From edf4fee48f7fbaf8c9e10637f8214fe85f690b4f Mon Sep 17 00:00:00 2001
From: Daniel Hofstetter <daniel.hofstetter@42dh.com>
Date: Fri, 17 Jun 2022 12:59:02 +0200
Subject: [PATCH] unexpand: implement "tabs" shortcuts

---
 src/uu/unexpand/src/unexpand.rs | 57 ++++++++++++++++++++++++++++++---
 tests/by-util/test_unexpand.rs  | 35 ++++++++++++++++++++
 2 files changed, 88 insertions(+), 4 deletions(-)

diff --git a/src/uu/unexpand/src/unexpand.rs b/src/uu/unexpand/src/unexpand.rs
index 31856bc61..477d2d917 100644
--- a/src/uu/unexpand/src/unexpand.rs
+++ b/src/uu/unexpand/src/unexpand.rs
@@ -7,7 +7,7 @@
 //  * For the full copyright and license information, please view the LICENSE
 //  * file that was distributed with this source code.
 
-// spell-checker:ignore (ToDO) nums aflag uflag scol prevtab amode ctype cwidth nbytes lastcol pctype
+// spell-checker:ignore (ToDO) nums aflag uflag scol prevtab amode ctype cwidth nbytes lastcol pctype Preprocess
 
 #[macro_use]
 extern crate uucore;
@@ -97,9 +97,9 @@ struct Options {
 
 impl Options {
     fn new(matches: &clap::ArgMatches) -> Result<Self, ParseError> {
-        let tabstops = match matches.value_of(options::TABS) {
+        let tabstops = match matches.values_of(options::TABS) {
             None => vec![DEFAULT_TABSTOP],
-            Some(s) => tabstops_parse(s)?,
+            Some(s) => tabstops_parse(&s.collect::<Vec<&str>>().join(","))?,
         };
 
         let aflag = (matches.is_present(options::ALL) || matches.is_present(options::TABS))
@@ -120,13 +120,49 @@ impl Options {
     }
 }
 
+/// Decide whether the character is either a digit or a comma.
+fn is_digit_or_comma(c: char) -> bool {
+    c.is_ascii_digit() || c == ','
+}
+
+/// Preprocess command line arguments and expand shortcuts. For example, "-7" is expanded to
+/// "--tabs=7 --first-only" and "-1,3" to "--tabs=1 --tabs=3 --first-only". However, if "-a" or
+/// "--all" is provided, "--first-only" is omitted.
+fn expand_shortcuts(args: &[String]) -> Vec<String> {
+    let mut processed_args = Vec::with_capacity(args.len());
+    let mut is_all_arg_provided = false;
+    let mut has_shortcuts = false;
+
+    for arg in args {
+        if arg.starts_with('-') && arg[1..].chars().all(is_digit_or_comma) {
+            arg[1..]
+                .split(',')
+                .filter(|s| !s.is_empty())
+                .for_each(|s| processed_args.push(format!("--tabs={}", s)));
+            has_shortcuts = true;
+        } else {
+            processed_args.push(arg.to_string());
+
+            if arg == "--all" || arg == "-a" {
+                is_all_arg_provided = true;
+            }
+        }
+    }
+
+    if has_shortcuts && !is_all_arg_provided {
+        processed_args.push("--first-only".into());
+    }
+
+    processed_args
+}
+
 #[uucore::main]
 pub fn uumain(args: impl uucore::Args) -> UResult<()> {
     let args = args
         .collect_str(InvalidEncodingHandling::Ignore)
         .accept_any();
 
-    let matches = uu_app().get_matches_from(args);
+    let matches = uu_app().get_matches_from(expand_shortcuts(&args));
 
     unexpand(&Options::new(&matches)?).map_err_context(String::new)
 }
@@ -163,6 +199,7 @@ pub fn uu_app<'a>() -> Command<'a> {
                 .long(options::TABS)
                 .help("use comma separated LIST of tab positions or have tabs N characters apart instead of 8 (enables -a)")
                 .takes_value(true)
+                .multiple_occurrences(true)
                 .value_name("N, LIST")
         )
         .arg(
@@ -379,3 +416,15 @@ fn unexpand(options: &Options) -> std::io::Result<()> {
     }
     output.flush()
 }
+
+#[cfg(test)]
+mod tests {
+    use crate::is_digit_or_comma;
+
+    #[test]
+    fn test_is_digit_or_comma() {
+        assert!(is_digit_or_comma('1'));
+        assert!(is_digit_or_comma(','));
+        assert!(!is_digit_or_comma('a'));
+    }
+}
diff --git a/tests/by-util/test_unexpand.rs b/tests/by-util/test_unexpand.rs
index ccb217393..e71e76d55 100644
--- a/tests/by-util/test_unexpand.rs
+++ b/tests/by-util/test_unexpand.rs
@@ -156,6 +156,41 @@ fn unexpand_read_from_two_file() {
         .success();
 }
 
+#[test]
+fn test_tabs_shortcut() {
+    new_ucmd!()
+        .arg("-3")
+        .pipe_in("   a   b")
+        .run()
+        .stdout_is("\ta   b");
+}
+
+#[test]
+fn test_tabs_shortcut_combined_with_all_arg() {
+    fn run_cmd(all_arg: &str) {
+        new_ucmd!()
+            .args(&[all_arg, "-3"])
+            .pipe_in("a  b  c")
+            .run()
+            .stdout_is("a\tb\tc");
+    }
+
+    let all_args = vec!["-a", "--all"];
+
+    for arg in all_args {
+        run_cmd(arg);
+    }
+}
+
+#[test]
+fn test_comma_separated_tabs_shortcut() {
+    new_ucmd!()
+        .args(&["-a", "-3,9"])
+        .pipe_in("a  b     c")
+        .run()
+        .stdout_is("a\tb\tc");
+}
+
 #[test]
 fn test_tabs_cannot_be_zero() {
     new_ucmd!()