From 9af6264d6b5127c8a6ef4c2a6b236829f0eced51 Mon Sep 17 00:00:00 2001
From: dearblue <dearblue@users.osdn.me>
Date: Fri, 1 Dec 2023 21:30:16 +0900
Subject: [PATCH] Implement `Fiber#to_s` method

If the filename and line number cannot be obtained, "(unknown):1" is used instead.

Also, the file name information of the terminated fiber cannot be retrieved and will be replaced as well.
This limitation is due to the fact that `cibase->proc` of the terminated fiber is collected by the GC.

```console
% bin/mruby -e 'p Fiber.new { p Fiber.current }.resume'
#<Fiber:0x82423bef0 -e:1 (resumed)>
#<Fiber:0x82423bef0 (unknown):1 (terminated)>
```
---
 mrbgems/mruby-fiber/src/fiber.c | 55 +++++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)

diff --git a/mrbgems/mruby-fiber/src/fiber.c b/mrbgems/mruby-fiber/src/fiber.c
index 62bcbc301..02fbb702b 100644
--- a/mrbgems/mruby-fiber/src/fiber.c
+++ b/mrbgems/mruby-fiber/src/fiber.c
@@ -1,8 +1,11 @@
 #include <mruby.h>
 #include <mruby/array.h>
 #include <mruby/class.h>
+#include <mruby/debug.h>
 #include <mruby/error.h>
+#include <mruby/numeric.h>
 #include <mruby/proc.h>
+#include <mruby/string.h>
 #include <mruby/presym.h>
 
 #define fiber_ptr(o) ((struct RFiber*)mrb_ptr(o))
@@ -348,6 +351,56 @@ fiber_eq(mrb_state *mrb, mrb_value self)
   return mrb_bool_value(fiber_ptr(self) == fiber_ptr(other));
 }
 
+/*
+ *  call-seq:
+ *      fiber.to_s      ->   string
+ *      fiber.inspect   ->   string
+ *
+ *  Returns fiber object information as a string.
+ *
+ *  If the file information cannot be obtained, it is replaced with `(unknown):1`.
+ *  Also, if the fiber is terminated, it will be replaced in the same way (mruby limitation).
+ */
+static mrb_value
+fiber_to_s(mrb_state *mrb, mrb_value self)
+{
+  fiber_check(mrb, self);
+  const struct RFiber *f = fiber_ptr(self);
+
+  mrb_value s = mrb_any_to_s(mrb, self);
+  mrb_assert(RSTRING_END(s)[-1] == '>');
+  RSTRING_END(s)[-1] = ' ';
+
+  const char *file;
+  int32_t line;
+  if (f->cxt->ci > f->cxt->cibase &&
+      mrb_debug_get_position(mrb, f->cxt->cibase->proc->body.irep, 0, &line, &file)) {
+    mrb_str_cat_cstr(mrb, s, file);
+    mrb_str_cat_lit(mrb, s, ":");
+    char buf[16];
+    mrb_str_cat_cstr(mrb, s, mrb_int_to_cstr(buf, sizeof(buf), line, 10));
+  }
+  else {
+    mrb_str_cat_lit(mrb, s, "(unknown):1");
+  }
+
+  const char *st;
+  switch (fiber_ptr(self)->cxt->status) {
+  case MRB_FIBER_CREATED:       st = "created"; break;
+  case MRB_FIBER_RUNNING:       st = "resumed"; break;
+  case MRB_FIBER_RESUMED:       st = "suspended by resuming"; break;
+  case MRB_FIBER_SUSPENDED:     st = "suspended"; break;
+  case MRB_FIBER_TRANSFERRED:   st = "suspended"; break;
+  case MRB_FIBER_TERMINATED:    st = "terminated"; break;
+  default:                      st = "UNKNOWN STATUS (BUG)"; break;
+  }
+  mrb_str_cat_lit(mrb, s, " (");
+  mrb_str_cat_cstr(mrb, s, st);
+  mrb_str_cat_lit(mrb, s, ")>");
+
+  return s;
+}
+
 /*
  *  call-seq:
  *     fiber.transfer(args, ...) -> obj
@@ -485,6 +538,8 @@ mrb_mruby_fiber_gem_init(mrb_state* mrb)
   mrb_define_method(mrb, c, "transfer",   fiber_transfer, MRB_ARGS_ANY());
   mrb_define_method(mrb, c, "alive?",     fiber_alive_p, MRB_ARGS_NONE());
   mrb_define_method(mrb, c, "==",         fiber_eq,      MRB_ARGS_REQ(1));
+  mrb_define_method(mrb, c, "to_s",       fiber_to_s,    MRB_ARGS_NONE());
+  mrb_define_alias(mrb, c, "inspect", "to_s");
 
   mrb_define_class_method(mrb, c, "yield", fiber_yield, MRB_ARGS_ANY());
   mrb_define_class_method(mrb, c, "current", fiber_current, MRB_ARGS_NONE());