Class ExampleAppConsole

src/third-party/imgui/imgui_demo.cpp:6459–6516

// Demonstrate creating a simple console window, with scrolling, filtering, completion and history.
// For the console example, we are using a more C++ like approach of declaring a class to hold both data and functions.
struct ExampleAppConsole
{
    char                  InputBuf[256];
    ImVector<char*>       Items;
    ImVector<const char*> Commands;
    ImVector<char*>       History;
    int                   HistoryPos;    // -1: new line, 0..History.Size-1 browsing history.
    ImGuiTextFilter       Filter;
    bool                  AutoScroll;
    bool                  ScrollToBottom;

    ExampleAppConsole()
    {
        IMGUI_DEMO_MARKER("Examples/Console");
        ClearLog();
        memset(InputBuf, 0, sizeof(InputBuf));
        HistoryPos = -1;

        // "CLASSIFY" is here to provide the test case where "C"+[tab] completes to "CL" and display multiple matches.
        Commands.push_back("HELP");
        Commands.push_back("HISTORY");
        Commands.push_back("CLEAR");
        Commands.push_back("CLASSIFY");
        AutoScroll = true;
        ScrollToBottom = false;
        AddLog("Welcome to Dear ImGui!");
    }
    ~ExampleAppConsole()
    {
        ClearLog();
        for (int i = 0; i < History.Size; i++)
            free(History[i]);
    }

    // Portable helpers
    static int   Stricmp(const char* s1, const char* s2)         { int d; while ((d = toupper(*s2) - toupper(*s1)) == 0 && *s1) { s1++; s2++; } return d; }
    static int   Strnicmp(const char* s1, const char* s2, int n) { int d = 0; while (n > 0 && (d = toupper(*s2) - toupper(*s1)) == 0 && *s1) { s1++; s2++; n--; } return d; }
    static char* Strdup(const char* s)                           { IM_ASSERT(s); size_t len = strlen(s) + 1; void* buf = malloc(len); IM_ASSERT(buf); return (char*)memcpy(buf, (const void*)s, len); }
    static void  Strtrim(char* s)                                { char* str_end = s + strlen(s); while (str_end > s && str_end[-1] == ' ') str_end--; *str_end = 0; }

    void    ClearLog()
    {
        for (int i = 0; i < Items.Size; i++)
            free(Items[i]);
        Items.clear();
    }

    void    AddLog(const char* fmt, ...) IM_FMTARGS(2)
    {
        // FIXME-OPT
        char buf[1024];
        va_list args;
        va_start(args, fmt);
        vsnprintf(buf, IM_ARRAYSIZE(buf), fmt, args);
        buf[IM_ARRAYSIZE(buf)-1] = 0;
        va_end(args);
        Items.push_back(Strdup(buf));
    }