feat: Update go version.

Note: I know some people have asked noot to depend on the sort.Slices, which is still flagged as
experimental.  However, it won't be one day it is well implemented. It is only used in one
place in the runtime and two places in an optional build tag antlr.statistics, I advise
users to make a fork if the really need to remove sort.Slice.

Signed-off-by: Jim.Idle <jimi@idle.ws>

antlrdoc.go

@@ -17,9 +17,9 @@ ANTLR4 that it is compatible with (I.E. uses the /v4 path).
 However, this was found to be problematic, as it meant that with the runtime embedded so far underneath the root
 of the repo, the `go get` and related commands could not properly resolve the location of the go runtime source code.
 This meant that the reference to the runtime in your `go.mod` file would refer to the correct source code, but would not
-list the release tag such as @4.12.0 - this was confusing, to say the least.
+list the release tag such as @4.13.1 - this was confusing, to say the least.
 
-As of 4.12.1, the runtime is now available as a go module in its own repo, and can be imported as `github.com/antlr4-go/antlr`
+As of 4.13.0, the runtime is now available as a go module in its own repo, and can be imported as `github.com/antlr4-go/antlr`
 (the go get command should also be used with this path). See the main documentation for the ANTLR4 project for more information,
 which is available at [ANTLR docs]. The documentation for using the Go runtime is available at [Go runtime docs].
 
@@ -49,7 +49,7 @@ Here is a general/recommended template for an ANTLR based recognizer in Go:
 	.
 	├── parser
 	│     ├── mygrammar.g4
-	│     ├── antlr-4.12.1-complete.jar
+	│     ├── antlr-4.13.1-complete.jar
 	│     ├── generate.go
 	│     └── generate.sh
 	├── parsing   - generated code goes here
@@ -71,7 +71,7 @@ And the generate.sh file will look similar to this:
 
 	#!/bin/sh
 
-	alias antlr4='java -Xmx500M -cp "./antlr4-4.12.1-complete.jar:$CLASSPATH" org.antlr.v4.Tool'
+	alias antlr4='java -Xmx500M -cp "./antlr4-4.13.1-complete.jar:$CLASSPATH" org.antlr.v4.Tool'
 	antlr4 -Dlanguage=Go -no-visitor -package parsing *.g4
 
 depending on whether you want visitors or listeners or any other ANTLR options. Not that another option here

atn.go

@@ -4,8 +4,6 @@
 
 package antlr
 
-import "sync"
-
 // ATNInvalidAltNumber is used to represent an ALT number that has yet to be calculated or
 // which is invalid for a particular struct such as [*antlr.BaseRuleContext]
 var ATNInvalidAltNumber int
@@ -56,9 +54,9 @@ type ATN struct {
 	//
 	states []ATNState
 
-	mu      sync.Mutex
-	stateMu sync.RWMutex
-	edgeMu  sync.RWMutex
+	mu      Mutex
+	stateMu RWMutex
+	edgeMu  RWMutex
 }
 
 // NewATN returns a new ATN struct representing the given grammarType and is used

atn_config.go

@@ -73,9 +73,6 @@ func NewATNConfig1(c *ATNConfig, state ATNState, context *PredictionContext) *AT
 // NewATNConfig creates a new ATNConfig instance given an existing config, a state, a context and a semantic context, other 'constructors'
 // are just wrappers around this one.
 func NewATNConfig(c *ATNConfig, state ATNState, context *PredictionContext, semanticContext SemanticContext) *ATNConfig {
-	if semanticContext == nil {
-		panic("semanticContext cannot be nil") // TODO: Remove this - probably put here for some bug that is now fixed
-	}
 	b := &ATNConfig{}
 	b.InitATNConfig(c, state, c.GetAlt(), context, semanticContext)
 	b.cType = parserConfig

go.mod

@@ -1,5 +1,5 @@
 module github.com/antlr4-go/antlr/v4
 
-go 1.20
+go 1.22
 
-require golang.org/x/exp v0.0.0-20230515195305-f3d0a9c9a5cc
+require golang.org/x/exp v0.0.0-20240506185415-9bf2ced13842

go.sum

@@ -1,4 +1,2 @@
-golang.org/x/exp v0.0.0-20220722155223-a9213eeb770e h1:+WEEuIdZHnUeJJmEUjyYC2gfUMj69yZXw17EnHg/otA=
-golang.org/x/exp v0.0.0-20220722155223-a9213eeb770e/go.mod h1:Kr81I6Kryrl9sr8s2FK3vxD90NdsKWRuOIl2O4CvYbA=
-golang.org/x/exp v0.0.0-20230515195305-f3d0a9c9a5cc h1:mCRnTeVUjcrhlRmO0VK8a6k6Rrf6TF9htwo2pJVSjIU=
-golang.org/x/exp v0.0.0-20230515195305-f3d0a9c9a5cc/go.mod h1:V1LtkGg67GoY2N1AnLN78QLrzxkLyJw7RJb1gzOOz9w=
+golang.org/x/exp v0.0.0-20240506185415-9bf2ced13842 h1:vr/HnozRka3pE4EsMEg1lgkXJkTFJCVUX+S/ZT6wYzM=
+golang.org/x/exp v0.0.0-20240506185415-9bf2ced13842/go.mod h1:XtvwrStGgqGPLc4cjQfWqZHG1YFdYs6swckp8vpsjnc=

input_stream.go

@@ -148,7 +148,7 @@ func (is *InputStream) GetTextFromInterval(i Interval) string {
 }
 
 func (*InputStream) GetSourceName() string {
-	return ""
+	return "Obtained from string"
 }
 
 // String returns the entire input stream as a string

jcollect.go

@@ -8,7 +8,6 @@ import (
 	"container/list"
 	"runtime/debug"
 	"sort"
-	"sync"
 )
 
 // Collectable is an interface that a struct should implement if it is to be
@@ -587,12 +586,12 @@ type VisitRecord struct {
 
 type VisitList struct {
 	cache *list.List
-	lock  sync.RWMutex
+	lock  RWMutex
 }
 
 var visitListPool = VisitList{
 	cache: list.New(),
-	lock:  sync.RWMutex{},
+	lock:  RWMutex{},
 }
 
 // NewVisitRecord returns a new VisitRecord instance from the pool if available.

lexer.go

@@ -207,7 +207,7 @@ func (b *BaseLexer) NextToken() Token {
 		for {
 			b.thetype = TokenInvalidType
 
-			ttype := b.safeMatch()
+			ttype := b.safeMatch() // Defaults to LexerSkip
 
 			if b.input.LA(1) == TokenEOF {
 				b.hitEOF = true

ll1_analyzer.go

@@ -40,6 +40,7 @@ func (la *LL1Analyzer) getDecisionLookahead(s ATNState) []*IntervalSet {
 	for alt := 0; alt < count; alt++ {
 
 		look[alt] = NewIntervalSet()
+		// TODO: This is one of the reasons that ATNConfigs are allocated and freed all the time - fix this tomorrow jim!
 		lookBusy := NewJStore[*ATNConfig, Comparator[*ATNConfig]](aConfEqInst, ClosureBusyCollection, "LL1Analyzer.getDecisionLookahead for lookBusy")
 		la.look1(s.GetTransitions()[alt].getTarget(), nil, BasePredictionContextEMPTY, look[alt], lookBusy, NewBitSet(), false, false)
 

mutex.go

@@ -0,0 +1,41 @@
+//go:build !antlr.nomutex
+// +build !antlr.nomutex
+
+package antlr
+
+import "sync"
+
+// Mutex is a simple mutex implementation which just delegates to sync.Mutex, it
+// is used to provide a mutex implementation for the antlr package, which users
+// can turn off with the build tag -tags antlr.nomutex
+type Mutex struct {
+	mu sync.Mutex
+}
+
+func (m *Mutex) Lock() {
+	m.mu.Lock()
+}
+
+func (m *Mutex) Unlock() {
+	m.mu.Unlock()
+}
+
+type RWMutex struct {
+	mu sync.RWMutex
+}
+
+func (m *RWMutex) Lock() {
+	m.mu.Lock()
+}
+
+func (m *RWMutex) Unlock() {
+	m.mu.Unlock()
+}
+
+func (m *RWMutex) RLock() {
+	m.mu.RLock()
+}
+
+func (m *RWMutex) RUnlock() {
+	m.mu.RUnlock()
+}

mutex_nomutex.go

@@ -0,0 +1,32 @@
+//go:build antlr.nomutex
+// +build antlr.nomutex
+
+package antlr
+
+type Mutex struct{}
+
+func (m *Mutex) Lock() {
+	// No-op
+}
+
+func (m *Mutex) Unlock() {
+	// No-op
+}
+
+type RWMutex struct{}
+
+func (m *RWMutex) Lock() {
+	// No-op
+}
+
+func (m *RWMutex) Unlock() {
+	// No-op
+}
+
+func (m *RWMutex) RLock() {
+	// No-op
+}
+
+func (m *RWMutex) RUnlock() {
+	// No-op
+}

parser_atn_simulator.go

@@ -10,8 +10,6 @@ import (
 	"strings"
 )
 
-var ()
-
 // ClosureBusy is a store of ATNConfigs and is a tiny abstraction layer over
 // a standard JStore so that we can use Lazy instantiation of the JStore, mostly
 // to avoid polluting the stats module with a ton of JStore instances with nothing in them.
@@ -883,7 +881,7 @@ func (p *ParserATNSimulator) getPredicatePredictions(ambigAlts *BitSet, altToPre
 // the ERROR state was reached, outerContext as the initial parser context from the paper
 // or the parser stack at the instant before prediction commences.
 //
-// Teh func returns the value to return from [AdaptivePredict], or
+// The func returns the value to return from [AdaptivePredict], or
 // [ATNInvalidAltNumber] if a suitable alternative was not
 // identified and [AdaptivePredict] should report an error instead.
 func (p *ParserATNSimulator) getSynValidOrSemInvalidAltThatFinishedDecisionEntryRule(configs *ATNConfigSet, outerContext ParserRuleContext) int {