Merge pull request #8931 from random-internet-cat/lazy-init

Add LazyInit

test/CMakeLists.txt

@@ -34,6 +34,7 @@ set(libsolutil_sources
     libsolutil/IterateReplacing.cpp
     libsolutil/JSON.cpp
     libsolutil/Keccak256.cpp
+    libsolutil/LazyInit.cpp
     libsolutil/StringUtils.cpp
     libsolutil/SwarmHash.cpp
     libsolutil/UTF8.cpp

test/contracts/AuctionRegistrar.cpp

@@ -24,9 +24,12 @@
 #include <test/contracts/ContractInterface.h>
 #include <test/EVMHost.h>
 
+#include <libsolutil/LazyInit.h>
+
 #include <boost/test/unit_test.hpp>
 
 #include <string>
+#include <optional>
 
 using namespace std;
 using namespace solidity;
@@ -212,17 +215,18 @@ contract GlobalRegistrar is Registrar, AuctionSystem {
 }
 )DELIMITER";
 
-static unique_ptr<bytes> s_compiledRegistrar;
+static LazyInit<bytes> s_compiledRegistrar;
 
 class AuctionRegistrarTestFramework: public SolidityExecutionFramework
 {
 protected:
 	void deployRegistrar()
 	{
-		if (!s_compiledRegistrar)
-			s_compiledRegistrar = make_unique<bytes>(compileContract(registrarCode, "GlobalRegistrar"));
+		bytes const& compiled = s_compiledRegistrar.init([&]{
+			return compileContract(registrarCode, "GlobalRegistrar");
+		});
 
-		sendMessage(*s_compiledRegistrar, true);
+		sendMessage(compiled, true);
 		BOOST_REQUIRE(m_transactionSuccessful);
 		BOOST_REQUIRE(!m_output.empty());
 	}

test/contracts/FixedFeeRegistrar.cpp

@@ -20,8 +20,11 @@
  * Tests for a fixed fee registrar contract.
  */
 
+#include <libsolutil/LazyInit.h>
+
 #include <string>
 #include <tuple>
+#include <optional>
 
 #if defined(_MSC_VER)
 #pragma warning(push)
@@ -122,17 +125,18 @@ contract FixedFeeRegistrar is Registrar {
 }
 )DELIMITER";
 
-static unique_ptr<bytes> s_compiledRegistrar;
+static LazyInit<bytes> s_compiledRegistrar;
 
 class RegistrarTestFramework: public SolidityExecutionFramework
 {
 protected:
 	void deployRegistrar()
 	{
-		if (!s_compiledRegistrar)
-			s_compiledRegistrar = make_unique<bytes>(compileContract(registrarCode, "FixedFeeRegistrar"));
+		bytes const& compiled = s_compiledRegistrar.init([&]{
+			return compileContract(registrarCode, "FixedFeeRegistrar");
+		});
 
-		sendMessage(*s_compiledRegistrar, true);
+		sendMessage(compiled, true);
 		BOOST_REQUIRE(m_transactionSuccessful);
 		BOOST_REQUIRE(!m_output.empty());
 	}

test/contracts/Wallet.cpp

@@ -20,8 +20,11 @@
  * Tests for a (comparatively) complex multisig wallet contract.
  */
 
+#include <libsolutil/LazyInit.h>
+
 #include <string>
 #include <tuple>
+#include <optional>
 
 #if defined(_MSC_VER)
 #pragma warning(push)
@@ -435,7 +438,7 @@ contract Wallet is multisig, multiowned, daylimit {
 }
 )DELIMITER";
 
-static unique_ptr<bytes> s_compiledWallet;
+static LazyInit<bytes> s_compiledWallet;
 
 class WalletTestFramework: public SolidityExecutionFramework
 {
@@ -447,11 +450,12 @@ protected:
 		u256 _dailyLimit = 0
 	)
 	{
-		if (!s_compiledWallet)
-			s_compiledWallet = make_unique<bytes>(compileContract(walletCode, "Wallet"));
+		bytes const& compiled = s_compiledWallet.init([&]{
+			return compileContract(walletCode, "Wallet");
+		});
 
 		bytes args = encodeArgs(u256(0x60), _required, _dailyLimit, u256(_owners.size()), _owners);
-		sendMessage(*s_compiledWallet + args, true, _value);
+		sendMessage(compiled + args, true, _value);
 		BOOST_REQUIRE(m_transactionSuccessful);
 		BOOST_REQUIRE(!m_output.empty());
 	}

test/libsolutil/LazyInit.cpp

@@ -0,0 +1,118 @@
+/*
+	This file is part of solidity.
+
+	solidity is free software: you can redistribute it and/or modify
+	it under the terms of the GNU General Public License as published by
+	the Free Software Foundation, either version 3 of the License, or
+	(at your option) any later version.
+
+	solidity is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+	GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with solidity.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include <libsolutil/LazyInit.h>
+
+#include <boost/test/unit_test.hpp>
+
+#include <utility>
+
+namespace solidity::util::test
+{
+
+namespace
+{
+
+template<typename T>
+void assertInitCalled(LazyInit<T> lazyInit, bool target)
+{
+	bool initCalled = false;
+
+	lazyInit.init([&]{
+	  initCalled = true;
+	  return T();
+	});
+
+	BOOST_REQUIRE_EQUAL(initCalled, target);
+}
+
+// Take ownership to ensure that it doesn't "mutate"
+template<typename T>
+void assertNotEmpty(LazyInit<T> _lazyInit) { assertInitCalled(std::move(_lazyInit), false); }
+
+// Take ownership to ensure that it doesn't "mutate"
+template<typename T>
+void assertEmpty(LazyInit<T> _lazyInit) { assertInitCalled(std::move(_lazyInit), true); }
+
+template<typename T>
+T valueOf(LazyInit<T> _lazyInit)
+{
+	return _lazyInit.init([&]{
+		BOOST_REQUIRE(false); // this should never be called
+		return T();
+	});
+}
+
+}
+
+BOOST_AUTO_TEST_SUITE(LazyInitTests)
+
+BOOST_AUTO_TEST_CASE(default_constructed_is_empty)
+{
+	assertEmpty(LazyInit<int>());
+	assertEmpty(LazyInit<int const>());
+}
+
+BOOST_AUTO_TEST_CASE(initialized_is_not_empty)
+{
+	LazyInit<int> lazyInit;
+	lazyInit.init([]{ return 12; });
+
+	assertNotEmpty(std::move(lazyInit));
+}
+
+BOOST_AUTO_TEST_CASE(init_returns_init_value)
+{
+	LazyInit<int> lazyInit;
+
+	BOOST_CHECK_EQUAL(lazyInit.init([]{ return 12; }), 12);
+
+	// A second call to init should not change the value
+	BOOST_CHECK_EQUAL(lazyInit.init([]{ return 42; }), 12);
+}
+
+BOOST_AUTO_TEST_CASE(moved_from_is_empty)
+{
+	{
+		LazyInit<int> lazyInit;
+		{ [[maybe_unused]] auto pilfered = std::move(lazyInit); }
+
+		assertEmpty(std::move(lazyInit));
+	}
+
+	{
+		LazyInit<int> lazyInit;
+		lazyInit.init([]{ return 12; });
+
+		{ [[maybe_unused]] auto pilfered = std::move(lazyInit); }
+
+		assertEmpty(std::move(lazyInit));
+	}
+}
+
+BOOST_AUTO_TEST_CASE(move_constructed_has_same_value_as_original)
+{
+	LazyInit<int> original;
+	original.init([]{ return 12; });
+
+	LazyInit<int> moveConstructed = std::move(original);
+	BOOST_CHECK_EQUAL(valueOf(std::move(moveConstructed)), 12);
+}
+
+BOOST_AUTO_TEST_SUITE_END()
+
+}