Implement `mrb_protect`, `mrb_ensure`, `mrb_rescue`, `mrb_rescue_exceptions`.

(`mrb_rescue_exceptions` is mruby implementation of `rb_rescue2`.)
Closes #2844, closes #2837.

1 files changed, 102 insertions, 0 deletions

diff --git a/mrbgems/mruby-error/src/exception.c b/mrbgems/mruby-error/src/exception.c
new file mode 100644
index 000000000..abd03bc29
--- /dev/null
+++ b/mrbgems/mruby-error/src/exception.c
@@ -0,0 +1,102 @@
+#include <stdarg.h>
+#include "mruby.h"
+#include "mruby/throw.h"
+#include "mruby/error.h"
+
+MRB_API mrb_value
+mrb_protect(mrb_state *mrb, mrb_func_t body, mrb_value data, mrb_bool *state)
+{
+  struct mrb_jmpbuf *prev_jmp = mrb->jmp;
+  struct mrb_jmpbuf c_jmp;
+  mrb_value result = mrb_nil_value();
+
+  if (state) { *state = FALSE; }
+
+  MRB_TRY(&c_jmp) {
+    mrb->jmp = &c_jmp;
+    result = body(mrb, data);
+    mrb->jmp = prev_jmp;
+  } MRB_CATCH(&c_jmp) {
+    mrb->jmp = prev_jmp;
+    mrb->exc = NULL;
+    if (state) { *state = TRUE; }
+  } MRB_END_EXC(&c_jmp);
+
+  mrb_gc_protect(mrb, result);
+  return result;
+}
+
+MRB_API mrb_value
+mrb_ensure(mrb_state *mrb, mrb_func_t body, mrb_value b_data, mrb_func_t ensure, mrb_value e_data)
+{
+  struct mrb_jmpbuf *prev_jmp = mrb->jmp;
+  struct mrb_jmpbuf c_jmp;
+  mrb_value result;
+
+  MRB_TRY(&c_jmp) {
+    mrb->jmp = &c_jmp;
+    result = body(mrb, b_data);
+    mrb->jmp = prev_jmp;
+  } MRB_CATCH(&c_jmp) {
+    mrb->jmp = prev_jmp;
+    ensure(mrb, e_data);
+    MRB_THROW(mrb->jmp); /* rethrow catched exceptions */
+  } MRB_END_EXC(&c_jmp);
+
+  ensure(mrb, e_data);
+  mrb_gc_protect(mrb, result);
+  return result;
+}
+
+MRB_API mrb_value
+mrb_rescue(mrb_state *mrb, mrb_func_t body, mrb_value b_data,
+           mrb_func_t rescue, mrb_value r_data)
+{
+  return mrb_rescue_exceptions(mrb, body, b_data, rescue, r_data, mrb->eStandardError_class, NULL);
+}
+
+MRB_API mrb_value
+mrb_rescue_exceptions(mrb_state *mrb, mrb_func_t body, mrb_value b_data, mrb_func_t rescue, mrb_value r_data, ...)
+{
+  struct mrb_jmpbuf *prev_jmp = mrb->jmp;
+  struct mrb_jmpbuf c_jmp;
+  mrb_value result;
+  va_list excs;
+  struct RClass *cls;
+  mrb_bool error_matched = FALSE;
+
+  MRB_TRY(&c_jmp) {
+    mrb->jmp = &c_jmp;
+    result = body(mrb, b_data);
+    mrb->jmp = prev_jmp;
+  } MRB_CATCH(&c_jmp) {
+    mrb->jmp = prev_jmp;
+
+    va_start(excs, r_data);
+    while((cls = va_arg(excs, struct RClass*))) {
+      if (mrb_obj_is_kind_of(mrb, mrb_obj_value(mrb->exc), cls)) {
+        error_matched = TRUE;
+        break;
+      }
+    }
+    va_end(excs);
+
+    if (!error_matched) { MRB_THROW(mrb->jmp); }
+
+    mrb->exc = NULL;
+    result = rescue(mrb, r_data);
+  } MRB_END_EXC(&c_jmp);
+
+  mrb_gc_protect(mrb, result);
+  return result;
+}
+
+void
+mrb_mruby_error_gem_init(mrb_state *mrb)
+{
+}
+
+void
+mrb_mruby_error_gem_final(mrb_state *mrb)
+{
+}