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Get rid of most .at calls (#6393)

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Use one of `get` or `getOr` instead which will either return a null-pointer (with a nicer error message) or a default value when the key is missing.
This commit is contained in:
Alain Zscheile 2022-05-04 07:44:32 +02:00 • committed by GitHub
parent 9489b4b7ef
commit 1385b20078
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GPG key ID: 4AEE18F83AFDEB23
22 changed files with 231 additions and 118 deletions
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4
src/libutil/experimental-features.cc
View file

@ -35,7 +35,9 @@ const std::optional<ExperimentalFeature> parseExperimentalFeature(const std::str
std::string_view showExperimentalFeature(const ExperimentalFeature feature)
{
return stringifiedXpFeatures.at(feature);
const auto ret = get(stringifiedXpFeatures, feature);
assert(ret);
return *ret;
}
std::set<ExperimentalFeature> parseFeatures(const std::set<std::string> & rawFeatures)

20
src/libutil/tests/tests.cc
View file

@ -548,7 +548,7 @@ namespace nix {
TEST(get, emptyContainer) {
StringMap s = { };
auto expected = std::nullopt;
auto expected = nullptr;
ASSERT_EQ(get(s, "one"), expected);
}
@ -559,7 +559,23 @@ namespace nix {
s["two"] = "er";
auto expected = "yi";
ASSERT_EQ(get(s, "one"), expected);
ASSERT_EQ(*get(s, "one"), expected);
}
TEST(getOr, emptyContainer) {
StringMap s = { };
auto expected = "yi";
ASSERT_EQ(getOr(s, "one", "yi"), expected);
}
TEST(getOr, getFromContainer) {
StringMap s;
s["one"] = "yi";
s["two"] = "er";
auto expected = "yi";
ASSERT_EQ(getOr(s, "one", "nope"), expected);
}
/* ----------------------------------------------------------------------------

14
src/libutil/util.cc
View file

@ -1586,6 +1586,20 @@ std::string stripIndentation(std::string_view s)
}
const nlohmann::json * get(const nlohmann::json & map, const std::string & key)
{
auto i = map.find(key);
if (i == map.end()) return nullptr;
return &*i;
}
nlohmann::json * get(nlohmann::json & map, const std::string & key)
{
auto i = map.find(key);
if (i == map.end()) return nullptr;
return &*i;
}
//////////////////////////////////////////////////////////////////////

27
src/libutil/util.hh
View file

@ -543,13 +543,34 @@ std::string stripIndentation(std::string_view s);
/* Get a value for the specified key from an associate container. */
template <class T>
std::optional<typename T::mapped_type> get(const T & map, const typename T::key_type & key)
const typename T::mapped_type * get(const T & map, const typename T::key_type & key)
{
auto i = map.find(key);
if (i == map.end()) return {};
return std::optional<typename T::mapped_type>(i->second);
if (i == map.end()) return nullptr;
return &i->second;
}
template <class T>
typename T::mapped_type * get(T & map, const typename T::key_type & key)
{
auto i = map.find(key);
if (i == map.end()) return nullptr;
return &i->second;
}
const nlohmann::json * get(const nlohmann::json & map, const std::string & key);
nlohmann::json * get(nlohmann::json & map, const std::string & key);
/* Get a value for the specified key from an associate container, or a default value if the key isn't present. */
template <class T>
const typename T::mapped_type & getOr(T & map,
const typename T::key_type & key,
const typename T::mapped_type & defaultValue)
{
auto i = map.find(key);
if (i == map.end()) return defaultValue;
return i->second;
}
/* Remove and return the first item from a container. */
template <class T>