[wpiutil] Replace LLVM StringMap impl with std::map

As string_view operations on std::map<std::string> won't be integrated
until C++26, placeholder implementations are used which are less efficient
in a couple of situations (e.g. insert with hint).

glass/src/lib/native/cpp/Context.cpp

@@ -53,7 +53,7 @@ static void WorkspaceInit() {
   }
 
   for (auto&& root : gContext->storageRoots) {
-    root.getValue()->Apply();
+    root.second->Apply();
   }
 }
 
@@ -176,7 +176,7 @@ static bool LoadStorageImpl(Context* ctx, std::string_view dir,
   bool rv = true;
   for (auto&& root : ctx->storageRoots) {
     std::string filename;
-    auto rootName = root.getKey();
+    auto& rootName = root.first;
     if (rootName.empty()) {
       filename = (fs::path{dir} / fmt::format("{}.json", name)).string();
     } else {
@@ -291,7 +291,7 @@ static bool SaveStorageImpl(Context* ctx, std::string_view dir,
   if (exiting && wpi::gui::gContext->resetOnExit) {
     fs::remove(dirPath / fmt::format("{}-window.json", name), ec);
     for (auto&& root : ctx->storageRoots) {
-      auto rootName = root.getKey();
+      auto& rootName = root.first;
       if (rootName.empty()) {
         fs::remove(dirPath / fmt::format("{}.json", name), ec);
       } else {
@@ -304,14 +304,14 @@ static bool SaveStorageImpl(Context* ctx, std::string_view dir,
       (dirPath / fmt::format("{}-window.json", name)).string());
 
   for (auto&& root : ctx->storageRoots) {
-    auto rootName = root.getKey();
+    auto& rootName = root.first;
     std::string filename;
     if (rootName.empty()) {
       filename = (dirPath / fmt::format("{}.json", name)).string();
     } else {
       filename = (dirPath / fmt::format("{}-{}.json", name, rootName)).string();
     }
-    if (!SaveStorageRootImpl(ctx, filename, *root.getValue())) {
+    if (!SaveStorageRootImpl(ctx, filename, *root.second)) {
       rv = false;
     }
   }
@@ -320,8 +320,7 @@ static bool SaveStorageImpl(Context* ctx, std::string_view dir,
 
 Context::Context()
     : sourceNameStorage{storageRoots.insert({"", std::make_unique<Storage>()})
-                            .first->getValue()
-                            ->GetChild("sourceNames")} {
+                            .first->second->GetChild("sourceNames")} {
   storageStack.emplace_back(storageRoots[""].get());
 
   // override ImGui ini saving

glass/src/lib/native/cpp/DataSource.cpp

@@ -112,5 +112,5 @@ DataSource* DataSource::Find(std::string_view id) {
   if (it == gContext->sources.end()) {
     return nullptr;
   }
-  return it->getValue();
+  return it->second;
 }

glass/src/lib/native/cpp/Storage.cpp

@@ -331,7 +331,7 @@ std::vector<std::unique_ptr<Storage>>& Storage::GetChildArray(
 std::unique_ptr<Storage::Value> Storage::Erase(std::string_view key) {
   auto it = m_values.find(key);
   if (it != m_values.end()) {
-    auto rv = std::move(it->getValue());
+    auto rv = std::move(it->second);
     m_values.erase(it);
     return rv;
   }
@@ -339,11 +339,9 @@ std::unique_ptr<Storage::Value> Storage::Erase(std::string_view key) {
 }
 
 void Storage::EraseChildren() {
-  for (auto&& kv : m_values) {
-    if (kv.getValue()->type == Value::kChild) {
-      m_values.remove(&kv);
-    }
-  }
+  std::erase_if(m_values, [](const auto& kv) {
+    return kv.second->type == Value::kChild;
+  });
 }
 
 static bool JsonArrayToStorage(Storage::Value* valuePtr, const wpi::json& jarr,
@@ -559,7 +557,7 @@ wpi::json Storage::ToJson() const {
   wpi::json j = wpi::json::object();
   for (auto&& kv : m_values) {
     wpi::json jelem;
-    auto& value = *kv.getValue();
+    auto& value = *kv.second;
     switch (value.type) {
 #define CASE(CapsName, LowerName)                                        \
   case Value::k##CapsName:                                               \
@@ -602,7 +600,7 @@ wpi::json Storage::ToJson() const {
       default:
         continue;
     }
-    j.emplace(kv.getKey(), std::move(jelem));
+    j.emplace(kv.first, std::move(jelem));
   }
   return j;
 }
@@ -617,7 +615,7 @@ void Storage::Clear() {
 
 void Storage::ClearValues() {
   for (auto&& kv : m_values) {
-    auto& value = *kv.getValue();
+    auto& value = *kv.second;
     switch (value.type) {
       case Value::kInt:
         value.intVal = value.intDefault;
@@ -703,7 +701,7 @@ void Storage::Apply() {
 
 void Storage::ApplyChildren() {
   for (auto&& kv : m_values) {
-    auto& value = *kv.getValue();
+    auto& value = *kv.second;
     switch (value.type) {
       case Value::kChild:
         value.child->Apply();