gdb/unittests/function-view-selftests.c

   1 /* Self tests for function_view for GDB, the GNU debugger.
   2
   3    Copyright (C) 2017-2021 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #include "defs.h"
  21 #include "gdbsupport/selftest.h"
  22 #include "gdbsupport/function-view.h"
  23
  24 namespace selftests {
  25 namespace function_view {
  26
  27 static int
  28 plus_one_fn_int (int val)
  29 {
  30   return ++val;
  31 }
  32
  33 static short
  34 plus_one_fn_short (short val)
  35 {
  36   return ++val;
  37 }
  38
  39 static int
  40 call_callback_int (int val, gdb::function_view <int (int)> callback)
  41 {
  42   return callback (val);
  43 }
  44
  45 static void
  46 call_callback_void (int val, gdb::function_view <void (int)> callback)
  47 {
  48   callback (val);
  49 }
  50
  51 struct plus_one_int_func_obj
  52 {
  53   int operator () (int val)
  54   {
  55     ++call_count;
  56     return ++val;
  57   }
  58
  59   /* Number of times called.  */
  60   int call_count = 0;
  61 };
  62
  63 static void
  64 run_tests ()
  65 {
  66   /* A simple lambda.  */
  67   auto plus_one_lambda = [] (int val) { return ++val; };
  68
  69   /* A function_view that references the lambda.  */
  70   gdb::function_view<int (int)> plus_one_func_view (plus_one_lambda);
  71
  72   /* Check calling the lambda directly.  */
  73   SELF_CHECK (plus_one_lambda (0) == 1);
  74   SELF_CHECK (plus_one_lambda (1) == 2);
  75
  76   /* Check calling lambda via the view.  */
  77   SELF_CHECK (plus_one_func_view (2) == 3);
  78   SELF_CHECK (plus_one_func_view (3) == 4);
  79
  80   /* Check calling a function that takes a function_view as argument,
  81      by value.  Pass a lambda, making sure a function_view is properly
  82      constructed implicitly.  */
  83   SELF_CHECK (call_callback_int (1, [] (int val)
  84     {
  85       return val + 2;
  86     }) == 3);
  87
  88   /* Same, passing a named/lvalue lambda.  */
  89   SELF_CHECK (call_callback_int (1, plus_one_lambda) == 2);
  90   /* Same, passing a named/lvalue function_view (should copy).  */
  91   SELF_CHECK (call_callback_int (1, plus_one_func_view) == 2);
  92
  93   /* Check constructing a function view over a function-object
  94      callable, and calling it.  */
  95   plus_one_int_func_obj func_obj;
  96   SELF_CHECK (func_obj (0) == 1);
  97   SELF_CHECK (call_callback_int (1, func_obj) == 2);
  98   /* Check that the callable was referenced, not copied.  */
  99   SELF_CHECK (func_obj.call_count == 2);
 100
 101   /* Check constructing a function_view over a free-function callable,
 102      and calling it.  */
 103   SELF_CHECK (call_callback_int (1, plus_one_fn_int) == 2);
 104
 105   /* Check calling a function with a
 106      compatible-but-not-exactly-the-same prototype.  */
 107   SELF_CHECK (call_callback_int (1, [] (short val) -> short
 108     {
 109       return val + 2;
 110     }) == 3);
 111   /* Same, but passing a function pointer.  */
 112   SELF_CHECK (call_callback_int (1, plus_one_fn_short) == 2);
 113
 114   /* Like std::function, a function_view that expects a void return
 115      can reference callables with non-void return type.  The result is
 116      simply discarded.  Check a lambda, function object and a function
 117      pointer.  */
 118   call_callback_void (1, [] (int val) -> int
 119     {
 120       return val + 2;
 121     });
 122   call_callback_void (1, func_obj);
 123   call_callback_void (1, plus_one_fn_int);
 124
 125   /* Check that the main ctor doesn't hijack the copy ctor.  */
 126   auto plus_one_func_view2 (plus_one_func_view);
 127   auto plus_one_func_view3 (plus_one_func_view2);
 128   static_assert (std::is_same<decltype (plus_one_func_view),
 129                  decltype (plus_one_func_view2)>::value, "");
 130   static_assert (std::is_same<decltype (plus_one_func_view),
 131                  decltype (plus_one_func_view3)>::value, "");
 132
 133   SELF_CHECK (plus_one_func_view3 (1) == 2);
 134
 135   /* Likewise, but propagate a NULL callable.  If this calls the main
 136      function_view ctor instead of the copy ctor by mistake, then
 137      null_func_2 ends up non-NULL (because it'd instead reference
 138      null_func_1 as just another callable).  */
 139   constexpr gdb::function_view<int (int)> null_func_view_1 = nullptr;
 140   constexpr auto null_func_view_2 (null_func_view_1);
 141
 142   /* While at it, check whether the function_view is bound using
 143      various forms, op==, op!= and op bool.  */
 144
 145   /* op== */
 146   static_assert (null_func_view_2 == nullptr, "");
 147   static_assert (nullptr == null_func_view_2, "");
 148   static_assert (null_func_view_2 == NULL, "");
 149   static_assert (NULL == null_func_view_2, "");
 150
 151   /* op!= */
 152   static_assert (!(null_func_view_2 != nullptr), "");
 153   static_assert (!(nullptr != null_func_view_2), "");
 154   static_assert (!(null_func_view_2 != NULL), "");
 155   static_assert (!(NULL != null_func_view_2), "");
 156
 157   /* op bool */
 158   static_assert (!null_func_view_2, "");
 159
 160   /* Check the nullptr_t ctor.  */
 161   constexpr gdb::function_view<int (int)> check_ctor_nullptr (nullptr);
 162   static_assert (!check_ctor_nullptr, "");
 163
 164   /* Check the nullptr_t op= */
 165   gdb::function_view<int (int)> check_op_eq_null (plus_one_fn_int);
 166   SELF_CHECK (check_op_eq_null);
 167   check_op_eq_null = nullptr;
 168   SELF_CHECK (!check_op_eq_null);
 169 }
 170
 171 } /* namespace function_view */
 172 } /* namespace selftests */
 173
 174 void _initialize_function_view_selftests ();
 175 void
 176 _initialize_function_view_selftests ()
 177 {
 178   selftests::register_test ("function_view",
 179                             selftests::function_view::run_tests);
 180 }