internal/ceres/expression_ref.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_ref.h"
#include "glog/logging.h"

namespace ceres {
namespace internal {

ExpressionRef ExpressionRef::Create(ExpressionId id) {
  ExpressionRef ref;
  ref.id = id;
  return ref;
}

ExpressionRef::ExpressionRef(double compile_time_constant) {
  id = Expression::CreateCompileTimeConstant(compile_time_constant);
}

ExpressionRef::ExpressionRef(const ExpressionRef& other) { *this = other; }

ExpressionRef& ExpressionRef::operator=(const ExpressionRef& other) {
  // Assigning an uninitialized variable to another variable is an error.
  CHECK(other.IsInitialized()) << "Uninitialized Assignment.";

  if (IsInitialized()) {
    // Create assignment from other -> this
    Expression::CreateAssignment(id, other.id);
  } else {
    // Special case: "this" expressionref is invalid
    //    -> Skip assignment
    //    -> Let "this" point to the same variable as other
    id = other.id;
  }
  return *this;
}

// Compound operators
ExpressionRef& ExpressionRef::operator+=(ExpressionRef y) {
  *this = *this + y;
  return *this;
}

ExpressionRef& ExpressionRef::operator-=(ExpressionRef y) {
  *this = *this - y;
  return *this;
}

ExpressionRef& ExpressionRef::operator*=(ExpressionRef y) {
  *this = *this * y;
  return *this;
}

ExpressionRef& ExpressionRef::operator/=(ExpressionRef y) {
  *this = *this / y;
  return *this;
}

// Arith. Operators
ExpressionRef operator-(ExpressionRef x) {
  return ExpressionRef::Create(Expression::CreateUnaryArithmetic("-", x.id));
}

ExpressionRef operator+(ExpressionRef x) {
  return ExpressionRef::Create(Expression::CreateUnaryArithmetic("+", x.id));
}

ExpressionRef operator+(ExpressionRef x, ExpressionRef y) {
  return ExpressionRef::Create(
      Expression::CreateBinaryArithmetic("+", x.id, y.id));
}

ExpressionRef operator-(ExpressionRef x, ExpressionRef y) {
  return ExpressionRef::Create(
      Expression::CreateBinaryArithmetic("-", x.id, y.id));
}

ExpressionRef operator/(ExpressionRef x, ExpressionRef y) {
  return ExpressionRef::Create(
      Expression::CreateBinaryArithmetic("/", x.id, y.id));
}

ExpressionRef operator*(ExpressionRef x, ExpressionRef y) {
  return ExpressionRef::Create(
      Expression::CreateBinaryArithmetic("*", x.id, y.id));
}

// Functions
ExpressionRef MakeFunctionCall(const std::string& name,
                               const std::vector<ExpressionRef>& params) {
  std::vector<ExpressionId> ids;
  for (auto p : params) {
    ids.push_back(p.id);
  }
  return ExpressionRef::Create(Expression::CreateFunctionCall(name, ids));
}

ExpressionRef Ternary(ComparisonExpressionRef c,
                      ExpressionRef a,
                      ExpressionRef b) {
  return MakeFunctionCall("ternary", {c.id, a.id, b.id});
}

#define CERES_DEFINE_EXPRESSION_COMPARISON_OPERATOR(op)                   \
  ComparisonExpressionRef operator op(ExpressionRef a, ExpressionRef b) { \
    return ComparisonExpressionRef(ExpressionRef::Create(                 \
        Expression::CreateBinaryCompare(#op, a.id, b.id)));               \
  }

#define CERES_DEFINE_EXPRESSION_LOGICAL_OPERATOR(op)               \
  ComparisonExpressionRef operator op(ComparisonExpressionRef a,   \
                                      ComparisonExpressionRef b) { \
    return ComparisonExpressionRef(ExpressionRef::Create(          \
        Expression::CreateBinaryCompare(#op, a.id, b.id)));        \
  }

CERES_DEFINE_EXPRESSION_COMPARISON_OPERATOR(<)
CERES_DEFINE_EXPRESSION_COMPARISON_OPERATOR(<=)
CERES_DEFINE_EXPRESSION_COMPARISON_OPERATOR(>)
CERES_DEFINE_EXPRESSION_COMPARISON_OPERATOR(>=)
CERES_DEFINE_EXPRESSION_COMPARISON_OPERATOR(==)
CERES_DEFINE_EXPRESSION_COMPARISON_OPERATOR(!=)
CERES_DEFINE_EXPRESSION_LOGICAL_OPERATOR(&&)
CERES_DEFINE_EXPRESSION_LOGICAL_OPERATOR(||)
#undef CERES_DEFINE_EXPRESSION_COMPARISON_OPERATOR
#undef CERES_DEFINE_EXPRESSION_LOGICAL_OPERATOR

ComparisonExpressionRef operator!(ComparisonExpressionRef a) {
  return ComparisonExpressionRef(
      ExpressionRef::Create(Expression::CreateLogicalNegation(a.id)));
}

}  // namespace internal
}  // namespace ceres