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commenting refactoring

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This commit is contained in:
Florian Steurer 2016-04-13 11:38:07 +02:00
parent ae9220c04b
commit b1febd7a50
1 changed files with 59 additions and 13 deletions
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72
src/de/dhbwstuttgart/typeinference/unify/Unify.java
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@ -32,21 +32,36 @@ import de.dhbwstuttgart.typeinference.unify.model.Unifier;
*/
public class Unify {
/**
* The implementation of setOps that will be used during the unification
*/
protected ISetOperations setOps = new GuavaSetOperations();
/**
* The implementation of the standard unify that will be used during the unification
*/
protected IUnify stdUnify = new MartelliMontanariUnify();
/**
* The implementation of the rules that will be used during the unification.
*/
protected IRuleSet rules = new RuleSet();
/**
* Computes all principal type unifiers for a set of constraints.
* @param eq The set of constraints
* @param fc The finite closure
* @return The set of all principal type unifiers
*/
public Set<Set<UnifyPair>> unify(Set<UnifyPair> eq, IFiniteClosure fc) {
/*
* Step 1: Repeated application of reduce, adapt, erase, swap
*/
Set<UnifyPair> eq0 = applyTypeUnificationRules(eq, fc);
/*
* Step 2 and 3: Create a subset eq1s of pairs where both sides are TPH and eq2s of the other pairs
*/
Set<UnifyPair> eq1s = new HashSet<>();
Set<UnifyPair> eq2s = new HashSet<>();
splitEq(eq0, eq1s, eq2s);
@ -62,7 +77,7 @@ public class Unify {
// cartesian product of the sets created by pattern matching.
List<Set<Set<UnifyPair>>> topLevelSets = new ArrayList<>();
if(eq1s.size() != 0) {
if(eq1s.size() != 0) { // Do not add empty sets or the cartesian product will always be empty.
Set<Set<UnifyPair>> wrap = new HashSet<>();
wrap.add(eq1s);
topLevelSets.add(wrap); // Add Eq1'
@ -73,7 +88,7 @@ public class Unify {
.filter(x -> x.getPairOp() == PairOperator.EQUALSDOT && x.getLhsType() instanceof PlaceholderType)
.collect(Collectors.toSet());
if(bufferSet.size() != 0) {
if(bufferSet.size() != 0) { // Do not add empty sets or the cartesian product will always be empty.
Set<Set<UnifyPair>> wrap = new HashSet<>();
wrap.add(bufferSet);
topLevelSets.add(wrap);
@ -94,10 +109,12 @@ public class Unify {
* filters for pairs and sets can be applied here */
// Sub cartesian products of the second level (pattern matched) sets
// "the big (x)"
for(Set<Set<Set<UnifyPair>>> secondLevelSet : secondLevelSets) {
List<Set<Set<UnifyPair>>> secondLevelSetList = new ArrayList<>(secondLevelSet);
Set<List<Set<UnifyPair>>> cartResult = setOps.cartesianProduct(secondLevelSetList);
// Flatten and add to top level sets
Set<Set<UnifyPair>> flat = new HashSet<>();
for(List<Set<UnifyPair>> s : cartResult) {
Set<UnifyPair> flat1 = new HashSet<>();
@ -114,10 +131,7 @@ public class Unify {
.collect(Collectors.toCollection(HashSet::new));
//System.out.println(result);
/*
* Step 5: Substitution
*/
// Flatten the cartesian product
Set<Set<UnifyPair>> eqPrimeSetFlat = new HashSet<>();
for(Set<Set<UnifyPair>> setToFlatten : eqPrimeSet) {
Set<UnifyPair> buffer = new HashSet<>();
@ -125,6 +139,10 @@ public class Unify {
eqPrimeSetFlat.add(buffer);
}
/*
* Step 5: Substitution
*/
Set<Set<UnifyPair>> restartSet = new HashSet<>();
Set<Set<UnifyPair>> eqPrimePrimeSet = new HashSet<>();
@ -162,6 +180,11 @@ public class Unify {
}
/**
* Checks whether a set of pairs is in solved form.
* @param eqPrimePrime The set of pair
* @return True if in solved form, false otherwise.
*/
protected boolean isSolvedForm(Set<UnifyPair> eqPrimePrime) {
for(UnifyPair pair : eqPrimePrime) {
UnifyType lhsType = pair.getLhsType();
@ -170,13 +193,18 @@ public class Unify {
if(!(lhsType instanceof PlaceholderType))
return false;
// If operator is not equals, both sides must be placeholders
if(pair.getPairOp() != PairOperator.EQUALSDOT && !(rhsType instanceof PlaceholderType))
return false;
}
return true;
}
/**
* Repeatedly applies type unification rules to a set of equations.
* This is step one of the unification algorithm.
* @return The set of pairs that results from repeated application of the inference rules.
*/
protected Set<UnifyPair> applyTypeUnificationRules(Set<UnifyPair> eq, IFiniteClosure fc) {
/*
@ -255,6 +283,12 @@ public class Unify {
return targetSet;
}
/**
* Applies the rule swap to a pair if possible. Then adds the pair to the set if no erase rule applies.
* If an erase rule applies, the pair is not added (erased).
* @param pair The pair to swap and add or erase.
* @param collection The collection to which the pairs are added.
*/
protected void swapAddOrErase(UnifyPair pair, IFiniteClosure fc, Collection<UnifyPair> collection) {
Optional<UnifyPair> opt = rules.swap(pair);
UnifyPair pair2 = opt.isPresent() ? opt.get() : pair;
@ -265,6 +299,13 @@ public class Unify {
collection.add(pair2);
}
/**
* Splits the equation eq into a set eq1s where both terms are type variables,
* and a set eq2s where one of both terms is not a type variable.
* @param eq Set of pairs to be splitted.
* @param eq1s Subset of eq where both terms are type variables.
* @param eq2s eq/eq1s.
*/
protected void splitEq(Set<UnifyPair> eq, Set<UnifyPair> eq1s, Set<UnifyPair> eq2s) {
for(UnifyPair pair : eq)
if(pair.getLhsType() instanceof PlaceholderType && pair.getRhsType() instanceof PlaceholderType)
@ -273,16 +314,21 @@ public class Unify {
eq2s.add(pair);
}
/**
* Creates sets of pairs specified in the fourth step. Does not calculate cartesian products.
* @param undefined All pairs that did not match one of the 8 cases are added to this set.
* @return The set of the eight cases (without empty sets). Each case is a set, containing sets generated
* from the pairs that matched the case. Each generated set contains singleton sets or sets with few elements
* (as in case 1 where sigma is added to the innermost set).
*/
protected Set<Set<Set<Set<UnifyPair>>>> calculatePairSets(Set<UnifyPair> eq2s, IFiniteClosure fc, Set<UnifyPair> undefined) {
List<Set<Set<Set<UnifyPair>>>> result = new ArrayList<>();
List<Set<Set<Set<UnifyPair>>>> result = new ArrayList<>(8);
// Init all 8 cases
for(int i = 0; i < 8; i++)
result.add(new HashSet<>());
for(UnifyPair pair : eq2s) {
PairOperator pairOp = pair.getPairOp();
UnifyType lhsType = pair.getLhsType();
UnifyType rhsType = pair.getRhsType();
@ -323,9 +369,9 @@ public class Unify {
// Pairs that do not have one of the aboves form are contradictory.
else
undefined.add(pair);
}
// Filter empty sets or sets that only contain an empty set.
return result.stream().map(x -> x.stream().filter(y -> y.size() > 0).collect(Collectors.toCollection(HashSet::new)))
.filter(x -> x.size() > 0).collect(Collectors.toCollection(HashSet::new));
}