[v2,1/2] Add template functions assign_return/set_if_changed
Commit Message
Add template functions assign_return_if_changed and assign_set_if_changed in
gdb/utils.h:
...
template<typename T> void assign_set_if_changed (T &lval, T val, bool &changed)
{ ... }
template<typename T> bool assign_return_if_changed (T &lval, T val)
{ ... }
...
This allows us to rewrite code like this:
...
if (tui_border_attrs != entry->value)
{
tui_border_attrs = entry->value;
need_redraw = true;
}
...
into this:
...
need_redraw |= assign_return_if_changed<int> (tui_border_attrs, entry->value);
...
or:
...
assign_set_if_changed<int> (tui_border_attrs, entry->value, need_redraw);
...
The names are a composition of the functionality. The functions:
- assign VAL to LVAL, and either
- return true if the assignment changed LVAL, or
- set CHANGED to true if the assignment changed LVAL.
Tested on x86_64-linux.
---
gdb/utils.c | 39 +++++++++++++++++++++++++++++++++++++++
gdb/utils.h | 27 +++++++++++++++++++++++++++
2 files changed, 66 insertions(+)
base-commit: 12f7174bf069f407d5b6f12e926ceabe45e450e1
Comments
On 6/8/23 11:17, Tom de Vries via Gdb-patches wrote:
> template<typename T> void assign_set_if_changed (T &lval, T val, bool &changed)
> { ... }
> template<typename T> bool assign_return_if_changed (T &lval, T val)
> { ... }
I realize that "T val" could mean calling a copy constructor for passing
the argument, so I've changed this into a "const T &val".
With that change, I've pushed the series.
Thanks,
- Tom
@@ -3631,6 +3631,43 @@ copy_bitwise (gdb_byte *dest, ULONGEST dest_offset,
}
}
+#if GDB_SELF_TEST
+static void
+test_assign_set_return_if_changed ()
+{
+ bool changed;
+ int a;
+
+ for (bool initial : { false, true })
+ {
+ changed = initial;
+ a = 1;
+ assign_set_if_changed (a, 1, changed);
+ SELF_CHECK (a == 1);
+ SELF_CHECK (changed == initial);
+ }
+
+ for (bool initial : { false, true })
+ {
+ changed = initial;
+ a = 1;
+ assign_set_if_changed (a, 2, changed);
+ SELF_CHECK (a == 2);
+ SELF_CHECK (changed == true);
+ }
+
+ a = 1;
+ changed = assign_return_if_changed (a, 1);
+ SELF_CHECK (a == 1);
+ SELF_CHECK (changed == false);
+
+ a = 1;
+ assign_set_if_changed (a, 2, changed);
+ SELF_CHECK (a == 2);
+ SELF_CHECK (changed == true);
+}
+#endif
+
void _initialize_utils ();
void
_initialize_utils ()
@@ -3695,5 +3732,7 @@ When set, debugging messages will be marked with seconds and microseconds."),
selftests::register_test ("strncmp_iw_with_mode",
strncmp_iw_with_mode_tests);
selftests::register_test ("pager", test_pager);
+ selftests::register_test ("assign_set_return_if_changed",
+ test_assign_set_return_if_changed);
#endif
}
@@ -337,4 +337,31 @@ extern void copy_bitwise (gdb_byte *dest, ULONGEST dest_offset,
extern int readline_hidden_cols;
+/* Assign VAL to LVAL, and set CHANGED to true if the assignment changed
+ LVAL. */
+
+template<typename T>
+void
+assign_set_if_changed (T &lval, T val, bool &changed)
+{
+ if (lval == val)
+ return;
+
+ lval = val;
+ changed = true;
+}
+
+/* Assign VAL to LVAL, and return true if the assignment changed LVAL. */
+
+template<typename T>
+bool
+assign_return_if_changed (T &lval, T val)
+{
+ if (lval == val)
+ return false;
+
+ lval = val;
+ return true;
+}
+
#endif /* UTILS_H */