internal/ceres/expression_test.cc - ceres-solver - Git at Google

 // Ceres Solver - A fast non-linear least squares minimizer
 // Copyright 2019 Google Inc. All rights reserved.
 // http://code.google.com/p/ceres-solver/
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are met:
 //
 // * Redistributions of source code must retain the above copyright notice,
 //   this list of conditions and the following disclaimer.
 // * Redistributions in binary form must reproduce the above copyright notice,
 //   this list of conditions and the following disclaimer in the documentation
 //   and/or other materials provided with the distribution.
 // * Neither the name of Google Inc. nor the names of its contributors may be
 //   used to endorse or promote products derived from this software without
 //   specific prior written permission.
 //
 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 // AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 // IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 // ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 // LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 // CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 // SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 // INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 // CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 // ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 // POSSIBILITY OF SUCH DAMAGE.
 //
 // Author: darius.rueckert@fau.de (Darius Rueckert)
 //
 #define CERES_CODEGEN

 #include "ceres/codegen/internal/expression_graph.h"
 #include "ceres/codegen/internal/expression_ref.h"
 #include "ceres/jet.h"
 #include "gtest/gtest.h"

 namespace ceres {
 namespace internal {

 TEST(Expression, ConstructorAndAccessors) {
   Expression expr(ExpressionType::LOGICAL_NEGATION,
                   12345,
                   {1, 5, 8, 10},
                   "TestConstructor",
                   57.25);
   EXPECT_EQ(expr.type(), ExpressionType::LOGICAL_NEGATION);
   EXPECT_EQ(expr.lhs_id(), 12345);
   EXPECT_EQ(expr.arguments(), std::vector<ExpressionId>({1, 5, 8, 10}));
   EXPECT_EQ(expr.name(), "TestConstructor");
   EXPECT_EQ(expr.value(), 57.25);
 }

 TEST(Expression, CreateFunctions) {
   // clang-format off
   // The default constructor creates a NOP!
   EXPECT_EQ(Expression(), Expression(
             ExpressionType::NOP, kInvalidExpressionId, {}, "", 0));

   EXPECT_EQ(Expression::CreateCompileTimeConstant(72), Expression(
             ExpressionType::COMPILE_TIME_CONSTANT, kInvalidExpressionId, {}, "", 72));

   EXPECT_EQ(Expression::CreateInputAssignment("arguments[0][0]"), Expression(
             ExpressionType::INPUT_ASSIGNMENT, kInvalidExpressionId, {}, "arguments[0][0]", 0));

   EXPECT_EQ(Expression::CreateOutputAssignment(ExpressionId(5), "residuals[3]"), Expression(
             ExpressionType::OUTPUT_ASSIGNMENT, kInvalidExpressionId, {5}, "residuals[3]", 0));

   EXPECT_EQ(Expression::CreateAssignment(ExpressionId(3), ExpressionId(5)), Expression(
             ExpressionType::ASSIGNMENT, 3, {5}, "", 0));

   EXPECT_EQ(Expression::CreateBinaryArithmetic("+", ExpressionId(3),ExpressionId(5)), Expression(
             ExpressionType::BINARY_ARITHMETIC, kInvalidExpressionId, {3,5}, "+", 0));

   EXPECT_EQ(Expression::CreateUnaryArithmetic("-", ExpressionId(5)), Expression(
             ExpressionType::UNARY_ARITHMETIC, kInvalidExpressionId, {5}, "-", 0));

   EXPECT_EQ(Expression::CreateBinaryCompare("<",ExpressionId(3),ExpressionId(5)), Expression(
             ExpressionType::BINARY_COMPARISON, kInvalidExpressionId, {3,5}, "<", 0));

   EXPECT_EQ(Expression::CreateLogicalNegation(ExpressionId(5)), Expression(
             ExpressionType::LOGICAL_NEGATION, kInvalidExpressionId, {5}, "", 0));

   EXPECT_EQ(Expression::CreateFunctionCall("pow",{ExpressionId(3),ExpressionId(5)}), Expression(
             ExpressionType::FUNCTION_CALL, kInvalidExpressionId, {3,5}, "pow", 0));

   EXPECT_EQ(Expression::CreateIf(ExpressionId(5)), Expression(
             ExpressionType::IF, kInvalidExpressionId, {5}, "", 0));

   EXPECT_EQ(Expression::CreateElse(), Expression(
             ExpressionType::ELSE, kInvalidExpressionId, {}, "", 0));

   EXPECT_EQ(Expression::CreateEndIf(), Expression(
             ExpressionType::ENDIF, kInvalidExpressionId, {}, "", 0));
   // clang-format on
 }

 TEST(Expression, IsArithmeticExpression) {
   ASSERT_TRUE(
       Expression::CreateCompileTimeConstant(5).IsArithmeticExpression());
   ASSERT_TRUE(
       Expression::CreateFunctionCall("pow", {3, 5}).IsArithmeticExpression());
   // Logical expression are also arithmetic!
   ASSERT_TRUE(
       Expression::CreateBinaryCompare("<", 3, 5).IsArithmeticExpression());
   ASSERT_FALSE(Expression::CreateIf(5).IsArithmeticExpression());
   ASSERT_FALSE(Expression::CreateEndIf().IsArithmeticExpression());
   ASSERT_FALSE(Expression().IsArithmeticExpression());
 }

 TEST(Expression, IsControlExpression) {
   // In the current implementation this is the exact opposite of
   // IsArithmeticExpression.
   ASSERT_FALSE(Expression::CreateCompileTimeConstant(5).IsControlExpression());
   ASSERT_FALSE(
       Expression::CreateFunctionCall("pow", {3, 5}).IsControlExpression());
   ASSERT_FALSE(
       Expression::CreateBinaryCompare("<", 3, 5).IsControlExpression());
   ASSERT_TRUE(Expression::CreateIf(5).IsControlExpression());
   ASSERT_TRUE(Expression::CreateEndIf().IsControlExpression());
   ASSERT_TRUE(Expression().IsControlExpression());
 }

 TEST(Expression, IsCompileTimeConstantAndEqualTo) {
   ASSERT_TRUE(
       Expression::CreateCompileTimeConstant(5).IsCompileTimeConstantAndEqualTo(
           5));
   ASSERT_FALSE(
       Expression::CreateCompileTimeConstant(3).IsCompileTimeConstantAndEqualTo(
           5));
   ASSERT_FALSE(Expression::CreateBinaryCompare("<", 3, 5)
                    .IsCompileTimeConstantAndEqualTo(5));
 }

 TEST(Expression, IsReplaceableBy) {
   // Create 2 identical expression
   auto expr1 =
       Expression::CreateBinaryArithmetic("+", ExpressionId(3), ExpressionId(5));

   auto expr2 =
       Expression::CreateBinaryArithmetic("+", ExpressionId(3), ExpressionId(5));

   // They are idendical and of course replaceable
   ASSERT_EQ(expr1, expr2);
   ASSERT_EQ(expr2, expr1);
   ASSERT_TRUE(expr1.IsReplaceableBy(expr2));
   ASSERT_TRUE(expr2.IsReplaceableBy(expr1));

   // Give them different left hand sides
   expr1.set_lhs_id(72);
   expr2.set_lhs_id(42);

   // v_72 = v_3 + v_5
   // v_42 = v_3 + v_5
   // -> They should be replaceable by each other

   ASSERT_NE(expr1, expr2);
   ASSERT_NE(expr2, expr1);

   ASSERT_TRUE(expr1.IsReplaceableBy(expr2));
   ASSERT_TRUE(expr2.IsReplaceableBy(expr1));

   // A slightly differnt expression with the argument flipped
   auto expr3 =
       Expression::CreateBinaryArithmetic("+", ExpressionId(5), ExpressionId(3));

   ASSERT_NE(expr1, expr3);
   ASSERT_FALSE(expr1.IsReplaceableBy(expr3));
 }

 TEST(Expression, DirectlyDependsOn) {
   using T = ExpressionRef;

   StartRecordingExpressions();

   T unused(6);
   T a(2), b(3);
   T c = a + b;
   T d = c + a;

   auto graph = StopRecordingExpressions();

   ASSERT_FALSE(graph.ExpressionForId(a.id).DirectlyDependsOn(unused.id));
   ASSERT_TRUE(graph.ExpressionForId(c.id).DirectlyDependsOn(a.id));
   ASSERT_TRUE(graph.ExpressionForId(c.id).DirectlyDependsOn(b.id));
   ASSERT_TRUE(graph.ExpressionForId(d.id).DirectlyDependsOn(a.id));
   ASSERT_FALSE(graph.ExpressionForId(d.id).DirectlyDependsOn(b.id));
   ASSERT_TRUE(graph.ExpressionForId(d.id).DirectlyDependsOn(c.id));
 }

 TEST(Expression, Ternary) {
   using T = ExpressionRef;

   StartRecordingExpressions();
   T a(2);                   // 0
   T b(3);                   // 1
   auto c = a < b;           // 2
   T d = Ternary(c, a, b);   // 3
   MakeOutput(d, "result");  // 4
   auto graph = StopRecordingExpressions();

   EXPECT_EQ(graph.Size(), 5);

   // Expected code
   //   v_0 = 2;
   //   v_1 = 3;
   //   v_2 = v_0 < v_1;
   //   v_3 = Ternary(v_2, v_0, v_1);
   //   result = v_3;

   ExpressionGraph reference;
   // clang-format off
   // Id, Type, Lhs, Value, Name, Arguments
   reference.InsertBack({ ExpressionType::COMPILE_TIME_CONSTANT,   0,      {},        "",  2});
   reference.InsertBack({ ExpressionType::COMPILE_TIME_CONSTANT,   1,      {},        "",  3});
   reference.InsertBack({     ExpressionType::BINARY_COMPARISON,   2,   {0,1},       "<",  0});
   reference.InsertBack({         ExpressionType::FUNCTION_CALL,   3, {2,0,1}, "Ternary",  0});
   reference.InsertBack({     ExpressionType::OUTPUT_ASSIGNMENT,   4,     {3},  "result",  0});
   // clang-format on
   EXPECT_EQ(reference, graph);
 }

 TEST(Expression, Assignment) {
   using T = ExpressionRef;

   StartRecordingExpressions();
   T a = 1;
   T b = 2;
   b = a;
   auto graph = StopRecordingExpressions();

   EXPECT_EQ(graph.Size(), 3);

   ExpressionGraph reference;
   // clang-format off
   // Id, Type, Lhs, Value, Name, Arguments
   reference.InsertBack({ ExpressionType::COMPILE_TIME_CONSTANT,   0,       {},        "",  1});
   reference.InsertBack({ ExpressionType::COMPILE_TIME_CONSTANT,   1,       {},        "",  2});
   reference.InsertBack({            ExpressionType::ASSIGNMENT,   1,      {0},        "",  0});
   // clang-format on
   EXPECT_EQ(reference, graph);
 }

 TEST(Expression, AssignmentCreate) {
   using T = ExpressionRef;

   StartRecordingExpressions();
   T a = 2;
   T b = a;
   auto graph = StopRecordingExpressions();

   EXPECT_EQ(graph.Size(), 2);

   ExpressionGraph reference;
   // clang-format off
   // Id, Type, Lhs, Value, Name, Arguments
   reference.InsertBack({ ExpressionType::COMPILE_TIME_CONSTANT,   0,       {},        "",  2});
   reference.InsertBack({            ExpressionType::ASSIGNMENT,   1,      {0},        "",  0});
   // clang-format on
   EXPECT_EQ(reference, graph);
 }

 TEST(Expression, MoveAssignmentCreate) {
   using T = ExpressionRef;

   StartRecordingExpressions();
   T a = 1;
   T b = std::move(a);
   auto graph = StopRecordingExpressions();

   EXPECT_EQ(graph.Size(), 1);

   ExpressionGraph reference;
   // clang-format off
   // Id, Type, Lhs, Value, Name, Arguments
   reference.InsertBack({ ExpressionType::COMPILE_TIME_CONSTANT,   0,      {},        "",  1});
   // clang-format on
   EXPECT_EQ(reference, graph);
 }

 TEST(Expression, MoveAssignment) {
   using T = ExpressionRef;

   StartRecordingExpressions();
   T a = 1;
   T b = 2;
   b = std::move(a);
   auto graph = StopRecordingExpressions();

   EXPECT_EQ(graph.Size(), 3);

   ExpressionGraph reference;
   // clang-format off
   // Id, Type, Lhs, Value, Name, Arguments
   reference.InsertBack({ ExpressionType::COMPILE_TIME_CONSTANT,   0,       {},        "",  1});
   reference.InsertBack({ ExpressionType::COMPILE_TIME_CONSTANT,   1,       {},        "",  2});
   reference.InsertBack({            ExpressionType::ASSIGNMENT,   1,      {0},        "",  0});
   // clang-format on
   EXPECT_EQ(reference, graph);
 }

 }  // namespace internal
 }  // namespace ceres
	// Ceres Solver - A fast non-linear least squares minimizer
	// Copyright 2019 Google Inc. All rights reserved.
	// http://code.google.com/p/ceres-solver/
	//
	// Redistribution and use in source and binary forms, with or without
	// modification, are permitted provided that the following conditions are met:
	//
	// * Redistributions of source code must retain the above copyright notice,
	// this list of conditions and the following disclaimer.
	// * Redistributions in binary form must reproduce the above copyright notice,
	// this list of conditions and the following disclaimer in the documentation
	// and/or other materials provided with the distribution.
	// * Neither the name of Google Inc. nor the names of its contributors may be
	// used to endorse or promote products derived from this software without
	// specific prior written permission.
	//
	// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
	// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
	// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
	// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
	// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
	// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
	// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
	// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
	// POSSIBILITY OF SUCH DAMAGE.
	//
	// Author: darius.rueckert@fau.de (Darius Rueckert)
	//
	#define CERES_CODEGEN

	#include "ceres/codegen/internal/expression_graph.h"
	#include "ceres/codegen/internal/expression_ref.h"
	#include "ceres/jet.h"
	#include "gtest/gtest.h"

	namespace ceres {
	namespace internal {

	TEST(Expression, ConstructorAndAccessors) {
	Expression expr(ExpressionType::LOGICAL_NEGATION,
	12345,
	{1, 5, 8, 10},
	"TestConstructor",
	57.25);
	EXPECT_EQ(expr.type(), ExpressionType::LOGICAL_NEGATION);
	EXPECT_EQ(expr.lhs_id(), 12345);
	EXPECT_EQ(expr.arguments(), std::vector<ExpressionId>({1, 5, 8, 10}));
	EXPECT_EQ(expr.name(), "TestConstructor");
	EXPECT_EQ(expr.value(), 57.25);
	}

	TEST(Expression, CreateFunctions) {
	// clang-format off
	// The default constructor creates a NOP!
	EXPECT_EQ(Expression(), Expression(
	ExpressionType::NOP, kInvalidExpressionId, {}, "", 0));

	EXPECT_EQ(Expression::CreateCompileTimeConstant(72), Expression(
	ExpressionType::COMPILE_TIME_CONSTANT, kInvalidExpressionId, {}, "", 72));

	EXPECT_EQ(Expression::CreateInputAssignment("arguments[0][0]"), Expression(
	ExpressionType::INPUT_ASSIGNMENT, kInvalidExpressionId, {}, "arguments[0][0]", 0));

	EXPECT_EQ(Expression::CreateOutputAssignment(ExpressionId(5), "residuals[3]"), Expression(
	ExpressionType::OUTPUT_ASSIGNMENT, kInvalidExpressionId, {5}, "residuals[3]", 0));

	EXPECT_EQ(Expression::CreateAssignment(ExpressionId(3), ExpressionId(5)), Expression(
	ExpressionType::ASSIGNMENT, 3, {5}, "", 0));

	EXPECT_EQ(Expression::CreateBinaryArithmetic("+", ExpressionId(3),ExpressionId(5)), Expression(
	ExpressionType::BINARY_ARITHMETIC, kInvalidExpressionId, {3,5}, "+", 0));

	EXPECT_EQ(Expression::CreateUnaryArithmetic("-", ExpressionId(5)), Expression(
	ExpressionType::UNARY_ARITHMETIC, kInvalidExpressionId, {5}, "-", 0));

	EXPECT_EQ(Expression::CreateBinaryCompare("<",ExpressionId(3),ExpressionId(5)), Expression(
	ExpressionType::BINARY_COMPARISON, kInvalidExpressionId, {3,5}, "<", 0));

	EXPECT_EQ(Expression::CreateLogicalNegation(ExpressionId(5)), Expression(
	ExpressionType::LOGICAL_NEGATION, kInvalidExpressionId, {5}, "", 0));

	EXPECT_EQ(Expression::CreateFunctionCall("pow",{ExpressionId(3),ExpressionId(5)}), Expression(
	ExpressionType::FUNCTION_CALL, kInvalidExpressionId, {3,5}, "pow", 0));

	EXPECT_EQ(Expression::CreateIf(ExpressionId(5)), Expression(
	ExpressionType::IF, kInvalidExpressionId, {5}, "", 0));

	EXPECT_EQ(Expression::CreateElse(), Expression(
	ExpressionType::ELSE, kInvalidExpressionId, {}, "", 0));

	EXPECT_EQ(Expression::CreateEndIf(), Expression(
	ExpressionType::ENDIF, kInvalidExpressionId, {}, "", 0));
	// clang-format on
	}

	TEST(Expression, IsArithmeticExpression) {
	ASSERT_TRUE(
	Expression::CreateCompileTimeConstant(5).IsArithmeticExpression());
	ASSERT_TRUE(
	Expression::CreateFunctionCall("pow", {3, 5}).IsArithmeticExpression());
	// Logical expression are also arithmetic!
	ASSERT_TRUE(
	Expression::CreateBinaryCompare("<", 3, 5).IsArithmeticExpression());
	ASSERT_FALSE(Expression::CreateIf(5).IsArithmeticExpression());
	ASSERT_FALSE(Expression::CreateEndIf().IsArithmeticExpression());
	ASSERT_FALSE(Expression().IsArithmeticExpression());
	}

	TEST(Expression, IsControlExpression) {
	// In the current implementation this is the exact opposite of
	// IsArithmeticExpression.
	ASSERT_FALSE(Expression::CreateCompileTimeConstant(5).IsControlExpression());
	ASSERT_FALSE(
	Expression::CreateFunctionCall("pow", {3, 5}).IsControlExpression());
	ASSERT_FALSE(
	Expression::CreateBinaryCompare("<", 3, 5).IsControlExpression());
	ASSERT_TRUE(Expression::CreateIf(5).IsControlExpression());
	ASSERT_TRUE(Expression::CreateEndIf().IsControlExpression());
	ASSERT_TRUE(Expression().IsControlExpression());
	}

	TEST(Expression, IsCompileTimeConstantAndEqualTo) {
	ASSERT_TRUE(
	Expression::CreateCompileTimeConstant(5).IsCompileTimeConstantAndEqualTo(
	5));
	ASSERT_FALSE(
	Expression::CreateCompileTimeConstant(3).IsCompileTimeConstantAndEqualTo(
	5));
	ASSERT_FALSE(Expression::CreateBinaryCompare("<", 3, 5)
	.IsCompileTimeConstantAndEqualTo(5));
	}

	TEST(Expression, IsReplaceableBy) {
	// Create 2 identical expression
	auto expr1 =
	Expression::CreateBinaryArithmetic("+", ExpressionId(3), ExpressionId(5));

	auto expr2 =
	Expression::CreateBinaryArithmetic("+", ExpressionId(3), ExpressionId(5));

	// They are idendical and of course replaceable
	ASSERT_EQ(expr1, expr2);
	ASSERT_EQ(expr2, expr1);
	ASSERT_TRUE(expr1.IsReplaceableBy(expr2));
	ASSERT_TRUE(expr2.IsReplaceableBy(expr1));

	// Give them different left hand sides
	expr1.set_lhs_id(72);
	expr2.set_lhs_id(42);

	// v_72 = v_3 + v_5
	// v_42 = v_3 + v_5
	// -> They should be replaceable by each other

	ASSERT_NE(expr1, expr2);
	ASSERT_NE(expr2, expr1);

	ASSERT_TRUE(expr1.IsReplaceableBy(expr2));
	ASSERT_TRUE(expr2.IsReplaceableBy(expr1));

	// A slightly differnt expression with the argument flipped
	auto expr3 =
	Expression::CreateBinaryArithmetic("+", ExpressionId(5), ExpressionId(3));

	ASSERT_NE(expr1, expr3);
	ASSERT_FALSE(expr1.IsReplaceableBy(expr3));
	}

	TEST(Expression, DirectlyDependsOn) {
	using T = ExpressionRef;

	StartRecordingExpressions();

	T unused(6);
	T a(2), b(3);
	T c = a + b;
	T d = c + a;

	auto graph = StopRecordingExpressions();

	ASSERT_FALSE(graph.ExpressionForId(a.id).DirectlyDependsOn(unused.id));
	ASSERT_TRUE(graph.ExpressionForId(c.id).DirectlyDependsOn(a.id));
	ASSERT_TRUE(graph.ExpressionForId(c.id).DirectlyDependsOn(b.id));
	ASSERT_TRUE(graph.ExpressionForId(d.id).DirectlyDependsOn(a.id));
	ASSERT_FALSE(graph.ExpressionForId(d.id).DirectlyDependsOn(b.id));
	ASSERT_TRUE(graph.ExpressionForId(d.id).DirectlyDependsOn(c.id));
	}

	TEST(Expression, Ternary) {
	using T = ExpressionRef;

	StartRecordingExpressions();
	T a(2); // 0
	T b(3); // 1
	auto c = a < b; // 2
	T d = Ternary(c, a, b); // 3
	MakeOutput(d, "result"); // 4
	auto graph = StopRecordingExpressions();

	EXPECT_EQ(graph.Size(), 5);

	// Expected code
	// v_0 = 2;
	// v_1 = 3;
	// v_2 = v_0 < v_1;
	// v_3 = Ternary(v_2, v_0, v_1);
	// result = v_3;

	ExpressionGraph reference;
	// clang-format off
	// Id, Type, Lhs, Value, Name, Arguments
	reference.InsertBack({ ExpressionType::COMPILE_TIME_CONSTANT, 0, {}, "", 2});
	reference.InsertBack({ ExpressionType::COMPILE_TIME_CONSTANT, 1, {}, "", 3});
	reference.InsertBack({ ExpressionType::BINARY_COMPARISON, 2, {0,1}, "<", 0});
	reference.InsertBack({ ExpressionType::FUNCTION_CALL, 3, {2,0,1}, "Ternary", 0});
	reference.InsertBack({ ExpressionType::OUTPUT_ASSIGNMENT, 4, {3}, "result", 0});
	// clang-format on
	EXPECT_EQ(reference, graph);
	}

	TEST(Expression, Assignment) {
	using T = ExpressionRef;

	StartRecordingExpressions();
	T a = 1;
	T b = 2;
	b = a;
	auto graph = StopRecordingExpressions();

	EXPECT_EQ(graph.Size(), 3);

	ExpressionGraph reference;
	// clang-format off
	// Id, Type, Lhs, Value, Name, Arguments
	reference.InsertBack({ ExpressionType::COMPILE_TIME_CONSTANT, 0, {}, "", 1});
	reference.InsertBack({ ExpressionType::COMPILE_TIME_CONSTANT, 1, {}, "", 2});
	reference.InsertBack({ ExpressionType::ASSIGNMENT, 1, {0}, "", 0});
	// clang-format on
	EXPECT_EQ(reference, graph);
	}

	TEST(Expression, AssignmentCreate) {
	using T = ExpressionRef;

	StartRecordingExpressions();
	T a = 2;
	T b = a;
	auto graph = StopRecordingExpressions();

	EXPECT_EQ(graph.Size(), 2);

	ExpressionGraph reference;
	// clang-format off
	// Id, Type, Lhs, Value, Name, Arguments
	reference.InsertBack({ ExpressionType::COMPILE_TIME_CONSTANT, 0, {}, "", 2});
	reference.InsertBack({ ExpressionType::ASSIGNMENT, 1, {0}, "", 0});
	// clang-format on
	EXPECT_EQ(reference, graph);
	}

	TEST(Expression, MoveAssignmentCreate) {
	using T = ExpressionRef;

	StartRecordingExpressions();
	T a = 1;
	T b = std::move(a);
	auto graph = StopRecordingExpressions();

	EXPECT_EQ(graph.Size(), 1);

	ExpressionGraph reference;
	// clang-format off
	// Id, Type, Lhs, Value, Name, Arguments
	reference.InsertBack({ ExpressionType::COMPILE_TIME_CONSTANT, 0, {}, "", 1});
	// clang-format on
	EXPECT_EQ(reference, graph);
	}

	TEST(Expression, MoveAssignment) {
	using T = ExpressionRef;

	StartRecordingExpressions();
	T a = 1;
	T b = 2;
	b = std::move(a);
	auto graph = StopRecordingExpressions();

	EXPECT_EQ(graph.Size(), 3);

	ExpressionGraph reference;
	// clang-format off
	// Id, Type, Lhs, Value, Name, Arguments
	reference.InsertBack({ ExpressionType::COMPILE_TIME_CONSTANT, 0, {}, "", 1});
	reference.InsertBack({ ExpressionType::COMPILE_TIME_CONSTANT, 1, {}, "", 2});
	reference.InsertBack({ ExpressionType::ASSIGNMENT, 1, {0}, "", 0});
	// clang-format on
	EXPECT_EQ(reference, graph);
	}

	} // namespace internal
	} // namespace ceres