Rewrite Scope

paddle/framework/scope.cc

+/* Copyright (c) 2016 PaddlePaddle Authors. All Rights Reserve.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License. */
+
+#include "paddle/framework/scope.h"
+
+namespace paddle {
+namespace framework {
+
+Scope::~Scope() {
+  for (Variable* v : vars_) delete v;
+
+  for (Scope* s : kids_) delete s;
+}
+
+Scope& Scope::NewScope() {
+  kids_.push_back(new Scope(this));
+  return *kids_.back();
+}
+
+Variable* Scope::NewVar(const std::string& name) {
+  atuo iter = vars_.find(name);
+  if (iter != vars_.end()) {
+    return iter.second->get();
+  }
+  Variable* v = new Variable();
+  v->name_ = name;
+  var_[name] = v;
+  return v;
+}
+
+Variable* Scope::NewVar() {
+  return NewVar(string.Sprintf("%p.%d", this, vars_.size()));
+}
+
+Variable* Scope::FindVar(const std::string& name) const {
+  auto it = vars_.find(name);
+  if (it != vars_.end()) return it->second.get();
+  return (parent_ == nullptr) ? nullptr : parent_->FindVar(name);
+}
+
+Scope* Scope::FindScope(const Variable* var) const {
+  if (FindVar(var->name_) != nullptr) return this;
+  return (parent_ == nullptr) ? nullptr : parent_->FindScope(var);
+}
+
+}  // namespace framework
+}  // namespace paddle

paddle/framework/scope.h

@@ -14,9 +14,9 @@ limitations under the License. */
 
 #pragma once
 
+#include <list>
+#include <map>
 #include <string>
-#include <unordered_map>
-#include <vector>
 
 #include "paddle/framework/variable.h"
 
@@ -35,73 +35,36 @@ class Scope;
  */
 class Scope {
  public:
-  /**
-   * @brief Initialize s Scope without parent.
-   */
   Scope() {}
+  ~Scope();
 
-  /**
-   * @brief Initialize a Scope with parent.
-   */
-  explicit Scope(const std::shared_ptr<Scope>& parent) : parent_(parent) {}
+  // Create a sub-scope. Returns a reference other than a pointer so
+  // to prevent from manual deletion.
+  Scope& NewScope();
 
-  /**
-   * @brief Create Variable
-   *
-   * Create Variable in this Scope. Return the exist one if Variable already
-   * been created.
-   */
-  Variable* CreateVariable(const std::string& name) {
-    auto var = GetVariable(name);
-    if (var) {
-      return var;
-    } else {
-      auto ptr = new Variable();
-      name_to_var_[name] = std::unique_ptr<Variable>(ptr);
-      var_to_name_[ptr] = name;
-      return GetVariable(name);
-    }
-  }
-
-  /**
-   * @brief Get Variable.
-   *
-   * Get Variable from this Scope, this function will recursive find Variable
-   * from it's parent scope. Return nullptr if not found.
-   */
-  Variable* GetVariable(const std::string& name) const {
-    auto it = name_to_var_.find(name);
-    if (it != name_to_var_.end()) {
-      return it->second.get();
-    } else if (parent_ != nullptr) {
-      return parent_->GetVariable(name);
-    } else {
-      return nullptr;
-    }
-  }
-
-  /**
-   * @brief If this scope has a Var named name.
-   *
-   * Find if there is a Variable in this scope and it's parent scope
-   */
-  bool HasVariable(const std::string& name) const {
-    return (name_to_var_.find(name) != name_to_var_.end() ||
-            (parent_ && parent_->HasVariable(name)));
-  }
-
-  std::string GetVariableName(Variable* const var) const {
-    try {
-      return var_to_name_.at(var);
-    } catch (...) {
-      return "";
-    }
-  }
+  // Create a variable with given name if it doesn't exist.
+  Variable* NewVar(const std::string& name);
+
+  // Create a variable with a scope-unique name.
+  Variable* NewVar();
+
+  // Find a variable in the scope or any of its ancestors.  Returns
+  // nullptr if cannot find.
+  Variable* FindVar(const std::string& name) const;
+
+  // Find the scope or an ancestor scope that contains the given variable.
+  Scope* FindScope(const Variable* var) const;
+
+  // Returns the name of a variable in this scope.
+  std::string VarName(const Variable* var) const { return var->name_; }
 
  private:
-  std::unordered_map<Variable*, std::string> var_to_name_;
-  std::unordered_map<std::string, std::unique_ptr<Variable>> name_to_var_;
-  std::shared_ptr<Scope> parent_{nullptr};
+  // Call Scope::NewScope for a sub-scope.
+  explicit Scope(Scope* parent) : parent_(parent) {}
+
+  std::map<std::string, Variable*> vars_;
+  std::list<Scope*> kids_;
+  Scope* parent_{nullptr};
 };
 
 }  // namespace framework

paddle/framework/scope_test.cc

@@ -15,49 +15,42 @@ limitations under the License. */
 #include "paddle/framework/scope.h"
 #include "gtest/gtest.h"
 
-TEST(Scope, Create) {
-  using paddle::framework::Scope;
-  using paddle::framework::Variable;
+using paddle::framework::Scope;
+using paddle::framework::Variable;
 
-  auto scope = std::make_shared<Scope>();
+TEST(Scope, VarsShadowing) {
+  Scope s;
+  Scope& ss1 = s.NewScope();
+  Scope& ss2 = s.NewScope();
 
-  Variable* var0 = scope->CreateVariable("");
-  EXPECT_NE(var0, nullptr);
+  Variable* v0 = s.NewVar("a");
+  Variable* v1 = ss1.NewVar("a");
 
-  /// GetVariable will return nullptr if not exist.
-  Variable* var1 = scope->GetVariable("a");
-  EXPECT_EQ(var1, nullptr);
+  EXPECT_NE(v0, v1);
 
-  /// CreateVariable will return one.
-  Variable* var2 = scope->CreateVariable("a");
-  EXPECT_NE(var2, nullptr);
-
-  /// Get the created variable.
-  Variable* var3 = scope->GetVariable("a");
-  EXPECT_EQ(var2, var3);
+  EXPECT_EQ(v0, s.FindVar("a"));
+  EXPECT_EQ(v1, ss1.FindVar("a"));
+  EXPECT_EQ(v0, ss2.FindVar("a"));
+}
 
-  /// CreateVariable will just return the variable if it's
-  /// already exist.
-  Variable* var4 = scope->CreateVariable("a");
-  EXPECT_EQ(var4, var2);
+TEST(Scope, FindVar) {
+  Scope s;
+  Scope& ss = s.NewScope();
 
-  EXPECT_EQ("a", scope->GetVariableName(var4));
-  Scope scope2;
-  auto var = scope2.CreateVariable("tmp");
-  EXPECT_EQ("", scope->GetVariableName(var));
-}
+  EXPECT_EQ(nullptr, s.FindVar("a"));
+  EXPECT_EQ(nullptr, ss.FindVar("a"));
 
-TEST(Scope, Parent) {
-  using paddle::framework::Scope;
-  using paddle::framework::Variable;
+  ss.NewVar("a");
 
-  auto parent_scope = std::make_shared<Scope>();
-  auto scope = std::make_shared<Scope>(parent_scope);
+  EXPECT_EQ(nullptr, s.FindVar("a"));
+  EXPECT_NE(nullptr, ss.FindVar("a"));
+}
 
-  Variable* var0 = parent_scope->CreateVariable("a");
-  EXPECT_NE(var0, nullptr);
+TEST(Scope, FindScope) {
+  Scope s;
+  Scope& ss = s.NewScope();
+  s.NewVar("a");
 
-  /// GetVariable will get Variable from parent scope if exist.
-  Variable* var1 = scope->GetVariable("a");
-  EXPECT_EQ(var0, var1);
+  EXPECT_EQ(&s, s.FindVar("a"));
+  EXPECT_EQ(&s, ss.FindVar("a"));
 }

paddle/framework/variable.h

@@ -17,6 +17,7 @@
 #include <typeinfo>
 
 #include "paddle/platform/assert.h"
+#include "paddle/string/piece.h"
 
 namespace paddle {
 namespace framework {
@@ -65,6 +66,17 @@ class Variable {
 
   std::unique_ptr<Placeholder>
       holder_;  // pointers to a PlaceholderImpl object indeed.
+
+  // name_ is only meaningful with a Scope and accessible by it.
+  //
+  // NOTE: Please don't expose name_ by adding methods like
+  // Variable::Name or Scope::VarName!  A variable could have a human
+  // readable name or an auto-generated scope-unique name.  In the
+  // former case, the caller knows the name and doesn't need to access
+  // the name; in the latter case, the variable should be identified
+  // by its address but not the unreadable name.
+  friend class Scope;
+  string::Piece name_;
 };
 
 }  // namespace framework