added the parsing of expression statements

src/ast/statements/expression.hpp

@@ -0,0 +1,15 @@
+#include "ast/ast.hpp"
+#include "token/token.hpp"
+
+namespace ast {
+    struct expression_stmt : statement {
+        expression_stmt(token::token token);
+
+        token::token token;
+        ast::expression* expression;
+
+        std::string token_literal() const override;
+
+        ~expression_stmt();
+    };
+} // namespace ast