Update fmt to 8.0.0; drop support for wchar

Adds some boost-nowide headers to assist in
UTF-8/16 conversion for Windows API.

include/nowide/args.hpp

@@ -0,0 +1,194 @@
+//
+//  Copyright (c) 2012 Artyom Beilis (Tonkikh)
+//
+//  Distributed under the Boost Software License, Version 1.0. (See
+//  accompanying file LICENSE or copy at
+//  http://www.boost.org/LICENSE_1_0.txt)
+//
+#ifndef NOWIDE_ARGS_HPP_INCLUDED
+#define NOWIDE_ARGS_HPP_INCLUDED
+
+#include <nowide/config.hpp>
+#ifdef NOWIDE_WINDOWS
+#include <nowide/stackstring.hpp>
+#include <nowide/windows.hpp>
+#include <stdexcept>
+#include <vector>
+#endif
+
+namespace nowide {
+#if !defined(NOWIDE_WINDOWS) && !defined(NOWIDE_DOXYGEN)
+    class args
+    {
+    public:
+        args(int&, char**&)
+        {}
+        args(int&, char**&, char**&)
+        {}
+    };
+
+#else
+
+    ///
+    /// \brief \c args is a class that temporarily replaces standard main() function arguments with their
+    /// equal, but UTF-8 encoded values under Microsoft Windows for the lifetime of the instance.
+    ///
+    /// The class uses \c GetCommandLineW(), \c CommandLineToArgvW() and \c GetEnvironmentStringsW()
+    /// in order to obtain Unicode-encoded values.
+    /// It does not relate to actual values of argc, argv and env under Windows.
+    ///
+    /// It restores the original values in its destructor (usually at the end of the \c main function).
+    ///
+    /// If any of the system calls fails, an exception of type std::runtime_error will be thrown
+    /// and argc, argv, env remain unchanged.
+    ///
+    /// \note The class owns the memory of the newly allocated strings.
+    /// So you need to keep it alive as long as you use the values.
+    ///
+    /// Usage:
+    /// \code
+    /// int main(int argc, char** argv, char** env) {
+    ///   nowide::args _(argc, argv, env); // Note the _ as a "don't care" name for the instance
+    ///   // Use argv and env as usual, they are now UTF-8 encoded on Windows
+    ///   return 0; // Memory held by args is released
+    /// }
+    /// \endcode
+    class args
+    {
+    public:
+        ///
+        /// Fix command line arguments
+        ///
+        args(int& argc, char**& argv) :
+            old_argc_(argc), old_argv_(argv), old_env_(0), old_argc_ptr_(&argc), old_argv_ptr_(&argv), old_env_ptr_(0)
+        {
+            fix_args(argc, argv);
+        }
+        ///
+        /// Fix command line arguments and environment
+        ///
+        args(int& argc, char**& argv, char**& env) :
+            old_argc_(argc), old_argv_(argv), old_env_(env), old_argc_ptr_(&argc), old_argv_ptr_(&argv),
+            old_env_ptr_(&env)
+        {
+            fix_args(argc, argv);
+            fix_env(env);
+        }
+        ///
+        /// Restore original argc, argv, env values, if changed
+        ///
+        ~args()
+        {
+            if(old_argc_ptr_)
+                *old_argc_ptr_ = old_argc_;
+            if(old_argv_ptr_)
+                *old_argv_ptr_ = old_argv_;
+            if(old_env_ptr_)
+                *old_env_ptr_ = old_env_;
+        }
+
+    private:
+        class wargv_ptr
+        {
+            wchar_t** p;
+            int argc;
+
+        public:
+            wargv_ptr()
+            {
+                p = CommandLineToArgvW(GetCommandLineW(), &argc);
+            }
+            ~wargv_ptr()
+            {
+                if(p)
+                    LocalFree(p);
+            }
+            wargv_ptr(const wargv_ptr&) = delete;
+            wargv_ptr& operator=(const wargv_ptr&) = delete;
+
+            int size() const
+            {
+                return argc;
+            }
+            operator bool() const
+            {
+                return p != NULL;
+            }
+            const wchar_t* operator[](size_t i) const
+            {
+                return p[i];
+            }
+        };
+        class wenv_ptr
+        {
+            wchar_t* p;
+
+        public:
+            wenv_ptr() : p(GetEnvironmentStringsW())
+            {}
+            ~wenv_ptr()
+            {
+                if(p)
+                    FreeEnvironmentStringsW(p);
+            }
+            wenv_ptr(const wenv_ptr&) = delete;
+            wenv_ptr& operator=(const wenv_ptr&) = delete;
+
+            operator const wchar_t*() const
+            {
+                return p;
+            }
+        };
+
+        void fix_args(int& argc, char**& argv)
+        {
+            const wargv_ptr wargv;
+            if(!wargv)
+                throw std::runtime_error("Could not get command line!");
+            args_.resize(wargv.size() + 1, 0);
+            arg_values_.resize(wargv.size());
+            for(int i = 0; i < wargv.size(); i++)
+                args_[i] = arg_values_[i].convert(wargv[i]);
+            argc = wargv.size();
+            argv = &args_[0];
+        }
+        void fix_env(char**& env)
+        {
+            const wenv_ptr wstrings;
+            if(!wstrings)
+                throw std::runtime_error("Could not get environment strings!");
+            const wchar_t* wstrings_end = 0;
+            int count = 0;
+            for(wstrings_end = wstrings; *wstrings_end; wstrings_end += wcslen(wstrings_end) + 1)
+                count++;
+            env_.convert(wstrings, wstrings_end);
+            envp_.resize(count + 1, 0);
+            char* p = env_.get();
+            int pos = 0;
+            for(int i = 0; i < count; i++)
+            {
+                if(*p != '=')
+                    envp_[pos++] = p;
+                p += strlen(p) + 1;
+            }
+            env = &envp_[0];
+        }
+
+        std::vector<char*> args_;
+        std::vector<short_stackstring> arg_values_;
+        stackstring env_;
+        std::vector<char*> envp_;
+
+        int old_argc_;
+        char** old_argv_;
+        char** old_env_;
+
+        int* old_argc_ptr_;
+        char*** old_argv_ptr_;
+        char*** old_env_ptr_;
+    };
+
+#endif
+
+} // namespace nowide
+#endif