chromeos-dbus-bindings: Generate only single proxy accessor for singletons

For D-Bus objects with single fixed object path assume that they are
singletons and remove the object path parameter from the proxy
accessor ObjectManagerProxy::GetNNNProxy() method.

BUG=brillo:348
TEST=`FEATURES=test emerge-link chromeos-dbus-bindings`
     `FEATURES=test emerge-link peerd privetd buffet apmanager lorgnette`

Change-Id: I29419e2db5bd0fc8a4f508804c1e322c1880a3dd
Reviewed-on: https://chromium-review.googlesource.com/252422
Trybot-Ready: Alex Vakulenko <avakulenko@chromium.org>
Tested-by: Alex Vakulenko <avakulenko@chromium.org>
Reviewed-by: Christopher Wiley <wiley@chromium.org>
Commit-Queue: Alex Vakulenko <avakulenko@chromium.org>

2 files changed, 40 insertions, 28 deletions

diff --git a/chromeos-dbus-bindings/proxy_generator.cc b/chromeos-dbus-bindings/proxy_generator.cc
index bdf21d5..34d9e90 100644
--- a/chromeos-dbus-bindings/proxy_generator.cc
+++ b/chromeos-dbus-bindings/proxy_generator.cc
@@ -924,22 +924,38 @@ void ProxyGenerator::ObjectManager::AddInterfaceAccessors(
   string map_name = itf_name.MakeVariableName() + "_instances_";
 
   // GetProxy().
-  text->AddLine(StringPrintf("%s* Get%s(",
-                              itf_name.MakeProxyName(true).c_str(),
-                              itf_name.MakeProxyName(false).c_str()));
-  text->PushOffset(kLineContinuationOffset);
-  text->AddLine("const dbus::ObjectPath& object_path) {");
-  text->PopOffset();
-  text->PushOffset(kBlockOffset);
-  text->AddLine(StringPrintf("auto p = %s.find(object_path);",
-                              map_name.c_str()));
-  text->AddLine(StringPrintf("if (p != %s.end())", map_name.c_str()));
-  text->PushOffset(kBlockOffset);
-  text->AddLine("return p->second.get();");
-  text->PopOffset();
-  text->AddLine("return nullptr;");
-  text->PopOffset();
-  text->AddLine("}");
+  if (interface.path.empty()) {
+    // We have no fixed path, so there could be multiple instances of this itf.
+    text->AddLine(StringPrintf("%s* Get%s(",
+                                itf_name.MakeProxyName(true).c_str(),
+                                itf_name.MakeProxyName(false).c_str()));
+    text->PushOffset(kLineContinuationOffset);
+    text->AddLine("const dbus::ObjectPath& object_path) {");
+    text->PopOffset();
+    text->PushOffset(kBlockOffset);
+    text->AddLine(StringPrintf("auto p = %s.find(object_path);",
+                                map_name.c_str()));
+    text->AddLine(StringPrintf("if (p != %s.end())", map_name.c_str()));
+    text->PushOffset(kBlockOffset);
+    text->AddLine("return p->second.get();");
+    text->PopOffset();
+    text->AddLine("return nullptr;");
+    text->PopOffset();
+    text->AddLine("}");
+  } else {
+    // We have a fixed path, so the object could be considered a "singleton".
+    // Skip the object_path parameter and return the first available instance.
+    text->AddLine(StringPrintf("%s* Get%s() {",
+                                itf_name.MakeProxyName(true).c_str(),
+                                itf_name.MakeProxyName(false).c_str()));
+    text->PushOffset(kBlockOffset);
+    text->AddLine(StringPrintf("if (%s.empty())", map_name.c_str()));
+    text->AddLineWithOffset("return nullptr;", kBlockOffset);
+    text->AddLine(StringPrintf("return %s.begin()->second.get();",
+                               map_name.c_str()));
+    text->PopOffset();
+    text->AddLine("}");
+  }
 
   // GetInstances().
   text->AddLine(StringPrintf("std::vector<%s*> Get%sInstances() const {",
diff --git a/chromeos-dbus-bindings/proxy_generator_unittest.cc b/chromeos-dbus-bindings/proxy_generator_unittest.cc
index f0615a9..a157656 100644
--- a/chromeos-dbus-bindings/proxy_generator_unittest.cc
+++ b/chromeos-dbus-bindings/proxy_generator_unittest.cc
@@ -756,12 +756,10 @@ class ObjectManagerProxy : public dbus::ObjectManager::Interface {
     return dbus_object_manager_;
   }
 
-  org::chromium::Itf1Proxy* GetItf1Proxy(
-      const dbus::ObjectPath& object_path) {
-    auto p = itf1_instances_.find(object_path);
-    if (p != itf1_instances_.end())
-      return p->second.get();
-    return nullptr;
+  org::chromium::Itf1Proxy* GetItf1Proxy() {
+    if (itf1_instances_.empty())
+      return nullptr;
+    return itf1_instances_.begin()->second.get();
   }
   std::vector<org::chromium::Itf1Proxy*> GetItf1Instances() const {
     std::vector<org::chromium::Itf1Proxy*> values;
@@ -1103,12 +1101,10 @@ class ObjectManagerProxy : public dbus::ObjectManager::Interface {
     return dbus_object_manager_;
   }
 
-  org::chromium::Itf1Proxy* GetItf1Proxy(
-      const dbus::ObjectPath& object_path) {
-    auto p = itf1_instances_.find(object_path);
-    if (p != itf1_instances_.end())
-      return p->second.get();
-    return nullptr;
+  org::chromium::Itf1Proxy* GetItf1Proxy() {
+    if (itf1_instances_.empty())
+      return nullptr;
+    return itf1_instances_.begin()->second.get();
   }
   std::vector<org::chromium::Itf1Proxy*> GetItf1Instances() const {
     std::vector<org::chromium::Itf1Proxy*> values;