internal/ceres/codegen/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)
 //
 // This file tests the Expression class. For each member function one test is
 // included here.
 //
 #include "ceres/codegen/internal/expression.h"
 #include "gtest/gtest.h"

 namespace ceres {
 namespace internal {

 TEST(Expression, ConstructorAndAccessors) {
   Expression expr(ExpressionType::LOGICAL_NEGATION,
                   ExpressionReturnType::BOOLEAN,
                   12345,
                   {1, 5, 8, 10},
                   "TestConstructor",
                   57.25);
   EXPECT_EQ(expr.type(), ExpressionType::LOGICAL_NEGATION);
   EXPECT_EQ(expr.return_type(), ExpressionReturnType::BOOLEAN);
   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) {
   // The default constructor creates a NOP!
   EXPECT_EQ(Expression(),
             Expression(ExpressionType::NOP,
                        ExpressionReturnType::VOID,
                        kInvalidExpressionId,
                        {},
                        "",
                        0));

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

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

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

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

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

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

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

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

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

   EXPECT_EQ(
       Expression::CreateLogicalFunctionCall("isfinite", {ExpressionId(3)}),
       Expression(ExpressionType::FUNCTION_CALL,
                  ExpressionReturnType::BOOLEAN,
                  kInvalidExpressionId,
                  {3},
                  "isfinite",
                  0));

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

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

   EXPECT_EQ(Expression::CreateEndIf(),
             Expression(ExpressionType::ENDIF,
                        ExpressionReturnType::VOID,
                        kInvalidExpressionId,
                        {},
                        "",
                        0));

   EXPECT_EQ(Expression::CreateComment("Test"),
             Expression(ExpressionType::COMMENT,
                        ExpressionReturnType::VOID,
                        kInvalidExpressionId,
                        {},
                        "Test",
                        0));
 }

 TEST(Expression, IsArithmeticExpression) {
   ASSERT_TRUE(
       Expression::CreateCompileTimeConstant(5).IsArithmeticExpression());
   ASSERT_TRUE(Expression::CreateScalarFunctionCall("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::CreateScalarFunctionCall("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::CreateComment("Test").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, Replace) {
   auto expr1 =
       Expression::CreateBinaryArithmetic("+", ExpressionId(3), ExpressionId(5));
   expr1.set_lhs_id(13);

   auto expr2 =
       Expression::CreateAssignment(kInvalidExpressionId, ExpressionId(7));

   // We replace the arithmetic expr1 by an assignment from the variable 7. This
   // is the typical usecase in subexpression elimination.
   expr1.Replace(expr2);

   // expr1 should now be an assignment from 7 to 13
   EXPECT_EQ(expr1,
             Expression(ExpressionType::ASSIGNMENT,
                        ExpressionReturnType::SCALAR,
                        13,
                        {7},
                        "",
                        0));
 }

 TEST(Expression, DirectlyDependsOn) {
   auto expr1 =
       Expression::CreateBinaryArithmetic("+", ExpressionId(3), ExpressionId(5));

   ASSERT_TRUE(expr1.DirectlyDependsOn(ExpressionId(3)));
   ASSERT_TRUE(expr1.DirectlyDependsOn(ExpressionId(5)));
   ASSERT_FALSE(expr1.DirectlyDependsOn(ExpressionId(kInvalidExpressionId)));
   ASSERT_FALSE(expr1.DirectlyDependsOn(ExpressionId(42)));
 }
 TEST(Expression, MakeNop) {
   auto expr1 =
       Expression::CreateBinaryArithmetic("+", ExpressionId(3), ExpressionId(5));

   expr1.MakeNop();

   EXPECT_EQ(expr1,
             Expression(ExpressionType::NOP,
                        ExpressionReturnType::VOID,
                        kInvalidExpressionId,
                        {},
                        "",
                        0));
 }

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

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

   ASSERT_TRUE(expr1.IsSemanticallyEquivalentTo(expr1));
   ASSERT_TRUE(expr1.IsSemanticallyEquivalentTo(expr2));

   auto expr3 =
       Expression::CreateBinaryArithmetic("+", ExpressionId(3), ExpressionId(8));

   ASSERT_TRUE(expr1.IsSemanticallyEquivalentTo(expr3));

   auto expr4 =
       Expression::CreateBinaryArithmetic("-", ExpressionId(3), ExpressionId(5));

   ASSERT_FALSE(expr1.IsSemanticallyEquivalentTo(expr4));
 }

 }  // 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)
	//
	// This file tests the Expression class. For each member function one test is
	// included here.
	//
	#include "ceres/codegen/internal/expression.h"
	#include "gtest/gtest.h"

	namespace ceres {
	namespace internal {

	TEST(Expression, ConstructorAndAccessors) {
	Expression expr(ExpressionType::LOGICAL_NEGATION,
	ExpressionReturnType::BOOLEAN,
	12345,
	{1, 5, 8, 10},
	"TestConstructor",
	57.25);
	EXPECT_EQ(expr.type(), ExpressionType::LOGICAL_NEGATION);
	EXPECT_EQ(expr.return_type(), ExpressionReturnType::BOOLEAN);
	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) {
	// The default constructor creates a NOP!
	EXPECT_EQ(Expression(),
	Expression(ExpressionType::NOP,
	ExpressionReturnType::VOID,
	kInvalidExpressionId,
	{},
	"",
	0));

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

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

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

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

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

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

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

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

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

	EXPECT_EQ(
	Expression::CreateLogicalFunctionCall("isfinite", {ExpressionId(3)}),
	Expression(ExpressionType::FUNCTION_CALL,
	ExpressionReturnType::BOOLEAN,
	kInvalidExpressionId,
	{3},
	"isfinite",
	0));

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

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

	EXPECT_EQ(Expression::CreateEndIf(),
	Expression(ExpressionType::ENDIF,
	ExpressionReturnType::VOID,
	kInvalidExpressionId,
	{},
	"",
	0));

	EXPECT_EQ(Expression::CreateComment("Test"),
	Expression(ExpressionType::COMMENT,
	ExpressionReturnType::VOID,
	kInvalidExpressionId,
	{},
	"Test",
	0));
	}

	TEST(Expression, IsArithmeticExpression) {
	ASSERT_TRUE(
	Expression::CreateCompileTimeConstant(5).IsArithmeticExpression());
	ASSERT_TRUE(Expression::CreateScalarFunctionCall("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::CreateScalarFunctionCall("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::CreateComment("Test").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, Replace) {
	auto expr1 =
	Expression::CreateBinaryArithmetic("+", ExpressionId(3), ExpressionId(5));
	expr1.set_lhs_id(13);

	auto expr2 =
	Expression::CreateAssignment(kInvalidExpressionId, ExpressionId(7));

	// We replace the arithmetic expr1 by an assignment from the variable 7. This
	// is the typical usecase in subexpression elimination.
	expr1.Replace(expr2);

	// expr1 should now be an assignment from 7 to 13
	EXPECT_EQ(expr1,
	Expression(ExpressionType::ASSIGNMENT,
	ExpressionReturnType::SCALAR,
	13,
	{7},
	"",
	0));
	}

	TEST(Expression, DirectlyDependsOn) {
	auto expr1 =
	Expression::CreateBinaryArithmetic("+", ExpressionId(3), ExpressionId(5));

	ASSERT_TRUE(expr1.DirectlyDependsOn(ExpressionId(3)));
	ASSERT_TRUE(expr1.DirectlyDependsOn(ExpressionId(5)));
	ASSERT_FALSE(expr1.DirectlyDependsOn(ExpressionId(kInvalidExpressionId)));
	ASSERT_FALSE(expr1.DirectlyDependsOn(ExpressionId(42)));
	}
	TEST(Expression, MakeNop) {
	auto expr1 =
	Expression::CreateBinaryArithmetic("+", ExpressionId(3), ExpressionId(5));

	expr1.MakeNop();

	EXPECT_EQ(expr1,
	Expression(ExpressionType::NOP,
	ExpressionReturnType::VOID,
	kInvalidExpressionId,
	{},
	"",
	0));
	}

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

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

	ASSERT_TRUE(expr1.IsSemanticallyEquivalentTo(expr1));
	ASSERT_TRUE(expr1.IsSemanticallyEquivalentTo(expr2));

	auto expr3 =
	Expression::CreateBinaryArithmetic("+", ExpressionId(3), ExpressionId(8));

	ASSERT_TRUE(expr1.IsSemanticallyEquivalentTo(expr3));

	auto expr4 =
	Expression::CreateBinaryArithmetic("-", ExpressionId(3), ExpressionId(5));

	ASSERT_FALSE(expr1.IsSemanticallyEquivalentTo(expr4));
	}

	} // namespace internal
	} // namespace ceres