Upsilon/apps/calculation/calculation.cpp

#include "calculation.h"
#include "../shared/poincare_helpers.h"
#include "../global_preferences.h"
#include <poincare/exception_checkpoint.h>
#include <poincare/undefined.h>
#include <poincare/unreal.h>
#include <string.h>
#include <cmath>

using namespace Poincare;
using namespace Shared;

namespace Calculation {

static inline KDCoordinate maxCoordinate(KDCoordinate x, KDCoordinate y) { return x > y ? x : y; }

bool Calculation::operator==(const Calculation& c) {
  return strcmp(inputText(), c.inputText()) == 0
      && strcmp(approximateOutputText(), c.approximateOutputText()) == 0
      /* Some calculations can make appear trigonometric functions in their
       * exact output. Their argument will be different with the angle unit
       * preferences but both input and approximate output will be the same.
       * For example, i^(sqrt(3)) = cos(sqrt(3)*pi/2)+i*sin(sqrt(3)*pi/2) if
       * angle unit is radian and i^(sqrt(3)) = cos(sqrt(3)*90+i*sin(sqrt(3)*90)
       * in degree. */
      && strcmp(exactOutputText(), c.exactOutputText()) == 0;
}

Calculation * Calculation::next() const {
  const char * result = reinterpret_cast<const char *>(this) + sizeof(Calculation);
  for (int i = 0; i < 3; i++) {
    result = result + strlen(result) + 1; // Pass inputText, exactOutputText, ApproximateOutputText
  }
  return reinterpret_cast<Calculation *>(const_cast<char *>(result));
}

void Calculation::tidy() {
  /* Reset height memoization (the complex format could have changed when
   * re-entering Calculation app which would impact the heights). */
  m_height = -1;
  m_expandedHeight = -1;
}

const char * Calculation::approximateOutputText() const {
  const char * exactOutput = exactOutputText();
  return exactOutput + strlen(exactOutput) + 1;
}

Expression Calculation::input() {
  return Expression::Parse(m_inputText, nullptr);
}

Expression Calculation::exactOutput() {
  /* Because the angle unit might have changed, we do not simplify again. We
   * thereby avoid turning cos(Pi/4) into sqrt(2)/2 and displaying
   * 'sqrt(2)/2 = 0.999906' (which is totally wrong) instead of
   * 'cos(pi/4) = 0.999906' (which is true in degree). */
  Expression exactOutput = Expression::Parse(exactOutputText(), nullptr);
  assert(!exactOutput.isUninitialized());
  return exactOutput;
}

Expression Calculation::approximateOutput(Context * context) {
  Expression exp = Expression::Parse(approximateOutputText(), nullptr);
  assert(!exp.isUninitialized());
  /* Warning:
   * Since quite old versions of Epsilon, the Expression 'exp' was used to be
   * approximated again to ensure its content was in the expected form. That is
   * currently the case (see Poincare::Expression::simplifyAndApproximate). So
   * 'exp' does not need to be approximated. Moreover since the approximate
   * output may contain units and that a Poincare::Unit approximates to undef,
   * thus it must not be approximated. If another behavior is desired, the
   * previous considerations should be taken into account. */
  return exp;
}

Layout Calculation::createInputLayout() {
  return input().createLayout(Preferences::PrintFloatMode::Decimal, PrintFloat::k_numberOfStoredSignificantDigits);
}

Layout Calculation::createExactOutputLayout(bool * couldNotCreateExactLayout) {
  Poincare::ExceptionCheckpoint ecp;
  if (ExceptionRun(ecp)) {
    return PoincareHelpers::CreateLayout(exactOutput());
  } else {
    *couldNotCreateExactLayout = true;
    return Layout();
  }
}

Layout Calculation::createApproximateOutputLayout(Context * context, bool * couldNotCreateApproximateLayout) {
  Poincare::ExceptionCheckpoint ecp;
  if (ExceptionRun(ecp)) {
    return PoincareHelpers::CreateLayout(approximateOutput(context));
  } else {
    *couldNotCreateApproximateLayout = true;
    return Layout();
  }
}

KDCoordinate Calculation::height(Context * context, bool expanded, bool allExpressionsInline) {
  KDCoordinate result = expanded ? m_expandedHeight : m_height;
  if (result >= 0) {
    // Height already computed
    return result;
  }

  // Get input height
  Layout inputLayout = createInputLayout();
  KDCoordinate inputHeight = inputLayout.layoutSize().height();
  KDCoordinate inputBaseline = inputLayout.baseline();

  // Get exact output height if needed
  Poincare::Layout exactLayout;
  bool couldNotCreateExactLayout = false;
  if (DisplaysExact(displayOutput(context))) {
    // Create the exact output layout
    exactLayout = createExactOutputLayout(&couldNotCreateExactLayout);
    if (couldNotCreateExactLayout) {
      if (displayOutput(context) != DisplayOutput::ExactOnly) {
        forceDisplayOutput(DisplayOutput::ApproximateOnly);
      } else {
        /* We should only display the exact result, but we cannot create it
         * -> raise an exception. */
        ExceptionCheckpoint::Raise();
      }
    }
  }

  if (displayOutput(context) == DisplayOutput::ExactOnly) {
    KDCoordinate exactOutputHeight = exactLayout.layoutSize().height();
    if (allExpressionsInline) {
      KDCoordinate exactOutputBaseline = exactLayout.baseline();
      result = maxCoordinate(inputBaseline, exactOutputBaseline) + maxCoordinate(inputHeight - inputBaseline, exactOutputHeight-exactOutputBaseline);
    } else {
      result = inputHeight+exactOutputHeight;
    }
  } else {
    bool couldNotCreateApproximateLayout = false;
    Layout approximateLayout = createApproximateOutputLayout(context, &couldNotCreateApproximateLayout);
    if (couldNotCreateApproximateLayout) {
      if (displayOutput(context) == DisplayOutput::ApproximateOnly) {
        Poincare::ExceptionCheckpoint::Raise();
      } else {
        /* Set the display output to ApproximateOnly, make room in the pool by
         * erasing the exact layout, and retry to create the approximate layout */
        forceDisplayOutput(DisplayOutput::ApproximateOnly);
        exactLayout = Poincare::Layout();
        couldNotCreateApproximateLayout = false;
        approximateLayout = createApproximateOutputLayout(context, &couldNotCreateApproximateLayout);
        if (couldNotCreateApproximateLayout) {
          Poincare::ExceptionCheckpoint::Raise();
        }
      }
    }

    KDCoordinate approximateOutputHeight = approximateLayout.layoutSize().height();
    if (displayOutput(context) == DisplayOutput::ApproximateOnly || (!expanded && displayOutput(context) == DisplayOutput::ExactAndApproximateToggle)) {
      if (allExpressionsInline) {
        KDCoordinate approximateOutputBaseline = approximateLayout.baseline();
        result = maxCoordinate(inputBaseline, approximateOutputBaseline) + maxCoordinate(inputHeight - inputBaseline, approximateOutputHeight-approximateOutputBaseline);
      } else {
        result = inputHeight+approximateOutputHeight;
      }
    } else {
      assert(displayOutput(context) == DisplayOutput::ExactAndApproximate || (displayOutput(context) == DisplayOutput::ExactAndApproximateToggle && expanded));
      KDCoordinate exactOutputHeight = exactLayout.layoutSize().height();
      KDCoordinate exactOutputBaseline = exactLayout.baseline();
      KDCoordinate approximateOutputBaseline = approximateLayout.baseline();
      if (allExpressionsInline) {
        result = maxCoordinate(inputBaseline, maxCoordinate(exactOutputBaseline, approximateOutputBaseline)) + maxCoordinate(inputHeight - inputBaseline, maxCoordinate(exactOutputHeight - exactOutputBaseline, approximateOutputHeight-approximateOutputBaseline));
      } else {
        KDCoordinate outputHeight = maxCoordinate(exactOutputBaseline, approximateOutputBaseline) + maxCoordinate(exactOutputHeight-exactOutputBaseline, approximateOutputHeight-approximateOutputBaseline);
        result = inputHeight + outputHeight;
      }
    }
  }

  /* For all display outputs except ExactAndApproximateToggle, the selected
   * height and the usual height are identical. We update both heights in
   * theses cases. */
  if (displayOutput(context) != DisplayOutput::ExactAndApproximateToggle) {
    m_height = result;
    m_expandedHeight = result;
  } else {
    if (expanded) {
      m_expandedHeight = result;
    } else {
      m_height = result;
    }
  }
  return result;
}

Calculation::DisplayOutput Calculation::displayOutput(Context * context) {
  if (m_displayOutput != DisplayOutput::Unknown) {
    return m_displayOutput;
  }
  if (shouldOnlyDisplayExactOutput()) {
    m_displayOutput = DisplayOutput::ExactOnly;
  // Force all results to be ApproximateOnly in Dutch exam mode
  } else if (GlobalPreferences::sharedGlobalPreferences()->examMode() == GlobalPreferences::ExamMode::Dutch ||
      input().recursivelyMatches(
        [](const Expression e, Context * c) {
          constexpr int approximateOnlyTypesCount = 9;
          /* If the input contains the following types, we only display the
           * approximate output. */
          ExpressionNode::Type approximateOnlyTypes[approximateOnlyTypesCount] = {
            ExpressionNode::Type::Random,
            ExpressionNode::Type::Round,
            ExpressionNode::Type::FracPart,
            ExpressionNode::Type::Integral,
            ExpressionNode::Type::Product,
            ExpressionNode::Type::Sum,
            ExpressionNode::Type::Derivative,
            ExpressionNode::Type::ConfidenceInterval,
            ExpressionNode::Type::PredictionInterval
          };
          return e.isOfType(approximateOnlyTypes, approximateOnlyTypesCount);
        }, context, true))
  {
    m_displayOutput = DisplayOutput::ApproximateOnly;
  } else if (strcmp(exactOutputText(), approximateOutputText()) == 0) {
    /* If the exact and approximate results' texts are equal and their layouts
     * too, do not display the exact result. If the two layouts are not equal
     * because of the number of significant digits, we display both. */
    m_displayOutput = exactAndApproximateDisplayedOutputsAreEqual(context) == Calculation::EqualSign::Equal ? DisplayOutput::ApproximateOnly : DisplayOutput::ExactAndApproximate;
  } else if (strcmp(exactOutputText(), Undefined::Name()) == 0
      || strcmp(approximateOutputText(), Unreal::Name()) == 0
      || exactOutput().type() == ExpressionNode::Type::Undefined)
  {
    // If the approximate result is 'unreal' or the exact result is 'undef'
    m_displayOutput = DisplayOutput::ApproximateOnly;
  } else if (strcmp(approximateOutputText(), Undefined::Name()) == 0
      && strcmp(inputText(), exactOutputText()) == 0)
  {
    /* If the approximate result is 'undef' and the input and exactOutput are
     * equal */
    m_displayOutput = DisplayOutput::ApproximateOnly;
  } else if (input().recursivelyMatches(Expression::IsApproximate, context)
      || exactOutput().recursivelyMatches(Expression::IsApproximate, context))
  {
    m_displayOutput = DisplayOutput::ExactAndApproximateToggle;
  } else {
    m_displayOutput = DisplayOutput::ExactAndApproximate;
  }
  return m_displayOutput;
}

bool Calculation::shouldOnlyDisplayExactOutput() {
  /* If the input is a "store in a function", do not display the approximate
   * result. This prevents x->f(x) from displaying x = undef. */
  Expression i = input();
  return i.type() == ExpressionNode::Type::Store
    && i.childAtIndex(1).type() == ExpressionNode::Type::Function;
}

Calculation::EqualSign Calculation::exactAndApproximateDisplayedOutputsAreEqual(Poincare::Context * context) {
  if (m_equalSign != EqualSign::Unknown) {
    return m_equalSign;
  }
  /* Displaying the right equal symbol is less important than displaying a
   * result, so we do not want exactAndApproximateDisplayedOutputsAreEqual to
   * create a pool failure that would prevent from displaying a result that we
   * managed to compute. We thus encapsulate the method in an exception
   * checkpoint: if there was not enough memory on the pool to compute the equal
   * sign, just return EqualSign::Approximation.
   * We can safely use an exception checkpoint here because we are sure of not
   * modifying any pre-existing node in the pool. We are sure there cannot be a
   * Store in the exactOutput. */
  Poincare::ExceptionCheckpoint ecp;
  if (ExceptionRun(ecp)) {
    constexpr int bufferSize = Constant::MaxSerializedExpressionSize + 30;
    char buffer[bufferSize];
    Preferences * preferences = Preferences::sharedPreferences();
    Expression exactOutputExpression = PoincareHelpers::ParseAndSimplify(exactOutputText(), context, false);
    if (exactOutputExpression.isUninitialized()) {
      exactOutputExpression = Undefined::Builder();
    }
    Preferences::ComplexFormat complexFormat = Expression::UpdatedComplexFormatWithTextInput(preferences->complexFormat(), m_inputText);
    m_equalSign = exactOutputExpression.isEqualToItsApproximationLayout(approximateOutput(context), buffer, bufferSize, complexFormat, preferences->angleUnit(), preferences->displayMode(), preferences->numberOfSignificantDigits(), context) ? EqualSign::Equal : EqualSign::Approximation;
    return m_equalSign;
  } else {
    /* Do not override m_equalSign in case there is enough room in the pool
     * later to compute it. */
    return EqualSign::Approximation;
  }
}

Calculation::AdditionalInformationType Calculation::additionalInformationType(Context * context) {
  Preferences * preferences = Preferences::sharedPreferences();
  Preferences::ComplexFormat complexFormat = Expression::UpdatedComplexFormatWithTextInput(preferences->complexFormat(), m_inputText);
  Expression i = input();
  Expression o = exactOutput();
  /* Special case for Equal and Store:
   * Equal/Store nodes have to be at the root of the expression, which prevents
   * from creating new expressions with equal/store node as a child. We don't
   * return any additional outputs for them to avoid bothering with special
   * cases. */
  if (i.type() == ExpressionNode::Type::Equal || i.type() == ExpressionNode::Type::Store) {
    return AdditionalInformationType::None;
  }
  /* Trigonometry additional results are displayed if either input or output is a sin or a cos. Indeed, we want to capture both cases:
   * - > input: cos(60)
   *   > output: 1/2
   * - > input: 2cos(2) - cos(2)
   *   > output: cos(2)
   */
  if (input().isDefinedCosineOrSine(context, complexFormat, preferences->angleUnit()) || o.isDefinedCosineOrSine(context, complexFormat, preferences->angleUnit())) {
    return AdditionalInformationType::Trigonometry;
  }

  // TODO: return AdditionalInformationType::Unit
  if (o.isBasedIntegerCappedBy(k_maximalIntegerWithAdditionalInformation)) {
    return AdditionalInformationType::Integer;
  }
  // Find forms like [12]/[23] or -[12]/[23]
  if (o.isDivisionOfIntegers() || (o.type() == ExpressionNode::Type::Opposite && o.childAtIndex(0).isDivisionOfIntegers())) {
    return AdditionalInformationType::Rational;
  }
  if (o.hasDefinedComplexApproximation(context, complexFormat, preferences->angleUnit())) {
    return AdditionalInformationType::Complex;
  }
  return AdditionalInformationType::None;
}

}