From ec3512409f6f166939d0f0931899a4cc983ba966 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jaakko=20Kera=CC=88nen?= <jaakko.keranen@iki.fi>
Date: Tue, 22 Nov 2016 16:08:11 +0200
Subject: [PATCH] Widgets|libcore: Added a zero constant rule that can be used
 everywhere

---
 doomsday/sdk/libappfw/src/gridlayout.cpp      |  7 ++-----
 .../libcore/include/de/widgets/constantrule.h |  4 ++++
 .../sdk/libcore/src/widgets/constantrule.cpp  |  7 +++++++
 doomsday/sdk/libcore/src/widgets/rulebank.cpp | 20 ++++---------------
 4 files changed, 17 insertions(+), 21 deletions(-)

diff --git a/doomsday/sdk/libappfw/src/gridlayout.cpp b/doomsday/sdk/libappfw/src/gridlayout.cpp
index 1c33eb4f65..a769404e3c 100644
--- a/doomsday/sdk/libappfw/src/gridlayout.cpp
+++ b/doomsday/sdk/libappfw/src/gridlayout.cpp
@@ -43,7 +43,6 @@ DENG2_PIMPL(GridLayout)
     CellAlignments cellAlignment;
     Rule const *colPad;
     Rule const *rowPad;
-    Rule const *zeroRule;
 
     struct Metric {
         Rule const *fixedLength; ///< May be @c NULL.
@@ -98,7 +97,6 @@ DENG2_PIMPL(GridLayout)
         , fixedCellHeight(0)
         , colPad(0)
         , rowPad(0)
-        , zeroRule(new ConstantRule(0))
         , totalWidth(new ConstantRule(0))
         , totalHeight(new ConstantRule(0))
         , current(0)
@@ -117,7 +115,6 @@ DENG2_PIMPL(GridLayout)
         releaseRef(fixedCellHeight);
         releaseRef(colPad);
         releaseRef(rowPad);
-        releaseRef(zeroRule);
         releaseRef(totalWidth);
         releaseRef(totalHeight);
         releaseRef(publicWidth);
@@ -757,13 +754,13 @@ Rule const &GridLayout::overrideHeight() const
 Rule const &GridLayout::columnPadding() const
 {
     if (d->colPad) return *d->colPad;
-    return *d->zeroRule;
+    return ConstantRule::zero();
 }
 
 Rule const &GridLayout::rowPadding() const
 {
     if (d->rowPad) return *d->rowPad;
-    return *d->zeroRule;
+    return ConstantRule::zero();
 }
 
 void GridLayout::setCellAlignment(Vector2i const &cell, ui::Alignment cellAlign)
diff --git a/doomsday/sdk/libcore/include/de/widgets/constantrule.h b/doomsday/sdk/libcore/include/de/widgets/constantrule.h
index 75818d89e7..35a90986e5 100644
--- a/doomsday/sdk/libcore/include/de/widgets/constantrule.h
+++ b/doomsday/sdk/libcore/include/de/widgets/constantrule.h
@@ -69,6 +69,8 @@ class DENG2_PUBLIC ConstantRule : public Rule
 
     String description() const;
 
+    static ConstantRule const &zero();
+
 protected:
     void update();
 
@@ -79,12 +81,14 @@ class DENG2_PUBLIC ConstantRule : public Rule
 template <typename Type>
 ConstantRule::Builder<Type>::operator Rule const &() const
 {
+    if (fequal(float(_number), 0)) return ConstantRule::zero();
     return *refless(new ConstantRule(_number));
 }
 
 template <typename Type>
 ConstantRule::Builder<Type>::operator RefArg<Rule>() const
 {
+    if (fequal(float(_number), 0)) return RefArg<Rule>(ConstantRule::zero());
     return RefArg<Rule>(new ConstantRule(_number));
 }
 
diff --git a/doomsday/sdk/libcore/src/widgets/constantrule.cpp b/doomsday/sdk/libcore/src/widgets/constantrule.cpp
index fe99fda068..f6d5fdb895 100644
--- a/doomsday/sdk/libcore/src/widgets/constantrule.cpp
+++ b/doomsday/sdk/libcore/src/widgets/constantrule.cpp
@@ -22,6 +22,8 @@
 
 namespace de {
 
+static AutoRef<ConstantRule> zeroRule(new ConstantRule(0));
+
 ConstantRule::ConstantRule() : Rule(), _pendingValue(0)
 {
     // No valid value defined.
@@ -47,6 +49,11 @@ String ConstantRule::description() const
     return String("Constant(%1)").arg(cachedValue());
 }
 
+ConstantRule const &ConstantRule::zero()
+{
+    return zeroRule;
+}
+
 void ConstantRule::update()
 {
     setValue(_pendingValue);
diff --git a/doomsday/sdk/libcore/src/widgets/rulebank.cpp b/doomsday/sdk/libcore/src/widgets/rulebank.cpp
index 39e0f57be2..d504e945b6 100644
--- a/doomsday/sdk/libcore/src/widgets/rulebank.cpp
+++ b/doomsday/sdk/libcore/src/widgets/rulebank.cpp
@@ -13,7 +13,7 @@
  * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
  * General Public License for more details. You should have received a copy of
  * the GNU Lesser General Public License along with this program; if not, see:
- * http://www.gnu.org/licenses</small> 
+ * http://www.gnu.org/licenses</small>
  */
 
 #include "de/RuleBank"
@@ -22,7 +22,7 @@
 
 namespace de {
 
-DENG2_PIMPL(RuleBank)
+DENG2_PIMPL_NOREF(RuleBank)
 {
     struct RuleSource : public ISource
     {
@@ -46,21 +46,9 @@ DENG2_PIMPL(RuleBank)
         RuleData(Rule *r) : rule(holdRef(r)) {}
         ~RuleData() { releaseRef(rule); }
     };
-
-    ConstantRule *zero;
-
-    Impl(Public *i) : Base(i)
-    {
-        zero = new ConstantRule(0);
-    }
-
-    ~Impl()
-    {
-        releaseRef(zero);
-    }
 };
 
-RuleBank::RuleBank() : InfoBank("RuleBank", DisableHotStorage), d(new Impl(this))
+RuleBank::RuleBank() : InfoBank("RuleBank", DisableHotStorage), d(new Impl)
 {}
 
 void RuleBank::addFromInfo(File const &file)
@@ -72,7 +60,7 @@ void RuleBank::addFromInfo(File const &file)
 
 Rule const &RuleBank::rule(DotPath const &path) const
 {
-    if (path.isEmpty()) return *d->zero;
+    if (path.isEmpty()) return ConstantRule::zero();
     return *static_cast<Impl::RuleData &>(data(path)).rule;
 }