Let inspect recursion do the right thing

mrbgems/mruby-struct/mrblib/struct.rb

@@ -46,7 +46,9 @@ if Object.const_defined?(:Struct)
       ary
     end
 
-    def _inspect
+    def _inspect(recur_list)
+      return "#<struct #{self.class}:...>" if recur_list[self.object_id]
+      recur_list[self.object_id] = true
       name = self.class.to_s
       if name[0] == "#"
         str = "#<struct "
@@ -55,7 +57,7 @@ if Object.const_defined?(:Struct)
       end
       buf = []
       self.each_pair do |k,v|
-        buf.push [k.to_s + "=" + v._inspect]
+        buf.push [k.to_s + "=" + v._inspect(recur_list)]
       end
       str + buf.join(", ") + ">"
     end
@@ -70,11 +72,7 @@ if Object.const_defined?(:Struct)
     # 15.2.18.4.10(x)
     #
     def inspect
-      begin
-        self._inspect
-      rescue SystemStackError
-        "#<struct #{self.class.to_s}:...>"
-      end
+      self._inspect({})
     end
 
     ##

mrbgems/mruby-struct/test/struct.rb

@@ -116,9 +116,10 @@ assert('struct dup') do
 end
 
 assert('struct inspect') do
-  c = Struct.new(:m1, :m2, :m3, :m4, :m5)
-  cc = c.new(1,2,3,4,5)
-  assert_equal "#<struct m1=1, m2=2, m3=3, m4=4, m5=5>", cc.inspect
+  c = Struct.new(:m1, :m2, :m3, :m4, :m5, :recur)
+  cc = c.new(1,2,3,4,5,nil)
+  cc.recur = cc
+  assert_equal "#<struct m1=1, m2=2, m3=3, m4=4, m5=5, recur=#<struct #{cc.class}:...>>", cc.inspect
 end
 
 assert('Struct#length, Struct#size') do

mrblib/array.rb

@@ -83,20 +83,18 @@ class Array
     self
   end
 
-  def _inspect
+  def _inspect(recur_list)
     return "[]" if self.size == 0
-    "["+self.map{|x|x.inspect}.join(", ")+"]"
+    return "[...]" if recur_list[self.object_id]
+    recur_list[self.object_id] = true
+    "["+self.map{|x|x._inspect(recur_list)}.join(", ")+"]"
   end
   ##
   # Return the contents of this array as a string.
   #
   # ISO 15.2.12.5.31 (x)
   def inspect
-    begin
-      self._inspect
-    rescue SystemStackError
-      "[...]"
-    end
+    self._inspect({})
   end
   # ISO 15.2.12.5.32 (x)
   alias to_s inspect

mrblib/hash.rb

@@ -193,10 +193,12 @@ class Hash
   end
 
   # internal method for Hash inspection
-  def _inspect
+  def _inspect(recur_list)
     return "{}" if self.size == 0
+    return "{...}" if recur_list[self.object_id]
+    recur_list[self.object_id] = true
     "{"+self.map {|k,v|
-      k._inspect + "=>" + v._inspect
+      k._inspect(recur_list) + "=>" + v._inspect(recur_list)
     }.join(", ")+"}"
   end
   ##
@@ -204,11 +206,7 @@ class Hash
  #
   # ISO 15.2.13.4.30 (x)
   def inspect
-    begin
-      self._inspect
-    rescue SystemStackError
-      "{...}"
-    end
+    self._inspect({})
   end
   # ISO 15.2.13.4.31 (x)
   alias to_s inspect

mrblib/kernel.rb

@@ -40,7 +40,7 @@ module Kernel
   end
 
   # internal method for inspect
-  def _inspect
+  def _inspect(_recur_list)
     self.inspect
   end
 

test/t/array.rb

@@ -318,11 +318,12 @@ end
 
 assert('Array#to_s', '15.2.12.5.31 / 15.2.12.5.32') do
   a = [2, 3,   4, 5]
+  a[4] = a
   r1 = a.to_s
   r2 = a.inspect
 
   assert_equal(r2, r1)
-  assert_equal("[2, 3, 4, 5]", r1)
+  assert_equal("[2, 3, 4, 5, [...]]", r1)
 end
 
 assert('Array#==', '15.2.12.5.33') do

test/t/hash.rb

@@ -351,11 +351,13 @@ end
 
 assert('Hash#inspect') do
   h = { "c" => 300, "a" => 100, "d" => 400, "c" => 300  }
+  h["recur"] = h
   ret = h.to_s
 
   assert_include ret, '"c"=>300'
   assert_include ret, '"a"=>100'
   assert_include ret, '"d"=>400'
+  assert_include ret, '"recur"=>{...}'
 end
 
 assert('Hash#rehash') do