RequirementMachine: Factor out TypeDifference::getOriginalSubstitution()

Author: slavapestov

lib/AST/RequirementMachine/PropertyUnification.cpp

@@ -404,7 +404,7 @@ void PropertyMap::processTypeDifference(const TypeDifference &difference,
 
   for (const auto &pair : difference.SameTypes) {
     // Both sides are type parameters; add a same-type requirement.
-    MutableTerm lhsTerm(difference.LHS.getSubstitutions()[pair.first]);
+    auto lhsTerm = difference.getOriginalSubstitution(pair.first);
     MutableTerm rhsTerm(pair.second);
 
     if (debug) {
@@ -419,7 +419,7 @@ void PropertyMap::processTypeDifference(const TypeDifference &difference,
   for (const auto &pair : difference.ConcreteTypes) {
     // A type parameter is equated with a concrete type; add a concrete
     // type requirement.
-    MutableTerm rhsTerm(difference.LHS.getSubstitutions()[pair.first]);
+    auto rhsTerm = difference.getOriginalSubstitution(pair.first);
     MutableTerm lhsTerm(rhsTerm);
     lhsTerm.add(pair.second);
 

lib/AST/RequirementMachine/RewriteLoop.cpp

@@ -550,7 +550,7 @@ RewritePathEvaluator::applyLeftConcreteProjection(const RewriteStep &step,
   const auto &difference = system.getTypeDifference(step.getTypeDifferenceID());
   unsigned index = step.getSubstitutionIndex();
 
-  MutableTerm leftProjection(difference.LHS.getSubstitutions()[index]);
+  auto leftProjection = difference.getOriginalSubstitution(index);
 
   MutableTerm leftBaseTerm(difference.BaseTerm);
   leftBaseTerm.add(difference.LHS);
@@ -607,7 +607,7 @@ RewritePathEvaluator::applyRightConcreteProjection(const RewriteStep &step,
   const auto &difference = system.getTypeDifference(step.getTypeDifferenceID());
   unsigned index = step.getSubstitutionIndex();
 
-  MutableTerm leftProjection(difference.LHS.getSubstitutions()[index]);
+  auto leftProjection = difference.getOriginalSubstitution(index);
   auto rightProjection = difference.getReplacementSubstitution(index);
 
   MutableTerm leftBaseTerm(difference.BaseTerm);

lib/AST/RequirementMachine/TypeDifference.cpp

@@ -25,6 +25,10 @@
 using namespace swift;
 using namespace rewriting;
 
+MutableTerm TypeDifference::getOriginalSubstitution(unsigned index) const {
+  return MutableTerm(LHS.getSubstitutions()[index]);
+}
+
 MutableTerm TypeDifference::getReplacementSubstitution(unsigned index) const {
   for (const auto &pair : SameTypes) {
     if (pair.first == index) {
@@ -37,14 +41,14 @@ MutableTerm TypeDifference::getReplacementSubstitution(unsigned index) const {
     if (pair.first == index) {
       // Given a transformation Xn -> [concrete: D], return the
       // return Xn.[concrete: D].
-      MutableTerm result(LHS.getSubstitutions()[index]);
+      auto result = getOriginalSubstitution(index);
       result.add(pair.second);
       return result;
     }
   }
 
   // Otherwise return the original substitution Xn.
-  return MutableTerm(LHS.getSubstitutions()[index]);
+  return getOriginalSubstitution(index);
 }
 
 void TypeDifference::dump(llvm::raw_ostream &out) const {
@@ -53,12 +57,12 @@ void TypeDifference::dump(llvm::raw_ostream &out) const {
   llvm::errs() << "RHS: " << RHS << "\n";
 
   for (const auto &pair : SameTypes) {
-    out << "- " << LHS.getSubstitutions()[pair.first] << " (#";
+    out << "- " << getOriginalSubstitution(pair.first) << " (#";
     out << pair.first << ") -> " << pair.second << "\n";
   }
 
   for (const auto &pair : ConcreteTypes) {
-    out << "- " << LHS.getSubstitutions()[pair.first] << " (#";
+    out << "- " << getOriginalSubstitution(pair.first) << " (#";
     out << pair.first << ") -> " << pair.second << "\n";
   }
 }

lib/AST/RequirementMachine/TypeDifference.h

@@ -58,6 +58,7 @@ struct TypeDifference {
     : BaseTerm(baseTerm), LHS(lhs), RHS(rhs),
       SameTypes(sameTypes), ConcreteTypes(concreteTypes) {}
 
+  MutableTerm getOriginalSubstitution(unsigned index) const;
   MutableTerm getReplacementSubstitution(unsigned index) const;
 
   void dump(llvm::raw_ostream &out) const;