Colorize vswhere output (#244)

* Refactor formatters to consolidate arguments

* Colorize output by default unless piped

* Opt into color and add tests

Fails in PowerShell if you do something like `[xml](vswhere -format xml)` if color is enabled, so had to add -color switch. Not ideal since it otherwise disables color when piped, but still easier to read if colorized explicitly.

* Enable colors by default, add -nocolor switch

* Resolve PR feedback

* Ensure console is initialized

Could simply call Initialize wherever it needs to be called, but would rather be explicit.

src/vswhere.lib/CommandArgs.cpp

@@ -161,6 +161,10 @@ void CommandArgs::Parse(_In_ vector<CommandParser::Token> args)
 
             m_find = ParseArgument(it, args.end(), arg);
         }
+        else if (ArgumentEquals(arg.Value, L"nocolor"))
+        {
+            m_nocolor = true;
+        }
         else if (ArgumentEquals(arg.Value, L"nologo"))
         {
             m_nologo = true;

src/vswhere.lib/CommandArgs.h

@@ -17,6 +17,7 @@ class CommandArgs
         m_legacy(false),
         m_prerelease(false),
         m_includePackages(false),
+        m_nocolor(false),
         m_nologo(false),
         m_utf8(false),
         m_help(false)
@@ -39,6 +40,7 @@ class CommandArgs
         m_property(obj.m_property),
         m_includePackages(obj.m_includePackages),
         m_find(obj.m_find),
+        m_nocolor(obj.m_nocolor),
         m_nologo(obj.m_nologo),
         m_utf8(obj.m_utf8),
         m_help(obj.m_help)
@@ -130,6 +132,11 @@ class CommandArgs
         return m_find;
     }
 
+    const bool get_Color() const noexcept
+    {
+        return !m_nocolor;
+    }
+
     const bool get_Logo() const noexcept
     {
         return !m_nologo;
@@ -172,6 +179,7 @@ class CommandArgs
     std::wstring m_property;
     bool m_includePackages;
     std::wstring m_find;
+    bool m_nocolor;
     bool m_nologo;
     bool m_utf8;
     bool m_help;

src/vswhere.lib/Console.cpp

@@ -27,10 +27,31 @@ void Console::Initialize() noexcept
             ::setlocale(LC_CTYPE, sz);
         }
 
+        m_fColorSupported = IsVirtualTerminal(stdout);
         m_fInitialized = true;
     }
 }
 
+LPCWSTR Console::Color(_In_ LPCWSTR wzColor) const
+{
+    if (IsColorSupported())
+    {
+        return wzColor;
+    }
+
+    return L"";
+}
+
+LPCWSTR Console::ResetColor() const
+{
+    if (IsColorSupported())
+    {
+        return L"\033[0m";
+    }
+
+    return L"";
+}
+
 void __cdecl Console::Write(_In_ LPCWSTR wzFormat, ...)
 {
     va_list args;
@@ -66,12 +87,11 @@ void __cdecl Console::WriteLine(_In_ const std::wstring& value)
 
 void Console::Write(_In_ LPCWSTR wzFormat, va_list args)
 {
-    Initialize();
-
+    _ASSERTE(m_fInitialized);
     ::_vwprintf_p(wzFormat, args);
 }
 
-bool Console::IsConsole(_In_ FILE* f) const noexcept
+bool Console::IsConsole(_In_ FILE* f) noexcept
 {
     auto fno = ::_fileno(f);
     auto hFile = (HANDLE)::_get_osfhandle(fno);
@@ -92,3 +112,20 @@ bool Console::IsConsole(_In_ FILE* f) const noexcept
 
     return true;
 }
+
+bool Console::IsVirtualTerminal(_In_ FILE* f) noexcept
+{
+    auto fno = ::_fileno(f);
+    auto hFile = (HANDLE)::_get_osfhandle(fno);
+
+    DWORD dwMode;
+    if (::GetConsoleMode(hFile, &dwMode))
+    {
+        // Defined in newer SDK but can try to enable on older platforms.
+        const DWORD ENABLE_VIRTUAL_TERMINAL_PROCESSING = 0x4;
+
+        return 0 != ::SetConsoleMode(hFile, dwMode | ENABLE_VIRTUAL_TERMINAL_PROCESSING);
+    }
+
+    return false;
+}

src/vswhere.lib/Console.h

@@ -10,28 +10,48 @@ class Console
 public:
     Console(_In_ const CommandArgs& args) :
         m_args(args),
-        m_fInitialized(false)
+        m_fInitialized(false),
+        m_fColorSupported(false)
     {
     }
 
     Console(_In_ const Console& obj) :
         m_args(obj.m_args),
-        m_fInitialized(obj.m_fInitialized)
+        m_fInitialized(obj.m_fInitialized),
+        m_fColorSupported(obj.m_fColorSupported)
     {
     }
 
+    virtual void Initialize() noexcept;
+
+    LPCWSTR Color(_In_ LPCWSTR wzColor) const;
+    LPCWSTR ResetColor() const;
+
     void __cdecl Write(_In_ LPCWSTR wzFormat, ...);
     void __cdecl Write(_In_ const std::wstring& value);
     void __cdecl WriteLine(_In_ LPCWSTR wzFormat = NULL, ...);
     void __cdecl WriteLine(_In_ const std::wstring& value);
 
+    virtual bool IsColorSupported() const
+    {
+        _ASSERTE(m_fInitialized);
+        return m_fColorSupported && m_args.get_Color();
+    }
+
 protected:
-    virtual void Initialize() noexcept;
     virtual void Write(_In_ LPCWSTR wzFormat, va_list args);
 
+    const CommandArgs& Args() const noexcept
+    {
+        return m_args;
+    }
+
+    bool m_fInitialized;
+
 private:
-    bool IsConsole(_In_ FILE* f) const noexcept;
+    bool static IsConsole(_In_ FILE* f) noexcept;
+    bool static IsVirtualTerminal(_In_ FILE* f) noexcept;
 
     const CommandArgs& m_args;
-    bool m_fInitialized;
+    bool m_fColorSupported;
 };