Replace range-based for loop with std::fill

Use standard algorithm std::fill instead of manual loop to clear bleKeyMap array. This is more idiomatic C++ and expresses intent more clearly.

src/BleInput.cpp

@@ -77,7 +77,7 @@ const char* specialName(uint8_t value) {
 }
 }  // namespace
 
-void showConnectingUntilLinked(GfxRenderer& renderer, MappedInputManager& input) {
+void showConnectingUntilLinked(const GfxRenderer& renderer, const MappedInputManager& input) {
   if (!BleHid.isRunning() || BleHid.isConnected()) return;
   // drawPopup refreshes the panel itself, so draw once and let e-ink hold it while we
   // pump the host. Holds until the remote links, the user presses a button to bail, or

src/BleInput.h

@@ -44,6 +44,6 @@ void describeKey(uint8_t kind, uint8_t value, char* out, size_t outLen);
 // Draw a "BT Connecting..." popup and pump the BLE host until the bonded remote
 // links, the user presses a button to dismiss, or a timeout. No-op if BLE isn't
 // running or is already connected. The caller must redraw afterward to clear it.
-void showConnectingUntilLinked(GfxRenderer& renderer, MappedInputManager& input);
+void showConnectingUntilLinked(const GfxRenderer& renderer, const MappedInputManager& input);
 
 }  // namespace bleinput

src/JsonSettingsIO.cpp

@@ -5,7 +5,9 @@
 #include <Logging.h>
 #include <ObfuscationUtils.h>
 
+#include <algorithm>
 #include <cstring>
+#include <iterator>
 #include <string>
 
 #include "BookmarkEntry.h"
@@ -256,7 +258,7 @@ bool JsonSettingsIO::loadSettings(CrossPointSettings& s, const char* json, bool*
 
   // Bluetooth — managed by BluetoothSettingsActivity, not in SettingsList.
   s.bluetoothEnabled = clamp(doc["bluetoothEnabled"] | (uint8_t)0, 2, 0);
-  for (auto& e : s.bleKeyMap) e = CrossPointSettings::BleKeyMapEntry{};  // reset to empty
+  std::fill(std::begin(s.bleKeyMap), std::end(s.bleKeyMap), CrossPointSettings::BleKeyMapEntry{});  // reset to empty
   JsonArrayConst bleMap = doc["bleKeyMap"];
   if (!bleMap.isNull()) {
     uint8_t slot = 0;

src/activities/settings/BleButtonMapActivity.cpp

@@ -2,7 +2,9 @@
 
 #include <GfxRenderer.h>
 
+#include <algorithm>
 #include <cstdio>
+#include <iterator>
 
 #include "BleInput.h"
 #include "CrossPointSettings.h"
@@ -31,7 +33,7 @@ void BleButtonMapActivity::onEnter() {
   // Start every mapping session from a clean slate: the user re-maps each remote
   // button once, so a button can't be left bound to a stale action and there's no
   // separate "clear mappings" step to remember.
-  for (auto& e : SETTINGS.bleKeyMap) e = CrossPointSettings::BleKeyMapEntry{};
+  std::fill(std::begin(SETTINGS.bleKeyMap), std::end(SETTINGS.bleKeyMap), CrossPointSettings::BleKeyMapEntry{});
   SETTINGS.saveToFile();
   mappedInput.setBleCaptureMode(true);
   requestUpdate();
@@ -44,32 +46,32 @@ void BleButtonMapActivity::onExit() {
 
 bool BleButtonMapActivity::assignCapturedKey(MappedInputManager::Button button) {
   const uint8_t btn = static_cast<uint8_t>(button);
+  auto& map = SETTINGS.bleKeyMap;
+  using Entry = CrossPointSettings::BleKeyMapEntry;
+  const uint8_t kind = capturedKind;
+  const uint8_t value = capturedValue;
+
   // One key per action: drop any other key currently bound to this action so the same
   // action can't be triggered by two different remote buttons.
-  for (auto& e : SETTINGS.bleKeyMap) {
-    if (e.button == btn && !(e.keyKind == capturedKind && e.keyValue == capturedValue)) {
-      e = CrossPointSettings::BleKeyMapEntry{};
-    }
+  std::replace_if(
+      std::begin(map), std::end(map),
+      [&](const Entry& e) { return e.button == btn && !(e.keyKind == kind && e.keyValue == value); }, Entry{});
+
+  // Reuse the slot already bound to this key, else the first free slot.
+  auto* slot = std::find_if(std::begin(map), std::end(map), [&](const Entry& e) {
+    return e.button != 0xFF && e.keyKind == kind && e.keyValue == value;
+  });
+  if (slot == std::end(map)) {
+    slot = std::find_if(std::begin(map), std::end(map),
+                        [](const Entry& e) { return e.button == 0xFF || e.keyKind == 0xFF; });
   }
-  // Update an existing binding for this key, if present.
-  for (auto& e : SETTINGS.bleKeyMap) {
-    if (e.button != 0xFF && e.keyKind == capturedKind && e.keyValue == capturedValue) {
-      e.button = btn;
-      SETTINGS.saveToFile();
-      return true;
-    }
-  }
-  // Otherwise take a free slot.
-  for (auto& e : SETTINGS.bleKeyMap) {
-    if (e.button == 0xFF || e.keyKind == 0xFF) {
-      e.keyKind = capturedKind;
-      e.keyValue = capturedValue;
-      e.button = btn;
-      SETTINGS.saveToFile();
-      return true;
-    }
-  }
-  return false;  // table full
+  if (slot == std::end(map)) return false;  // table full
+
+  slot->keyKind = kind;
+  slot->keyValue = value;
+  slot->button = btn;
+  SETTINGS.saveToFile();
+  return true;
 }
 
 void BleButtonMapActivity::loop() {