lexer: add re-quote helper

lexer/lexer.go

@@ -2,12 +2,17 @@ package lexer
 
 import (
 	"fmt"
+	"strings"
 )
 
 func isWhitespace(r byte) bool {
 	return (r == ' ' || r == '\t' || r == '\r' || r == '\n')
 }
 
+func Quote(input string) string {
+	return `"` + strings.ReplaceAll(strings.ReplaceAll(input, `\`, `\\`), `"`, `\"`) + `"`
+}
+
 // Fields splits a string into separate tokens using something kind of vaguely
 // like how SQL would do it.
 // The result still includes the quote and backslash characters.