internal/ceres/expression_test.cc

// Ceres Solver - A fast non-linear least squares minimizer
// Copyright 2019 Google Inc. All rights reserved.
// http://code.google.com/p/ceres-solver/
//
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//
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//   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
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//
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// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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// Author: darius.rueckert@fau.de (Darius Rueckert)
//

#define CERES_CODEGEN

#include "ceres/expression_test.h"
#include "ceres/jet.h"

namespace ceres {
namespace internal {

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

  StartRecordingExpressions();

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

  auto graph = StopRecordingExpressions();

  ASSERT_TRUE(graph.ExpressionForId(a.id).IsArithmeticExpression());
  ASSERT_TRUE(graph.ExpressionForId(b.id).IsArithmeticExpression());
  ASSERT_TRUE(graph.ExpressionForId(c.id).IsArithmeticExpression());
  ASSERT_TRUE(graph.ExpressionForId(d.id).IsArithmeticExpression());
}

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

  StartRecordingExpressions();

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

  auto graph = StopRecordingExpressions();

  ASSERT_TRUE(graph.ExpressionForId(a.id).IsCompileTimeConstantAndEqualTo(2));
  ASSERT_FALSE(graph.ExpressionForId(a.id).IsCompileTimeConstantAndEqualTo(0));
  ASSERT_TRUE(graph.ExpressionForId(b.id).IsCompileTimeConstantAndEqualTo(3));
  ASSERT_FALSE(graph.ExpressionForId(c.id).IsCompileTimeConstantAndEqualTo(0));
}

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

  StartRecordingExpressions();

  // a2 should be replaceable by a
  T a(2), b(3), a2(2);

  // two redundant expressions
  // -> d should be replaceable by c
  T c = a + b;
  T d = a + b;

  auto graph = StopRecordingExpressions();

  ASSERT_TRUE(graph.ExpressionForId(a2.id).IsReplaceableBy(
      graph.ExpressionForId(a.id)));
  ASSERT_TRUE(
      graph.ExpressionForId(d.id).IsReplaceableBy(graph.ExpressionForId(c.id)));
  ASSERT_FALSE(graph.ExpressionForId(d.id).IsReplaceableBy(
      graph.ExpressionForId(a2.id)));
}

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, Jet) {
  using T = Jet<ExpressionRef, 1>;

  StartRecordingExpressions();

  T a(2, 0);
  T b = a * a;

  auto graph = StopRecordingExpressions();

  // b is valid during the assignment so we expect an
  // additional assignment expression.
  EXPECT_EQ(graph.Size(), 8);

  // Expected code
  //   v_0 = 2;
  //   v_1 = 0;
  //   v_2 = 1;
  //   v_1 = v_2;
  //   v_3 = v_0 * v_0;
  //   v_4 = v_0 * v_1;
  //   v_5 = v_1 * v_0;
  //   v_6 = v_3 * v_4;
  //   v_7 = v_5 * v_6;

  // clang-format off
  // Id, Type, Lhs, Value, Name, Arguments
  CHECK_EXPRESSION(  0,  COMPILE_TIME_CONSTANT,   0,   2,   "",     );
  CHECK_EXPRESSION(  1,  COMPILE_TIME_CONSTANT,   1,   0,   "",     );
  CHECK_EXPRESSION(  2,  COMPILE_TIME_CONSTANT,   2,   1,   "",     );
  CHECK_EXPRESSION(  3,             ASSIGNMENT,   1,   0,   "", 2   );
  CHECK_EXPRESSION(  4,      BINARY_ARITHMETIC,   4,   0,  "*", 0, 0);
  CHECK_EXPRESSION(  5,      BINARY_ARITHMETIC,   5,   0,  "*", 0, 1);
  CHECK_EXPRESSION(  6,      BINARY_ARITHMETIC,   6,   0,  "*", 1, 0);
  CHECK_EXPRESSION(  7,      BINARY_ARITHMETIC,   7,   0,  "+", 5, 6);
  // clang-format on

  // Variables after execution:
  //
  // b.a         <=> v_4
  // b.v[0]      <=> v_7
  EXPECT_EQ(b.a.id, 4);
  EXPECT_EQ(b.v[0].id, 7);
}

// Todo: remaining functions of Expression

}  // namespace internal
}  // namespace ceres