Function calls

Makefile

@@ -38,6 +38,10 @@ doc: Doxyfile src/*.cc src/*.hh
 	doxygen
 	cd doc; $(MAKE) html
 
+.PHONY: doc-open
+doc-open: doc
+	xdg-open ./doc/build/html/index.html
+
 bin/unit-tests: src/tests/*.cc $(Obj)
 	g++ $(CXXFLAGS) $(CPPFLAGS) -o $@ $^
 

src/errors.cc

@@ -103,6 +103,15 @@ Error errors::unrecognized_character(u32 invalid_character, Location location)
 	return unrecognized_character(invalid_character).with(std::move(location));
 }
 
+Error errors::unexpected_token(Token const& unexpected)
+{
+	Error err;
+	err.type = errors::Unexpected_Token_Type;
+	err.location = unexpected.location;
+	err.message = format("unexpected ", unexpected.type);
+	return err;
+}
+
 Error errors::unexpected_token(Token::Type expected, Token const& unexpected)
 {
 	Error err;

src/musique.hh

@@ -289,11 +289,13 @@ struct Ast
 	// Named constructors of AST structure
 	static Ast literal(Token);
 	static Ast binary(Token, Ast lhs, Ast rhs);
+	static Ast call(std::vector<Ast> call);
 
 	enum class Type
 	{
-		Literal,  // Compile time known constant like c or 1
-		Binary    // Binary operator application like 1 + 2
+		Literal,  // Compile time known constant like `c` or `1`
+		Binary,   // Binary operator application like `1` + `2`
+		Call      // Function call application like `print 42`
 	};
 
 	Type type;
@@ -314,9 +316,10 @@ struct Parser
 	static Result<Ast> parse(std::string_view source, std::string_view filename);
 
 	Result<Ast> parse_expression();
-	Result<Ast> parse_binary_operator();
-	Result<Ast> parse_literal();
+	Result<Ast> parse_infix_expression();
+	Result<Ast> parse_atomic_expression();
 
+	Result<Token> peek() const;
 	Result<Token::Type> peek_type() const;
 	Token consume();
 
@@ -334,6 +337,7 @@ namespace errors
 	Error unrecognized_character(u32 invalid_character, Location location);
 
 	Error unexpected_token(Token::Type expected, Token const& unexpected);
+	Error unexpected_token(Token const& unexpected);
 	Error unexpected_end_of_source(Location location);
 
 	[[noreturn]]

src/parser.cc

@@ -1,4 +1,5 @@
 #include <musique.hh>
+#include <iostream>
 
 Result<Ast> Parser::parse(std::string_view source, std::string_view filename)
 {
@@ -25,26 +26,39 @@ Result<Ast> Parser::parse(std::string_view source, std::string_view filename)
 
 Result<Ast> Parser::parse_expression()
 {
-	return parse_binary_operator();
+	return parse_infix_expression();
 }
 
-Result<Ast> Parser::parse_binary_operator()
+Result<Ast> Parser::parse_infix_expression()
 {
-	return parse_literal().and_then([&](Ast lhs) -> tl::expected<Ast, Error> {
-		if (expect(Token::Type::Operator)) {
-			auto op = consume();
-			return parse_expression().map([&](Ast rhs) {
-				return Ast::binary(std::move(op), std::move(lhs), std::move(rhs));
-			});
-		} else {
-			return lhs;
-		}
-	});
+	std::vector<Ast> atomics;
+	Result<Ast> expr;
+	while ((expr = parse_atomic_expression()).has_value()) {
+		atomics.push_back(std::move(expr).value());
+	}
+
+	if (atomics.empty()) {
+		return expr;
+	}
+
+	auto lhs = atomics.size() == 1
+		? std::move(atomics[0])
+		: Ast::call(std::move(atomics));
+
+	if (expect(Token::Type::Operator)) {
+		auto op = consume();
+		return parse_expression().map([&](Ast rhs) {
+			return Ast::binary(std::move(op), std::move(lhs), std::move(rhs));
+		});
+	}
+
+	return lhs;
 }
 
-Result<Ast> Parser::parse_literal()
+Result<Ast> Parser::parse_atomic_expression()
 {
 	switch (Try(peek_type())) {
+	case Token::Type::Symbol:
 	case Token::Type::Numeric:
 		return Ast::literal(consume());
 
@@ -57,15 +71,22 @@ Result<Ast> Parser::parse_literal()
 		});
 
 	default:
-		unimplemented();
+		return peek().and_then([](auto const& token) -> tl::expected<Ast, Error> {
+			return tl::unexpected(errors::unexpected_token(token));
+		});
 	}
 }
 
+Result<Token> Parser::peek() const
+{
+	return token_id >= tokens.size()
+		? errors::unexpected_end_of_source(tokens.back().location)
+		: Result<Token>(tokens[token_id]);
+}
+
 Result<Token::Type> Parser::peek_type() const
 {
-	return token_id >= tokens.size()
-		? errors::unexpected_end_of_source(tokens.back().location)
-		: Result<Token::Type>(tokens[token_id].type);
+	return peek().map([](Token const& token) { return token.type; });
 }
 
 Token Parser::consume()
@@ -105,6 +126,14 @@ Ast Ast::binary(Token token, Ast lhs, Ast rhs)
 	return ast;
 }
 
+Ast Ast::call(std::vector<Ast> call)
+{
+	Ast ast;
+	ast.type = Type::Call;
+	ast.arguments = std::move(call);
+	return ast;
+}
+
 bool operator==(Ast const& lhs, Ast const& rhs)
 {
 	if (lhs.type != rhs.type) {
@@ -120,6 +149,10 @@ bool operator==(Ast const& lhs, Ast const& rhs)
 			&& lhs.token.source == rhs.token.source
 			&& lhs.arguments.size() == rhs.arguments.size()
 			&& std::equal(lhs.arguments.begin(), lhs.arguments.end(), rhs.arguments.begin());
+
+	case Ast::Type::Call:
+		return lhs.arguments.size() == rhs.arguments.size()
+			&& std::equal(lhs.arguments.begin(), lhs.arguments.end(), rhs.arguments.begin());
 	}
 
 	unreachable();

src/tests/parser.cc

@@ -78,4 +78,35 @@ suite parser_test = [] {
 				)
 		));
 	};
+
+	"Explicit function call"_test = [] {
+		expect_ast("foo 1 2", Ast::call({
+			Ast::literal({ Token::Type::Symbol, "foo", {} }),
+			Ast::literal({ Token::Type::Numeric, "1", {} }),
+			Ast::literal({ Token::Type::Numeric, "2", {} })
+		}));
+
+		expect_ast("say (fib (n - 1) + fib (n - 2))", Ast::call({
+			Ast::literal({ Token::Type::Symbol, "say", {} }),
+			Ast::binary(
+				{ Token::Type::Operator, "+", {} },
+				Ast::call({
+					Ast::literal({ Token::Type::Symbol, "fib", {} }),
+					Ast::binary(
+						{ Token::Type::Operator, "-", {} },
+						Ast::literal({ Token::Type::Symbol, "n", {} }),
+						Ast::literal({ Token::Type::Numeric, "1", {} })
+					)
+				}),
+				Ast::call({
+					Ast::literal({ Token::Type::Symbol, "fib", {} }),
+					Ast::binary(
+						{ Token::Type::Operator, "-", {} },
+						Ast::literal({ Token::Type::Symbol, "n", {} }),
+						Ast::literal({ Token::Type::Numeric, "2", {} })
+					)
+				})
+			)
+		}));
+	};
 };