Reflow long comment lines which don't end with a period

_fixtures/comments.go

@@ -3,13 +3,18 @@ package fixtures
 import "fmt"
 
 // Short prefix
-// This is a really, really long comment on a single line. We should try to break it up if possible because it's longer than 100 chars. In fact, it's so long that it should probably be on three lines instead of two. Wow, so long!!
+// This is a really, really long comment on a single line. We should try to break it up if possible because it's longer than 100 chars. In fact, it's so long that it should probably be on three lines instead of two. Wow, so long.
 // Short suffix
 //
 
 // This comment contains multiple contiguous lines which are greater than the target maximum line length.
 // The expected result is a sequence of shortened (reflown) lines without preserving the position of line breaks.
 
+// Unlike the above comment block, only the current line in this comment block has length greater than the
+// target maximum line length
+// but since the previous line doesn't end with a period, it should be reflown with this line
+// despite both the lines being shorter than the target maximum line length.
+
 // Another comment
 
 /*
@@ -28,7 +33,7 @@ func testFunc() {
 
 			// These are comments like the ones in https://github.com/segmentio/golines/issues/9
 			//
-			// Documentation: https://swagger.io/docs/specification/authentication/bearer-authentication/more/more/more/more/more
+			// Documentation: https://swagger.io/docs/specification/authentication/bearer-authentication/more/more/more/more/more.
 			//
 			// More documentation:
 			// https://swagger.io/docs/specification/authentication/bearer-authentication/more/more/more/more/more

_fixtures/comments__exp.go

@@ -5,14 +5,19 @@ import "fmt"
 // Short prefix
 // This is a really, really long comment on a single line. We should try to break it up if possible
 // because it's longer than 100 chars. In fact, it's so long that it should probably be on three
-// lines instead of two. Wow, so long!!
+// lines instead of two. Wow, so long.
 // Short suffix
 //
 
 // This comment contains multiple contiguous lines which are greater than the target maximum line
 // length. The expected result is a sequence of shortened (reflown) lines without preserving the
 // position of line breaks.
 
+// Unlike the above comment block, only the current line in this comment block has length greater
+// than the target maximum line length but since the previous line doesn't end with a period, it
+// should be reflown with this line despite both the lines being shorter than the target maximum
+// line length.
+
 // Another comment
 
 /*
@@ -33,7 +38,7 @@ func testFunc() {
 			// These are comments like the ones in https://github.com/segmentio/golines/issues/9
 			//
 			// Documentation:
-			// https://swagger.io/docs/specification/authentication/bearer-authentication/more/more/more/more/more
+			// https://swagger.io/docs/specification/authentication/bearer-authentication/more/more/more/more/more.
 			//
 			// More documentation:
 			// https://swagger.io/docs/specification/authentication/bearer-authentication/more/more/more/more/more

shortener.go

@@ -276,16 +276,25 @@ func (s *Shortener) removeAnnotations(contents []byte) []byte {
 func (s *Shortener) shortenCommentsFunc(contents []byte) []byte {
 	cleanedLines := []string{}
 	words := []string{} // all words in a contiguous sequence of long comments
+	prevLineLen := 0    // length of reflown words from previous long comment
 	prefix := ""
 	lines := strings.Split(string(contents), "\n")
+
+	shorten := func(line string) bool {
+		return s.isComment(line) && !IsAnnotation(line) && !s.isGoDirective(line)
+	}
+
+	getCurrLineWords := func(line string) ([]string, int) {
+		start := strings.Index(line, "//")
+		prefix = line[0:(start + 2)]
+		trimmedLine := strings.Trim(line[(start+2):], " ")
+		currLineWords := strings.Split(trimmedLine, " ")
+		return currLineWords, len(trimmedLine)
+	}
+
 	for _, line := range lines {
-		if s.isComment(line) && !IsAnnotation(line) &&
-			!s.isGoDirective(line) &&
-			s.lineLen(line) > s.config.MaxLen {
-			start := strings.Index(line, "//")
-			prefix = line[0:(start + 2)]
-			trimmedLine := strings.Trim(line[(start+2):], " ")
-			currLineWords := strings.Split(trimmedLine, " ")
+		if shorten(line) && prevLineLen+s.lineLen(line) > s.config.MaxLen {
+			currLineWords, _ := getCurrLineWords(line)
 			words = append(words, currLineWords...)
 		} else {
 			// Reflow the accumulated `words` before appending the unprocessed `line`.
@@ -309,18 +318,29 @@ func (s *Shortener) shortenCommentsFunc(contents []byte) []byte {
 				currLineLen += 1 + len(word)
 			}
 			if currLineLen > 0 {
-				cleanedLines = append(
-					cleanedLines,
-					fmt.Sprintf(
-						"%s %s",
-						prefix,
-						strings.Join(currLineWords, " "),
-					),
-				)
+				lastWord := currLineWords[len(currLineWords)-1]
+				if shorten(line) && !strings.HasSuffix(lastWord, ".") {
+					// The previous long line didn't end with a period, and the current
+					// line is a comment. Hence they are reflown.
+					w, l := getCurrLineWords(line)
+					prevLineLen = currLineLen + l
+					words = append(currLineWords, w...)
+					continue // skip reprocessing `line` later
+				} else {
+					cleanedLines = append(
+						cleanedLines,
+						fmt.Sprintf(
+							"%s %s",
+							prefix,
+							strings.Join(currLineWords, " "),
+						),
+					)
+				}
 			}
 			words = []string{}
 
 			cleanedLines = append(cleanedLines, line)
+			prevLineLen = 0
 		}
 	}
 	return []byte(strings.Join(cleanedLines, "\n"))