Adding optional to differentiate between empty sets and unset attributes

Signed-off-by: Ethan Mahintorabi <ethanmoon@google.com>

include/sta/ConcreteLibrary.hh

@@ -17,6 +17,7 @@
 #pragma once
 
 #include <functional>
+#include <optional>
 
 #include "Vector.hh"
 #include "Map.hh"
@@ -108,7 +109,7 @@ public:
   void setIsLeaf(bool is_leaf);
   void setAttribute(const std::string &key,
                     const std::string &value);
-  std::string getAttribute(const std::string &key) const;
+  std::optional<std::string> getAttribute(const std::string &key) const;
 
   // Cell acts as port factory.
   ConcretePort *makePort(const char *name);

include/sta/ConcreteNetwork.hh

@@ -17,6 +17,7 @@
 #pragma once
 
 #include <functional>
+#include <optional>
 
 #include "Map.hh"
 #include "Set.hh"
@@ -75,7 +76,7 @@ public:
                             const PatternMatch *pattern) const override;
 
   const char *name(const Cell *cell) const override;
-  std::string getAttribute(const Cell *cell,
+  std::optional<std::string> getAttribute(const Cell *cell,
                                           const std::string &key) const override;
   ObjectId id(const Cell *cell) const override;
   Library *library(const Cell *cell) const override;
@@ -111,7 +112,7 @@ public:
   PortMemberIterator *memberIterator(const Port *port) const override;
 
   const char *name(const Instance *instance) const override;
-  std::string getAttribute(const Instance *inst,
+  std::optional<std::string> getAttribute(const Instance *inst,
                                           const std::string &key) const override;
   ObjectId id(const Instance *instance) const override;
   Cell *cell(const Instance *instance) const override;
@@ -298,7 +299,7 @@ public:
   InstanceChildIterator *childIterator() const;
   void setAttribute(const std::string &key,
                     const std::string &value);
-  std::string getAttribute(const std::string &key) const;
+  std::optional<std::string> getAttribute(const std::string &key) const;
   void addChild(ConcreteInstance *child);
   void deleteChild(ConcreteInstance *child);
   void addPin(ConcretePin *pin);

include/sta/Network.hh

@@ -17,6 +17,7 @@
 #pragma once
 
 #include <functional>
+#include <optional>
 
 #include "Map.hh"
 #include "StringUtil.hh"
@@ -145,7 +146,7 @@ public:
   // Filename may return null.
   virtual const char *filename(const Cell *cell) = 0;
   // Attributes can be null
-  virtual std::string getAttribute(const Cell *cell,
+  virtual std::optional<std::string> getAttribute(const Cell *cell,
                                                   const std::string &key) const = 0;
   // Name can be a simple, bundle, bus, or bus bit name.
   virtual Port *findPort(const Cell *cell,
@@ -209,7 +210,7 @@ public:
                                             const PatternMatch *pattern) const;
   virtual InstanceSeq findInstancesHierMatching(const Instance *instance,
                                                 const PatternMatch *pattern) const;
-  virtual std::string getAttribute(const Instance *inst,
+  virtual std::optional<std::string> getAttribute(const Instance *inst,
                                                   const std::string &key) const = 0;
   // Hierarchical path name.
   virtual const char *pathName(const Instance *instance) const;

include/sta/SdcNetwork.hh

@@ -17,6 +17,7 @@
 #pragma once
 
 #include <functional>
+#include <optional>
 
 #include "Network.hh"
 
@@ -45,7 +46,7 @@ public:
                             const PatternMatch *pattern) const override;
 
   const char *name(const Cell *cell) const override;
-  std::string getAttribute(const Cell *cell,
+  std::optional<std::string> getAttribute(const Cell *cell,
                                           const std::string &key) const override;
   ObjectId id(const Cell *cell) const override;
   Library *library(const Cell *cell) const override;
@@ -82,7 +83,7 @@ public:
   bool hasMembers(const Port *port) const override;
 
   ObjectId id(const Instance *instance) const override;
-  std::string getAttribute(const Instance *inst,
+  std::optional<std::string> getAttribute(const Instance *inst,
                                           const std::string &key) const override;
   Instance *topInstance() const override;
   Cell *cell(const Instance *instance) const override;

network/ConcreteLibrary.cc

@@ -275,11 +275,14 @@ ConcreteCell::setAttribute(const std::string &key,
   attribute_map_.insert(key, value);
 }
 
-std::string
+std::optional<std::string>
 ConcreteCell::getAttribute(const std::string &key) const 
 {
+  if (attribute_map_.hasKey(key)) {
     return attribute_map_.findKey(key);
   }
+  return {};
+}
 
 ConcretePort *
 ConcreteCell::findPort(const char *name) const

network/ConcreteNetwork.cc

@@ -606,7 +606,7 @@ ConcreteNetwork::filename(const Cell *cell)
   return ccell->filename();
 }
 
-std::string
+std::optional<std::string>
 ConcreteNetwork::getAttribute(const Cell *cell,
                               const std::string &key) const
 {
@@ -938,7 +938,7 @@ ConcreteNetwork::id(const Instance *instance) const
   return inst->id();
 }
 
-std::string
+std::optional<std::string>
 ConcreteNetwork::getAttribute(const Instance *inst,
                               const std::string &key) const
 {
@@ -1689,11 +1689,14 @@ ConcreteInstance::setAttribute(const std::string &key,
   attribute_map_.insert(key, value);
 }
 
-std::string
+std::optional<std::string>
 ConcreteInstance::getAttribute(const std::string &key) const
 {
+  if (attribute_map_.hasKey(key)) {
     return attribute_map_.findKey(key);
   }
+  return {};
+}
 
 void
 ConcreteInstance::addChild(ConcreteInstance *child)

network/SdcNetwork.cc

@@ -122,7 +122,7 @@ NetworkNameAdapter::id(const Cell *cell) const
   return network_->id(cell);
 }
 
-std::string
+std::optional<std::string>
 NetworkNameAdapter::getAttribute(const Cell *cell,
                                  const std::string &key) const
 {
@@ -334,7 +334,7 @@ NetworkNameAdapter::cell(const Instance *instance) const
   return network_->cell(instance);
 }
 
-std::string
+std::optional<std::string>
 NetworkNameAdapter::getAttribute(const Instance *inst,
                                  const std::string &key) const
 {

tcl/StaTcl.i

@@ -4186,7 +4186,14 @@ LibertyCell *liberty_cell() { return cmdNetwork()->libertyCell(self); }
 bool is_leaf() { return cmdNetwork()->isLeaf(self); }
 CellPortIterator *
 port_iterator() { return cmdNetwork()->portIterator(self); }
-string get_attribute(const char *key) { return cmdNetwork()->getAttribute(self, key); }
+string get_attribute(const char *key)
+{ 
+  std::optional<std::string> result = cmdNetwork()->getAttribute(self, key);
+  if (result) {
+    return result.value();
+  }
+  return "";
+}
 
 Port *
 find_port(const char *name)
@@ -4411,6 +4418,14 @@ find_pin(const char *name)
 {
   return cmdLinkedNetwork()->findPin(self, name);
 }
+string get_attribute(const char *key)
+{ 
+  std::optional<std::string> result = cmdNetwork()->getAttribute(self, key);
+  if (result) {
+    return result.value();
+  }
+  return "";
+}
 } // Instance methods
 
 %extend InstanceChildIterator {