From 3ac682b2de45e7267a6f0efb47d45a785bd90b23 Mon Sep 17 00:00:00 2001
From: dearblue <dearblue@gmx.com>
Date: Sat, 24 Jan 2026 11:31:32 +0900
Subject: [PATCH] Add the `MRB_ENSURE()` macro

---
 include/mruby.h       |  4 ++++
 include/mruby/error.h | 36 ++++++++++++++++++++++++++++++++++++
 2 files changed, 40 insertions(+)

diff --git a/include/mruby.h b/include/mruby.h
index 542215541..b5a66dc18 100644
--- a/include/mruby.h
+++ b/include/mruby.h
@@ -1615,6 +1615,10 @@ mrbmemset(void *s, int c, size_t n)
 
 #define mrb_int_hash_func(mrb,key) (uint32_t)((key)^((key)<<2)^((key)>>2))
 
+#define MRB_UNIQNAME(name)         MRB_UNIQNAME_1(name, __LINE__)
+#define MRB_UNIQNAME_1(name, line) MRB_UNIQNAME_2(name, line)
+#define MRB_UNIQNAME_2(name, line) name##line
+
 MRB_END_DECL
 
 #endif  /* MRUBY_H */
diff --git a/include/mruby/error.h b/include/mruby/error.h
index e8c63dc3e..ba091fcfe 100644
--- a/include/mruby/error.h
+++ b/include/mruby/error.h
@@ -127,6 +127,42 @@ MRB_API mrb_value mrb_rescue_exceptions(mrb_state *mrb, mrb_func_t body, mrb_val
                                         mrb_func_t rescue, mrb_value r_data,
                                         mrb_int len, struct RClass **classes);
 
+/**
+ *  Calls `func` via `mrb_protect_error()` and then always executes the user block exactly once.
+ *  Even if a global jump (similar to a Ruby exception) occurs within `func`, the block will be executed,
+ *  and after the block's completion, the global jump will be re-thrown.
+ *
+ *  By checking `mrb->exc != NULL` within the block, you can determine if a global jump occurred in `func`.
+ *
+ *  If you want to suppress the global jump and continue processing, use `mrb_clear_error(mrb); break;`.
+ *
+ *  - `mrb`: The mruby state reference
+ *  - `result_var`: Pre-defined mrb_value type variable (to receive `func`'s return value)
+ *  - `func`: Function to call (compatible with `mrb_protect_error_func`)
+ *  - `data`: User data to pass to `func`
+ *
+ *  Example:
+ *
+ *      mrb_value result;
+ *      MRB_ENSURE(mrb, result, body_func, userdata) {
+ *        // This block is always executed (equivalent to Ruby's ensure)
+ *
+ *        if (mrb->exc) {
+ *          // Post-processing when an exception occurs
+ *        }
+ *
+ *        // To ignore the global jump, use `mrb_clear_error(mrb); break;` here
+ *      }
+ */
+#define MRB_ENSURE(mrb, result_var, func, data) \
+        for (mrb_bool MRB_UNIQNAME(_break_) = FALSE; \
+             !MRB_UNIQNAME(_break_) && \
+                (((result_var) = mrb_protect_error(mrb, func, data, &MRB_UNIQNAME(_break_))), \
+                 ((mrb)->exc = (MRB_UNIQNAME(_break_) ? mrb_obj_ptr((result_var)) : NULL)), \
+                 TRUE); \
+             (void)(MRB_UNIQNAME(_break_) && (mrb)->jmp && (mrb_exc_raise(mrb, result_var), TRUE)), \
+                MRB_UNIQNAME(_break_) = TRUE)
+
 MRB_END_DECL
 
 #endif  /* MRUBY_ERROR_H */