Fix the prediction cache and the comparison algorithms from the legacy code

runtime-testsuite/resources/org/antlr/v4/test/runtime/descriptors/Performance/DropLoopEntryBranchInLRRule_4.txt

@@ -56,4 +56,5 @@ Python3
 JavaScript
 TypeScript
 PHP
+Go
 

runtime/Go/antlr/v4/array_prediction_context.go

@@ -63,7 +63,7 @@ func (a *ArrayPredictionContext) getReturnState(index int) int {
 
 // Equals is the default comparison function for ArrayPredictionContext when no specialized
 // implementation is needed for a collection
-func (a *ArrayPredictionContext) Equals(o interface{}) bool {
+func (a *ArrayPredictionContext) Equals(o Collectable[PredictionContext]) bool {
 	if a == o {
 		return true
 	}
@@ -76,7 +76,7 @@ func (a *ArrayPredictionContext) Equals(o interface{}) bool {
 	}
 
 	// Must compare the actual array elements and not just the array address
-	//
+	// TODO: The hash hashes in all the return states anyway, to we maybe don't need to compare them here?
 	return slices.Equal(a.returnStates, other.returnStates) &&
 		slices.EqualFunc(a.parents, other.parents, func(x, y PredictionContext) bool {
 			return x.Equals(y)

runtime/Go/antlr/v4/atn_config.go

@@ -14,33 +14,33 @@ import (
 // state. The semantic context is the tree of semantic predicates encountered
 // before reaching an ATN state.
 type ATNConfig interface {
-
+	
 	// Equals compares this ATNConfig to another for equality
 	Equals(o Collectable[ATNConfig]) bool
-
+	
 	// Hash returns the hash code for this ATNConfig for use in maps and comparisons
 	Hash() int
-
+	
 	// GetState returns the ATN state associated with this configuration
 	GetState() ATNState
 	// GetAlt returns the alternative associated with this configuration
 	GetAlt() int
 	// GetSemanticContext returns the semantic context associated with this configuration
 	GetSemanticContext() SemanticContext
-
+	
 	// GetContext returns the rule invocation stack associated with this configuration
 	GetContext() PredictionContext
 	// SetContext sets the rule invocation stack associated with this configuration
 	SetContext(PredictionContext)
-
+	
 	// GetReachesIntoOuterContext returns the count of references to an outer context from this configuration
 	GetReachesIntoOuterContext() int
 	// SetReachesIntoOuterContext sets the count of references to an outer context from this configuration
 	SetReachesIntoOuterContext(int)
-
+	
 	// String returns a string representation of the configuration
 	String() string
-
+	
 	getPrecedenceFilterSuppressed() bool
 	setPrecedenceFilterSuppressed(bool)
 }
@@ -78,7 +78,7 @@ func NewBaseATNConfig5(state ATNState, alt int, context PredictionContext, seman
 	if semanticContext == nil {
 		panic("semanticContext cannot be nil") // TODO: Necessary?
 	}
-
+	
 	return &BaseATNConfig{state: state, alt: alt, context: context, semanticContext: semanticContext}
 }
 
@@ -108,15 +108,15 @@ func NewBaseATNConfig(c ATNConfig, state ATNState, context PredictionContext, se
 	if semanticContext == nil {
 		panic("semanticContext cannot be nil") // TODO: Remove this - probably put here for some bug that is now fixed
 	}
-
+	
 	b := &BaseATNConfig{}
 	b.InitBaseATNConfig(c, state, c.GetAlt(), context, semanticContext)
-
+	
 	return b
 }
 
 func (b *BaseATNConfig) InitBaseATNConfig(c ATNConfig, state ATNState, alt int, context PredictionContext, semanticContext SemanticContext) {
-
+	
 	b.state = state
 	b.alt = alt
 	b.context = context
@@ -179,28 +179,28 @@ func (b *BaseATNConfig) Equals(o Collectable[ATNConfig]) bool {
 	} else if o == nil {
 		return false
 	}
-
+	
 	var other, ok = o.(*BaseATNConfig)
-
+	
 	if !ok {
 		return false
 	}
-
+	
 	var equal bool
-
+	
 	if b.context == nil {
 		equal = other.context == nil
 	} else {
 		equal = b.context.Equals(other.context)
 	}
-
+	
 	var (
 		nums = b.state.GetStateNumber() == other.state.GetStateNumber()
 		alts = b.alt == other.alt
 		cons = b.semanticContext.Equals(other.semanticContext)
 		sups = b.precedenceFilterSuppressed == other.precedenceFilterSuppressed
 	)
-
+	
 	return nums && alts && cons && sups && equal
 }
 
@@ -211,7 +211,7 @@ func (b *BaseATNConfig) Hash() int {
 	if b.context != nil {
 		c = b.context.Hash()
 	}
-
+	
 	h := murmurInit(7)
 	h = murmurUpdate(h, b.state.GetStateNumber())
 	h = murmurUpdate(h, b.alt)
@@ -223,19 +223,19 @@ func (b *BaseATNConfig) Hash() int {
 // String returns a string representation of the BaseATNConfig, usually used for debugging purposes
 func (b *BaseATNConfig) String() string {
 	var s1, s2, s3 string
-
+	
 	if b.context != nil {
 		s1 = ",[" + fmt.Sprint(b.context) + "]"
 	}
-
+	
 	if b.semanticContext != SemanticContextNone {
 		s2 = "," + fmt.Sprint(b.semanticContext)
 	}
-
+	
 	if b.reachesIntoOuterContext > 0 {
 		s3 = ",up=" + fmt.Sprint(b.reachesIntoOuterContext)
 	}
-
+	
 	return fmt.Sprintf("(%v,%v%v%v%v)", b.state, b.alt, s1, s2, s3)
 }
 
@@ -249,7 +249,7 @@ type LexerATNConfig struct {
 }
 
 func NewLexerATNConfig6(state ATNState, alt int, context PredictionContext) *LexerATNConfig {
-
+	
 	return &LexerATNConfig{
 		BaseATNConfig: BaseATNConfig{
 			state:           state,
@@ -274,7 +274,7 @@ func NewLexerATNConfig5(state ATNState, alt int, context PredictionContext, lexe
 
 func NewLexerATNConfig4(c *LexerATNConfig, state ATNState) *LexerATNConfig {
 	lac := &LexerATNConfig{
-
+		
 		lexerActionExecutor:            c.lexerActionExecutor,
 		passedThroughNonGreedyDecision: checkNonGreedyDecision(c, state),
 	}
@@ -340,32 +340,27 @@ func (l *LexerATNConfig) Equals(other Collectable[ATNConfig]) bool {
 		return true
 	}
 	var otherT, ok = other.(*LexerATNConfig)
-
-	if l == other {
-		return true
-	} else if !ok {
+	if !ok {
 		return false
 	} else if l.passedThroughNonGreedyDecision != otherT.passedThroughNonGreedyDecision {
 		return false
 	}
-
-	var b bool
-
-	if l.lexerActionExecutor != nil {
-		b = !l.lexerActionExecutor.Equals(otherT.lexerActionExecutor)
-	} else {
-		b = otherT.lexerActionExecutor != nil
+
+	switch {
+	case l.lexerActionExecutor == nil && otherT.lexerActionExecutor == nil:
+	case l.lexerActionExecutor != nil && otherT.lexerActionExecutor != nil:
+		if !l.lexerActionExecutor.Equals(otherT.lexerActionExecutor) {
+			return false
+		}
+	default:
+		return false // One but not both, are nil
 	}
-
-	if b {
-		return false
-	}
-
+
 	return l.BaseATNConfig.Equals(&otherT.BaseATNConfig)
 }
 
 func checkNonGreedyDecision(source *LexerATNConfig, target ATNState) bool {
 	var ds, ok = target.(DecisionState)
-
+	
 	return source.passedThroughNonGreedyDecision || (ok && ds.getNonGreedy())
 }