Fix working with non-ascii symbols.

checks.go

@@ -77,9 +77,9 @@ func checkCommentForPeriod(c comment) *Issue {
 	// Make a replacement. Use `pos.line` to get an original line from
 	// attached lines. Use `iss.Pos.Column` because it's a position in
 	// the original line.
-	original := []rune(c.lines[pos.line-1])
-	iss.Replacement = string(original[:iss.Pos.Column-1]) + "." +
-		string(original[iss.Pos.Column-1:])
+	original := c.lines[pos.line-1]
+	iss.Replacement = original[:iss.Pos.Column-1] + "." +
+		original[iss.Pos.Column-1:]
 
 	// Save replacement to raw lines to be able to combine it with
 	// further replacements
@@ -118,9 +118,11 @@ func checkCommentForCapital(c comment) []Issue {
 		// Make a replacement. Use `pos.line` to get an original line from
 		// attached lines. Use `iss.Pos.Column` because it's a position in
 		// the original line.
-		rep := []rune(c.lines[pos.line-1])
-		rep[iss.Pos.Column-1] = unicode.ToTitle(rep[iss.Pos.Column-1])
-		iss.Replacement = string(rep)
+		line := c.lines[pos.line-1]
+		col := byteToRuneColumn(line, iss.Pos.Column) - 1
+		rep := string(unicode.ToTitle([]rune(line)[col])) // capital letter
+		iss.Replacement = line[:iss.Pos.Column-1] + rep +
+			line[iss.Pos.Column-1+len(rep):]
 
 		// Save replacement to raw lines to be able to combine it with
 		// further replacements
@@ -158,7 +160,7 @@ func checkPeriod(comment string) (pos position, ok bool) {
 		return position{}, true
 	}
 
-	pos.column = len([]rune(line)) + 1
+	pos.column = len(line) + 1
 	return pos, false
 }
 
@@ -209,7 +211,10 @@ func checkCapital(comment string, skipFirst bool) (pp []position) {
 			continue
 		}
 		if state == endOfSentence && unicode.IsLower(r) {
-			pp = append(pp, position{line: pos.line, column: pos.column})
+			pp = append(pp, position{
+				line:   pos.line,
+				column: runeToByteColumn(comment, pos.column),
+			})
 		}
 		state = empty
 	}
@@ -267,3 +272,22 @@ func hasSuffix(s string, suffixes []string) bool {
 	}
 	return false
 }
+
+// The following two functions convert byte and rune indexes.
+//
+// Example:
+//   text:  a b c Ш e f
+//   runes: 1 2 3 4 5 6
+//   bytes: 0 1 2 3 5 6
+// The reason of the difference is that the size of "Ш" is 2 bytes.
+// NOTE: Works only for 1-based indexes (line columns).
+
+// byteToRuneColumn converts byte index inside the string to rune index.
+func byteToRuneColumn(s string, i int) int {
+	return len([]rune(s[:i-1])) + 1
+}
+
+// runeToByteColumn converts rune index inside the string to byte index.
+func runeToByteColumn(s string, i int) int {
+	return len(string([]rune(s)[:i-1])) + 1
+}

checks_test.go

@@ -82,7 +82,7 @@ func TestCheckPeriod(t *testing.T) {
 		{
 			name:  "cyrillic, without period",
 			text:  "Кириллица",
-			issue: position{line: 1, column: 10},
+			issue: position{line: 1, column: 19},
 		},
 		{
 			name: "parenthesis, with period",
@@ -169,7 +169,7 @@ func TestCheckCapital(t *testing.T) {
 			text:      "Кириллица? кириллица!",
 			skipFirst: false,
 			issues: []position{
-				{line: 1, column: 12},
+				{line: 1, column: 21},
 			},
 		},
 		{
@@ -395,3 +395,77 @@ func TestHasSuffix(t *testing.T) {
 		})
 	}
 }
+
+func TestByteToRuneColumn(t *testing.T) {
+	testCases := []struct {
+		name  string
+		str   string
+		index int
+		out   int
+	}{
+		{
+			name:  "ascii symbols",
+			str:   "hello, world",
+			index: 5,
+			out:   5,
+		},
+		{
+			name:  "cyrillic symbols at the end",
+			str:   "hello, мир",
+			index: 5,
+			out:   5,
+		},
+		{
+			name:  "cyrillic symbols at the beginning",
+			str:   "привет, world",
+			index: 15,
+			out:   9,
+		},
+	}
+
+	for _, tt := range testCases {
+		tt := tt
+		t.Run(tt.name, func(t *testing.T) {
+			if out := byteToRuneColumn(tt.str, tt.index); out != tt.out {
+				t.Fatalf("Wrong column\n  expected: %d\n       got: %d", tt.out, out)
+			}
+		})
+	}
+}
+
+func TestRuneToByteColumn(t *testing.T) {
+	testCases := []struct {
+		name  string
+		str   string
+		index int
+		out   int
+	}{
+		{
+			name:  "ascii symbols",
+			str:   "hello, world",
+			index: 5,
+			out:   5,
+		},
+		{
+			name:  "cyrillic symbols at the end",
+			str:   "hello, мир",
+			index: 5,
+			out:   5,
+		},
+		{
+			name:  "cyrillic symbols at the beginning",
+			str:   "привет, world",
+			index: 9,
+			out:   15,
+		},
+	}
+
+	for _, tt := range testCases {
+		tt := tt
+		t.Run(tt.name, func(t *testing.T) {
+			if out := runeToByteColumn(tt.str, tt.index); out != tt.out {
+				t.Fatalf("Wrong column\n  expected: %d\n       got: %d", tt.out, out)
+			}
+		})
+	}
+}

godot.go

@@ -27,8 +27,8 @@ type Issue struct {
 
 // position is a position inside a comment (might be multiline comment).
 type position struct {
-	line   int
-	column int
+	line   int // starts at 1
+	column int // starts at 1, byte count
 }
 
 // comment is an internal representation of AST comment entity with additional