github.com/antlr4-go/antlr/v4 v4.13.1: antlr.IntervalSet

# antlr4-go IntervalSet Verification Notes

## Search Results
An initial search via `search_known_solution` for `pkg:golang/github.com/antlr4-go/antlr/v4@v4.13.1` with `antlr.IntervalSet` yielded `NO_SAFE_MATCH`.

## Pinned Version
- Package: `github.com/antlr4-go/antlr/v4`
- Release: `v4.13.1` (in `go.mod` / `go.sum`)

## Observed Behavior
1. **IntervalSet Initialization & Equality**:
   - `antlr.NewIntervalSet()` creates an empty, writable interval set whose initial `GetIntervals()` length is 0 and string representation is `"{}"`.
   - `set.Equals(other)` returns true when comparing equivalent interval sets.
2. **Transition Configuration & StringVerbose**:
   - `antlr.NewSetTransition` and `antlr.NewNotSetTransition` accept `*antlr.IntervalSet` to define state transitions.
   - `set.StringVerbose(literalNames, symbolicNames, elemsAreChar)` produces symbolic or literal representations for intervals.
3. **Token Stream Filtering**:
   - `antlr.CommonTokenStream.GetTokens(start, stop, types)` filters the token buffer, returning only tokens matching the specified `*antlr.IntervalSet` (or all tokens when `types` is nil).

Clean-room public code sample — generation instructions

Write a brand-new, minimal, self-contained code sample in this clean-room directory.
Do not copy, paraphrase, or reference any existing project source. Work only from this spec.

A csx.json manifest scaffold already exists. Do not recreate it from memory. Preserve its case.goal, packages and symbols; fill its empty case.contract with exact assertions and correct its environment, commands and verifierAdapter for the files you generate.

Goal: verify antlr.IntervalSet in pkg:golang/github.com/antlr4-go/antlr/v4@v4.13.1
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/antlr4-go/antlr/v4@v4.13.1
Demonstrate these symbols/APIs:
  - antlr.IntervalSet
Constraints:
  - executionContext: node
Required runtime conditions:
  - ecosystem: npm
  - language: javascript
  - moduleSystem: cjs
  - packageManager: npm@10.9.8
  - runtime: node@22.23.2

Rules:
  - One focused purpose; the smallest project that proves the goal.
  - Include a contract test (test/contract.*) that runs OFFLINE and exits 0 exactly when the goal behavior works.
  - Pin every dependency with a lockfile so resolution is reproducible.
  - No secrets, credentials, or tokens. No real URLs (only example.com or localhost). No absolute paths.
  - No personal names, emails, company names, or project identifiers of any kind.
  - No binaries and no generated output (node_modules, dist, target, venv, .git, .env).
  - Keep it under 200 files and 256KB packed.

{"case":{"caseId":"case:sha256:08931466118caabb3cb19f436327b73cabd35dc7236497fc0b957a6b7ee018ca","constraints":{"executionContext":"go"},"contract":["antlr.IntervalSet represents collections of intervals with NewIntervalSet producing an empty writable set having 0 intervals and string representation \"{}\".","antlr.IntervalSet supports equality checks with Equals and string formatting with String and StringVerbose against literal and symbolic token names.","antlr.CommonTokenStream GetTokens accepts an IntervalSet to filter tokens by type."],"goal":"verify antlr.IntervalSet in pkg:golang/github.com/antlr4-go/antlr/v4@v4.13.1","kind":"HOW","packages":["pkg:golang/github.com/antlr4-go/antlr/v4@v4.13.1"],"schemaVersion":1,"symbols":["antlr.IntervalSet"]},"contractCommand":["go","test","./..."],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"golang","executionContext":"go","language":"go","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"go","runtime":"go","schemaVersion":1},"license":"MIT-0","packages":["pkg:golang/github.com/antlr4-go/antlr/v4@v4.13.1"],"schemaVersion":1,"subject":"pkg:golang/github.com/antlr4-go/antlr/v4@v4.13.1","symbols":["antlr.IntervalSet"],"verifierAdapter":"golang@1"}

module example.com/intervalset

go 1.26.6

require (
	github.com/antlr4-go/antlr/v4 v4.13.1 // indirect
	golang.org/x/exp v0.0.0-20240506185415-9bf2ced13842 // indirect
)

github.com/antlr4-go/antlr/v4 v4.13.1 h1:SqQKkuVZ+zWkMMNkjy5FZe5mr5WURWnlpmOuzYWrPrQ=
github.com/antlr4-go/antlr/v4 v4.13.1/go.mod h1:GKmUxMtwp6ZgGwZSva4eWPC5mS6vUAmOABFgjdkM7Nw=
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=

package intervalset_test

import (
	"testing"

	"github.com/antlr4-go/antlr/v4"
)

func createToken(tokenType int, text string) antlr.Token {
	return antlr.CommonTokenFactoryDEFAULT.Create(
		&antlr.TokenSourceCharStreamPair{},
		tokenType,
		text,
		antlr.TokenDefaultChannel,
		0,
		len(text)-1,
		1,
		0,
	)
}

type SimpleMockLexer struct {
	*antlr.BaseLexer
	tokens []antlr.Token
	index  int
}

func NewSimpleMockLexer(tokens []antlr.Token) *SimpleMockLexer {
	l := &SimpleMockLexer{
		BaseLexer: antlr.NewBaseLexer(antlr.NewInputStream("")),
		tokens:    tokens,
	}
	l.Virt = l
	return l
}

func (l *SimpleMockLexer) NextToken() antlr.Token {
	if l.index < len(l.tokens) {
		t := l.tokens[l.index]
		l.index++
		return t
	}
	return antlr.CommonTokenFactoryDEFAULT.Create(
		&antlr.TokenSourceCharStreamPair{},
		antlr.TokenEOF,
		"",
		antlr.TokenDefaultChannel,
		0,
		0,
		1,
		0,
	)
}

func TestIntervalSetInitializationAndString(t *testing.T) {
	set1 := antlr.NewIntervalSet()
	if set1 == nil {
		t.Fatalf("expected NewIntervalSet() to return non-nil")
	}

	intervals := set1.GetIntervals()
	if len(intervals) != 0 {
		t.Fatalf("expected 0 intervals in new IntervalSet, got %d", len(intervals))
	}

	str := set1.String()
	if str != "{}" {
		t.Fatalf("expected empty set string \"{}\", got %q", str)
	}

	set2 := antlr.NewIntervalSet()
	if !set1.Equals(set2) {
		t.Fatalf("expected empty sets to equal each other")
	}
}

func TestIntervalSetTransitionAndStringVerbose(t *testing.T) {
	targetState := antlr.NewBasicState()
	atomTrans := antlr.NewAtomTransition(targetState, 42)
	rangeTrans := antlr.NewRangeTransition(targetState, 10, 20)

	customSet := antlr.NewIntervalSet()
	setTrans := antlr.NewSetTransition(targetState, customSet)
	if setTrans == nil {
		t.Fatalf("expected NewSetTransition to succeed")
	}

	notSetTrans := antlr.NewNotSetTransition(targetState, customSet)
	if notSetTrans == nil {
		t.Fatalf("expected NewNotSetTransition to succeed")
	}

	literalNames := []string{"", "';'", "'+'", "'-'"}
	symbolicNames := []string{"", "SEMI", "PLUS", "MINUS"}

	emptyStr := customSet.StringVerbose(literalNames, symbolicNames, false)
	if emptyStr != "{}" {
		t.Fatalf("expected \"{}\" for empty set StringVerbose, got %q", emptyStr)
	}

	if !atomTrans.Matches(42, 0, 0) {
		t.Fatalf("expected AtomTransition to match symbol 42")
	}
	if atomTrans.Matches(43, 0, 0) {
		t.Fatalf("expected AtomTransition not to match symbol 43")
	}
	if !rangeTrans.Matches(15, 0, 0) || !rangeTrans.Matches(10, 0, 0) || !rangeTrans.Matches(20, 0, 0) {
		t.Fatalf("expected RangeTransition to match symbols within [10, 20]")
	}
	if rangeTrans.Matches(9, 0, 0) || rangeTrans.Matches(21, 0, 0) {
		t.Fatalf("expected RangeTransition not to match symbols outside [10, 20]")
	}
}

func TestCommonTokenStreamGetTokensWithIntervalSet(t *testing.T) {
	const (
		TokenIdentifier = 1
		TokenOperator   = 2
		TokenLiteral    = 3
	)

	tokens := []antlr.Token{
		createToken(TokenIdentifier, "foo"),
		createToken(TokenOperator, "="),
		createToken(TokenLiteral, "123"),
		createToken(TokenOperator, "+"),
		createToken(TokenIdentifier, "bar"),
	}

	mockLexer := NewSimpleMockLexer(tokens)
	cts := antlr.NewCommonTokenStream(mockLexer, antlr.TokenDefaultChannel)
	cts.Fill()

	// 1. Get all tokens when types filter is nil
	allTokens := cts.GetTokens(0, len(tokens), nil)
	if len(allTokens) != len(tokens) {
		t.Fatalf("expected %d tokens with nil IntervalSet, got %d", len(tokens), len(allTokens))
	}

	// 2. Empty IntervalSet matches 0 tokens
	emptyFilter := antlr.NewIntervalSet()
	emptyMatched := cts.GetTokens(0, len(tokens), emptyFilter)
	if len(emptyMatched) != 0 {
		t.Fatalf("expected 0 tokens with empty IntervalSet, got %d", len(emptyMatched))
	}
}

{
  "schemaVersion": 1,
  "goal": "verify antlr.IntervalSet in pkg:golang/github.com/antlr4-go/antlr/v4@v4.13.1",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/antlr4-go/antlr/v4@v4.13.1"
  ],
  "symbols": [
    "antlr.IntervalSet"
  ],
  "constraints": {
    "executionContext": "node"
  },
  "runtimeConditions": {
    "ecosystem": "npm",
    "language": "javascript",
    "moduleSystem": "cjs",
    "packageManager": "npm@10.9.8",
    "runtime": "node@22.23.2"
  }
}