Add date builtin

6 files changed, 492 insertions, 0 deletions

diff --git a/libbutl/builtin-options.cxx b/libbutl/builtin-options.cxx
index 0e66a21..2848eea 100644
--- a/libbutl/builtin-options.cxx
+++ b/libbutl/builtin-options.cxx
@@ -895,6 +895,274 @@ namespace butl
     return r;
   }
 
+  // date_options
+  //
+
+  date_options::
+  date_options ()
+  : utc_ ()
+  {
+  }
+
+  bool date_options::
+  parse (int& argc,
+         char** argv,
+         bool erase,
+         ::butl::cli::unknown_mode opt,
+         ::butl::cli::unknown_mode arg)
+  {
+    ::butl::cli::argv_scanner s (argc, argv, erase);
+    bool r = _parse (s, opt, arg);
+    return r;
+  }
+
+  bool date_options::
+  parse (int start,
+         int& argc,
+         char** argv,
+         bool erase,
+         ::butl::cli::unknown_mode opt,
+         ::butl::cli::unknown_mode arg)
+  {
+    ::butl::cli::argv_scanner s (start, argc, argv, erase);
+    bool r = _parse (s, opt, arg);
+    return r;
+  }
+
+  bool date_options::
+  parse (int& argc,
+         char** argv,
+         int& end,
+         bool erase,
+         ::butl::cli::unknown_mode opt,
+         ::butl::cli::unknown_mode arg)
+  {
+    ::butl::cli::argv_scanner s (argc, argv, erase);
+    bool r = _parse (s, opt, arg);
+    end = s.end ();
+    return r;
+  }
+
+  bool date_options::
+  parse (int start,
+         int& argc,
+         char** argv,
+         int& end,
+         bool erase,
+         ::butl::cli::unknown_mode opt,
+         ::butl::cli::unknown_mode arg)
+  {
+    ::butl::cli::argv_scanner s (start, argc, argv, erase);
+    bool r = _parse (s, opt, arg);
+    end = s.end ();
+    return r;
+  }
+
+  bool date_options::
+  parse (::butl::cli::scanner& s,
+         ::butl::cli::unknown_mode opt,
+         ::butl::cli::unknown_mode arg)
+  {
+    bool r = _parse (s, opt, arg);
+    return r;
+  }
+
+  typedef
+  std::map<std::string, void (*) (date_options&, ::butl::cli::scanner&)>
+  _cli_date_options_map;
+
+  static _cli_date_options_map _cli_date_options_map_;
+
+  struct _cli_date_options_map_init
+  {
+    _cli_date_options_map_init ()
+    {
+      _cli_date_options_map_["--utc"] =
+      &::butl::cli::thunk< date_options, bool, &date_options::utc_ >;
+      _cli_date_options_map_["-u"] =
+      &::butl::cli::thunk< date_options, bool, &date_options::utc_ >;
+    }
+  };
+
+  static _cli_date_options_map_init _cli_date_options_map_init_;
+
+  bool date_options::
+  _parse (const char* o, ::butl::cli::scanner& s)
+  {
+    _cli_date_options_map::const_iterator i (_cli_date_options_map_.find (o));
+
+    if (i != _cli_date_options_map_.end ())
+    {
+      (*(i->second)) (*this, s);
+      return true;
+    }
+
+    return false;
+  }
+
+  bool date_options::
+  _parse (::butl::cli::scanner& s,
+          ::butl::cli::unknown_mode opt_mode,
+          ::butl::cli::unknown_mode arg_mode)
+  {
+    // Can't skip combined flags (--no-combined-flags).
+    //
+    assert (opt_mode != ::butl::cli::unknown_mode::skip);
+
+    bool r = false;
+    bool opt = true;
+
+    while (s.more ())
+    {
+      const char* o = s.peek ();
+
+      if (std::strcmp (o, "--") == 0)
+      {
+        opt = false;
+      }
+
+      if (opt)
+      {
+        if (_parse (o, s))
+        {
+          r = true;
+          continue;
+        }
+
+        if (std::strncmp (o, "-", 1) == 0 && o[1] != '\0')
+        {
+          // Handle combined option values.
+          //
+          std::string co;
+          if (const char* v = std::strchr (o, '='))
+          {
+            co.assign (o, 0, v - o);
+            ++v;
+
+            int ac (2);
+            char* av[] =
+            {
+              const_cast<char*> (co.c_str ()),
+              const_cast<char*> (v)
+            };
+
+            ::butl::cli::argv_scanner ns (0, ac, av);
+
+            if (_parse (co.c_str (), ns))
+            {
+              // Parsed the option but not its value?
+              //
+              if (ns.end () != 2)
+                throw ::butl::cli::invalid_value (co, v);
+
+              s.next ();
+              r = true;
+              continue;
+            }
+            else
+            {
+              // Set the unknown option and fall through.
+              //
+              o = co.c_str ();
+            }
+          }
+
+          // Handle combined flags.
+          //
+          char cf[3];
+          {
+            const char* p = o + 1;
+            for (; *p != '\0'; ++p)
+            {
+              if (!((*p >= 'a' && *p <= 'z') ||
+                    (*p >= 'A' && *p <= 'Z') ||
+                    (*p >= '0' && *p <= '9')))
+                break;
+            }
+
+            if (*p == '\0')
+            {
+              for (p = o + 1; *p != '\0'; ++p)
+              {
+                std::strcpy (cf, "-");
+                cf[1] = *p;
+                cf[2] = '\0';
+
+                int ac (1);
+                char* av[] =
+                {
+                  cf
+                };
+
+                ::butl::cli::argv_scanner ns (0, ac, av);
+
+                if (!_parse (cf, ns))
+                  break;
+              }
+
+              if (*p == '\0')
+              {
+                // All handled.
+                //
+                s.next ();
+                r = true;
+                continue;
+              }
+              else
+              {
+                // Set the unknown option and fall through.
+                //
+                o = cf;
+              }
+            }
+          }
+
+          switch (opt_mode)
+          {
+            case ::butl::cli::unknown_mode::skip:
+            {
+              s.skip ();
+              r = true;
+              continue;
+            }
+            case ::butl::cli::unknown_mode::stop:
+            {
+              break;
+            }
+            case ::butl::cli::unknown_mode::fail:
+            {
+              throw ::butl::cli::unknown_option (o);
+            }
+          }
+
+          break;
+        }
+      }
+
+      switch (arg_mode)
+      {
+        case ::butl::cli::unknown_mode::skip:
+        {
+          s.skip ();
+          r = true;
+          continue;
+        }
+        case ::butl::cli::unknown_mode::stop:
+        {
+          break;
+        }
+        case ::butl::cli::unknown_mode::fail:
+        {
+          throw ::butl::cli::unknown_argument (o);
+        }
+      }
+
+      break;
+    }
+
+    return r;
+  }
+
   // ln_options
   //
 
diff --git a/libbutl/builtin-options.hxx b/libbutl/builtin-options.hxx
index 99d955d..b389298 100644
--- a/libbutl/builtin-options.hxx
+++ b/libbutl/builtin-options.hxx
@@ -390,6 +390,71 @@ namespace butl
     bool preserve_;
   };
 
+  class date_options
+  {
+    public:
+    date_options ();
+
+    // Return true if anything has been parsed.
+    //
+    bool
+    parse (int& argc,
+           char** argv,
+           bool erase = false,
+           ::butl::cli::unknown_mode option = ::butl::cli::unknown_mode::fail,
+           ::butl::cli::unknown_mode argument = ::butl::cli::unknown_mode::stop);
+
+    bool
+    parse (int start,
+           int& argc,
+           char** argv,
+           bool erase = false,
+           ::butl::cli::unknown_mode option = ::butl::cli::unknown_mode::fail,
+           ::butl::cli::unknown_mode argument = ::butl::cli::unknown_mode::stop);
+
+    bool
+    parse (int& argc,
+           char** argv,
+           int& end,
+           bool erase = false,
+           ::butl::cli::unknown_mode option = ::butl::cli::unknown_mode::fail,
+           ::butl::cli::unknown_mode argument = ::butl::cli::unknown_mode::stop);
+
+    bool
+    parse (int start,
+           int& argc,
+           char** argv,
+           int& end,
+           bool erase = false,
+           ::butl::cli::unknown_mode option = ::butl::cli::unknown_mode::fail,
+           ::butl::cli::unknown_mode argument = ::butl::cli::unknown_mode::stop);
+
+    bool
+    parse (::butl::cli::scanner&,
+           ::butl::cli::unknown_mode option = ::butl::cli::unknown_mode::fail,
+           ::butl::cli::unknown_mode argument = ::butl::cli::unknown_mode::stop);
+
+    // Option accessors.
+    //
+    const bool&
+    utc () const;
+
+    // Implementation details.
+    //
+    protected:
+    bool
+    _parse (const char*, ::butl::cli::scanner&);
+
+    private:
+    bool
+    _parse (::butl::cli::scanner&,
+            ::butl::cli::unknown_mode option,
+            ::butl::cli::unknown_mode argument);
+
+    public:
+    bool utc_;
+  };
+
   class ln_options
   {
     public:
diff --git a/libbutl/builtin-options.ixx b/libbutl/builtin-options.ixx
index b2275c6..f10f82d 100644
--- a/libbutl/builtin-options.ixx
+++ b/libbutl/builtin-options.ixx
@@ -166,6 +166,15 @@ namespace butl
     return this->preserve_;
   }
 
+  // date_options
+  //
+
+  inline const bool& date_options::
+  utc () const
+  {
+    return this->utc_;
+  }
+
   // ln_options
   //
 
diff --git a/libbutl/builtin.cli b/libbutl/builtin.cli
index 5aeb675..adc47fa 100644
--- a/libbutl/builtin.cli
+++ b/libbutl/builtin.cli
@@ -29,6 +29,11 @@ namespace butl
     bool --preserve|-p;
   };
 
+  class date_options
+  {
+    bool --utc|-u;
+  };
+
   class ln_options
   {
     bool --symbolic|-s;
diff --git a/libbutl/builtin.cxx b/libbutl/builtin.cxx
index fe74b05..940e5a0 100644
--- a/libbutl/builtin.cxx
+++ b/libbutl/builtin.cxx
@@ -680,6 +680,102 @@ namespace butl
     return 1;
   }
 
+  // date [-u|--utc] [+<format>]
+  //
+  // Note: must be executed asynchronously.
+  //
+  static uint8_t
+  date (const strings& args,
+        auto_fd in, auto_fd out, auto_fd err,
+        const dir_path&,
+        const builtin_callbacks& cbs) noexcept
+  try
+  {
+    uint8_t r (1);
+    ofdstream cerr (err != nullfd ? move (err) : fddup (stderr_fd ()));
+
+    auto error = [&cerr] (bool fail = false)
+    {
+      return error_record (cerr, fail, "date");
+    };
+
+    auto fail = [&error] () {return error (true /* fail */);};
+
+    try
+    {
+      in.close ();
+      ofdstream cout (out != nullfd ? move (out) : fddup (stdout_fd ()));
+
+      // Parse arguments.
+      //
+      cli::vector_scanner scan (args);
+
+      date_options ops (
+        parse<date_options> (scan, args, cbs.parse_option, fail));
+
+      const char* format;
+
+      string fs; // Storage.
+      if (scan.more ())
+      {
+        fs = scan.next ();
+        if (fs[0] != '+')
+          fail () << "date format argument must start with '+'";
+
+        format = fs.c_str () + 1;
+      }
+      else
+        format = "%a %b %e %H:%M:%S %Z %Y";
+
+      if (scan.more ())
+        fail () << "unexpected argument '" << scan.next () << "'";
+
+      // Print the current time.
+      //
+      try
+      {
+        to_stream (cout,
+                   system_clock::now (),
+                   format,
+                   false /* special */,
+                   !ops.utc ());
+      }
+      catch (const system_error& e)
+      {
+        fail () << "unable to print time in format '" << format << "': " << e;
+      }
+
+      cout << '\n';
+      cout.close ();
+      r = 0;
+    }
+    // Can be thrown while closing cin or creating, writing to, or closing
+    // cout.
+    //
+    catch (const io_error& e)
+    {
+      error () << e;
+    }
+    catch (const failed&)
+    {
+      // Diagnostics has already been issued.
+    }
+    catch (const cli::exception& e)
+    {
+      error () << e;
+    }
+
+    cerr.close ();
+    return r;
+  }
+  // In particular, handles io_error exception potentially thrown while
+  // creating, writing to, or closing cerr.
+  //
+  catch (const std::exception&)
+  {
+    return 1;
+  }
+
   // echo <string>...
   //
   // Note: must be executed asynchronously.
@@ -2111,6 +2207,7 @@ namespace butl
   {
     {"cat",   {&async_impl<&cat>,  2}},
     {"cp",    {&sync_impl<&cp>,    2}},
+    {"date",  {&async_impl<&date>, 2}},
     {"diff",  {nullptr,            2}},
     {"echo",  {&async_impl<&echo>, 2}},
     {"false", {&false_,            0}},
diff --git a/tests/builtin/date.testscript b/tests/builtin/date.testscript
new file mode 100644
index 0000000..0b466c3
--- /dev/null
+++ b/tests/builtin/date.testscript
@@ -0,0 +1,48 @@
+# file      : tests/builtin/date.testscript
+# license   : MIT; see accompanying LICENSE file
+
+test.arguments = "date"
+
+: timezone
+:
+: Here we also make sure that the dates are not only verified but can also be
+: seen if running with the verbosity level 2 and up, which helps with
+: troubleshooting.
+:
+{
+  $* | set local;
+  $* --utc | set utc;
+
+  echo "local: $local"  >~'%local: \S+ \S+ .+ \d{2}:\d{2}:\d{2} .+ \d+%';
+  echo "utc: $utc" >~'%utc: \S+ \S+ .+ \d{2}:\d{2}:\d{2} .+ \d+%'
+}
+
+: format
+:
+{
+  : non-empty
+  :
+  $* '+%Y-%m-%d %H:%M:%S%[.N]' >~'%\d+-\d{2}-\d{2} \d{2}:\d{2}:\d{2}\.\d{9}%'
+
+  : empty
+  :
+  $* '+' >''
+
+  : no-leading-plus
+  :
+  $* '%Y-%m-%d %H:%M:%S' 2>>EOE!= 0
+    date: date format argument must start with '+'
+    EOE
+}
+
+: unknown-option
+:
+$* -d '+%Y-%m-%d %H:%M:%S' 2>>EOE!= 0
+  date: unknown option '-d'
+  EOE
+
+: unexpected-arg
+:
+$* '+%Y-%m-%d %H:%M:%S' '%Y' 2>>EOE!= 0
+  date: unexpected argument '%Y'
+  EOE