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Subject[PATCH] kconfig: Document automatic submenu creation code
Date
It's tricky to figure out what it does (and how) without staring at the
code for a long time. Document it to make it more transparent.

No functional changes. Only comments added.

Signed-off-by: Ulf Magnusson <ulfalizer@gmail.com>
---
scripts/kconfig/menu.c | 38 ++++++++++++++++++++++++++++++++++++++
1 file changed, 38 insertions(+)

diff --git a/scripts/kconfig/menu.c b/scripts/kconfig/menu.c
index e935793..d5fa572 100644
--- a/scripts/kconfig/menu.c
+++ b/scripts/kconfig/menu.c
@@ -347,25 +347,63 @@ void menu_finalize(struct menu *parent)
for (menu = parent->list; menu; menu = menu->next)
menu_finalize(menu);
} else if (sym) {
+ /*
+ * Automatic submenu creation. If sym, A, B, C, ..., are
+ * consecutive symbols and A, B, C, ... all depend on sym, the
+ * following menu structure will be created:
+ *
+ * sym
+ * +-A
+ * +-B
+ * +-C
+ * ...
+ *
+ * This also works recursively, giving the following structure
+ * if B depends on A:
+ *
+ * sym
+ * +-A
+ * | +-B
+ * +-C
+ * ...
+ */
+
basedep = parent->prompt ? parent->prompt->visible.expr : NULL;
basedep = expr_trans_compare(basedep, E_UNEQUAL, &symbol_no);
basedep = expr_eliminate_dups(expr_transform(basedep));
+
+ /* Examine consecutive elements after sym */
last_menu = NULL;
for (menu = parent->next; menu; menu = menu->next) {
dep = menu->prompt ? menu->prompt->visible.expr : menu->dep;
if (!expr_contains_symbol(dep, sym))
+ /* No dependency, quit */
break;
if (expr_depends_symbol(dep, sym))
+ /* Absolute dependency, put in submenu */
goto next;
+
+ /*
+ * Also consider it a dependency on sym if our
+ * dependencies contain sym and are a "superset" of
+ * sym's dependencies, e.g. '(sym || Q) && R' when sym
+ * depends on R.
+ *
+ * Note that 'R' might be from an enclosing menu or if,
+ * making this a more common case than it might seem.
+ */
+
dep = expr_trans_compare(dep, E_UNEQUAL, &symbol_no);
dep = expr_eliminate_dups(expr_transform(dep));
dep2 = expr_copy(basedep);
expr_eliminate_eq(&dep, &dep2);
expr_free(dep);
if (!expr_is_yes(dep2)) {
+ /* Not superset, quit */
expr_free(dep2);
break;
}
+ /* Superset, put in submenu */
expr_free(dep2);
next:
menu_finalize(menu);
--
2.7.4
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