Add initial -output support, see hsutter#48

Author: hsutter

source/common.h

@@ -270,18 +270,20 @@ class cmdline_processor
  };
  std::vector<arg> args;
 
- using callback = void (*)();
+ using callback0 = void (*)();
+ using callback1 = void (*)(std::string const&);
  struct flag
  {
  int group = 0;
  std::string name;
  int unique_prefix = 0;
  std::string description;
- callback handler;
+ callback0 handler0;
+ callback1 handler1;
  std::string synonym;
 
- flag(int g, std::string_view n, std::string_view d, callback h, std::string_view s)
- : group{g}, name{n}, description{d}, handler{h}, synonym{s}
+ flag(int g, std::string_view n, std::string_view d, callback0 h0, callback1 h1, std::string_view s)
+ : group{g}, name{n}, description{d}, handler0{h0}, handler1{h1}, synonym{s}
  { }
  };
  std::vector<flag> flags;
@@ -315,42 +317,59 @@ class cmdline_processor
  }
 
  // Look for matches
- for (auto& arg : args)
+ for (auto arg = args.begin(); arg != args.end(); ++arg)
  {
  // The arg should never be empty, but we're going to do a [0]
  // subscript next so we should either check or assert
- if (arg.text.empty()) {
+ if (arg->text.empty()) {
  continue;
  }
 
  // Provide a way to ignore the rest of the command line
  // for the purpose of looking for switches
- if (arg.text == "--") {
- arg.pos = processed;
+ if (arg->text == "--") {
+ arg->pos = processed;
  break;
  }
 
  for (auto& flag : flags) {
- auto length_to_match = std::max(flag.unique_prefix, as<int>(arg.text.length())-1);
+ auto length_to_match = std::max(flag.unique_prefix, as<int>(arg->text.length())-1);
  // Allow a switch to start with either - or /
- if (arg.text.starts_with("-" + flag.name.substr(0, length_to_match)) ||
- arg.text.starts_with("/" + flag.name.substr(0, length_to_match)) ||
- arg.text == "-" + flag.synonym ||
- arg.text == "/" + flag.synonym
+ if (arg->text.starts_with("-" + flag.name.substr(0, length_to_match)) ||
+ arg->text.starts_with("/" + flag.name.substr(0, length_to_match)) ||
+ arg->text == "-" + flag.synonym ||
+ arg->text == "/" + flag.synonym
  )
  {
- flag.handler();
- arg.pos = processed;
+ assert(flag.handler0 || flag.handler1);
+
+ // If this is a standalone switch, just process it
+ if (flag.handler0) {
+ flag.handler0();
+ }
+
+ // Else this is a switch that takes the next arg as its value, so pass that
+ else {
+ if (arg+1 == args.end()) {
+ print("Missing argument to option " + arg->text + " (try -help)\n");
+ help_requested = true;
+ }
+ arg->pos = processed;
+ ++arg; // move to next argument, which is the argument to this switch
+ flag.handler1(arg->text);
+ }
+
+ arg->pos = processed;
  break;
  }
  }
 
  // For now comment this out to try leaving unmatched switches alone, so that
  // Unix absolute filenames work... and in case an absolute filename collides
  // with a legit switch name, also added "--" above... let's see how this works
- //if (arg.pos != processed && (arg.text.starts_with("-") || arg.text.starts_with("/"))) {
- // arg.pos = processed;
- // print("Unknown option: " + arg.text + " (try -help)\n");
+ //if (arg->pos != processed && (arg->text.starts_with("-") || arg->text.starts_with("/"))) {
+ // arg->pos = processed;
+ // print("Unknown option: " + arg->text + " (try -help)\n");
  // help_requested = true;
  //}
  }
@@ -391,14 +410,14 @@ class cmdline_processor
  }
  }
 
- auto add_flag(int group, std::string_view name, std::string_view description, callback handler, std::string_view synonym) {
- flags.emplace_back( group, name, description, handler, synonym );
+ auto add_flag(int group, std::string_view name, std::string_view description, callback0 handler0, callback1 handler1, std::string_view synonym) {
+ flags.emplace_back( group, name, description, handler0, handler1, synonym );
  if (max_flag_length < std::ssize(name)) {
  max_flag_length = std::ssize(name);
  }
  }
  struct register_flag {
- register_flag(int group, std::string_view name, std::string_view description, callback handler, std::string_view synonym = {});
+ register_flag(int group, std::string_view name, std::string_view description, callback0 handler0, callback1 handler1 = nullptr, std::string_view synonym = {});
  };
 
  auto set_args(int argc, char* argv[]) -> void {
@@ -431,15 +450,16 @@ class cmdline_processor
 
 } cmdline;
 
-cmdline_processor::register_flag::register_flag(int group, std::string_view name, std::string_view description, callback handler, std::string_view synonym) {
- cmdline.add_flag( group, name, description, handler, synonym );
+cmdline_processor::register_flag::register_flag(int group, std::string_view name, std::string_view description, callback0 handler0, callback1 handler1, std::string_view synonym) {
+ cmdline.add_flag( group, name, description, handler0, handler1, synonym );
 }
 
 static cmdline_processor::register_flag cmd_help (
  0,
  "help",
  "Print help",
  []{ cmdline.print_help(); },
+ nullptr,
  "?"
 );
 

source/cppfront.cpp

@@ -100,6 +100,15 @@ static cmdline_processor::register_flag cmd_enable_source_info(
  []{ flag_use_source_location = true; }
 );
 
+static auto flag_cpp1_filename = std::string{};
+static cmdline_processor::register_flag cmd_cpp1_filename(
+ 2,
+ "output",
+ "Output filename (default is *.cpp)",
+ nullptr,
+ [](std::string const& name) { flag_cpp1_filename = name; }
+);
+
 
 struct text_with_pos{
  std::string text;
@@ -707,10 +716,21 @@ class cppfront
  }
 
  // Now we'll open the .cpp file
+ auto cpp1_filename = sourcefile.substr(0, std::ssize(sourcefile) - 1);
+ if (!flag_cpp1_filename.empty()) {
+ cpp1_filename = flag_cpp1_filename; // use override if present
+ }
  printer.open(
- sourcefile.substr(0, std::ssize(sourcefile) - 1),
+ cpp1_filename,
  tokens.get_comments()
  );
+ if (!printer.is_open()) {
+ errors.emplace_back(
+ source_position{},
+ "could not open output file " + cpp1_filename
+ );
+ return;
+ }
 
  // Only emit extra lines if we actually have Cpp2, because
  // we want pure-Cpp1 files to pass through with zero changes