Fix command history cycling with DOWN ARROW key

src/host/history.cpp

@@ -1,6 +1,3 @@
-// Copyright (c) Microsoft Corporation.
-// Licensed under the MIT license.
-
 #include "precomp.h"
 
 #include "history.h"
@@ -849,3 +846,23 @@ HRESULT ApiRoutines::GetConsoleCommandHistoryWImpl(const std::wstring_view exeNa
     }
     CATCH_RETURN();
 }
+
+std::wstring_view CommandHistory::CycleCommandHistory(const SearchDirection searchDirection)
+{
+    if (_commands.empty())
+    {
+        LastDisplayed = 0;
+        return {};
+    }
+
+    if (searchDirection == SearchDirection::Previous)
+    {
+        LastDisplayed = (LastDisplayed - 1 + GetNumberOfCommands()) % GetNumberOfCommands();
+    }
+    else
+    {
+        LastDisplayed = (LastDisplayed + 1) % GetNumberOfCommands();
+    }
+
+    return _commands.at(LastDisplayed);
+}

src/host/history.h

@@ -1,96 +1,95 @@
-// Copyright (c) Microsoft Corporation.
-// Licensed under the MIT license.
-
-#pragma once
-
-class CommandHistory
-{
-public:
-    using Index = int32_t;
-    static constexpr Index IndexMax = INT32_MAX;
-
-    // CommandHistory Flags
-    static constexpr int CLE_ALLOCATED = 0x00000001;
-    static constexpr int CLE_RESET = 0x00000002;
-
-    static CommandHistory* s_Allocate(const std::wstring_view appName, const HANDLE processHandle);
-    static CommandHistory* s_Find(const HANDLE processHandle);
-    static CommandHistory* s_FindByExe(const std::wstring_view appName);
-    static void s_ReallocExeToFront(const std::wstring_view appName, const size_t commands);
-    static void s_Free(const HANDLE processHandle);
-    static void s_ResizeAll(const size_t commands);
-    static size_t s_CountOfHistories();
-
-    enum class MatchOptions
-    {
-        None = 0x0,
-        ExactMatch = 0x1,
-        JustLooking = 0x2
-    };
-
-    enum class SearchDirection
-    {
-        Previous,
-        Next
-    };
-
-    bool FindMatchingCommand(const std::wstring_view command,
-                             const Index startingIndex,
-                             Index& indexFound,
-                             const MatchOptions options);
-    bool IsAppNameMatch(const std::wstring_view other) const;
-
-    [[nodiscard]] HRESULT Add(const std::wstring_view command,
-                              const bool suppressDuplicates);
-
-    std::wstring_view Retrieve(const SearchDirection searchDirection);
-    std::wstring_view RetrieveNth(Index index);
-
-    Index GetNumberOfCommands() const;
-    std::wstring_view GetNth(Index index) const;
-    const std::vector<std::wstring>& GetCommands() const noexcept;
-
-    void Realloc(Index commands);
-    void Empty();
-
-    std::wstring Remove(const Index iDel);
-
-    bool AtFirstCommand() const;
-    bool AtLastCommand() const;
-
-    std::wstring_view GetLastCommand() const;
-
-    void Swap(const Index indexA, const Index indexB);
-
-private:
-    void _Reset();
-
-    // _Next and _Prev go to the next and prev command
-    // _Inc  and _Dec go to the next and prev slots
-    // Don't get the two confused - it matters when the cmd history is not full!
-    void _Prev(Index& ind) const;
-    void _Next(Index& ind) const;
-    void _Dec(Index& ind) const;
-    void _Inc(Index& ind) const;
-
-    // NOTE: In conhost v1 this used to be a circular buffer because removal at the
-    // start is a very common operation. It seems this was lost in the C++ refactor.
-    std::vector<std::wstring> _commands;
-    Index _maxCommands = 0;
-
-    std::wstring _appName;
-    HANDLE _processHandle = nullptr;
-
-    static std::list<CommandHistory> s_historyLists;
-
-public:
-    DWORD Flags = 0;
-    Index LastDisplayed = 0;
-
-#ifdef UNIT_TESTING
-    static void s_ClearHistoryListStorage();
-    friend class HistoryTests;
-#endif
-};
-
-DEFINE_ENUM_FLAG_OPERATORS(CommandHistory::MatchOptions);
+#pragma once
+
+class CommandHistory
+{
+public:
+    using Index = int32_t;
+    static constexpr Index IndexMax = INT32_MAX;
+
+    // CommandHistory Flags
+    static constexpr int CLE_ALLOCATED = 0x00000001;
+    static constexpr int CLE_RESET = 0x00000002;
+
+    static CommandHistory* s_Allocate(const std::wstring_view appName, const HANDLE processHandle);
+    static CommandHistory* s_Find(const HANDLE processHandle);
+    static CommandHistory* s_FindByExe(const std::wstring_view appName);
+    static void s_ReallocExeToFront(const std::wstring_view appName, const size_t commands);
+    static void s_Free(const HANDLE processHandle);
+    static void s_ResizeAll(const size_t commands);
+    static size_t s_CountOfHistories();
+
+    enum class MatchOptions
+    {
+        None = 0x0,
+        ExactMatch = 0x1,
+        JustLooking = 0x2
+    };
+
+    enum class SearchDirection
+    {
+        Previous,
+        Next
+    };
+
+    bool FindMatchingCommand(const std::wstring_view command,
+                             const Index startingIndex,
+                             Index& indexFound,
+                             const MatchOptions options);
+    bool IsAppNameMatch(const std::wstring_view other) const;
+
+    [[nodiscard]] HRESULT Add(const std::wstring_view command,
+                              const bool suppressDuplicates);
+
+    std::wstring_view Retrieve(const SearchDirection searchDirection);
+    std::wstring_view RetrieveNth(Index index);
+
+    Index GetNumberOfCommands() const;
+    std::wstring_view GetNth(Index index) const;
+    const std::vector<std::wstring>& GetCommands() const noexcept;
+
+    void Realloc(Index commands);
+    void Empty();
+
+    std::wstring Remove(const Index iDel);
+
+    bool AtFirstCommand() const;
+    bool AtLastCommand() const;
+
+    std::wstring_view GetLastCommand() const;
+
+    void Swap(const Index indexA, const Index indexB);
+
+    std::wstring_view CycleCommandHistory(const SearchDirection searchDirection);
+
+private:
+    void _Reset();
+
+    // _Next and _Prev go to the next and prev command
+    // _Inc  and _Dec go to the next and prev slots
+    // Don't get the two confused - it matters when the cmd history is not full!
+    void _Prev(Index& ind) const;
+    void _Next(Index& ind) const;
+    void _Dec(Index& ind) const;
+    void _Inc(Index& ind) const;
+
+    // NOTE: In conhost v1 this used to be a circular buffer because removal at the
+    // start is a very common operation. It seems this was lost in the C++ refactor.
+    std::vector<std::wstring> _commands;
+    Index _maxCommands = 0;
+
+    std::wstring _appName;
+    HANDLE _processHandle = nullptr;
+
+    static std::list<CommandHistory> s_historyLists;
+
+public:
+    DWORD Flags = 0;
+    Index LastDisplayed = 0;
+
+#ifdef UNIT_TESTING
+    static void s_ClearHistoryListStorage();
+    friend class HistoryTests;
+#endif
+};
+
+DEFINE_ENUM_FLAG_OPERATORS(CommandHistory::MatchOptions);