feat: Add R support (#332)

Updates #1

Signed-off-by: Ian Lewis <ianlewis@google.com>

CHANGELOG.md

@@ -9,7 +9,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
-- Support for Erlang, SQL, and Haskell programming languages has been added.
+- Support for Erlang, Haskell, R, and SQL programming languages has been added.
 
 ## [0.4.0] - 2023-08-23
 

internal/scanner/config.go

@@ -214,6 +214,17 @@ var (
 		escapeFunc: backslashEscape,
 	}
 
+	// RConfig is a config for R.
+	RConfig = Config{
+		LineCommentStart: []string{"#"},
+		// NOTE: R has no multi-line comments.
+		Strings: [][2]string{
+			{"\"", "\""},
+			{"'", "'"},
+		},
+		escapeFunc: backslashEscape,
+	}
+
 	// RubyConfig is a config for Ruby.
 	RubyConfig = Config{
 		LineCommentStart:      []string{"#"},

internal/scanner/scanner_test.go

@@ -720,6 +720,83 @@ var scannerTestCases = []*struct {
 		},
 	},
 
+	// R
+	{
+		name: "line_comments.r",
+		src: `# file comment
+
+			# TODO is a function
+			TODO <- function() {
+				print("Hello World") # Random comment
+			`,
+		config: RConfig,
+		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.r",
+		src: `# file comment
+
+			# TODO is a function
+			TODO <- function() {
+				print("# Random comment")
+				print('# Random comment')
+			`,
+		config: RConfig,
+		comments: []struct {
+			text string
+			line int
+		}{
+			{
+				text: "# file comment",
+				line: 1,
+			},
+			{
+				text: "# TODO is a function",
+				line: 3,
+			},
+		},
+	},
+	{
+		name: "escaped_string.r",
+		src: `# file comment
+
+			# TODO is a function
+			TODO <- function() {
+				print("\"# Random comment")
+				print('\'# Random comment')
+			`,
+		config: RConfig,
+		comments: []struct {
+			text string
+			line int
+		}{
+			{
+				text: "# file comment",
+				line: 1,
+			},
+			{
+				text: "# TODO is a function",
+				line: 3,
+			},
+		},
+	},
+
 	// Ruby
 	{
 		name: "raw_string.rb",