[ADT] Add a unittest for the ScopedHashTable class (#120183)

The ScopedHashTable class is particularly used to develop string tables
for parsers and code convertors. For instance, the MLIRGen class from the
toy example for MLIR actively uses this class to define scopes for
declared variables. To demonstrate common use cases for the
ScopedHashTable class as well as to check its behavior in different
situations, the unittest has been added.

Signed-off-by: Pavel Samolysov <[email protected]>

Author: samolisov

llvm/unittests/ADT/CMakeLists.txt

@@ -67,6 +67,7 @@ add_llvm_unittest(ADTTests
   SCCIteratorTest.cpp
   STLExtrasTest.cpp
   STLForwardCompatTest.cpp
+  ScopedHashTableTest.cpp
   ScopeExitTest.cpp
   SequenceTest.cpp
   SetOperationsTest.cpp

llvm/unittests/ADT/ScopedHashTableTest.cpp

@@ -0,0 +1,145 @@
+//===- ScopedHashTableTest.cpp - ScopedHashTable unit tests ---------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/ScopedHashTable.h"
+#include "llvm/ADT/StringRef.h"
+#include "gtest/gtest.h"
+#include <memory>
+#include <stack>
+
+using ::llvm::ScopedHashTable;
+using ::llvm::ScopedHashTableScope;
+using ::llvm::StringLiteral;
+using ::llvm::StringRef;
+
+using ::testing::Test;
+
+class ScopedHashTableTest : public Test {
+protected:
+  ScopedHashTableTest() { symbolTable.insert(kGlobalName, kGlobalValue); }
+
+  ScopedHashTable<StringRef, StringRef> symbolTable{};
+  ScopedHashTableScope<StringRef, StringRef> globalScope{symbolTable};
+
+  static constexpr StringLiteral kGlobalName = "global";
+  static constexpr StringLiteral kGlobalValue = "gvalue";
+  static constexpr StringLiteral kLocalName = "local";
+  static constexpr StringLiteral kLocalValue = "lvalue";
+  static constexpr StringLiteral kLocalValue2 = "lvalue2";
+};
+
+TEST_F(ScopedHashTableTest, AccessWithNoActiveScope) {
+  EXPECT_EQ(symbolTable.count(kGlobalName), 1U);
+}
+
+TEST_F(ScopedHashTableTest, AccessWithAScope) {
+  [[maybe_unused]] ScopedHashTableScope varScope(symbolTable);
+  EXPECT_EQ(symbolTable.count(kGlobalName), 1U);
+}
+
+TEST_F(ScopedHashTableTest, InsertInScope) {
+  [[maybe_unused]] ScopedHashTableScope varScope(symbolTable);
+  symbolTable.insert(kLocalName, kLocalValue);
+  EXPECT_EQ(symbolTable.count(kLocalName), 1U);
+}
+
+TEST_F(ScopedHashTableTest, InsertInLinearSortedScope) {
+  [[maybe_unused]] ScopedHashTableScope varScope(symbolTable);
+  [[maybe_unused]] ScopedHashTableScope varScope2(symbolTable);
+  [[maybe_unused]] ScopedHashTableScope varScope3(symbolTable);
+  symbolTable.insert(kLocalName, kLocalValue);
+  EXPECT_EQ(symbolTable.count(kLocalName), 1U);
+}
+
+TEST_F(ScopedHashTableTest, InsertInOutedScope) {
+  {
+    [[maybe_unused]] ScopedHashTableScope varScope(symbolTable);
+    symbolTable.insert(kLocalName, kLocalValue);
+  }
+  EXPECT_EQ(symbolTable.count(kLocalName), 0U);
+}
+
+TEST_F(ScopedHashTableTest, OverrideInScope) {
+  [[maybe_unused]] ScopedHashTableScope funScope(symbolTable);
+  symbolTable.insert(kLocalName, kLocalValue);
+  {
+    [[maybe_unused]] ScopedHashTableScope varScope(symbolTable);
+    symbolTable.insert(kLocalName, kLocalValue2);
+    EXPECT_EQ(symbolTable.lookup(kLocalName), kLocalValue2);
+  }
+  EXPECT_EQ(symbolTable.lookup(kLocalName), kLocalValue);
+}
+
+TEST_F(ScopedHashTableTest, GetCurScope) {
+  EXPECT_EQ(symbolTable.getCurScope(), &globalScope);
+  {
+    ScopedHashTableScope funScope(symbolTable);
+    ScopedHashTableScope funScope2(symbolTable);
+    EXPECT_EQ(symbolTable.getCurScope(), &funScope2);
+    {
+      ScopedHashTableScope blockScope(symbolTable);
+      EXPECT_EQ(symbolTable.getCurScope(), &blockScope);
+    }
+    EXPECT_EQ(symbolTable.getCurScope(), &funScope2);
+  }
+  EXPECT_EQ(symbolTable.getCurScope(), &globalScope);
+}
+
+TEST_F(ScopedHashTableTest, PopScope) {
+  using SymbolTableScopeTy = ScopedHashTable<StringRef, StringRef>::ScopeTy;
+
+  std::stack<StringRef> ExpectedValues;
+  std::stack<std::unique_ptr<SymbolTableScopeTy>> Scopes;
+
+  Scopes.emplace(std::make_unique<SymbolTableScopeTy>(symbolTable));
+  ExpectedValues.emplace(kLocalValue);
+  symbolTable.insert(kGlobalName, kLocalValue);
+
+  Scopes.emplace(std::make_unique<SymbolTableScopeTy>(symbolTable));
+  ExpectedValues.emplace(kLocalValue2);
+  symbolTable.insert(kGlobalName, kLocalValue2);
+
+  while (symbolTable.getCurScope() != &globalScope) {
+    EXPECT_EQ(symbolTable.getCurScope(), Scopes.top().get());
+    EXPECT_EQ(symbolTable.lookup(kGlobalName), ExpectedValues.top());
+    ExpectedValues.pop();
+    Scopes.pop(); // destructs the SymbolTableScopeTy instance implicitly
+                  // calling Scopes.top()->~SymbolTableScopeTy();
+    EXPECT_NE(symbolTable.getCurScope(), nullptr);
+  }
+  ASSERT_TRUE(ExpectedValues.empty());
+  ASSERT_TRUE(Scopes.empty());
+  EXPECT_EQ(symbolTable.lookup(kGlobalName), kGlobalValue);
+}
+
+TEST_F(ScopedHashTableTest, DISABLED_PopScopeOnStack) {
+  using SymbolTableScopeTy = ScopedHashTable<StringRef, StringRef>::ScopeTy;
+  SymbolTableScopeTy funScope(symbolTable);
+  symbolTable.insert(kGlobalName, kLocalValue);
+  SymbolTableScopeTy funScope2(symbolTable);
+  symbolTable.insert(kGlobalName, kLocalValue2);
+
+  std::stack<StringRef> expectedValues{{kLocalValue, kLocalValue2}};
+  std::stack<SymbolTableScopeTy *> expectedScopes{{&funScope, &funScope2}};
+
+  while (symbolTable.getCurScope() != &globalScope) {
+    EXPECT_EQ(symbolTable.getCurScope(), expectedScopes.top());
+    expectedScopes.pop();
+    EXPECT_EQ(symbolTable.lookup(kGlobalName), expectedValues.top());
+    expectedValues.pop();
+    symbolTable.getCurScope()->~SymbolTableScopeTy();
+    EXPECT_NE(symbolTable.getCurScope(), nullptr);
+  }
+
+  // We have imbalanced scopes here:
+  // Assertion `HT.CurScope == this && "Scope imbalance!"' failed
+  // HT.CurScope is a pointer to the `globalScope` while
+  // `SymbolTableScopeTy.this` is still a pointer to `funScope2`.
+  // There is no way to write an assert on an assert in googletest so that we
+  // mark the test case as DISABLED.
+}