Fix FindReaderIndex channel handling, doc example, filename typos; Go 1.24

go.mod

@@ -1,3 +1,3 @@
 module github.com/vertoforce/streamregex
 
-go 1.12
+go 1.24

streamregexdoc_test.go

@@ -43,5 +43,5 @@ func ExampleFindReaderIndex() {
 		fmt.Println(match, index)
 	}
 
-	// Output: stream    of
+	// Output: stream    of [20 32]
 }

steamregexindex.go → streamregexindex.go

@@ -36,16 +36,23 @@ func SplitRegexIndex(re *regexp.Regexp, maxMatchLength int, indexChannel chan []
 	}
 }
 
-// FindReaderIndex returns a channel of matched []byte from the reader and a channel of the locations at wich the matches where found
-// This function will allocate maxMatchLength*2 bytes of memory
+// FindReaderIndex returns a channel of matched strings from the reader and a channel of the locations
+// ([start, end] byte offsets) at which the matches were found.
+// This function will allocate maxMatchLength*2 bytes of memory.
+//
+// Both channels are closed once scanning finishes. The caller MUST drain both channels
+// (read every match and its corresponding index); each match sends its index before the
+// match itself, so reading matches without also reading indexes will deadlock the scanner.
+// Canceling ctx stops scanning after the current match.
 func FindReaderIndex(ctx context.Context, r *regexp.Regexp, maxMatchLength int, reader io.Reader) (chan string, chan []int) {
 	allMatches := make(chan string)
-	allIndexes := make(chan []int, 1) // Avoid deadlock because if location is not read it blocks SplitRegexIndex from returning the match
+	allIndexes := make(chan []int, 1) // Buffered so SplitRegexIndex can send the index and still return the match before the consumer reads the index
 
 	buf := make([]byte, maxMatchLength*2)
 
 	go func() {
 		defer close(allMatches)
+		defer close(allIndexes)
 
 		scanner := bufio.NewScanner(reader)
 		scanner.Buffer(buf, maxMatchLength)