feat(furc): introduce native and import functions

Closes: #19

furc/include/furc/ast/declaration.hpp

@@ -79,6 +79,12 @@ struct function_declaration_param {
     type        type;
 };
 
+enum class function_declaration_node_t {
+    Normal = 0,
+    Import,
+    Native,
+};
+
 /**
  * @brief Function declaration AST node.
  */
@@ -92,11 +98,16 @@ public:
      * @param type Return type of the function.
      */
     template <typename T, typename ParamsFwd>
-    function_declaration_node(struct location location, T&& name, std::optional<type>&& returnType, ParamsFwd&& params)
+    function_declaration_node(struct location location,
+        T&&                                   name,
+        std::optional<type>&&                 returnType,
+        ParamsFwd&&                           params,
+        function_declaration_node_t           type = function_declaration_node_t::Normal)
       : declaration_node(location),
         p_name(std::forward<T>(name)),
         p_returnType(std::move(returnType)),
-        p_params(std::forward<ParamsFwd>(params)) {}
+        p_params(std::forward<ParamsFwd>(params)),
+        p_type(type) {}
 public:
     /**
      * @brief Returns this node's declaration type.
@@ -125,6 +136,13 @@ public:
      * @return Function's parameters.
      */
     const std::vector<function_declaration_param>& params() const { return p_params; }
+
+    /**
+     * @brief Returns function's type.
+     *
+     * @return Function's type.
+     */
+    function_declaration_node_t type() const { return p_type; }
 public:
     void accept(visitor& visitor) const override;
 
@@ -140,12 +158,17 @@ protected:
     /**
      * @brief Return type of the function.
      */
-    std::optional<type> p_returnType;
+    std::optional<class type> p_returnType;
 
     /**
      * @brief Parameters of the function.
      */
     std::vector<function_declaration_param> p_params;
+
+    /**
+     * @brief Type of the function declaration.
+     */
+    function_declaration_node_t p_type;
 };
 
 /**
@@ -164,7 +187,7 @@ public:
     template <typename T, typename ParamsFwd>
     function_definition_node(struct location location,
         T&&                                  name,
-        std::optional<type>&&                type,
+        std::optional<class type>&&          type,
         ParamsFwd&&                          params,
         body&&                               body)
       : function_declaration_node(location, std::forward<T>(name), std::move(type), std::forward<ParamsFwd>(params)),

furc/include/furc/front/token.hpp

@@ -153,6 +153,8 @@ enum class keyword_token {
     If,     /**< `if` */
     Else,   /**< `else` */
     While,  /**< `while` */
+    Import, /**< `import` */
+    Native, /**< `native` */
 
     Int32, /**< `int32` */
 };
@@ -165,6 +167,8 @@ static inline std::ostream& operator<<(std::ostream& os, keyword_token keyword)
     case keyword_token::If: return os << "if";
     case keyword_token::Else: return os << "else";
     case keyword_token::While: return os << "while";
+    case keyword_token::Import: return os << "import";
+    case keyword_token::Native: return os << "native";
     case keyword_token::Int32: return os << "int32";
     }
     return os;
@@ -178,6 +182,8 @@ static inline std::string operator+(const std::string& str, keyword_token keywor
     case keyword_token::If: return str + "if";
     case keyword_token::Else: return str + "else";
     case keyword_token::While: return str + "while";
+    case keyword_token::Import: return str + "import";
+    case keyword_token::Native: return str + "native";
     case keyword_token::Int32: return str + "int32";
     }
     return str;

furc/src/front/lexer.cpp

@@ -100,6 +100,8 @@ token_r lexer::next_token() {
                 { "if", keyword_token::If },
                 { "else", keyword_token::Else },
                 { "while", keyword_token::While },
+                { "import", keyword_token::Import },
+                { "native", keyword_token::Native },
                 { "int32", keyword_token::Int32 },
             };
 

furc/src/front/parser.cpp

@@ -38,14 +38,11 @@ ast::program_node_r parser::parse() & {
 
     while (peek_token().has_value()) {
         auto decl = parse_declaration();
-        if (decl.has_error()) {
+        if (decl.has_error()) return ast::program_node_r(ast::error{ decl.error().location });
-            program = nullptr;
-        } else if (program != nullptr) {
         program->push(std::move(decl.value()));
     }
-    }
 
-    return program != nullptr ? std::move(program) : ast::program_node_r(ast::error{ location{ m_filename } });
+    return program;
 }
 
 ast::type_r parser::parse_type() {
@@ -59,8 +56,20 @@ ast::declaration_node_r parser::parse_declaration() {
     const auto& first = peek_token();
     switch (first->type) {
     case token_t::Keyword: {
+        ast::function_declaration_node_t funcDeclType{};
+
         auto first = next_token();
         switch ((*first)->keyword) {
+        case keyword_token::Import:
+        case keyword_token::Native: {
+            funcDeclType = ((*first)->keyword == keyword_token::Import) ? ast::function_declaration_node_t::Import
+                                                                        : ast::function_declaration_node_t::Native;
+
+            first = eat_token(token_t::Keyword);
+            if (first.has_error()) return ast::declaration_node_r(ast::error{ first.error().location });
+            if (first->value.keyword != keyword_token::Func)
+                return ast::declaration_node_r(ast::error{ first->location });
+        }
         case keyword_token::Func: {
             auto name = eat_token(token_t::Identifier);
             if (name.has_error()) return ast::declaration_node_r(ast::error{ name.error().location });
@@ -103,6 +112,8 @@ ast::declaration_node_r parser::parse_declaration() {
             case token_t::LBrace: {
                 ast::body_r body = parse_body();
                 if (body.has_error()) return ast::declaration_node_r(ast::error{ body.error().location });
+                if (funcDeclType != ast::function_declaration_node_t::Normal)
+                    return ast::declaration_node_r(ast::error{ body->begin });
                 return m_arena->allocate_shared<ast::function_definition_node>(first->location,
                     name->value.string,
                     std::move(returnType),
@@ -114,7 +125,8 @@ ast::declaration_node_r parser::parse_declaration() {
                 return m_arena->allocate_shared<ast::function_declaration_node>(first->location,
                     name->value.string,
                     std::move(returnType),
-                    std::move(params));
+                    std::move(params),
+                    funcDeclType);
             }
             default: return ast::declaration_node_r(ast::error{ tok->location });
             }

furc/src/main.cpp

@@ -13,6 +13,8 @@
 int main(void) {
     try {
         std::string               programStr = R"(
+    native func print(value: int32);
+
     func main() -> int32 {
         x = 0;
         y = 10;