From: Tom de Vries <tdevries@suse.de>
To: gdb-patches@sourceware.org
Subject: [PATCH] [gdb] Add template functions assign_set/return_if_changed
Date: Tue, 23 May 2023 09:19:12 +0200 [thread overview]
Message-ID: <20230523071912.2197-1-tdevries@suse.de> (raw)
Add template function assign_set_if_changed in gdb/utils.h:
...
template<typename T>
void
assign_set_if_changed (T &lval, T val, bool &changed)
{
if (lval == val)
return;
lval = val;
changed = true;
}
...
This allows us to rewrite code like this:
...
if (tui_border_attrs != entry->value)
{
tui_border_attrs = entry->value;
need_redraw = true;
}
...
into this:
...
assign_set_if_changed<int> (tui_border_attrs, entry->value, need_redraw);
...
The name is a composition of its functionality:
- it assigns val to lval, and
- is sets changed to true if the assignment changed lval.
I've initially considered using assign_return_if_changed for the rewrite:
...
template<typename T>
bool
assign_return_if_changed (T &lval, T val)
{
if (lval == val)
return false;
lval = val;
changed = true;
}
...
but liked the resulting bitwise operator on the boolean a bit less:
...
need_redraw |= assign_return_if_changed<int> (tui_border_attrs, entry->value);
...
I've included it anyway, it may be the preferred choice in other cases.
Tested on x86_64-linux.
---
gdb/utils.c | 39 +++++++++++++++++++++++++++++++++++++++
gdb/utils.h | 27 +++++++++++++++++++++++++++
2 files changed, 66 insertions(+)
diff --git a/gdb/utils.c b/gdb/utils.c
index f18228d1086..46bfd9a5bbb 100644
--- a/gdb/utils.c
+++ b/gdb/utils.c
@@ -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
}
diff --git a/gdb/utils.h b/gdb/utils.h
index 00b123e6117..d78d54911bf 100644
--- a/gdb/utils.h
+++ b/gdb/utils.h
@@ -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 */
base-commit: e1eecd81cc6a40b3547a7c5d456919275a0b4a27
--
2.35.3
next reply other threads:[~2023-05-23 7:19 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-23 7:19 Tom de Vries [this message]
2023-05-23 9:57 ` Lancelot SIX
2023-05-23 16:20 ` Tom de Vries
2023-06-08 9:26 ` Tom de Vries
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