fix(#27): resolve possibilities on their root path rather than first …

…subpath

grammar.go

@@ -156,7 +156,7 @@ func Parse(input []byte, grammar *Grammar, rootRulename string) ([]*Path, error)
 		if poss.End == len(input) {
 			pth := poss.Subpaths[0]
 			pth.MatchRule = rootRulename
-			outPoss = append(outPoss, pth)
+			outPoss = append(outPoss, poss)
 		}
 	}
 
@@ -764,6 +764,9 @@ func lexABNF(input []byte, path *Path) (any, error) {
 		}, nil
 	}
 
+	if len(path.Subpaths) == 1 {
+		return lexABNF(input, path.Subpaths[0])
+	}
 	panic(fmt.Sprintf("unhandlable path from %d to %d: \"%s\" ; sneek peak around \"%s\"", path.Start, path.End, input[path.Start:path.End], input[max(path.Start-10, 0):min(path.End+10, 0)]))
 }
 

grammar_test.go

@@ -41,6 +41,9 @@ var fixedAbnfAbnf []byte
 //go:embed testdata/fixed-abnf-raw.abnf
 var fixedAbnfRawAbnf []byte
 
+//go:embed testdata/aftn.abnf
+var aftnAbnf []byte
+
 //go:embed testdata/fuzz_regex_eaa469604868c87f.abnf
 var fuzzRegex_eaa469604868c87fAbnf []byte
 
@@ -109,6 +112,11 @@ var testsParseAbnf = map[string]struct {
 		Validate:  false,
 		ExpectErr: false,
 	},
+	"aftn": {
+		Input:     aftnAbnf,
+		Validate:  false,
+		ExpectErr: false,
+	},
 	"Fuzz_9de7f1cac25b4c59": {
 		// This fuzz crasher enabled detecting invalid repetition's repeat
 		// min/max values extraction.

testdata/aftn.abnf

@@ -0,0 +1,6 @@
+header = heading address originator
+heading = ("0" / "1") 3ALPHAUPPER 4DIGIT SP 1*10DIGIT
+address = CRLF ("AA" / "BB" / "CC") SP 8ALPHAUPPER CRLF
+originator = 6DIGIT SP 8ALPHAUPPER CRLF ("0" / "2")
+
+ALPHAUPPER = %x41-5a