encoding.csv: allow passing a custom delimiter to the `new_reader` function (#13910)

vlib/encoding/csv/reader.v

@@ -50,12 +50,19 @@ pub mut:
 	row_pos           int
 }
 
-// new_reader initializes a Reader with string data to parse
-pub fn new_reader(data string) &Reader {
+[params]
+pub struct ReaderConfig {
+	delimiter byte = `,`
+	comment   byte = `#`
+}
+
+// new_reader initializes a Reader with string data to parse and,
+// optionally, a custom delimiter.
+pub fn new_reader(data string, config ReaderConfig) &Reader {
 	return &Reader{
-		delimiter: `,`
-		comment: `#`
 		data: data
+		delimiter: config.delimiter
+		comment: config.comment
 	}
 }
 

vlib/encoding/csv/reader_test.v

@@ -28,6 +28,34 @@ fn test_encoding_csv_reader() {
 	assert row_count == 3
 }
 
+fn test_encoding_csv_reader_with_custom_delimiter() {
+	data := 'name|email|phone|other\njoe|joe@blow.com|0400000000|test\nsam|sam@likesham.com|0433000000|"test quoted field"\n#chris|chris@nomail.com|94444444|"commented row"\n'
+	mut csv_reader := csv.new_reader(data, delimiter: `|`)
+	mut row_count := 0
+	for {
+		row := csv_reader.read() or { break }
+		row_count++
+		if row_count == 1 {
+			assert row[0] == 'name'
+			assert row[1] == 'email'
+			assert row[2] == 'phone'
+			assert row[3] == 'other'
+		} else if row_count == 2 {
+			assert row[0] == 'joe'
+			assert row[1] == 'joe@blow.com'
+			assert row[2] == '0400000000'
+			assert row[3] == 'test'
+		} else if row_count == 3 {
+			assert row[0] == 'sam'
+			assert row[1] == 'sam@likesham.com'
+			assert row[2] == '0433000000'
+			// quoted field
+			assert row[3] == 'test quoted field'
+		}
+	}
+	assert row_count == 3
+}
+
 fn test_line_break_lf() {
 	lf_data := 'name,email\njoe,joe@blow.com\n'
 	mut csv_reader := csv.new_reader(lf_data)