melib/imap: add utils module to protocol_parser

Add utils module with parser helpers for syntax items that can be NIL

Signed-off-by: Manos Pitsidianakis <manos@pitsidianak.is>

melib/src/imap/protocol_parser.rs

@@ -26,6 +26,7 @@ use std::{convert::TryFrom, str::FromStr};
 pub mod id_ext;
 #[cfg(test)]
 mod tests;
+pub mod utils;
 
 use nom::{
     branch::{alt, permutation},
@@ -1270,15 +1271,12 @@ pub fn envelope_addresses<'a>(
 // ("Terry Gray" NIL "gray" "cac.washington.edu")
 pub fn envelope_address(input: &[u8]) -> IResult<&[u8], Address> {
     const WS: &[u8] = b"\r\n\t ";
-    let (input, name) = alt((quoted, map(tag("NIL"), |_| Vec::new())))(input)?;
+    let (input, name) = utils::nil_to_default(quoted)(input)?;
     let (input, _) = is_a(WS)(input)?;
-    let (input, _) = alt((quoted, map(tag("NIL"), |_| Vec::new())))(input)?;
+    let (input, _) = utils::nil_to_default(quoted)(input)?;
     let (input, _) = is_a(WS)(input)?;
-    let (input, mailbox_name) = alt((quoted, map(tag("NIL"), |_| Vec::new())))(input)?;
-    let (input, host_name) = opt(preceded(
-        is_a(WS),
-        alt((quoted, map(tag("NIL"), |_| Vec::new()))),
-    ))(input)?;
+    let (input, mailbox_name) = utils::nil_to_default(quoted)(input)?;
+    let (input, host_name) = opt(preceded(is_a(WS), utils::nil_to_default(quoted)))(input)?;
     Ok((
         input,
         Address::Mailbox(MailboxAddress {
@@ -1368,8 +1366,9 @@ pub fn quoted(input: &[u8]) -> IResult<&[u8], Vec<u8>> {
     ))
 }
 
+#[inline]
 pub fn quoted_or_nil(input: &[u8]) -> IResult<&[u8], Option<Vec<u8>>> {
-    alt((map(tag("NIL"), |_| None), map(quoted, Some)))(input.ltrim())
+    utils::nil_to_none(quoted)(input.ltrim())
 }
 
 pub fn uid_fetch_envelopes_response<'a>(

melib/src/imap/protocol_parser/utils.rs

@@ -0,0 +1,41 @@
+//
+// meli
+//
+// Copyright 2024 Emmanouil Pitsidianakis <manos@pitsidianak.is>
+//
+// This file is part of meli.
+//
+// meli is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// meli is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with meli. If not, see <http://www.gnu.org/licenses/>.
+//
+// SPDX-License-Identifier: EUPL-1.2 OR GPL-3.0-or-later
+
+//! # IMAP Parsing utility functions
+
+use nom::{branch::alt, bytes::complete::tag, combinator::map};
+
+use crate::email::parser::IResult;
+
+#[inline]
+pub fn nil_to_none<'i, T>(
+    parser: fn(&'i [u8]) -> IResult<&'i [u8], T>,
+) -> impl FnMut(&'i [u8]) -> IResult<&'i [u8], Option<T>> {
+    alt((map(tag("NIL"), |_| None), map(parser, Some)))
+}
+
+#[inline]
+pub fn nil_to_default<'i, T: Default>(
+    parser: fn(&'i [u8]) -> IResult<&'i [u8], T>,
+) -> impl FnMut(&'i [u8]) -> IResult<&'i [u8], T> {
+    alt((map(tag("NIL"), |_| T::default()), parser))
+}