settings: query for specific entry

separate search and value retrieval

code/espurna/button.cpp

@@ -834,7 +834,7 @@ bool checkSamePrefix(StringView key) {
 }
 
 String findValueFrom(StringView key) {
-    return espurna::settings::query::IndexedSetting::findValueFrom(
+    return espurna::settings::query::findValueFrom(
         button::internal::buttons.size(), IndexedSettings, key);
 }
 

code/espurna/homeassistant.cpp

@@ -126,7 +126,7 @@ bool checkSamePrefix(espurna::StringView key) {
 }
 
 String findValueFrom(espurna::StringView key) {
-    return espurna::settings::query::Setting::findValueFrom(Settings, key);
+    return espurna::settings::query::findValueFrom(Settings, key);
 }
 
 void setup() {

code/espurna/led.cpp

@@ -635,7 +635,7 @@ bool checkSamePrefix(StringView key) {
 }
 
 String findValueFrom(StringView key) {
-    return espurna::settings::query::IndexedSetting::findValueFrom(
+    return espurna::settings::query::findValueFrom(
         ::espurna::led::internal::leds.size(), IndexedSettings, key);
 }
 

code/espurna/mqtt.cpp

@@ -411,7 +411,7 @@ bool checkSamePrefix(espurna::StringView key) {
 }
 
 String findValueFrom(espurna::StringView key) {
-    return espurna::settings::query::Setting::findValueFrom(Settings, key);
+    return espurna::settings::query::findValueFrom(Settings, key);
 }
 
 void setup() {

code/espurna/relay.cpp

@@ -3322,7 +3322,7 @@ bool checkSamePrefix(StringView key) {
 }
 
 String findIndexedValueFrom(StringView key) {
-    return espurna::settings::query::IndexedSetting::findValueFrom(_relays.size(), IndexedSettings, key);
+    return espurna::settings::query::findValueFrom(_relays.size(), IndexedSettings, key);
 }
 
 bool checkExact(StringView key) {
@@ -3336,7 +3336,7 @@ bool checkExact(StringView key) {
 }
 
 String findValueFrom(StringView key) {
-    return espurna::settings::query::Setting::findValueFrom(Settings, key);
+    return espurna::settings::query::findValueFrom(Settings, key);
 }
 
 void setup() {

code/espurna/scheduler.cpp

@@ -421,7 +421,7 @@ bool checkSamePrefix(StringView key) {
 }
 
 String findIndexedValueFrom(StringView key) {
-    return espurna::settings::query::IndexedSetting::findValueFrom(count(), IndexedSettings, key);
+    return espurna::settings::query::findValueFrom(count(), IndexedSettings, key);
 }
 
 void setup() {

code/espurna/sensors/DigitalSensor.h

@@ -194,7 +194,7 @@ bool checkSamePrefix(StringView key) {
 }
 
 String findValueFrom(StringView key) {
-    return espurna::settings::query::IndexedSetting::findValueFrom(
+    return espurna::settings::query::findValueFrom(
         build::SensorsMax, IndexedSettings, key);
 }
 

code/espurna/settings.cpp

@@ -41,53 +41,73 @@ static kvs_type kv_store(
 
 namespace query {
 
-const Setting* Setting::findFrom(const Setting* begin, const Setting* end, StringView key) {
+String Result::value() const {
+    if (_ptr == nullptr) {
+        return String();
+    }
+
+    return (_index == IndexMax)
+        ? (*reinterpret_cast<const Setting*>(_ptr)).value()
+        : (*reinterpret_cast<const IndexedSetting*>(_ptr)).value(_index);
+}
+
+Result findFrom(const Setting* begin, const Setting* end, StringView key) {
     for (auto it = begin; it != end; ++it) {
         if ((*it) == key) {
-            return it;
+            return Result(it);
         }
     }
 
-    return end;
+    return Result(nullptr);
 }
 
-String Setting::findValueFrom(const Setting* begin, const Setting* end, StringView key) {
+String findValueFrom(const Setting* begin, const Setting* end, StringView key) {
     String out;
 
-    const auto value = findFrom(begin, end, key);
-    if (value != end) {
-        out = (*value).value();
+    const auto result = findFrom(begin, end, key);
+    if (result.ok()) {
+        out = result.value();
     }
 
     return out;
 }
 
-bool IndexedSetting::findSamePrefix(const IndexedSetting* begin, const IndexedSetting* end, StringView key) {
+const IndexedSetting* findSamePrefix(const IndexedSetting* begin, const IndexedSetting* end, StringView key) {
+    const IndexedSetting* out { nullptr };
+
     for (auto it = begin; it != end; ++it) {
         if (key.startsWith((*it).prefix())) {
-            return true;
+            out = it;
+            break;
         }
     }
 
-    return false;
+    return out;
 }
 
-String IndexedSetting::findValueFrom(Iota iota, const IndexedSetting* begin, const IndexedSetting* end, StringView key) {
-    String out;
-
+Result findFrom(Iota iota, const IndexedSetting* begin, const IndexedSetting* end, StringView key) {
     while (iota) {
         for (auto it = begin; it != end; ++it) {
             const auto expected = Key(
                 (*it).prefix().toString(), *iota);
             if (key == expected.value()) {
-                out = (*it).value(*iota);
-                goto output;
+                return Result(it, *iota);
             }
         }
         ++iota;
     }
 
-output:
+    return Result(nullptr);
+}
+
+String findValueFrom(Iota iota, const IndexedSetting* begin, const IndexedSetting* end, StringView key) {
+    String out;
+
+    const auto result = findFrom(iota, begin, end, key);
+    if (result.pointer() != end) {
+        out = result.value();
+    }
+
     return out;
 }
 

code/espurna/settings_helpers.h

@@ -347,6 +347,8 @@ private:
 // both require a linear iterators as input e.g. most commonly - a static array
 // (either a plain [], or an std::array. template should treat both equally)
 
+struct Result;
+
 // single key variant, exact match of the provided string
 struct alignas(8) Setting {
     using ValueFunc = String(*)();
@@ -373,20 +375,6 @@ struct alignas(8) Setting {
         return _key == key;
     }
 
-    static const Setting* findFrom(const Setting* begin, const Setting* end, StringView key);
-
-    template <typename T>
-    static const Setting* findFrom(const T& settings, StringView key) {
-        return findFrom(std::begin(settings), std::end(settings), key);
-    }
-
-    static String findValueFrom(const Setting* begin, const Setting* end, StringView key);
-
-    template <typename T>
-    static String findValueFrom(const T& settings, StringView key) {
-        return findValueFrom(std::begin(settings), std::end(settings), key);
-    }
-
 private:
     StringView _key;
     ValueFunc _func;
@@ -415,30 +403,104 @@ struct alignas(8) IndexedSetting {
         return _prefix;
     }
 
-    static bool findSamePrefix(const IndexedSetting* begin, const IndexedSetting* end, StringView key);
+private:
+    StringView _prefix;
+    ValueFunc _func;
+};
 
-    template <typename T>
-    static bool findSamePrefix(const T& settings, StringView key) {
-        return findSamePrefix(std::begin(settings), std::end(settings), key);
-    }
+// generic way to retrieve specific settings entry or report its absence
+struct Result {
+    static constexpr size_t IndexMax = std::numeric_limits<size_t>::max();
 
-    static String findValueFrom(Iota iota, const IndexedSetting* begin, const IndexedSetting* end, StringView key);
+    Result(const Result&) = default;
+    Result& operator=(const Result&) = default;
 
-    template <typename T>
-    static String findValueFrom(Iota iota, const T& settings, StringView key) {
-        return findValueFrom(iota, std::begin(settings), std::end(settings), key);
+    Result(Result&&) = default;
+    Result& operator=(Result&&) = default;
+
+    Result() = default;
+
+    explicit Result(const Setting* setting) :
+        _ptr(setting)
+    {}
+
+    Result(const IndexedSetting* setting, size_t index) :
+        _ptr(setting),
+        _index(index)
+    {}
+
+    bool ok() const {
+        return _ptr != nullptr;
     }
 
-    template <typename T>
-    static String findValueFrom(size_t size, const T& settings, StringView key) {
-        return findValueFrom(Iota{size}, settings, key);
+    explicit operator bool() const {
+        return ok();
+    }
+
+    String value() const;
+
+    const void* pointer() const {
+        return _ptr;
     }
 
 private:
-    StringView _prefix;
-    ValueFunc _func;
+    const void* _ptr { nullptr };
+    size_t _index { IndexMax };
 };
 
+Result findFrom(const Setting* begin, const Setting* end, StringView key);
+
+template <typename T>
+inline Result findFrom(const T& settings, StringView key) {
+    return findFrom(std::begin(settings), std::end(settings), key);
+}
+
+String findValueFrom(const Setting* begin, const Setting* end, StringView key);
+
+template <typename T>
+inline String findValueFrom(const T& settings, StringView key) {
+    return findValueFrom(std::begin(settings), std::end(settings), key);
+}
+
+Result findFrom(Iota iota, const IndexedSetting* begin, const IndexedSetting* end, StringView key);
+
+template <typename T>
+inline Result findFrom(Iota iota, const T& settings, StringView key) {
+    return findFrom(iota, std::begin(settings), std::end(settings), key);
+}
+
+template <typename T>
+inline Result findFrom(size_t size, const T& settings, StringView key) {
+    return findFrom(Iota{size}, settings, key);
+}
+
+String findValueFrom(Iota iota, const IndexedSetting* begin, const IndexedSetting* end, StringView key);
+
+template <typename T>
+inline String findValueFrom(Iota iota, const T& settings, StringView key) {
+    return findValueFrom(iota, std::begin(settings), std::end(settings), key);
+}
+
+template <typename T>
+inline String findValueFrom(size_t size, const T& settings, StringView key) {
+    return findValueFrom(Iota{size}, settings, key);
+}
+
+const IndexedSetting* findSamePrefix(const IndexedSetting* begin, const IndexedSetting* end, StringView key);
+
+template <typename T>
+inline const IndexedSetting* findSamePrefix(const T& settings, StringView key) {
+    return findSamePrefix(std::begin(settings), std::end(settings), key);
+}
+
+inline bool hasSamePrefix(const IndexedSetting* begin, const IndexedSetting* end, StringView key) {
+    return nullptr != findSamePrefix(begin, end, key);
+}
+
+template <typename T>
+inline bool hasSamePrefix(const T& settings, StringView key) {
+    return hasSamePrefix(std::begin(settings), std::end(settings), key);
+}
 
 } // namespace query
 } // namespace settings

code/espurna/system.cpp

@@ -599,11 +599,11 @@ static constexpr std::array<espurna::settings::query::Setting, 5> Settings PROGM
 }};
 
 bool checkExact(StringView key) {
-    return espurna::settings::query::Setting::findFrom(Settings, key) != Settings.end();
+    return espurna::settings::query::findFrom(Settings, key).ok();
 }
 
 String findValueFrom(StringView key) {
-    return espurna::settings::query::Setting::findValueFrom(Settings, key);
+    return espurna::settings::query::findValueFrom(Settings, key);
 }
 
 void setup() {

code/espurna/telnet.cpp

@@ -131,7 +131,7 @@ bool checkExactPrefix(StringView key) {
 }
 
 String findValueFrom(StringView key) {
-    return espurna::settings::query::Setting::findValueFrom(Settings, key);
+    return espurna::settings::query::findValueFrom(Settings, key);
 }
 
 void setup() {

code/espurna/uart.cpp

@@ -461,7 +461,7 @@ bool checkSamePrefix(StringView key) {
 }
 
 String findIndexedValueFrom(StringView key) {
-    return espurna::settings::query::IndexedSetting::findValueFrom(
+    return espurna::settings::query::findValueFrom(
         ports(), IndexedSettings, key);
 
 }

code/espurna/wifi.cpp

@@ -2264,7 +2264,7 @@ static constexpr std::array<espurna::settings::query::Setting, 11> Settings PROG
 
 // indexed settings for 'sta' connections
 bool checkIndexedPrefix(StringView key) {
-    return espurna::settings::query::IndexedSetting::findSamePrefix(
+    return espurna::settings::query::hasSamePrefix(
         sta::settings::query::Settings, key);
 }
 
@@ -2274,15 +2274,13 @@ bool checkExactPrefix(StringView key) {
 }
 
 String findIndexedValueFrom(StringView key) {
-    using espurna::settings::query::IndexedSetting;
-    return IndexedSetting::findValueFrom(
+    return espurna::settings::query::findValueFrom(
         sta::countNetworks(),
         sta::settings::query::Settings, key);
 }
 
 String findValueFrom(StringView key) {
-    using espurna::settings::query::Setting;
-    return Setting::findValueFrom(Settings, key);
+    return espurna::settings::query::findValueFrom(Settings, key);
 }
 
 void setup() {