Added class Lazy<T>
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ddcadad710
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@ -224,6 +224,7 @@ set(SOURCE_FILES
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src/tupleHash.h
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src/ThreadPool.cpp src/ThreadPool.h
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src/ObjectPool.h
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src/Lazy.h
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)
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add_executable(rhubarb ${SOURCE_FILES})
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target_link_libraries(rhubarb ${Boost_LIBRARIES} cppFormat sphinxbase pocketSphinx flite webRTC)
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@ -239,6 +240,7 @@ set(TEST_FILES
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tests/pairsTests.cpp
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tests/tokenizationTests.cpp
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tests/g2pTests.cpp
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tests/LazyTests.cpp
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src/stringTools.cpp src/stringTools.h
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src/Timeline.h
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src/TimeRange.cpp src/TimeRange.h
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@ -249,6 +251,7 @@ set(TEST_FILES
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src/g2p.cpp src/g2p.h
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src/logging.cpp src/logging.h
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src/tools.cpp src/tools.h
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src/Lazy.h
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)
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add_executable(runTests ${TEST_FILES})
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target_link_libraries(runTests gtest gmock gmock_main flite cppFormat)
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@ -0,0 +1,51 @@
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#pragma once
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#include <memory>
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#include <mutex>
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template<typename T>
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class Lazy {
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public:
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using value_type = T;
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explicit Lazy(std::function<T()> createValue) :
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createValue(createValue)
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{}
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explicit operator bool() const {
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return static_cast<bool>(_value);
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}
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T& value() {
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init();
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return *_value;
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}
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const T& value() const {
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init();
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return *_value;
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}
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T* operator->() {
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return &value();
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}
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const T* operator->() const {
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return &value();
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}
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T& operator*() {
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return value();
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}
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const T& operator*() const {
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return value();
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}
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private:
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void init() const {
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std::call_once(initialized, [&] { _value = std::make_unique<T>(createValue()); });
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}
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std::function<T()> createValue;
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mutable std::once_flag initialized;
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mutable std::unique_ptr<T> _value;
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};
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@ -0,0 +1,58 @@
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#include <gmock/gmock.h>
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#include "Lazy.h"
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using namespace testing;
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using std::make_unique;
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// Not copyable, no default constrctor, movable
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struct Foo {
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const int value;
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Foo(int value) : value(value) {}
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Foo() = delete;
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Foo(const Foo&) = delete;
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Foo& operator=(const Foo &) = delete;
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Foo(Foo&&) = default;
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Foo& operator=(Foo&&) = default;
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};
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TEST(Lazy, basicUsage) {
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bool lambdaCalled = false;
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Lazy<Foo> lazy([&lambdaCalled] { lambdaCalled = true; return Foo(42); });
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EXPECT_FALSE(lambdaCalled);
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EXPECT_FALSE(static_cast<bool>(lazy));
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EXPECT_EQ(42, (*lazy).value);
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EXPECT_EQ(42, lazy.value().value);
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EXPECT_EQ(42, lazy->value);
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EXPECT_TRUE(lambdaCalled);
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EXPECT_TRUE(static_cast<bool>(lazy));
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}
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TEST(Lazy, constUsage) {
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bool lambdaCalled = false;
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const Lazy<Foo> lazy([&lambdaCalled] { lambdaCalled = true; return Foo(42); });
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EXPECT_FALSE(lambdaCalled);
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EXPECT_FALSE(static_cast<bool>(lazy));
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EXPECT_EQ(42, (*lazy).value);
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EXPECT_EQ(42, lazy.value().value);
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EXPECT_EQ(42, lazy->value);
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EXPECT_TRUE(lambdaCalled);
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EXPECT_TRUE(static_cast<bool>(lazy));
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}
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using Expensive = Foo;
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#define member value;
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TEST(Lazy, demo) {
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// Constructor takes function
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Lazy<Expensive> lazy([] { return Expensive(42); });
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// Multiple ways to access value
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Expensive& a = *lazy;
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Expensive& b = lazy.value();
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auto c = lazy->member;
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// Check if initialized
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if (lazy) { /* ... */ }
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}
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