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[poincare/multiplication] Optimize shallowBeautify for units: do not use deepReduce repeatedly

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This commit is contained in:
Ruben Dashyan
2020-01-13 11:53:40 +01:00
committed by Léa Saviot
parent 8f41bd7cd0
commit eba529d5ee
2 changed files with 83 additions and 24 deletions
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2
poincare/include/poincare/unit.h
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@@ -435,6 +435,8 @@ public:
static bool CanParse(const char * symbol, size_t length,
const Dimension * * dimension, const Representative * * representative, const Prefix * * prefix);
const Dimension * dimension() const { return static_cast<const UnitNode *>(node())->dimension(); }
Unit(const UnitNode * node) : Expression(node) {}
static Unit Builder(const Dimension * dimension, const Representative * representative, const Prefix * prefix);

105
poincare/src/multiplication.cpp
View File

@@ -277,8 +277,25 @@ Expression Multiplication::shallowReduce(ExpressionNode::ReductionContext reduct
return privateShallowReduce(reductionContext, true, true);
}
static void BaseUnitProductMetrics(const Expression units, size_t & supportSize, Integer & norm) {
static void ExponentsCopy(Integer (&dst)[7], const Integer (&src)[7]) {
for (int i = 0; i < 7; i++) {
dst[i] = src[i];
}
}
static void ExponentsMetrics(const Integer (&exponents)[7], size_t & supportSize, Integer & norm) {
assert(supportSize == 0 && norm.isZero());
for (int i = 0; i < 7; i++) {
Integer unsignedExponent = exponents[i];
unsignedExponent.setNegative(false);
if (!unsignedExponent.isZero()) {
supportSize++;
norm = Integer::Addition(norm, unsignedExponent);
}
}
}
static void ExponentsOfBaseUnits(const Expression units, Integer (&exponents)[7]) {
// Make sure the provided Expression is a Multiplication
Expression u = units;
if (u.type() == ExpressionNode::Type::Unit || u.type() == ExpressionNode::Type::Power) {
@@ -293,7 +310,7 @@ static void BaseUnitProductMetrics(const Expression units, size_t & supportSize,
if (factor.type() == ExpressionNode::Type::Power) {
Expression exp = factor.childAtIndex(1);
assert(exp.type() == ExpressionNode::Type::Rational && static_cast<Rational &>(exp).isInteger());
exponent = static_cast<Rational &>(exp).unsignedIntegerNumerator();
exponent = static_cast<Rational &>(exp).signedIntegerNumerator();
factor = factor.childAtIndex(0);
}
@@ -302,30 +319,41 @@ static void BaseUnitProductMetrics(const Expression units, size_t & supportSize,
continue;
}
// Compute the metrics
if (!exponent.isZero()) {
supportSize++;
norm = Integer::Addition(norm, exponent);
}
// Fill the exponents array with the unit's exponent
const int indexInTable = static_cast<Unit &>(factor).dimension() - Unit::DimensionTable;
assert(0 <= indexInTable && indexInTable < 7);
exponents[indexInTable] = exponent;
}
}
static bool CanSimplifyUnitProduct(
const Expression units, const Expression entryUnit,
ExpressionNode::ReductionContext reductionContext,
Expression & bestUnit, Expression & bestRemainder, size_t & bestRemainderSupportSize, Integer & bestRemainderNorm) {
/* This function tries to simplify a Unit product by applying a given
* operation. If the result of the operation is simpler, 'bestUnit' and
const Integer (&unitsExponents)[7], const Integer (&entryUnitExponents)[7], const Expression entryUnit,
Integer (*operationOnExponents)(const Integer & unitsExponent, const Integer & entryUnitExponent),
Expression & bestUnit, Integer (&bestRemainderExponents)[7], size_t & bestRemainderSupportSize, Integer & bestRemainderNorm) {
/* This function tries to simplify a Unit product (given as the
* 'unitsExponents' Integer array), by applying a given operation. If the
* result of the operation is simpler, 'bestUnit' and
* 'bestRemainder' are updated accordingly. */
Expression simplified = Division::Builder(units.clone(), entryUnit.clone()).deepReduce(reductionContext);
Integer simplifiedExponents[7] = {
Integer(0),
Integer(0),
Integer(0),
Integer(0),
Integer(0),
Integer(0),
Integer(0),
};
for (int i = 0; i < 7; i++) {
simplifiedExponents[i] = operationOnExponents(unitsExponents[i], entryUnitExponents[i]);
}
size_t simplifiedSupportSize = 0;
Integer simplifiedNorm(0);
BaseUnitProductMetrics(simplified, simplifiedSupportSize, simplifiedNorm);
ExponentsMetrics(simplifiedExponents, simplifiedSupportSize, simplifiedNorm);
bool isSimpler = simplifiedSupportSize < bestRemainderSupportSize ||
(simplifiedSupportSize == bestRemainderSupportSize && simplifiedNorm.isLowerThan(bestRemainderNorm));
if (isSimpler) {
bestUnit = entryUnit;
bestRemainder = simplified;
ExponentsCopy(bestRemainderExponents, simplifiedExponents);
bestRemainderSupportSize = simplifiedSupportSize;
bestRemainderNorm = simplifiedNorm;
}
@@ -363,26 +391,54 @@ Expression Multiplication::shallowBeautify(ExpressionNode::ReductionContext redu
* - Repeat those steps until no more simplification is possible.
*/
Multiplication unitsAccu = Multiplication::Builder();
Integer unitsExponents[7] = {
Integer(0),
Integer(0),
Integer(0),
Integer(0),
Integer(0),
Integer(0),
Integer(0),
};
ExponentsOfBaseUnits(units, unitsExponents);
size_t unitsSupportSize = 0;
Integer unitsNorm(0);
BaseUnitProductMetrics(units, unitsSupportSize, unitsNorm);
ExponentsMetrics(unitsExponents, unitsSupportSize, unitsNorm);
Integer bestRemainderExponents[7] = {
Integer(0),
Integer(0),
Integer(0),
Integer(0),
Integer(0),
Integer(0),
Integer(0),
};
while (unitsSupportSize > 1) {
Expression bestUnit;
Expression bestRemainder;
size_t bestRemainderSupportSize = unitsSupportSize - 1;
Integer bestRemainderNorm = Integer::Subtraction(unitsNorm, Integer(1));
for (const Unit::Dimension * dim = Unit::DimensionTable + 7; dim < Unit::DimensionTableUpperBound; dim++) {
Unit entryUnit = Unit::Builder(dim, dim->stdRepresentative(), dim->stdRepresentativePrefix());
Integer entryUnitExponents[7] = {
Integer(0),
Integer(0),
Integer(0),
Integer(0),
Integer(0),
Integer(0),
Integer(0),
};
ExponentsOfBaseUnits(entryUnit.clone().deepReduce(reductionContext), entryUnitExponents);
CanSimplifyUnitProduct(
units, entryUnit,
reductionContext,
bestUnit, bestRemainder, bestRemainderSupportSize, bestRemainderNorm
unitsExponents, entryUnitExponents, entryUnit,
Integer::Subtraction,
bestUnit, bestRemainderExponents, bestRemainderSupportSize, bestRemainderNorm
)
||
CanSimplifyUnitProduct(
units, Power::Builder(entryUnit, Rational::Builder(-1)),
reductionContext,
bestUnit, bestRemainder, bestRemainderSupportSize, bestRemainderNorm
unitsExponents, entryUnitExponents, Power::Builder(entryUnit, Rational::Builder(-1)),
Integer::Addition,
bestUnit, bestRemainderExponents, bestRemainderSupportSize, bestRemainderNorm
);
}
if (bestUnit.isUninitialized()) {
@@ -390,11 +446,12 @@ Expression Multiplication::shallowBeautify(ExpressionNode::ReductionContext redu
}
const int position = unitsAccu.numberOfChildren();
unitsAccu.addChildAtIndexInPlace(bestUnit, position, position);
units = bestRemainder;
ExponentsCopy(unitsExponents, bestRemainderExponents);
unitsSupportSize = bestRemainderSupportSize;
unitsNorm = bestRemainderNorm;
}
if (unitsAccu.numberOfChildren() > 0) {
units = Division::Builder(units, unitsAccu.clone()).deepReduce(reductionContext);
units = Multiplication::Builder(unitsAccu, units).shallowReduce(reductionContext);
}
}