ceres-solver/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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// Author: darius.rueckert@fau.de (Darius Rueckert)
//

#include "ceres/internal/expression_graph.h"
#include "ceres/internal/expression_ref.h"

#include "gtest/gtest.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_FALSE(graph.ExpressionForId(a.id).IsArithmetic());
  ASSERT_FALSE(graph.ExpressionForId(b.id).IsArithmetic());
  ASSERT_TRUE(graph.ExpressionForId(c.id).IsArithmetic());
  ASSERT_TRUE(graph.ExpressionForId(d.id).IsArithmetic());
}

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));
}

// Todo: remaining functions of Expression

}  // namespace internal
}  // namespace ceres