Method DataTypeApplyFromText

src/external/imgui/imgui_widgets.cpp:2091–2131

User can input math operators (e.g. +100) to edit a numerical values. NB: This is _not_ a full expression evaluator. We should probably add one and replace this dumb mess..

// User can input math operators (e.g. +100) to edit a numerical values.
// NB: This is _not_ a full expression evaluator. We should probably add one and replace this dumb mess..
bool ImGui::DataTypeApplyFromText(const char* buf, ImGuiDataType data_type, void* p_data, const char* format)
{
    while (ImCharIsBlankA(*buf))
        buf++;
    if (!buf[0])
        return false;

    // Copy the value in an opaque buffer so we can compare at the end of the function if it changed at all.
    const ImGuiDataTypeInfo* type_info = DataTypeGetInfo(data_type);
    ImGuiDataTypeTempStorage data_backup;
    memcpy(&data_backup, p_data, type_info->Size);

    // Sanitize format
    // - For float/double we have to ignore format with precision (e.g. "%.2f") because sscanf doesn't take them in, so force them into %f and %lf
    // - In theory could treat empty format as using default, but this would only cover rare/bizarre case of using InputScalar() + integer + format string without %.
    char format_sanitized[32];
    if (data_type == ImGuiDataType_Float || data_type == ImGuiDataType_Double)
        format = type_info->ScanFmt;
    else
        format = ImParseFormatSanitizeForScanning(format, format_sanitized, IM_ARRAYSIZE(format_sanitized));

    // Small types need a 32-bit buffer to receive the result from scanf()
    int v32 = 0;
    if (sscanf(buf, format, type_info->Size >= 4 ? p_data : &v32) < 1)
        return false;
    if (type_info->Size < 4)
    {
        if (data_type == ImGuiDataType_S8)
            *(ImS8*)p_data = (ImS8)ImClamp(v32, (int)IM_S8_MIN, (int)IM_S8_MAX);
        else if (data_type == ImGuiDataType_U8)
            *(ImU8*)p_data = (ImU8)ImClamp(v32, (int)IM_U8_MIN, (int)IM_U8_MAX);
        else if (data_type == ImGuiDataType_S16)
            *(ImS16*)p_data = (ImS16)ImClamp(v32, (int)IM_S16_MIN, (int)IM_S16_MAX);
        else if (data_type == ImGuiDataType_U16)
            *(ImU16*)p_data = (ImU16)ImClamp(v32, (int)IM_U16_MIN, (int)IM_U16_MAX);
        else
            IM_ASSERT(0);
    }

    return memcmp(&data_backup, p_data, type_info->Size) != 0;
}

template<typename T>
static int DataTypeCompareT(const T* lhs, const T* rhs)