css_property.hxx"
 #include "frozen/unordered_map.h"
 #include "frozen/string.h"
+#include "libutil/cxx/util.hxx"
 
 namespace rspamd::css {
 
@@ -43,10 +44,10 @@ auto token_string_to_property(const std::string_view &inp)
 
 	css_property_type ret = css_property_type::PROPERTY_NYI;
 
-	auto known_type = prop_names_map.find(inp);
+	auto known_type = find_map(prop_names_map, inp);
 
-	if (known_type != prop_names_map.end()) {
-		ret = known_type->second;
+	if (known_type) {
+		ret = known_type.value().get();
 	}
 
 	return ret;
diff --git a/src/libserver/css/css_tokeniser.cxx b/src/libserver/css/css_tokeniser.cxx
index 22544053c..2391140dd 100644
--- a/src/libserver/css/css_tokeniser.cxx
+++ b/src/libserver/css/css_tokeniser.cxx
@@ -154,10 +154,10 @@ css_parser_token::adjust_dim(const css_parser_token &dim_token) -> bool
 	auto num = std::get<float>(value);
 	auto sv = std::get<std::string_view>(dim_token.value);
 
-	auto dim_found = dimensions_map.find(sv);
+	auto dim_found = find_map(dimensions_map, sv);
 
-	if (dim_found != dimensions_map.end()) {
-		auto dim_elt = dim_found->second;
+	if (dim_found) {
+		auto dim_elt = dim_found.value().get();
 		dimension_type = dim_elt.dtype;
 		flags |= css_parser_token::number_dimension;
 		num *= dim_elt.mult;
diff --git a/src/libutil/cxx/util.hxx b/src/libutil/cxx/util.hxx
index fa9aa1802..11c134d1f 100644
--- a/src/libutil/cxx/util.hxx
+++ b/src/libutil/cxx/util.hxx
@@ -21,6 +21,7 @@
 #include <memory>
 #include <array>
 #include <string_view>
+#include <optional>
 
 /*
  * Common C++ utilities
@@ -76,6 +77,20 @@ constexpr auto array_of(T&&... t) -> std::array<V, sizeof...(T)>
 	return {{ std::forward<T>(t)... }};
 }
 
+template<class C, class K, class V = typename C::mapped_type, typename std::enable_if_t<
+		std::is_constructible_v<typename C::key_type, K>
+		&& std::is_constructible_v<typename C::mapped_type, V>, bool> = false>
+constexpr auto find_map(const C &c, const K &k) -> std::optional<std::reference_wrapper<const V>>
+{
+	auto f = c.find(k);
+
+	if (f != c.end()) {
+		return std::cref<V>(f->second);
+	}
+
+	return std::nullopt;
+}
+
 }
 
 #endif //RSPAMD_UTIL_HXX