[PATCH] dynarray: Implement begin/end functions in the spirit of C++

[fweimer at redhat dot com (Florian Weimer)]

2017-06-13  Florian Weimer  <fweimer@redhat.com>

	* malloc/dynarray-skeleton.c: List begin/end/at as defined
	functions.  The at function was missing by accident.
	(DYNARRAY_PREFIX##begin, DYNARRAY_PREFIX##end): New functions.
	* malloc/tst-dynarray-shared.h (CHECK_EMPTY): Add tests for
	begin/end.
	* malloc/tst-dynarray.c (test_int): Test dynarray_int_begin,
	dynarray_int_end.
	(test_str): Test dynarray_str_begin, dynarray_str_end.

diff --git a/malloc/dynarray-skeleton.c b/malloc/dynarray-skeleton.c
index 7a10e08..b0ee818 100644
--- a/malloc/dynarray-skeleton.c
+++ b/malloc/dynarray-skeleton.c
@@ -65,6 +65,10 @@
      bool DYNARRAY_PREFIX##has_failed (const struct DYNARRAY_STRUCT *);
      void DYNARRAY_PREFIX##mark_failed (struct DYNARRAY_STRUCT *);
      size_t DYNARRAY_PREFIX##size (const struct DYNARRAY_STRUCT *);
+     DYNARRAY_ELEMENT *DYNARRAY_PREFIX##at
+       (const struct DYNARRAY_STRUCT *, size_t);
+     DYNARRAY_ELEMENT *DYNARRAY_PREFIX##begin (const struct DYNARRAY_STRUCT *);
+     DYNARRAY_ELEMENT *DYNARRAY_PREFIX##end (const struct DYNARRAY_STRUCT *);
      DYNARRAY_ELEMENT *DYNARRAY_PREFIX##at (struct DYNARRAY_STRUCT *, size_t);
      void DYNARRAY_PREFIX##add (struct DYNARRAY_STRUCT *, DYNARRAY_ELEMENT);
      DYNARRAY_ELEMENT *DYNARRAY_PREFIX##emplace (struct DYNARRAY_STRUCT *);
@@ -248,6 +252,26 @@ DYNARRAY_NAME (at) (struct DYNARRAY_STRUCT *list, size_t index)
   return list->dynarray_header.array + index;
 }
 
+/* Return a pointer to the first array element, if any.  For a
+   zero-length array, the pointer can be NULL even though the dynamic
+   array has not entered the failure state.  */
+__attribute__ ((nonnull (1)))
+static inline DYNARRAY_ELEMENT *
+DYNARRAY_NAME (begin) (struct DYNARRAY_STRUCT *list)
+{
+  return list->dynarray_header.array;
+}
+
+/* Return a pointer one element past the last array element.  For a
+   zero-length array, the pointer can be NULL even though the dynamic
+   array has not entered the failure state.  */
+__attribute__ ((nonnull (1)))
+static inline DYNARRAY_ELEMENT *
+DYNARRAY_NAME (end) (struct DYNARRAY_STRUCT *list)
+{
+  return list->dynarray_header.array + list->dynarray_header.used;
+}
+
 /* Internal function.  Slow path for the add function below.  */
 static void
 DYNARRAY_NAME (add__) (struct DYNARRAY_STRUCT *list, DYNARRAY_ELEMENT item)
diff --git a/malloc/tst-dynarray-shared.h b/malloc/tst-dynarray-shared.h
index faba66f..1de9c04 100644
--- a/malloc/tst-dynarray-shared.h
+++ b/malloc/tst-dynarray-shared.h
@@ -73,5 +73,8 @@ struct str_array
     TEST_VERIFY_EXIT (dynarray_##type##_emplace (dyn) == NULL);      \
     dynarray_##type##_free (dyn);                                    \
     CHECK_INIT_STATE (type, (dyn));                                  \
+    /* These functions should not assert.  */                        \
+    dynarray_##type##_begin (dyn);                                   \
+    dynarray_##type##_end (dyn);                                     \
     (void) 0;                                                        \
   })
diff --git a/malloc/tst-dynarray.c b/malloc/tst-dynarray.c
index 7aee85a..2206d75 100644
--- a/malloc/tst-dynarray.c
+++ b/malloc/tst-dynarray.c
@@ -111,6 +111,13 @@ test_int (void)
                 }
               TEST_VERIFY_EXIT (dynarray_int_size (&dyn) == count);
               TEST_VERIFY_EXIT (count <= dyn.dynarray_header.allocated);
+              if (count > 0)
+                {
+                  TEST_VERIFY (dynarray_int_begin (&dyn)
+                               == dynarray_int_at (&dyn, 0));
+                  TEST_VERIFY (dynarray_int_end (&dyn)
+                               == dynarray_int_at (&dyn, count - 1) + 1);
+                }
               unsigned final_count;
               bool heap_array = dyn.dynarray_header.array != dyn.scratch;
               if (do_remove_last)
@@ -123,6 +130,13 @@ test_int (void)
                 }
               else
                 final_count = count;
+              if (final_count > 0)
+                {
+                  TEST_VERIFY (dynarray_int_begin (&dyn)
+                               == dynarray_int_at (&dyn, 0));
+                  TEST_VERIFY (dynarray_int_end (&dyn)
+                               == dynarray_int_at (&dyn, final_count - 1) + 1);
+                }
               if (do_clear)
                 {
                   dynarray_int_clear (&dyn);
@@ -225,6 +239,13 @@ test_str (void)
                 }
               TEST_VERIFY_EXIT (dynarray_str_size (&dyn) == count);
               TEST_VERIFY_EXIT (count <= dyn.dynarray_header.allocated);
+              if (count > 0)
+                {
+                  TEST_VERIFY (dynarray_str_begin (&dyn)
+                               == dynarray_str_at (&dyn, 0));
+                  TEST_VERIFY (dynarray_str_end (&dyn)
+                               == dynarray_str_at (&dyn, count - 1) + 1);
+                }
               unsigned final_count;
               bool heap_array = dyn.dynarray_header.array != dyn.scratch;
               if (do_remove_last)
@@ -237,6 +258,13 @@ test_str (void)
                 }
               else
                 final_count = count;
+              if (final_count > 0)
+                {
+                  TEST_VERIFY (dynarray_str_begin (&dyn)
+                               == dynarray_str_at (&dyn, 0));
+                  TEST_VERIFY (dynarray_str_end (&dyn)
+                               == dynarray_str_at (&dyn, final_count - 1) + 1);
+                }
               if (do_clear)
                 {
                   dynarray_str_clear (&dyn);