From 20690026a7dd7622c7d824de71e337a68a293b63 Mon Sep 17 00:00:00 2001
From: nobu <nobu@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Mon, 16 Nov 2015 09:21:56 +0000
Subject: [PATCH] struct.c: dig

* object.c (rb_obj_dig): dig in nested structs too.
* struct.c (rb_struct_dig): new method Struct#dig.
  [Feature #11688]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@52596 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 ChangeLog                |  7 +++++++
 NEWS                     |  3 +++
 internal.h               |  1 +
 object.c                 |  9 ++++++++-
 struct.c                 | 28 ++++++++++++++++++++++++++++
 test/ruby/test_struct.rb |  7 +++++++
 6 files changed, 54 insertions(+), 1 deletion(-)

diff --git a/ChangeLog b/ChangeLog
index 0c5d05b82dff35..8ed37cf96dffbc 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+Mon Nov 16 18:21:52 2015  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* object.c (rb_obj_dig): dig in nested structs too.
+
+	* struct.c (rb_struct_dig): new method Struct#dig.
+	  [Feature #11688]
+
 Mon Nov 16 17:41:33 2015  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* compile.c (iseq_peephole_optimize): optimize tail calls on aref
diff --git a/NEWS b/NEWS
index 6724aaf40257a8..a7d2da980aed94 100644
--- a/NEWS
+++ b/NEWS
@@ -95,6 +95,9 @@ with all sufficient information, see the ChangeLog file.
     Backtrace doesn't show each methods (show block lines directly).
     TracePoint also ignore these calls. [Feature #11569]
 
+* Struct
+  * Struct#dig [Feature #11686]
+
 * Thread
   * Thread#name, Thread#name= are added to handle thread names [Feature #11251]
 
diff --git a/internal.h b/internal.h
index 600ad8e7d35d95..7e6f26db1121f2 100644
--- a/internal.h
+++ b/internal.h
@@ -1141,6 +1141,7 @@ VALUE rb_cstr_intern(const char *ptr, long len, rb_encoding *enc);
 
 /* struct.c */
 VALUE rb_struct_init_copy(VALUE copy, VALUE s);
+VALUE rb_struct_lookup(VALUE s, VALUE idx);
 
 /* time.c */
 struct timeval rb_time_timeval(VALUE);
diff --git a/object.c b/object.c
index ed5d12ea2c9653..5023f64b0db5be 100644
--- a/object.c
+++ b/object.c
@@ -3165,7 +3165,7 @@ dig_basic_p(VALUE obj, struct dig_method *cache)
 VALUE
 rb_obj_dig(int argc, VALUE *argv, VALUE obj, VALUE notfound)
 {
-    struct dig_method hash = {Qnil}, ary = {Qnil};
+    struct dig_method hash = {Qnil}, ary = {Qnil}, strt = {Qnil};
 
     for (; argc > 0; ++argv, --argc) {
 	if (!SPECIAL_CONST_P(obj)) {
@@ -3181,6 +3181,13 @@ rb_obj_dig(int argc, VALUE *argv, VALUE obj, VALUE notfound)
 		    obj = rb_ary_at(obj, *argv);
 		    continue;
 		}
+		break;
+	      case T_STRUCT:
+		if (dig_basic_p(obj, &strt)) {
+		    obj = rb_struct_lookup(obj, *argv);
+		    continue;
+		}
+		break;
 	    }
 	}
 	return rb_check_funcall_default(obj, id_dig, argc, argv, notfound);
diff --git a/struct.c b/struct.c
index 60ef6d8cfdf41f..d8c781efa6e3a8 100644
--- a/struct.c
+++ b/struct.c
@@ -923,6 +923,23 @@ rb_struct_aset(VALUE s, VALUE idx, VALUE val)
     return val;
 }
 
+FUNC_MINIMIZED(VALUE rb_struct_lookup(VALUE s, VALUE idx));
+NOINLINE(static VALUE rb_struct_lookup_default(VALUE s, VALUE idx, VALUE notfound));
+
+VALUE
+rb_struct_lookup(VALUE s, VALUE idx)
+{
+    return rb_struct_lookup_default(s, idx, Qnil);
+}
+
+static VALUE
+rb_struct_lookup_default(VALUE s, VALUE idx, VALUE notfound)
+{
+    int i = rb_struct_pos(s, &idx);
+    if (i < 0) return notfound;
+    return RSTRUCT_GET(s, i);
+}
+
 static VALUE
 struct_entry(VALUE s, long n)
 {
@@ -1109,6 +1126,16 @@ rb_struct_size(VALUE s)
     return LONG2FIX(RSTRUCT_LEN(s));
 }
 
+static VALUE
+rb_struct_dig(int argc, VALUE *argv, VALUE self)
+{
+    rb_check_arity(argc, 1, UNLIMITED_ARGUMENTS);
+    self = rb_struct_lookup(self, *argv);
+    if (!--argc) return self;
+    ++argv;
+    return rb_obj_dig(argc, argv, self, Qnil);
+}
+
 /*
  *  A Struct is a convenient way to bundle a number of attributes together,
  *  using accessor methods, without having to write an explicit class.
@@ -1166,6 +1193,7 @@ InitVM_Struct(void)
     rb_define_method(rb_cStruct, "values_at", rb_struct_values_at, -1);
 
     rb_define_method(rb_cStruct, "members", rb_struct_members_m, 0);
+    rb_define_method(rb_cStruct, "dig", rb_struct_dig, -1);
 }
 
 #undef rb_intern
diff --git a/test/ruby/test_struct.rb b/test/ruby/test_struct.rb
index f51432cfd6b379..780d344b8ecaa5 100644
--- a/test/ruby/test_struct.rb
+++ b/test/ruby/test_struct.rb
@@ -353,6 +353,13 @@ def test_setter_method_returns_value
     assert_equal "[Bug #9353]", x.send(:a=, "[Bug #9353]")
   end
 
+  def test_dig
+    klass = @Struct.new(:a)
+    o = klass.new(klass.new({b: [1, 2, 3]}))
+    assert_equal(1, o.dig(:a, :a, :b, 0))
+    assert_nil(o.dig(:b, 0))
+  end
+
   class TopStruct < Test::Unit::TestCase
     include TestStruct