More ergonomic solution using macros, but still needs improvement

Makefile

@@ -13,7 +13,7 @@ CLOX_OUT  = clox
 all: cclox clox
 
 cclox: ${CCLOX_SRC}
-	${CXX} ${CFLAGS} ${CCLOX_SRC} -o ${CCLOX_OUT}
+	${CXX} -std=c++20 ${CFLAGS} ${CCLOX_SRC} -o ${CCLOX_OUT}
 
 clox: ${CLOX_SRC}
 	${CC} ${CFLAGS} ${CLOX_SRC} -o ${CLOX_OUT}

cclox_src/main.cc

@@ -17,24 +17,14 @@ int main(int argc, char *argv[]) {
   //
   // run_interpreter(argc, argv);
 
-  ExprPtr left = std::make_shared<Expr>(
-    make_expr(
-      Unary{
-        Token{TokenType::MINUS, "-", Object{}, 1},
-        std::make_shared<Expr>(make_expr(Literal{123}))
-      }
-    )
-  );
+  Token unary_op{TokenType::MINUS, "-", Object{}, 1};
+  ExprPtr left = UnaryExprPtr(unary_op, LiteralExprPtr(123));
 
   Token op{TokenType::STAR, "*", Object{}, 1};
 
-  ExprPtr right = std::make_shared<Expr>(
-    make_expr(
-      Grouping{std::make_shared<Expr>(make_expr(Literal{45.67}))}
-    )
-  );
+  ExprPtr right = GroupingExprPtr(LiteralExprPtr(45.67));
 
-  Expr expr = {ExprType::BINARY, Binary{left, op, right}};
+  Expr expr = BinaryExpr(left, op, right);
 
   AstPrinter printer{};
   std::cout << printer.print(expr) << '\n';

cclox_src/parser/expr.cc

@@ -5,26 +5,6 @@
 #include <vector>
 #include <sstream>
 
-template <>
-Expr make_expr<Binary>(Binary value) {
-  return Expr(ExprType::BINARY, value);
-}
-
-template <>
-Expr make_expr<Grouping>(Grouping value) {
-  return Expr(ExprType::GROUPING, value);
-}
-
-template <>
-Expr make_expr<Literal>(Literal value) {
-  return Expr(ExprType::LITERAL, value);
-}
-
-template <>
-Expr make_expr<Unary>(Unary value) {
-  return Expr(ExprType::UNARY, value);
-}
-
 std::string AstPrinter::print(const Expr &expr) {
   switch (expr.type) {
     case ExprType::BINARY: {

cclox_src/parser/expr.hh

@@ -6,33 +6,55 @@
 #include <string>
 #include <variant>
 
+#define BinaryExpr(LEFT, OP, RIGHT) ( \
+      Expr{ \
+        .type = ExprType::BINARY, \
+        .value = Binary{.left = LEFT, .op = OP, .right = RIGHT} \
+      } \
+    )
+#define GroupingExpr(EXPR) ( \
+      Expr{ \
+        .type = ExprType::GROUPING, \
+        .value = Grouping{.expression = EXPR} \
+      } \
+    )
+#define LiteralExpr(VALUE) ( \
+      Expr{ \
+        .type = ExprType::LITERAL, \
+        .value = Literal{.value = VALUE} \
+      } \
+    )
+#define UnaryExpr(OP, RIGHT) ( \
+      Expr{ \
+        .type = ExprType::UNARY, \
+        .value = Unary{.op = OP, .right = RIGHT} \
+      } \
+    )
+
+#define BinaryExprPtr(LEFT, OP, RIGHT) (std::make_shared<Expr>(BinaryExpr(LEFT, OP, RIGHT)))
+#define GroupingExprPtr(EXPR) (std::make_shared<Expr>(GroupingExpr(EXPR)))
+#define LiteralExprPtr(VALUE) (std::make_shared<Expr>(LiteralExpr(VALUE)))
+#define UnaryExprPtr(OP, RIGHT) (std::make_shared<Expr>(UnaryExpr(OP, RIGHT)))
+
 struct Expr;
 
 using ExprPtr = std::shared_ptr<Expr>;
 
 struct Binary {
-  Binary(ExprPtr left, Token op, ExprPtr right) : left{left}, op{op}, right{right} {};
-
   ExprPtr left;
   Token op;
   ExprPtr right;
 };
 
 struct Grouping {
-  Grouping(ExprPtr expr) : expression{expr} {};
-
   ExprPtr expression;
 };
 
 struct Literal {
-  Literal(Object value) : value{value} {};
-
   Object value;
 };
 
 struct Unary {
-  Unary(Token op, ExprPtr right) : op{op}, right{right} {};
-
   Token op;
   ExprPtr right;
 };
@@ -47,14 +69,10 @@ enum class ExprType {
 using Expression = std::variant<Binary, Grouping, Literal, Unary>;
 
 struct Expr {
-  Expr(ExprType type, Expression value) : type{type}, value{value} {}
   ExprType type;
   Expression value;
 };
 
-template <typename T>
-Expr make_expr(T value);
-
 class AstPrinter {
 public:
   std::string print(const Expr &expr);