feat(furc): introduce function declaration parameters

Closes: #16

furc/include/furc/ast/declaration.hpp

@@ -7,6 +7,7 @@
 #include <optional>
 #include <string>
 #include <type_traits>
+#include <vector>
 
 namespace furc {
 namespace ast {
@@ -70,6 +71,14 @@ protected:
     bool equal(const node& rhs) const override;
 };
 
+/**
+ * @brief Parameter of function declaration AST node.
+ */
+struct function_declaration_param {
+    std::string name;
+    type        type;
+};
+
 /**
  * @brief Function declaration AST node.
  */
@@ -82,9 +91,12 @@ public:
      * @param name Name of the function.
      * @param type Return type of the function.
      */
-    template <typename T>
-    function_declaration_node(struct location location, T&& name, std::optional<type>&& returnType)
-      : declaration_node(location), p_name(std::forward<T>(name)), p_returnType(std::move(returnType)) {}
+    template <typename T, typename ParamsFwd>
+    function_declaration_node(struct location location, T&& name, std::optional<type>&& returnType, ParamsFwd&& params)
+      : declaration_node(location),
+        p_name(std::forward<T>(name)),
+        p_returnType(std::move(returnType)),
+        p_params(std::forward<ParamsFwd>(params)) {}
 public:
     /**
      * @brief Returns this node's declaration type.
@@ -106,6 +118,13 @@ public:
      * @return Function's return type.
      */
     const std::optional<type>& return_type() const { return p_returnType; }
+
+    /**
+     * @brief Returns function's parameters.
+     *
+     * @return Function's parameters.
+     */
+    const std::vector<function_declaration_param>& params() const { return p_params; }
 public:
     void accept(visitor& visitor) const override;
 
@@ -122,6 +141,11 @@ protected:
      * @brief Return type of the function.
      */
     std::optional<type> p_returnType;
+
+    /**
+     * @brief Parameters of the function.
+     */
+    std::vector<function_declaration_param> p_params;
 };
 
 /**
@@ -137,9 +161,14 @@ public:
      * @param type Return type of the function.
      * @param body Body of the function.
      */
-    template <typename T>
-    function_definition_node(struct location location, T&& name, std::optional<type>&& type, body&& body)
-      : function_declaration_node(location, std::forward<T>(name), std::move(type)), m_body(std::move(body)) {}
+    template <typename T, typename ParamsFwd>
+    function_definition_node(struct location location,
+        T&&                                  name,
+        std::optional<type>&&                type,
+        ParamsFwd&&                          params,
+        body&&                               body)
+      : function_declaration_node(location, std::forward<T>(name), std::move(type), std::forward<ParamsFwd>(params)),
+        m_body(std::move(body)) {}
 public:
     /**
      * @brief Returns this node's declaration type.

furc/src/front/parser.cpp

@@ -12,6 +12,7 @@
 #include <iostream>
 #include <string>
 #include <unordered_map>
+#include <vector>
 
 namespace furc::front {
 
@@ -66,6 +67,25 @@ ast::declaration_node_r parser::parse_declaration() {
 
             auto tok = eat_token(token_t::LParen);
             if (tok.has_error()) return ast::declaration_node_r(ast::error{ tok.error().location });
+
+            std::vector<ast::function_declaration_param> params;
+            if (peek_token().has_value() && peek_token()->type != token_t::RParen) {
+                while (true) {
+                    auto name = eat_token(token_t::Identifier);
+                    if (name.has_error()) return ast::declaration_node_r(ast::error{ name.error().location });
+                    auto colon = eat_token(token_t::Colon);
+                    if (colon.has_error()) return ast::declaration_node_r(ast::error{ colon.error().location });
+                    auto type = parse_type();
+                    if (type.has_error()) return ast::declaration_node_r(ast::error{ type.error().location });
+
+                    params.push_back(
+                        ast::function_declaration_param{ std::string(name->value.string), std::move(*type) });
+
+                    auto comma = eat_token(token_t::Comma);
+                    if (comma.has_error()) break;
+                }
+            }
+
             tok = eat_token(token_t::RParen);
             if (tok.has_error()) return ast::declaration_node_r(ast::error{ tok.error().location });
 
@@ -86,13 +106,15 @@ ast::declaration_node_r parser::parse_declaration() {
                 return m_arena->allocate_shared<ast::function_definition_node>(first->location,
                     name->value.string,
                     std::move(returnType),
+                    std::move(params),
                     std::move(body.value()));
             }
             case token_t::Semicolon: {
                 m_peekBuffer.clear();
                 return m_arena->allocate_shared<ast::function_declaration_node>(first->location,
                     name->value.string,
-                    std::move(returnType));
+                    std::move(returnType),
+                    std::move(params));
             }
             default: return ast::declaration_node_r(ast::error{ tok->location });
             }
@@ -465,15 +487,14 @@ const token_r& parser::peek_token() {
 }
 
 token_r parser::eat_token(token_t type) {
-    auto token = next_token();
+    if (const auto& token = peek_token(); token.has_error() || peek_token()->type != type) {
         if (token.has_error()) return token;
-    if (token->type != type) {
         if (token->type == token_t::None)
             return token_r(token_error{ token->location, token_error_t::UnexpectedToken, ", expected " + type });
         return token_r(
             token_error{ token->location, token_error_t::UnexpectedToken, ""s + token->type + ", expected " + type });
     }
-    return token;
+    return next_token();
 }
 
 } // namespace furc::front