Dynamic allocation of equality engine in Theory (#4890)

This commit updates Theory so that equality engines are allocated dynamically. The plan is to make this configurable based on the theory combination method.

The fundamental changes include:
- Add `d_equalityEngine` (raw) pointer to Theory, which is the "official" equality engine of the theory.
- Standardize methods for initializing Theory. This is now made more explicit in the documentation in theory.h, and includes a method `finishInitStandalone` for users of Theory that don't have an associated TheoryEngine.
- Refactor TheoryEngine::finishInit, including how Theory is initialized to incorporate the new policy.
- Things related to master equality engine are now specific to EqEngineManagerDistributed and hence can be removed from TheoryEngine. This will be further refactored in forthcoming PRs.

Note that the majority of changes are due to changing `d_equalityEngine.` to `d_equalityEngine->` throughout. 

1 files changed, 10 insertions, 11 deletions

diff --git a/src/theory/strings/term_registry.cpp b/src/theory/strings/term_registry.cpp
index f28db4c35..71b45915f 100644
--- a/src/theory/strings/term_registry.cpp
+++ b/src/theory/strings/term_registry.cpp
@@ -37,12 +37,10 @@ typedef expr::Attribute<StringsProxyVarAttributeId, bool>
     StringsProxyVarAttribute;
 
 TermRegistry::TermRegistry(SolverState& s,
-                           eq::EqualityEngine& ee,
                            OutputChannel& out,
                            SequencesStatistics& statistics,
                            ProofNodeManager* pnm)
     : d_state(s),
-      d_ee(ee),
       d_out(out),
       d_statistics(statistics),
       d_hasStrCode(false),
@@ -129,6 +127,7 @@ void TermRegistry::preRegisterTerm(TNode n)
   {
     return;
   }
+  eq::EqualityEngine* ee = d_state.getEqualityEngine();
   d_preregisteredTerms.insert(n);
   Trace("strings-preregister")
       << "TheoryString::preregister : " << n << std::endl;
@@ -156,15 +155,15 @@ void TermRegistry::preRegisterTerm(TNode n)
       ss << "Equality between regular expressions is not supported";
       throw LogicException(ss.str());
     }
-    d_ee.addTriggerEquality(n);
+    ee->addTriggerEquality(n);
     return;
   }
   else if (k == STRING_IN_REGEXP)
   {
     d_out.requirePhase(n, true);
-    d_ee.addTriggerPredicate(n);
-    d_ee.addTerm(n[0]);
-    d_ee.addTerm(n[1]);
+    ee->addTriggerPredicate(n);
+    ee->addTerm(n[0]);
+    ee->addTerm(n[1]);
     return;
   }
   else if (k == STRING_TO_CODE)
@@ -196,17 +195,17 @@ void TermRegistry::preRegisterTerm(TNode n)
         }
       }
     }
-    d_ee.addTerm(n);
+    ee->addTerm(n);
   }
   else if (tn.isBoolean())
   {
     // Get triggered for both equal and dis-equal
-    d_ee.addTriggerPredicate(n);
+    ee->addTriggerPredicate(n);
   }
   else
   {
     // Function applications/predicates
-    d_ee.addTerm(n);
+    ee->addTerm(n);
   }
   // Set d_functionsTerms stores all function applications that are
   // relevant to theory combination. Notice that this is a subset of
@@ -216,7 +215,7 @@ void TermRegistry::preRegisterTerm(TNode n)
   // Concatenation terms do not need to be considered here because
   // their arguments have string type and do not introduce any shared
   // terms.
-  if (n.hasOperator() && d_ee.isFunctionKind(k) && k != STRING_CONCAT)
+  if (n.hasOperator() && ee->isFunctionKind(k) && k != STRING_CONCAT)
   {
     d_functionsTerms.push_back(n);
   }
@@ -313,7 +312,7 @@ void TermRegistry::registerType(TypeNode tn)
   {
     // preregister the empty word for the type
     Node emp = Word::mkEmptyWord(tn);
-    if (!d_ee.hasTerm(emp))
+    if (!d_state.hasTerm(emp))
     {
       preRegisterTerm(emp);
     }