Playing MIDI!

src/interpreter.cc

@@ -1,6 +1,8 @@
 #include <musique.hh>
 
+#include <chrono>
 #include <iostream>
+#include <thread>
 
 template<typename Binary_Operation>
 constexpr auto binary_operator()
@@ -110,6 +112,14 @@ Interpreter::Interpreter(std::ostream& out)
 			}
 		});
 
+		global.force_define("play", +[](Interpreter &i, std::vector<Value> args) -> Result<Value> {
+			for (auto &arg : args) {
+				assert(arg.type == Value::Type::Music, "Only music values can be played"); // TODO(assert)
+				i.play(arg.note);
+			}
+			return Value{};
+		});
+
 		operators["+"] = binary_operator<std::plus<>>();
 		operators["-"] = binary_operator<std::minus<>>();
 		operators["*"] = binary_operator<std::multiplies<>>();
@@ -230,3 +240,17 @@ void Interpreter::leave_scope()
 	assert(env != Env::global, "Cannot leave global scope");
 	env = env->leave();
 }
+
+void Interpreter::play(Note note)
+{
+	assert(midi_connection, "To play midi Interpreter requires instance of MIDI connection");
+
+	auto &ctx = context_stack.back();
+	note = ctx.fill(std::move(note));
+
+	auto dur = ctx.length_to_duration(note.length);
+
+	midi_connection->send_note_on(0, *note.into_midi_note(), 127);
+	std::this_thread::sleep_for(dur);
+	midi_connection->send_note_off(0, *note.into_midi_note(), 127);
+}

src/main.cc

@@ -1,10 +1,11 @@
+#define MIDI_ENABLE_ALSA_SUPPORT
+
 #include <filesystem>
 #include <fstream>
 #include <iostream>
 #include <span>
 
 #include <musique.hh>
-#define MIDI_ENABLE_ALSA_SUPPORT
 #include <midi.hh>
 
 namespace fs = std::filesystem;
@@ -34,7 +35,20 @@ void usage()
 	std::exit(1);
 }
 
-static Result<void> run(std::string_view source, std::string_view filename)
+struct Runner
+{
+	midi::ALSA alsa;
+	Interpreter interpreter;
+
+	Runner(std::string port)
+		: alsa("musique"), interpreter(std::cout)
+	{
+		alsa.init_sequencer();
+		alsa.connect(port);
+		interpreter.midi_connection = &alsa;
+	}
+
+	Result<void> run(std::string_view source, std::string_view filename)
 	{
 		auto ast = Try(Parser::parse(source, filename));
 
@@ -42,28 +56,33 @@ static Result<void> run(std::string_view source, std::string_view filename)
 			dump(ast);
 			return {};
 		}
-	Interpreter interpreter;
 		std::cout << Try(interpreter.eval(std::move(ast))) << std::endl;
 		return {};
 	}
+};
 
 // We make sure that through life of interpreter source code is allways allocated
 std::vector<std::string> eternal_sources;
 
+struct Run
+{
+	bool is_file = true;
+	std::string_view argument;
+};
+
 static Result<void> Main(std::span<char const*> args)
 {
 	if (args.empty()) {
 		usage();
 	}
 
-	bool runned_something = false;
-	std::vector<std::string_view> files;
+	std::vector<Run> runnables;
 
 	while (not args.empty()) {
 		std::string_view arg = pop(args);
 
 		if (arg == "-" || !arg.starts_with('-')) {
-			files.push_back(std::move(arg));
+			runnables.push_back({ .is_file = true, .argument = std::move(arg) });
 			continue;
 		}
 
@@ -79,10 +98,7 @@ static Result<void> Main(std::span<char const*> args)
 				std::cerr << "musique: error: option " << arg << " requires an argument" << std::endl;
 				std::exit(1);
 			}
-
-			auto const source = pop(args);
-			Try(run(source, "arguments"));
-			runned_something = true;
+			runnables.push_back({ .is_file = false, .argument = pop(args) });
 			continue;
 		}
 
@@ -95,11 +111,18 @@ static Result<void> Main(std::span<char const*> args)
 		std::exit(1);
 	}
 
-	if (!runned_something && files.empty()) {
+	if (runnables.empty()) {
 		usage();
 	}
 
-	for (auto const& path : files) {
+	Runner runner("14");
+
+	for (auto const& [is_file, argument] : runnables) {
+		if (!is_file) {
+			Try(runner.run(argument, "<arguments>"));
+			continue;
+		}
+		auto const path = argument;
 		if (path == "-") {
 			eternal_sources.emplace_back(std::istreambuf_iterator<char>(std::cin), std::istreambuf_iterator<char>());
 		} else {
@@ -111,7 +134,7 @@ static Result<void> Main(std::span<char const*> args)
 			eternal_sources.emplace_back(std::istreambuf_iterator<char>(source_file), std::istreambuf_iterator<char>());
 		}
 
-		Try(run(eternal_sources.back(), path));
+		Try(runner.run(eternal_sources.back(), path));
 	}
 
 	return {};

src/musique.hh

@@ -9,9 +9,11 @@
 #include <ostream>
 #include <span>
 #include <string_view>
-#include <tl/expected.hpp>
 #include <variant>
 
+#include <midi.hh>
+#include <tl/expected.hpp>
+
 #if defined(__cpp_lib_source_location)
 #include <source_location>
 #endif
@@ -579,6 +581,10 @@ struct Context
 
 struct Interpreter
 {
+	/// MIDI connection that is used to play music.
+	/// It's optional for simple interpreter testing.
+	midi::Connection *midi_connection = nullptr;
+
 	/// Output of IO builtins like `say`
 	std::ostream &out;
 
@@ -603,6 +609,9 @@ struct Interpreter
 	// Scope managment
 	void enter_scope();
 	void leave_scope();
+
+	/// Play note resolving any missing parameters with context via `midi_connection` member.
+	void play(Note n);
 };
 
 namespace errors

src/value.cc

@@ -8,7 +8,10 @@ concept Indexable = requires(T t, Index i) {
 /// Create hash out of note literal like `c` or `e#`
 constexpr u16 hash_note(Indexable<usize, char> auto const& note)
 {
-	return u8(note[0]) | (note[1] << 8);
+	/// TODO Some assertion that we have snd character
+	u8 snd = note[1];
+	if (snd != '#') snd = 0;
+	return u8(note[0]) | (snd << 8);
 }
 
 /// Finds numeric value of note. This form is later used as in