Parser: read_input so we can provide unaltered input read by a parser.

src/GenericParser/Parser.purs

@@ -1,5 +1,5 @@
 module GenericParser.Parser where
-import Prelude (between, (<<<), bind, (==), ($), pure, class Bind, unit, (+), (<>), class Applicative, class Functor, Unit, class Apply)
+import Prelude (between, (<<<), bind, (==), ($), pure, class Bind, unit, (+), (-), (<>), class Applicative, class Functor, Unit, class Apply)
 
 import Control.Alt (class Alt)
 import Control.Alternative (class Alternative)
@@ -202,3 +202,24 @@ parse_last_char s p = case last_char s of
     -- Get the last character of a String.
     last_char :: String -> Maybe Char
     last_char = A.last <<< CU.toCharArray
+
+-- | `read_input`: take a parser and provide the whole read input segment, unaltered.
+-- | This function allows to create complex parsers only reading input, not re-assembling it once read.
+-- | This prevents errors while concatenating strings while the unaltered input already is there to be used.
+-- |
+-- | This function can be used to verify a parser doesn't alter its input.
+-- |
+-- | Example, the following function `func` uses a combination of several
+-- | parsers without having to handle the input in any way (no manipulation whatsoever).
+-- | Yet, thanks to `read_input` the returned value of `func` is the whole, unaltered read input.
+-- | ```
+-- | func :: forall e. Parser e String
+-- | func = read_input do _ <- something
+-- |                      _ <- tryMaybe something_else
+-- |                      void very_complex_stuff
+-- | ```
+read_input :: forall e s. Parser e s -> Parser e String
+read_input p = do input <- current_input
+                  _ <- p
+                  endpos <- current_position
+                  pure $ CU.take (endpos - input.position) input.string

test/Main.purs

@@ -8,6 +8,7 @@ import Effect.Console (log)
 import Effect (Effect, foreachE)
 
 import GenericParser.Parser (Parser(..))
+import GenericParser.Parser as P
 import GenericParser.DomainParser.Common (ldh_str, DomainError(..))
 import GenericParser.DomainParserRFC1035 as RFC1035
 import GenericParser.DomainParser as ModernDomains
@@ -86,5 +87,15 @@ main = do
 
   log ""
   let spaces   = [ """" """", """ " """" ]
+      lreturns = [ """" \r\nx"""", """ "\r\n"""", """ "\r\n """" ]
+      characters = [ "\r", "\n", "\"" ]
   test_series "E.quoted_string (short)" E.quoted_string id showerror_email spaces
   test_series "E.qcontent (short)" E.qcontent id showerror_email spaces
+
+  test_series "E.quoted_string (lreturns)" E.quoted_string id showerror_email lreturns
+  test_series "E.qcontent (characters)" E.qcontent id showerror_email characters
+
+  log ""
+  let quotedstrings = [ """" "spaces?""", """ " " """ ]
+  test_series "E.quoted_string---------------" E.quoted_string id showerror_email quotedstrings
+  test_series "P.read_input (E.quoted_string)" (P.read_input E.quoted_string) id showerror_email quotedstrings