Add InstructionSequence#type method

This method returns a symbol representing the type of the instruction
sequence object.

Author: tenderlove

iseq.c

@@ -1624,6 +1624,27 @@ iseqw_inspect(VALUE self)
     }
 }
 
+static VALUE
+iseqw_type(VALUE self)
+{
+    const rb_iseq_t *iseq = iseqw_check(self);
+    const struct rb_iseq_constant_body *const body = ISEQ_BODY(iseq);
+
+    switch(body->type) {
+#define CASE_TYPE(t) case ISEQ_TYPE_ ## t: return ID2SYM(rb_intern(#t)); break;
+        CASE_TYPE(TOP);
+        CASE_TYPE(METHOD);
+        CASE_TYPE(BLOCK);
+        CASE_TYPE(CLASS);
+        CASE_TYPE(RESCUE);
+        CASE_TYPE(ENSURE);
+        CASE_TYPE(EVAL);
+        CASE_TYPE(MAIN);
+        CASE_TYPE(PLAIN);
+#undef CASE_TYPE
+    }
+}
+
 /*
  *  Returns the path of this instruction sequence.
  *
@@ -3915,6 +3936,7 @@ Init_ISeq(void)
     rb_cISeq = rb_define_class_under(rb_cRubyVM, "InstructionSequence", rb_cObject);
     rb_undef_alloc_func(rb_cISeq);
     rb_define_method(rb_cISeq, "inspect", iseqw_inspect, 0);
+    rb_define_method(rb_cISeq, "type", iseqw_type, 0);
     rb_define_method(rb_cISeq, "disasm", iseqw_disasm, 0);
     rb_define_method(rb_cISeq, "disassemble", iseqw_disasm, 0);
     rb_define_method(rb_cISeq, "to_a", iseqw_to_a, 0);

test/ruby/test_iseq.rb

@@ -167,6 +167,13 @@ def obj.foo(*) nil.instance_eval{ ->{super} } end
     end
   end
 
+  def test_type
+    iseq = RubyVM::InstructionSequence.of(method(__method__))
+    assert_equal :METHOD, iseq.type
+    iseq = RubyVM::InstructionSequence.of(->() { })
+    assert_equal :BLOCK, iseq.type
+  end
+
   def test_disasm_encoding
     src = "\u{3042} = 1; \u{3042}; \u{3043}"
     asm = compile(src).disasm