refactor(parser): change node handles to node results

Refs: #1

furc/include/furc/ast/expression.hpp

@@ -108,6 +108,8 @@ enum class unaryop_expression_node_t {
  * @brief Unary operation expression AST node.
  */
 class unaryop_expression_node final : public expression_node {
+public:
+    using value_type = std::optional<expression_node_r>; /**< Value type. */
 public:
     /**
      * @brief Construct a new unaryop expression node object from type and expression node handle.
@@ -115,7 +117,7 @@ public:
      * @param type Operation type.
      * @param node Handle to the inner expression node.
      */
-    unaryop_expression_node(unaryop_expression_node_t type, expression_node_h&& node)
+    unaryop_expression_node(unaryop_expression_node_t type, expression_node_r&& node)
       : m_type(type), m_node(std::move(node)) {}
 
     /**
@@ -123,7 +125,7 @@ public:
      *
      * @param node New node handle.
      */
-    void set_node(expression_node_h&& node) { m_node = std::move(node); }
+    void set_node(expression_node_r&& node) { m_node = std::move(node); }
 
     /**
      * @brief Returns the type of this node's operation.
@@ -137,21 +139,21 @@ public:
      *
      * @return The inner expression.
      */
-    const expression_node_h& get_node() const { return m_node; }
+    const value_type& get_node() const { return m_node; }
 
     /**
      * @brief Returns this node's inner expression.
      *
      * @return The inner expression.
      */
-    expression_node_h& get_node() { return m_node; }
+    value_type& get_node() { return m_node; }
 
     /**
      * @brief Moves this node's inner expression.
      *
      * @return The moved inner expression.
      */
-    expression_node_h&& move_node() { return std::move(m_node); }
+    value_type&& move_node() { return std::move(m_node); }
 public:
     /**
      * @brief Returns this node's expression type.
@@ -167,7 +169,7 @@ protected:
     bool equal(const node& rhs) const override;
 private:
     unaryop_expression_node_t m_type;
-    expression_node_h         m_node; /**< The inner expression. */
+    value_type                m_node; /**< The inner expression. */
 };
 
 /**
@@ -201,7 +203,7 @@ public:
      * @param lhs Left-hand-side expression.
      * @param rhs Right-hand-side expression.
      */
-    binop_expression_node(binop_expression_node_t type, expression_node_h&& lhs, expression_node_h&& rhs)
+    binop_expression_node(binop_expression_node_t type, expression_node_r&& lhs, expression_node_r&& rhs)
       : m_type(type), m_lhs(std::move(lhs)), m_rhs(std::move(rhs)) {}
 
     /**
@@ -216,42 +218,42 @@ public:
      *
      * @return The left-hand-side expression.
      */
-    const expression_node_h& lhs() const { return m_lhs; };
+    const expression_node_r& lhs() const { return m_lhs; };
 
     /**
      * @brief Returns this node's left-hand-side expression.
      *
      * @return The left-hand-side expression.
      */
-    expression_node_h& lhs() { return m_lhs; };
+    expression_node_r& lhs() { return m_lhs; };
 
     /**
      * @brief Moves this node's left-hand-side expression.
      *
      * @return The moved left-hand-side expression.
      */
-    expression_node_h&& move_lhs() { return std::move(m_lhs); };
+    expression_node_r&& move_lhs() { return std::move(m_lhs); };
 
     /**
      * @brief Returns this node's right-hand-side expression.
      *
      * @return The right-hand-side expression.
      */
-    const expression_node_h& rhs() const { return m_rhs; };
+    const expression_node_r& rhs() const { return m_rhs; };
 
     /**
      * @brief Returns this node's right-hand-side expression.
      *
      * @return The right-hand-side expression.
      */
-    expression_node_h& rhs() { return m_rhs; };
+    expression_node_r& rhs() { return m_rhs; };
 
     /**
      * @brief Moves this node's right-hand-side expression.
      *
      * @return The moved right-hand-side expression.
      */
-    expression_node_h&& move_rhs() { return std::move(m_rhs); };
+    expression_node_r&& move_rhs() { return std::move(m_rhs); };
 public:
     expression_node_t expression_type() const override { return expression_node_t::Binop; }
 public:
@@ -262,8 +264,8 @@ protected:
     bool equal(const node& rhs) const override;
 private:
     binop_expression_node_t m_type;
-    expression_node_h       m_lhs;
-    expression_node_h       m_rhs;
+    expression_node_r       m_lhs;
+    expression_node_r       m_rhs;
 };
 
 /**
@@ -277,7 +279,7 @@ public:
      * @param lhs Left-hand-side expression handle.
      * @param rhs Right-hand-side expression handle.
      */
-    var_assign_expression_node(expression_node_h&& lhs, expression_node_h&& rhs)
+    var_assign_expression_node(expression_node_r&& lhs, expression_node_r&& rhs)
       : m_compound(binop_expression_node_t::None), m_lhs(std::move(lhs)), m_rhs(std::move(rhs)) {}
 
     /**
@@ -287,7 +289,7 @@ public:
      * @param lhs Left-hand-side expression handle.
      * @param rhs Right-hand-side expression handle.
      */
-    var_assign_expression_node(binop_expression_node_t compound, expression_node_h&& lhs, expression_node_h&& rhs)
+    var_assign_expression_node(binop_expression_node_t compound, expression_node_r&& lhs, expression_node_r&& rhs)
       : m_compound(compound), m_lhs(std::move(lhs)), m_rhs(std::move(rhs)) {}
 
     /**
@@ -302,14 +304,14 @@ public:
      *
      * @return The left-hand-side expression.
      */
-    const expression_node_h& lhs() const { return m_lhs; }
+    const expression_node_r& lhs() const { return m_lhs; }
 
     /**
      * @brief Returns this node's right-hand-side expression.
      *
      * @return The right-hand-side expression.
      */
-    const expression_node_h& rhs() const { return m_rhs; }
+    const expression_node_r& rhs() const { return m_rhs; }
 public:
     /**
      * @brief Returns this node's expression type.
@@ -325,8 +327,8 @@ protected:
     bool equal(const node& rhs) const override;
 private:
     binop_expression_node_t m_compound;
-    expression_node_h       m_lhs;
-    expression_node_h       m_rhs;
+    expression_node_r       m_lhs;
+    expression_node_r       m_rhs;
 };
 
 } // namespace ast

furc/include/furc/ast/fwd.hpp

@@ -2,10 +2,9 @@
 #define FURC_AST_FWD_HPP
 
 #include "furc/diag.hpp"
-#include "furc/handle.hpp"
 #include "furlang/result.hpp"
 
-#include <string>
+#include <memory>
 #include <vector>
 
 namespace furc {
@@ -50,12 +49,12 @@ struct error {
 class node;
 
 /**
- * @brief Alias for handle to node.
+ * @brief Alias for node result.
  *
  * @tparam T AST node type.
  */
 template <typename T>
-using node_handle = handle<T*, std::string>;
+using node_r = furlang::result<std::shared_ptr<T>, error>;
 
 class literal_node;
 
@@ -63,7 +62,7 @@ class literal_node;
  * @brief Alias for handle to literal_node.
  * @see literal_node
  */
-using literal_node_h = node_handle<literal_node>;
+using literal_node_r = node_r<literal_node>;
 
 class expression_node;
 
@@ -71,7 +70,7 @@ class expression_node;
  * @brief Alias for handle to expression_node.
  * @see expression_node
  */
-using expression_node_h = node_handle<expression_node>;
+using expression_node_r = node_r<expression_node>;
 
 class declaration_node;
 
@@ -79,7 +78,7 @@ class declaration_node;
  * @brief Alias for handle to declaration_node.
  * @see declaration_node
  */
-using declaration_node_h = node_handle<declaration_node>;
+using declaration_node_r = node_r<declaration_node>;
 
 class statement_node;
 
@@ -87,7 +86,7 @@ class statement_node;
  * @brief Alias for handle to statement_node.
  * @see statement_node
  */
-using statement_node_h = node_handle<statement_node>;
+using statement_node_r = node_r<statement_node>;
 
 class program_node;
 
@@ -95,7 +94,7 @@ class program_node;
  * @brief Alias for handle to program_node.
  * @see program_node
  */
-using program_node_h = node_handle<program_node>;
+using program_node_r = node_r<program_node>;
 
 class string_literal_node;
 
@@ -103,7 +102,7 @@ class string_literal_node;
  * @brief Alias for handle to string_literal_node.
  * @see string_literal_node
  */
-using string_literal_node_h = node_handle<string_literal_node>;
+using string_literal_node_r = node_r<string_literal_node>;
 
 class integer_literal_node;
 
@@ -111,7 +110,7 @@ class integer_literal_node;
  * @brief Alias for handle to integer_literal_node.
  * @see integer_literal_node
  */
-using integer_literal_node_h = node_handle<integer_literal_node>;
+using integer_literal_node_r = node_r<integer_literal_node>;
 
 class var_read_expression_node;
 
@@ -119,7 +118,7 @@ class var_read_expression_node;
  * @brief Alias for handle to var_read_expression_node.
  * @see var_read_expression_node
  */
-using var_read_expression_node_h = node_handle<var_read_expression_node>;
+using var_read_expression_node_r = node_r<var_read_expression_node>;
 
 class unaryop_expression_node;
 
@@ -127,7 +126,7 @@ class unaryop_expression_node;
  * @brief Alias for handle to unaryop_expression_node.
  * @see unaryop_expression_node
  */
-using unaryop_expression_node_h = node_handle<unaryop_expression_node>;
+using unaryop_expression_node_r = node_r<unaryop_expression_node>;
 
 class binop_expression_node;
 
@@ -135,7 +134,7 @@ class binop_expression_node;
  * @brief Alias for handle to binop_expression_node.
  * @see binop_expression_node
  */
-using binop_expression_node_h = node_handle<binop_expression_node>;
+using binop_expression_node_r = node_r<binop_expression_node>;
 
 class var_assign_expression_node;
 
@@ -143,7 +142,7 @@ class var_assign_expression_node;
  * @brief Alias for handle to var_assign_expression_node.
  * @see var_assign_expression_node
  */
-using var_assign_expression_node_h = node_handle<var_assign_expression_node>;
+using var_assign_expression_node_r = node_r<var_assign_expression_node>;
 
 /**
  * @brief List of statements.
@@ -162,7 +161,7 @@ struct body {
     /**
      * @brief List of statements.
      */
-    std::vector<statement_node_h> statements;
+    std::vector<statement_node_r> statements;
 
     /**
      * @brief Compares two bodies for equality.
@@ -204,7 +203,7 @@ class function_declaration_node;
  * @brief Alias for handle to function_declaration_node.
  * @see function_declaration_node
  */
-using function_declaration_node_h = node_handle<function_declaration_node>;
+using function_declaration_node_r = node_r<function_declaration_node>;
 
 class function_definition_node;
 
@@ -212,7 +211,7 @@ class function_definition_node;
  * @brief Alias for handle to function_definition_node.
  * @see function_definition_node
  */
-using function_definition_node_h = node_handle<function_definition_node>;
+using function_definition_node_r = node_r<function_definition_node>;
 
 class return_statement_node;
 
@@ -220,7 +219,7 @@ class return_statement_node;
  * @brief Alias for handle to return_statement_node.
  * @see return_statement_node
  */
-using return_statement_node_h = node_handle<return_statement_node>;
+using return_statement_node_r = node_r<return_statement_node>;
 
 class if_statement_node;
 
@@ -228,7 +227,7 @@ class if_statement_node;
  * @brief Alias for handle to if_statement_node.
  * @see if_statement_node
  */
-using if_statement_node_h = node_handle<if_statement_node>;
+using if_statement_node_r = node_r<if_statement_node>;
 
 class compound_statement_node;
 
@@ -236,7 +235,7 @@ class compound_statement_node;
  * @brief Alias for handle to compound_statement_node.
  * @see compound_statement_node
  */
-using compound_statement_node_h = node_handle<compound_statement_node>;
+using compound_statement_node_r = node_r<compound_statement_node>;
 
 } // namespace ast
 } // namespace furc

furc/include/furc/ast/program.hpp

@@ -23,14 +23,14 @@ public:
      *
      * @param declaration Declaration to add.
      */
-    void push(node_handle<declaration_node>&& declaration) { m_declarations.push_back(std::move(declaration)); }
+    void push(node_r<declaration_node>&& declaration) { m_declarations.push_back(std::move(declaration)); }
 
     /**
      * @brief Returns a list of declarations of this program.
      *
      * @return The list of this program's declarations.
      */
-    const std::vector<node_handle<declaration_node>>& declarations() const { return m_declarations; }
+    const std::vector<node_r<declaration_node>>& declarations() const { return m_declarations; }
 public:
     void accept(visitor& visitor) const override;
 
@@ -38,7 +38,7 @@ public:
 protected:
     bool equal(const node& rhs) const override;
 private:
-    std::vector<node_handle<declaration_node>> m_declarations;
+    std::vector<node_r<declaration_node>> m_declarations;
 };
 
 } // namespace ast

furc/include/furc/ast/statement.hpp

@@ -3,6 +3,8 @@
 
 #include "furc/ast/node.hpp"
 
+#include <optional>
+
 namespace furc {
 namespace ast {
 
@@ -43,6 +45,8 @@ protected:
  * @brief Return statement AST node.
  */
 class return_statement_node final : public statement_node {
+public:
+    using value_type = std::optional<expression_node_r>; /**< Value type. */
 public:
     return_statement_node() = default;
 
@@ -51,7 +55,7 @@ public:
      *
      * @param value Return value handle.
      */
-    return_statement_node(expression_node_h&& value)
+    return_statement_node(expression_node_r&& value)
       : m_value(std::move(value)) {}
 public:
     /**
@@ -59,7 +63,7 @@ public:
      *
      * @return The return value handle.
      */
-    expression_node_h value() const { return m_value; }
+    value_type value() const { return m_value; }
 public:
     /**
      * @brief Returns this node's statement type.
@@ -74,7 +78,7 @@ public:
 protected:
     bool equal(const node& rhs) const override;
 private:
-    expression_node_h m_value; /**< Return value handle. */
+    value_type m_value; /**< Return value handle. */
 };
 
 /**
@@ -88,7 +92,7 @@ public:
      * @param cond Condition expression handle.
      * @param then Then statement handle.
      */
-    if_statement_node(expression_node_h&& cond, statement_node_h&& then)
+    if_statement_node(expression_node_r&& cond, statement_node_r&& then)
       : m_cond(std::move(cond)), m_then(std::move(then)) {}
 
     /**
@@ -98,7 +102,7 @@ public:
      * @param then Then statement handle.
      * @param elze Else statement handle.
      */
-    if_statement_node(expression_node_h&& cond, statement_node_h&& then, statement_node_h&& elze)
+    if_statement_node(expression_node_r&& cond, statement_node_r&& then, statement_node_r&& elze)
       : m_cond(std::move(cond)), m_then(std::move(then)), m_else(std::move(elze)) {}
 public:
     /**
@@ -106,21 +110,21 @@ public:
      *
      * @return The condition expression handle.
      */
-    expression_node_h cond() const { return m_cond; }
+    expression_node_r cond() const { return m_cond; }
 
     /**
      * @brief Returns this node's then statement handle.
      *
      * @return The then statement handle.
      */
-    const statement_node_h& then() const { return m_then; }
+    const statement_node_r& then() const { return m_then; }
 
     /**
      * @brief Returns this node's else statement handle.
      *
      * @return The else statement handle.
      */
-    const statement_node_h& elze() const { return m_else; }
+    const std::optional<statement_node_r>& elze() const { return m_else; }
 public:
     /**
      * @brief Returns this node's statement type.
@@ -135,9 +139,9 @@ public:
 protected:
     bool equal(const node& rhs) const override;
 private:
-    expression_node_h m_cond; /**< The condition expression handle */
-    statement_node_h  m_then; /**< The then statement handle */
-    statement_node_h  m_else; /**< The else statement handle */
+    expression_node_r               m_cond; /**< The condition expression handle */
+    statement_node_r                m_then; /**< The then statement handle */
+    std::optional<statement_node_r> m_else; /**< The else statement handle */
 };
 
 /**

furc/include/furc/ast/visitor.hpp

@@ -123,11 +123,11 @@ public:
     virtual void visit(const compound_statement_node& node) {}
 
     /**
-     * @brief Visit a node handle with an error.
+     * @brief Visit an AST error.
      *
-     * @param handle Node handle.
+     * @param error AST error.
      */
-    virtual void visit_error(const node_handle<node>& handle) {}
+    virtual void visit_error(const ast::error& error) {}
 };
 
 } // namespace ast

furc/include/furc/front/parser.hpp

@@ -54,20 +54,18 @@ public:
      *
      * @return Handle to an AST node of the program.
      */
-    ast::program_node_h parse() &;
+    ast::program_node_r parse() &;
 private:
-    ast::declaration_node_h parse_declaration();
-    ast::statement_node_h   parse_statement();
-    ast::expression_node_h  parse_expression(std::uint32_t precedence = 16);
-    ast::literal_node_h     parse_literal();
+    ast::declaration_node_r parse_declaration();
+    ast::statement_node_r   parse_statement();
+    ast::expression_node_r  parse_expression(std::uint32_t precedence = 16);
+    ast::literal_node_r     parse_literal();
 
-    ast::expression_node_h parse_expression_primary();
-    ast::expression_node_h parse_expression_unary(std::uint32_t precedence);
-    ast::expression_node_h parse_expression_rhs(ast::expression_node_h&& init, std::uint32_t precedence);
+    ast::expression_node_r parse_expression_primary();
+    ast::expression_node_r parse_expression_unary(std::uint32_t precedence);
+    ast::expression_node_r parse_expression_rhs(ast::expression_node_r&& init, std::uint32_t precedence);
 
     ast::body_r parse_body();
-private:
-    static ast::node_handle<ast::node> error_handle(const token_r& result);
 private:
     token_r        next_token();
     const token_r& peek_token();