* ext/dl/cptr.c (rb_dlptr_inspect, rb_dlptr_plus, rb_dlptr_minus)

  documenting +, -, inspect
* text/dl/test_cptr.rb (test_minus, test_plus, test_inspect) testing
  minus, plus, and inspect

git-svn-id: http://svn.ruby-lang.org/repos/ruby/trunk@25675 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

2 files changed, 43 insertions, 3 deletions

diff --git a/ext/dl/cptr.c b/ext/dl/cptr.c
index cdcc23c72..393cc1165 100644
--- a/ext/dl/cptr.c
+++ b/ext/dl/cptr.c
@@ -331,7 +331,13 @@ rb_dlptr_to_str(int argc, VALUE argv[], VALUE self)
     return val;
 }
 
-VALUE
+/*
+ * call-seq: inspect
+ *
+ * Returns a string formatted with an easily readable representation of the
+ * internal state of the DL::CPtr
+ */
+static VALUE
 rb_dlptr_inspect(VALUE self)
 {
     struct ptr_data *data;
@@ -386,7 +392,13 @@ rb_dlptr_cmp(VALUE self, VALUE other)
     return diff > 0 ? INT2NUM(1) : INT2NUM(-1);
 }
 
-VALUE
+/*
+ * call-seq:
+ *    ptr + n   => new cptr
+ *
+ * Returns a new DL::CPtr that has been advanced +n+ bytes.
+ */
+static VALUE
 rb_dlptr_plus(VALUE self, VALUE other)
 {
     void *ptr;
@@ -398,7 +410,13 @@ rb_dlptr_plus(VALUE self, VALUE other)
     return rb_dlptr_new((char *)ptr + num, size - num, 0);
 }
 
-VALUE
+/*
+ * call-seq:
+ *    ptr - n   => new cptr
+ *
+ * Returns a new DL::CPtr that has been moved back +n+ bytes.
+ */
+static VALUE
 rb_dlptr_minus(VALUE self, VALUE other)
 {
     void *ptr;
diff --git a/test/dl/test_cptr.rb b/test/dl/test_cptr.rb
index 3c4b5e686..43605f84c 100644
--- a/test/dl/test_cptr.rb
+++ b/test/dl/test_cptr.rb
@@ -3,6 +3,28 @@ require_relative '../ruby/envutil'
 
 module DL
   class TestCPtr < TestBase
+    def test_minus
+      str = "hello world"
+      ptr = CPtr[str]
+      assert_equal ptr.to_s, (ptr + 3 - 3).to_s
+    end
+
+    # TODO: what if the pointer size is 0?  raise an exception? do we care?
+    def test_plus
+      str = "hello world"
+      ptr = CPtr[str]
+      new_str = ptr + 3
+      assert_equal 'lo world', new_str.to_s
+    end
+
+    def test_inspect
+      ptr = CPtr.new(0)
+      inspect = ptr.inspect
+      assert_match(/size=#{ptr.size}/, inspect)
+      assert_match(/free=#{ptr.free}/, inspect)
+      assert_match(/ptr=#{ptr.to_i}/, inspect)
+    end
+
     def test_to_ptr_string
       str = "hello world"
       ptr = CPtr[str]