Upsilon/poincare/src/sequence.cpp

#include <poincare/sequence.h>
#include <poincare/integer.h>
#include <poincare/code_point_layout.h>
#include <poincare/horizontal_layout.h>
#include <poincare/vertical_offset_layout.h>
#include <poincare/based_integer.h>
#include <poincare/layout_helper.h>
#include <poincare/serialization_helper.h>
#include <poincare/parenthesis.h>
#include <poincare/complex.h>
#include <apps/shared/sequence.h>
#include <poincare/context.h>
#include <poincare/rational.h>
#include <poincare/undefined.h>
#include <ion/storage.h>

namespace Poincare {

SequenceNode::SequenceNode(const char * newName, int length) : SymbolAbstractNode() {
  strlcpy(const_cast<char*>(name()), newName, length+1);
}

Expression SequenceNode::replaceSymbolWithExpression(const SymbolAbstract & symbol, const Expression & expression) {
  return Sequence(this).replaceSymbolWithExpression(symbol, expression);
}

int SequenceNode::simplificationOrderSameType(const ExpressionNode * e, bool ascending, bool canBeInterrupted, bool ignoreParentheses) const {
  /* This function ensures that terms like u(n) and u(n+1), u(n) and v(n),
   * u(a) and u(b) do not factorize.
   * We never want to factorize. The only cases where it could be useful are
   * like the following : u(n)+u(n). But thanks to the cache system, no
   * computation is needed for the second term.*/
  assert(type() == e->type());
  assert(numberOfChildren() == 1);
  assert(e->numberOfChildren() == 1);
  ExpressionNode * seq = const_cast<ExpressionNode*>(e);
  int delta = strcmp(name(), reinterpret_cast<SequenceNode *>(seq)->name());
  if (delta == 0) {
    return SimplificationOrder(childAtIndex(0), e->childAtIndex(0), ascending, canBeInterrupted, ignoreParentheses);
  }
  return delta;
}

Layout SequenceNode::createLayout(Preferences::PrintFloatMode floatDisplayMode, int numberOfSignificantDigits) const {
  assert(name()[0] >= 'u' && name()[0] <= 'w');
  Layout rank = childAtIndex(0)->createLayout(floatDisplayMode, numberOfSignificantDigits);
  return HorizontalLayout::Builder(
    CodePointLayout::Builder(name()[0]),
    VerticalOffsetLayout::Builder(rank, VerticalOffsetLayoutNode::Position::Subscript));
}

int SequenceNode::serialize(char * buffer, int bufferSize, Preferences::PrintFloatMode floatDisplayMode, int numberOfSignificantDigits) const {
  return SerializationHelper::Prefix(this, buffer, bufferSize, floatDisplayMode, numberOfSignificantDigits, name());
}

Expression SequenceNode::shallowReduce(ReductionContext reductionContext) {
  return Sequence(this).shallowReduce(reductionContext);
}

Evaluation<float> SequenceNode::approximate(SinglePrecision p, ApproximationContext approximationContext) const {
  return templatedApproximate<float>(approximationContext);
}

Evaluation<double> SequenceNode::approximate(DoublePrecision p, ApproximationContext approximationContext) const {
  return templatedApproximate<double>(approximationContext);
}

template<typename T>
Evaluation<T> SequenceNode::templatedApproximate(ApproximationContext approximationContext) const {
  if (approximationContext.withinReduce() || childAtIndex(0)->approximate((T)1, approximationContext).isUndefined()) {
    /* If we're inside a reducing routine, we want to escape the sequence
     * approximation. Indeed, in order to know that the sequence is well defined
     * (especially for self-referencing or inter-dependently defined sequences),
     * we need to reduce the sequence definition (done by calling
     * 'expressionForSymbolAbstract'); if we're within a reduce routine, we
     * would create an infinite loop. Returning a NAN approximation for
     * sequences within reduce routine does not really matter: we just have
     * access to less information in order to simplify (abs(u(n)) might not be
     * reduced for instance). */
    return Complex<T>::Undefined();
  }
  Expression e = approximationContext.context()->expressionForSymbolAbstract(this, false);
  if (e.isUninitialized()) {
    return Complex<T>::Undefined();
  }
  return e.node()->approximate(T(), approximationContext);
}

Sequence Sequence::Builder(const char * name, size_t length, Expression child) {
  Sequence seq = SymbolAbstract::Builder<Sequence, SequenceNode>(name, length);
  if (!child.isUninitialized()) {
    seq.replaceChildAtIndexInPlace(0, child);
  }
  return seq;
}

Expression Sequence::replaceSymbolWithExpression(const SymbolAbstract & symbol, const Expression & expression) {
  // Replace the symbol in the child
  childAtIndex(0).replaceSymbolWithExpression(symbol, expression);
  if (symbol.type() == ExpressionNode::Type::Sequence && hasSameNameAs(symbol)) {
    Expression value = expression.clone();
    Expression p = parent();
    if (!p.isUninitialized() && p.node()->childAtIndexNeedsUserParentheses(value, p.indexOfChild(*this))) {
      value = Parenthesis::Builder(value);
    }
    replaceWithInPlace(value);
    return value;
  }
  return *this;
}

Expression Sequence::shallowReduce(ExpressionNode::ReductionContext reductionContext) {
  if (reductionContext.symbolicComputation() == ExpressionNode::SymbolicComputation::ReplaceAllSymbolsWithUndefined) {
    return replaceWithUndefinedInPlace();
  }

  if (reductionContext.symbolicComputation() == ExpressionNode::SymbolicComputation::DoNotReplaceAnySymbol) {
    return *this;
  }

  Expression result = replacedByDefinitionIfPossible(reductionContext.context()); // We don't need to check if the result is uninitialized
  result = Expression::ExpressionWithoutSymbols(result, reductionContext.context());

  if (result.isUninitialized()) {
    return *this;
  }

  replaceWithInPlace(result);

  // We simplify the expression entered by the user
  return result.deepReduce(reductionContext);
}

Expression SequenceNode::deepReplaceReplaceableSymbols(Context * context, bool * didReplace, bool replaceFunctionsOnly, int parameteredAncestorsCount) {
  return Sequence(this).deepReplaceReplaceableSymbols(context, didReplace, replaceFunctionsOnly, parameteredAncestorsCount);
}

Expression Sequence::deepReplaceReplaceableSymbols(Context * context, bool * didReplace, bool replaceFunctionsOnly, int parameteredAncestorsCount) {
  {
    // Replace replaceable symbols in child
    Expression self = defaultReplaceReplaceableSymbols(context, didReplace, replaceFunctionsOnly, parameteredAncestorsCount);
    if (self.isUninitialized()) { // if the child is circularly defined, escape
      return self;
    }
    assert(*this == self);
  }
  Expression e = replacedByDefinitionIfPossible(context);
  if (e.isUninitialized()) {
    return *this;
  }
  // If the function contains itself, return undefined
  if (e.hasExpression([](Expression e, const void * context) {
          if (e.type() != ExpressionNode::Type::Sequence) {
            return false;
          }
          return strcmp(static_cast<Sequence&>(e).name(), reinterpret_cast<const char *>(context)) == 0;
        }, reinterpret_cast<const void *>(name())))
  {
    return Expression();
  }
  replaceWithInPlace(e);
  *didReplace = true;
  return e;
  return *this;
}

Expression Sequence::replacedByDefinitionIfPossible(Context * context) {
  // We try to replace the sequence by his definition ONLY if the index is an integer

  if (childAtIndex(0).integerStatus(context) != ExpressionNode::IntegerStatus::Integer) {
    return Expression();
  }

  Ion::Storage::Record r = Ion::Storage::sharedStorage()->recordBaseNamedWithExtension(name(), Ion::Storage::seqExtension);

  if (r.isNull()) {
    return Expression();
  }

  Shared::Sequence seq(r);

  if (seq.type() != Shared::Sequence::Type::Explicit) {
    return Expression();
  }

  Expression result = seq.expressionClone();

  if (result.hasExpression([](Expression e, const void * context) {
          if (e.type() != ExpressionNode::Type::Sequence) {
            return false;
          }
          return strcmp(static_cast<Sequence&>(e).name(), reinterpret_cast<const char *>(context)) == 0;
        }, reinterpret_cast<const void *>(name())))
  {
    return Expression();
  }

  return result.replaceSymbolWithExpression(Symbol::Builder(UCodePointUnknown), childAtIndex(0));
}

}