feat: Add support for Lua

internal/scanner/config.go

@@ -36,6 +36,7 @@ var (
 		"JavaScript":   &JavascriptConfig,
 		// NOTE: Some JSON files support JS comments (e.g. tsconfig.json)
 		"JSON":        &JavascriptConfig,
+		"Lua":         &LuaConfig,
 		"Makefile":    &MakefileConfig,
 		"Objective-C": &ObjectiveCConfig,
 		"Perl":        &PerlConfig,
@@ -111,6 +112,17 @@ var (
 		},
 	}
 
+	// LuaConfig is a config for Lua.
+	LuaConfig = Config{
+		LineCommentStart:      []string{"--"},
+		MultilineCommentStart: "--[[",
+		MultilineCommentEnd:   "--]]",
+		Strings: [][2]string{
+			{"\"", "\""},
+			{"'", "'"}, // character
+		},
+	}
+
 	// MakefileConfig is a config for Makefiles.
 	MakefileConfig = ShellConfig
 

internal/scanner/scanner.go

@@ -214,29 +214,28 @@ func (s *CommentScanner) Scan() bool {
 func (s *CommentScanner) processCode(st *stateCode) (state, error) {
 	for {
 		// Check for line comment
-		for _, start := range s.config.LineCommentStart {
-			eq, err := s.peekEqual(start)
-			if err != nil {
-				return st, err
-			}
-			if eq {
+		m, err := s.lineMatch()
+		if err != nil {
+			return st, err
+		}
+
+		mm, err := s.multiLineMatch()
+		if err != nil {
+			return st, err
+		}
+
+		if len(m) > 0 || len(mm) > 0 {
+			if len(m) >= len(mm) {
 				return &stateLineComment{}, nil
 			}
-		}
 
-		// Check for line comment
-		if len(s.config.MultilineCommentStart) != 0 {
-			if eq, err := s.peekEqual(s.config.MultilineCommentStart); err == nil && eq {
-				// Discard the opening. It will be added by processMultilineComment.
-				if _, errDiscard := s.reader.Discard(len(s.config.MultilineCommentStart)); errDiscard != nil {
-					return st, errDiscard
-				}
-				return &stateMultilineComment{
-					line: s.line,
-				}, nil
-			} else if err != nil {
-				return st, err
+			// Discard the opening. It will be added by processMultilineComment.
+			if _, errDiscard := s.reader.Discard(len(s.config.MultilineCommentStart)); errDiscard != nil {
+				return st, errDiscard
 			}
+			return &stateMultilineComment{
+				line: s.line,
+			}, nil
 		}
 
 		// Check for string
@@ -263,6 +262,32 @@ func (s *CommentScanner) processCode(st *stateCode) (state, error) {
 	}
 }
 
+func (s *CommentScanner) lineMatch() ([]rune, error) {
+	// Check for line comment
+	for _, start := range s.config.LineCommentStart {
+		eq, err := s.peekEqual(start)
+		if err != nil {
+			return nil, err
+		}
+		if eq {
+			return start, nil
+		}
+	}
+	return nil, nil
+}
+
+func (s *CommentScanner) multiLineMatch() ([]rune, error) {
+	// Check for line comment
+	if len(s.config.MultilineCommentStart) != 0 {
+		if eq, err := s.peekEqual(s.config.MultilineCommentStart); err == nil && eq {
+			return s.config.MultilineCommentStart, nil
+		} else if err != nil {
+			return nil, err
+		}
+	}
+	return nil, nil
+}
+
 // processString processes strings and returns the next state.
 func (s *CommentScanner) processString(st *stateString) (state, error) {
 	for {

internal/scanner/scanner_test.go

@@ -36,6 +36,7 @@ var scannerTestCases = []*struct {
 		line int
 	}
 }{
+	// Go
 	{
 		name: "line_comments.go",
 		src: `package foo
@@ -64,33 +65,6 @@ var scannerTestCases = []*struct {
 			},
 		},
 	},
-	{
-		name: "line_comments.php",
-		src: `// file comment
-
-			# TODO is a function.
-			function TODO() {
-				return // Random comment
-			}`,
-		config: PHPConfig,
-		comments: []struct {
-			text string
-			line int
-		}{
-			{
-				text: "// file comment",
-				line: 1,
-			},
-			{
-				text: "# TODO is a function.",
-				line: 3,
-			},
-			{
-				text: "// Random comment",
-				line: 5,
-			},
-		},
-	},
 	{
 		name: "comments_in_string.go",
 		src: `package foo
@@ -208,35 +182,150 @@ var scannerTestCases = []*struct {
 			},
 		},
 	},
+
+	// PHP
 	{
-		name: "raw_string.rb",
-		src: `# file comment
+		name: "line_comments.php",
+		src: `// file comment
 
-			z = %{
 			# TODO is a function.
-			}
+			function TODO() {
+				return // Random comment
+			}`,
+		config: PHPConfig,
+		comments: []struct {
+			text string
+			line int
+		}{
+			{
+				text: "// file comment",
+				line: 1,
+			},
+			{
+				text: "# TODO is a function.",
+				line: 3,
+			},
+			{
+				text: "// Random comment",
+				line: 5,
+			},
+		},
+	},
 
-			def foo()
-				# Random comment
-				x = "\"# Random comment x"
-				y = '\'# Random comment y'
+	// Lua
+	{
+		name: "line_comments.lua",
+		src: `-- package comment
+
+			-- TODO is a function.
+			function TODO() {
+				return -- Random comment
+			}`,
+		config: LuaConfig,
+		comments: []struct {
+			text string
+			line int
+		}{
+			{
+				text: "-- package comment",
+				line: 1,
+			},
+			{
+				text: "-- TODO is a function.",
+				line: 3,
+			},
+			{
+				text: "-- Random comment",
+				line: 5,
+			},
+		},
+	},
+	{
+		name: "comments_in_string.lua",
+		src: `-- package comment
+
+			-- TODO is a function.
+			func TODO() {
+				x = "-- Random comment"
+				y = '-- Random comment'
 				return x + y
-			end`,
-		config: RubyConfig,
+			}`,
+		config: LuaConfig,
 		comments: []struct {
 			text string
 			line int
 		}{
 			{
-				text: "# file comment",
+				text: "-- package comment",
 				line: 1,
 			},
 			{
-				text: "# Random comment",
-				line: 8,
+				text: "-- TODO is a function.",
+				line: 3,
+			},
+		},
+	},
+	{
+		name: "escaped_string.lua",
+		src: `-- package comment
+
+			-- TODO is a function.
+			func TODO() {
+				x = "\"-- Random comment"
+				y = '\'-- Random comment'
+				return x + y
+			}`,
+		config: LuaConfig,
+		comments: []struct {
+			text string
+			line int
+		}{
+			{
+				text: "-- package comment",
+				line: 1,
+			},
+			{
+				text: "-- TODO is a function.",
+				line: 3,
+			},
+		},
+	},
+	{
+		name: "multi_line.lua",
+		src: `-- package comment
+
+			--[[
+			TODO is a function.
+			--]]
+			func TODO() {
+				return -- Random comment
+			}
+			--[[ extra comment --]]`,
+		config: LuaConfig,
+		comments: []struct {
+			text string
+			line int
+		}{
+			{
+				text: "-- package comment",
+				line: 1,
+			},
+			{
+				text: "--[[\n\t\t\tTODO is a function.\n\t\t\t--]]",
+				line: 3,
+			},
+			{
+				text: "-- Random comment",
+				line: 7,
+			},
+			{
+				text: "--[[ extra comment --]]",
+				line: 9,
 			},
 		},
 	},
+
+	// Python
 	{
 		name: "raw_string.py",
 		src: `# file comment
@@ -295,6 +384,39 @@ var scannerTestCases = []*struct {
 			},
 		},
 	},
+
+	// Ruby
+	{
+		name: "raw_string.rb",
+		src: `# file comment
+
+			z = %{
+			# TODO is a function.
+			}
+
+			def foo()
+				# Random comment
+				x = "\"# Random comment x"
+				y = '\'# Random comment y'
+				return x + y
+			end`,
+		config: RubyConfig,
+		comments: []struct {
+			text string
+			line int
+		}{
+			{
+				text: "# file comment",
+				line: 1,
+			},
+			{
+				text: "# Random comment",
+				line: 8,
+			},
+		},
+	},
+
+	// Shell
 	{
 		name: "line_comments.sh",
 		src: `#!/bin/bash