join: add support for multibyte separators (#6736)

* join: add test for multibyte separators

* join: implement support for multibyte separators

* join: use a trait instead of an enum for separator

* join: test whitespace merging

src/uu/join/src/join.rs

@@ -3,11 +3,11 @@
 // For the full copyright and license information, please view the LICENSE
 // file that was distributed with this source code.
 
-// spell-checker:ignore (ToDO) autoformat FILENUM whitespaces pairable unpairable nocheck
+// spell-checker:ignore (ToDO) autoformat FILENUM whitespaces pairable unpairable nocheck memmem
 
 use clap::builder::ValueParser;
 use clap::{crate_version, Arg, ArgAction, Command};
-use memchr::{memchr3_iter, memchr_iter};
+use memchr::{memchr_iter, memmem::Finder, Memchr3};
 use std::cmp::Ordering;
 use std::error::Error;
 use std::ffi::OsString;
@@ -60,13 +60,114 @@ enum FileNum {
     File2,
 }
 
-#[derive(Copy, Clone, PartialEq)]
-enum Sep {
-    Char(u8),
+#[derive(Clone)]
+enum SepSetting {
+    /// Any single-byte separator.
+    Byte(u8),
+    /// A single character more than one byte long.
+    Char(Vec<u8>),
+    /// No separators, join on the entire line.
     Line,
+    /// Whitespace separators.
     Whitespaces,
 }
 
+trait Separator: Clone {
+    /// Using this separator, return the start and end index of all fields in the haystack.
+    fn field_ranges(&self, haystack: &[u8], len_guess: usize) -> Vec<(usize, usize)>;
+    /// The separator as it appears when in the output.
+    fn output_separator(&self) -> &[u8];
+}
+
+/// Simple separators one byte in length.
+#[derive(Copy, Clone)]
+struct OneByteSep {
+    byte: [u8; 1],
+}
+
+impl Separator for OneByteSep {
+    fn field_ranges(&self, haystack: &[u8], len_guess: usize) -> Vec<(usize, usize)> {
+        let mut field_ranges = Vec::with_capacity(len_guess);
+        let mut last_end = 0;
+
+        for i in memchr_iter(self.byte[0], haystack) {
+            field_ranges.push((last_end, i));
+            last_end = i + 1;
+        }
+        field_ranges.push((last_end, haystack.len()));
+        field_ranges
+    }
+
+    fn output_separator(&self) -> &[u8] {
+        &self.byte
+    }
+}
+
+/// Multi-byte (but still single character) separators.
+#[derive(Clone)]
+struct MultiByteSep<'a> {
+    finder: Finder<'a>,
+}
+
+impl<'a> Separator for MultiByteSep<'a> {
+    fn field_ranges(&self, haystack: &[u8], len_guess: usize) -> Vec<(usize, usize)> {
+        let mut field_ranges = Vec::with_capacity(len_guess);
+        let mut last_end = 0;
+
+        for i in self.finder.find_iter(haystack) {
+            field_ranges.push((last_end, i));
+            last_end = i + self.finder.needle().len();
+        }
+        field_ranges.push((last_end, haystack.len()));
+        field_ranges
+    }
+
+    fn output_separator(&self) -> &[u8] {
+        self.finder.needle()
+    }
+}
+
+/// Whole-line separator.
+#[derive(Copy, Clone)]
+struct LineSep {}
+
+impl Separator for LineSep {
+    fn field_ranges(&self, haystack: &[u8], _len_guess: usize) -> Vec<(usize, usize)> {
+        vec![(0, haystack.len())]
+    }
+
+    fn output_separator(&self) -> &[u8] {
+        &[]
+    }
+}
+
+/// Default whitespace separator.
+#[derive(Copy, Clone)]
+struct WhitespaceSep {}
+
+impl Separator for WhitespaceSep {
+    fn field_ranges(&self, haystack: &[u8], len_guess: usize) -> Vec<(usize, usize)> {
+        let mut field_ranges = Vec::with_capacity(len_guess);
+        let mut last_end = 0;
+
+        // GNU join used Bourne shell field splitters by default
+        // FIXME: but now uses locale-dependent whitespace
+        for i in Memchr3::new(b' ', b'\t', b'\n', haystack) {
+            // leading whitespace should be dropped, contiguous whitespace merged
+            if i > last_end {
+                field_ranges.push((last_end, i));
+            }
+            last_end = i + 1;
+        }
+        field_ranges.push((last_end, haystack.len()));
+        field_ranges
+    }
+
+    fn output_separator(&self) -> &[u8] {
+        b" "
+    }
+}
+
 #[derive(Copy, Clone, PartialEq)]
 enum CheckOrder {
     Default,
@@ -82,7 +183,7 @@ struct Settings {
     print_joined: bool,
     ignore_case: bool,
     line_ending: LineEnding,
-    separator: Sep,
+    separator: SepSetting,
     autoformat: bool,
     format: Vec<Spec>,
     empty: Vec<u8>,
@@ -100,7 +201,7 @@ impl Default for Settings {
             print_joined: true,
             ignore_case: false,
             line_ending: LineEnding::Newline,
-            separator: Sep::Whitespaces,
+            separator: SepSetting::Whitespaces,
             autoformat: false,
             format: vec![],
             empty: vec![],
@@ -111,15 +212,15 @@ impl Default for Settings {
 }
 
 /// Output representation.
-struct Repr<'a> {
+struct Repr<'a, Sep: Separator> {
     line_ending: LineEnding,
-    separator: u8,
-    format: &'a [Spec],
+    separator: Sep,
+    format: Vec<Spec>,
     empty: &'a [u8],
 }
 
-impl<'a> Repr<'a> {
-    fn new(line_ending: LineEnding, separator: u8, format: &'a [Spec], empty: &'a [u8]) -> Self {
+impl<'a, Sep: Separator> Repr<'a, Sep> {
+    fn new(line_ending: LineEnding, separator: Sep, format: Vec<Spec>, empty: &'a [u8]) -> Self {
         Repr {
             line_ending,
             separator,
@@ -155,7 +256,7 @@ impl<'a> Repr<'a> {
     ) -> Result<(), std::io::Error> {
         for i in 0..line.field_ranges.len() {
             if i != index {
-                writer.write_all(&[self.separator])?;
+                writer.write_all(self.separator.output_separator())?;
                 writer.write_all(line.get_field(i).unwrap())?;
             }
         }
@@ -169,7 +270,7 @@ impl<'a> Repr<'a> {
     {
         for i in 0..self.format.len() {
             if i > 0 {
-                writer.write_all(&[self.separator])?;
+                writer.write_all(self.separator.output_separator())?;
             }
 
             let field = match f(&self.format[i]) {
@@ -188,13 +289,13 @@ impl<'a> Repr<'a> {
 }
 
 /// Input processing parameters.
-struct Input {
+struct Input<Sep: Separator> {
     separator: Sep,
     ignore_case: bool,
     check_order: CheckOrder,
 }
 
-impl Input {
+impl<Sep: Separator> Input<Sep> {
     fn new(separator: Sep, ignore_case: bool, check_order: CheckOrder) -> Self {
         Self {
             separator,
@@ -271,24 +372,8 @@ struct Line {
 }
 
 impl Line {
-    fn new(string: Vec<u8>, separator: Sep, len_guess: usize) -> Self {
-        let mut field_ranges = Vec::with_capacity(len_guess);
-        let mut last_end = 0;
-        if separator == Sep::Whitespaces {
-            // GNU join uses Bourne shell field splitters by default
-            for i in memchr3_iter(b' ', b'\t', b'\n', &string) {
-                if i > last_end {
-                    field_ranges.push((last_end, i));
-                }
-                last_end = i + 1;
-            }
-        } else if let Sep::Char(sep) = separator {
-            for i in memchr_iter(sep, &string) {
-                field_ranges.push((last_end, i));
-                last_end = i + 1;
-            }
-        }
-        field_ranges.push((last_end, string.len()));
+    fn new<Sep: Separator>(string: Vec<u8>, separator: &Sep, len_guess: usize) -> Self {
+        let field_ranges = separator.field_ranges(&string, len_guess);
 
         Self {
             field_ranges,
@@ -351,7 +436,12 @@ impl<'a> State<'a> {
     }
 
     /// Skip the current unpaired line.
-    fn skip_line(&mut self, writer: &mut impl Write, input: &Input, repr: &Repr) -> UResult<()> {
+    fn skip_line<Sep: Separator>(
+        &mut self,
+        writer: &mut impl Write,
+        input: &Input<Sep>,
+        repr: &Repr<'a, Sep>,
+    ) -> UResult<()> {
         if self.print_unpaired {
             self.print_first_line(writer, repr)?;
         }
@@ -362,7 +452,7 @@ impl<'a> State<'a> {
 
     /// Keep reading line sequence until the key does not change, return
     /// the first line whose key differs.
-    fn extend(&mut self, input: &Input) -> UResult<Option<Line>> {
+    fn extend<Sep: Separator>(&mut self, input: &Input<Sep>) -> UResult<Option<Line>> {
         while let Some(line) = self.next_line(input)? {
             let diff = input.compare(self.get_current_key(), line.get_field(self.key));
 
@@ -377,11 +467,11 @@ impl<'a> State<'a> {
     }
 
     /// Print lines in the buffers as headers.
-    fn print_headers(
+    fn print_headers<Sep: Separator>(
         &self,
         writer: &mut impl Write,
         other: &State,
-        repr: &Repr,
+        repr: &Repr<'a, Sep>,
     ) -> Result<(), std::io::Error> {
         if self.has_line() {
             if other.has_line() {
@@ -397,11 +487,11 @@ impl<'a> State<'a> {
     }
 
     /// Combine two line sequences.
-    fn combine(
+    fn combine<Sep: Separator>(
         &self,
         writer: &mut impl Write,
         other: &State,
-        repr: &Repr,
+        repr: &Repr<'a, Sep>,
     ) -> Result<(), std::io::Error> {
         let key = self.get_current_key();
 
@@ -444,13 +534,16 @@ impl<'a> State<'a> {
         }
     }
 
-    fn reset_read_line(&mut self, input: &Input) -> Result<(), std::io::Error> {
-        let line = self.read_line(input.separator)?;
+    fn reset_read_line<Sep: Separator>(
+        &mut self,
+        input: &Input<Sep>,
+    ) -> Result<(), std::io::Error> {
+        let line = self.read_line(&input.separator)?;
         self.reset(line);
         Ok(())
     }
 
-    fn reset_next_line(&mut self, input: &Input) -> Result<(), JoinError> {
+    fn reset_next_line<Sep: Separator>(&mut self, input: &Input<Sep>) -> Result<(), JoinError> {
         let line = self.next_line(input)?;
         self.reset(line);
         Ok(())
@@ -460,7 +553,7 @@ impl<'a> State<'a> {
         !self.seq.is_empty()
     }
 
-    fn initialize(&mut self, read_sep: Sep, autoformat: bool) -> usize {
+    fn initialize<Sep: Separator>(&mut self, read_sep: &Sep, autoformat: bool) -> usize {
         if let Some(line) = crash_if_err!(1, self.read_line(read_sep)) {
             self.seq.push(line);
 
@@ -471,7 +564,12 @@ impl<'a> State<'a> {
         0
     }
 
-    fn finalize(&mut self, writer: &mut impl Write, input: &Input, repr: &Repr) -> UResult<()> {
+    fn finalize<Sep: Separator>(
+        &mut self,
+        writer: &mut impl Write,
+        input: &Input<Sep>,
+        repr: &Repr<'a, Sep>,
+    ) -> UResult<()> {
         if self.has_line() {
             if self.print_unpaired {
                 self.print_first_line(writer, repr)?;
@@ -491,7 +589,7 @@ impl<'a> State<'a> {
     }
 
     /// Get the next line without the order check.
-    fn read_line(&mut self, sep: Sep) -> Result<Option<Line>, std::io::Error> {
+    fn read_line<Sep: Separator>(&mut self, sep: &Sep) -> Result<Option<Line>, std::io::Error> {
         match self.lines.next() {
             Some(value) => {
                 self.line_num += 1;
@@ -506,8 +604,8 @@ impl<'a> State<'a> {
     }
 
     /// Get the next line with the order check.
-    fn next_line(&mut self, input: &Input) -> Result<Option<Line>, JoinError> {
-        if let Some(line) = self.read_line(input.separator)? {
+    fn next_line<Sep: Separator>(&mut self, input: &Input<Sep>) -> Result<Option<Line>, JoinError> {
+        if let Some(line) = self.read_line(&input.separator)? {
             if input.check_order == CheckOrder::Disabled {
                 return Ok(Some(line));
             }
@@ -543,11 +641,11 @@ impl<'a> State<'a> {
         self.seq[0].get_field(self.key)
     }
 
-    fn print_line(
+    fn print_line<Sep: Separator>(
         &self,
         writer: &mut impl Write,
         line: &Line,
-        repr: &Repr,
+        repr: &Repr<'a, Sep>,
     ) -> Result<(), std::io::Error> {
         if repr.uses_format() {
             repr.print_format(writer, |spec| match *spec {
@@ -568,31 +666,53 @@ impl<'a> State<'a> {
         repr.print_line_ending(writer)
     }
 
-    fn print_first_line(&self, writer: &mut impl Write, repr: &Repr) -> Result<(), std::io::Error> {
+    fn print_first_line<Sep: Separator>(
+        &self,
+        writer: &mut impl Write,
+        repr: &Repr<'a, Sep>,
+    ) -> Result<(), std::io::Error> {
         self.print_line(writer, &self.seq[0], repr)
     }
 }
 
-fn parse_separator(value_os: &OsString) -> UResult<Sep> {
+fn parse_separator(value_os: &OsString) -> UResult<SepSetting> {
+    // Five possible separator values:
+    // No argument supplied, separate on whitespace; handled implicitly as the default elsewhere
+    // An empty string arg, whole line separation
+    // On unix-likes only, a single arbitrary byte
+    // The two-character "\0" string, interpreted as a single 0 byte
+    // A single scalar valid in the locale encoding (currently only UTF-8)
+
+    if value_os.is_empty() {
+        return Ok(SepSetting::Line);
+    }
+
     #[cfg(unix)]
-    let value = value_os.as_bytes();
-    #[cfg(not(unix))]
-    let value = match value_os.to_str() {
-        Some(value) => value.as_bytes(),
-        None => {
-            return Err(USimpleError::new(
-                1,
-                "unprintable field separators are only supported on unix-like platforms",
-            ));
+    {
+        let value = value_os.as_bytes();
+        if value.len() == 1 {
+            return Ok(SepSetting::Byte(value[0]));
         }
+    }
+
+    let Some(value) = value_os.to_str() else {
+        #[cfg(unix)]
+        return Err(USimpleError::new(1, "non-UTF-8 multi-byte tab"));
+        #[cfg(not(unix))]
+        return Err(USimpleError::new(
+            1,
+            "unprintable field separators are only supported on unix-like platforms",
+        ));
     };
-    match value.len() {
-        0 => Ok(Sep::Line),
-        1 => Ok(Sep::Char(value[0])),
-        2 if value[0] == b'\\' && value[1] == b'0' => Ok(Sep::Char(0)),
+
+    let mut chars = value.chars();
+    let c = chars.next().expect("valid string with at least one byte");
+    match chars.next() {
+        None => Ok(SepSetting::Char(value.into())),
+        Some('0') if c == '\\' => Ok(SepSetting::Byte(0)),
         _ => Err(USimpleError::new(
             1,
-            format!("multi-character tab {}", value_os.to_string_lossy()),
+            format!("multi-character tab {}", value),
         )),
     }
 }
@@ -695,7 +815,20 @@ pub fn uumain(args: impl uucore::Args) -> UResult<()> {
         return Err(USimpleError::new(1, "both files cannot be standard input"));
     }
 
-    exec(file1, file2, settings)
+    let sep = settings.separator.clone();
+    match sep {
+        SepSetting::Byte(byte) => exec(file1, file2, settings, OneByteSep { byte: [byte] }),
+        SepSetting::Char(c) => exec(
+            file1,
+            file2,
+            settings,
+            MultiByteSep {
+                finder: Finder::new(&c),
+            },
+        ),
+        SepSetting::Whitespaces => exec(file1, file2, settings, WhitespaceSep {}),
+        SepSetting::Line => exec(file1, file2, settings, LineSep {}),
+    }
 }
 
 pub fn uu_app() -> Command {
@@ -816,7 +949,7 @@ FILENUM is 1 or 2, corresponding to FILE1 or FILE2",
         )
 }
 
-fn exec(file1: &str, file2: &str, settings: Settings) -> UResult<()> {
+fn exec<Sep: Separator>(file1: &str, file2: &str, settings: Settings, sep: Sep) -> UResult<()> {
     let stdin = stdin();
 
     let mut state1 = State::new(
@@ -837,16 +970,12 @@ fn exec(file1: &str, file2: &str, settings: Settings) -> UResult<()> {
         settings.print_unpaired2,
     )?;
 
-    let input = Input::new(
-        settings.separator,
-        settings.ignore_case,
-        settings.check_order,
-    );
+    let input = Input::new(sep.clone(), settings.ignore_case, settings.check_order);
 
     let format = if settings.autoformat {
         let mut format = vec![Spec::Key];
         let mut initialize = |state: &mut State| {
-            let max_fields = state.initialize(settings.separator, settings.autoformat);
+            let max_fields = state.initialize(&sep, settings.autoformat);
             for i in 0..max_fields {
                 if i != state.key {
                     format.push(Spec::Field(state.file_num, i));
@@ -857,20 +986,12 @@ fn exec(file1: &str, file2: &str, settings: Settings) -> UResult<()> {
         initialize(&mut state2);
         format
     } else {
-        state1.initialize(settings.separator, settings.autoformat);
-        state2.initialize(settings.separator, settings.autoformat);
+        state1.initialize(&sep, settings.autoformat);
+        state2.initialize(&sep, settings.autoformat);
         settings.format
     };
 
-    let repr = Repr::new(
-        settings.line_ending,
-        match settings.separator {
-            Sep::Char(sep) => sep,
-            _ => b' ',
-        },
-        &format,
-        &settings.empty,
-    );
+    let repr = Repr::new(settings.line_ending, sep, format, &settings.empty);
 
     let stdout = stdout();
     let mut writer = BufWriter::new(stdout.lock());

tests/by-util/test_join.rs

@@ -58,6 +58,25 @@ fn default_arguments() {
         .stdout_only_fixture("default.expected");
 }
 
+#[test]
+fn only_whitespace_separators_merge() {
+    new_ucmd!()
+        .arg("contiguous_separators.txt")
+        .arg("-")
+        .pipe_in(" a  ,c ")
+        .succeeds()
+        .stdout_only("a ,,,b ,c \n");
+
+    new_ucmd!()
+        .arg("contiguous_separators.txt")
+        .arg("-t")
+        .arg(",")
+        .arg("-")
+        .pipe_in(" a  ,c ")
+        .succeeds()
+        .stdout_only(" a  ,,,b,c \n");
+}
+
 #[test]
 fn different_fields() {
     new_ucmd!()
@@ -208,9 +227,9 @@ fn tab_multi_character() {
         .arg("semicolon_fields_1.txt")
         .arg("semicolon_fields_2.txt")
         .arg("-t")
-        .arg("э")
+        .arg("ab")
         .fails()
-        .stderr_is("join: multi-character tab э\n");
+        .stderr_is("join: multi-character tab ab\n");
 }
 
 #[test]
@@ -437,14 +456,22 @@ fn non_unicode() {
 
     #[cfg(unix)]
     {
-        let invalid_utf8: u8 = 167;
+        let non_utf8_byte: u8 = 167;
         new_ucmd!()
             .arg("-t")
-            .arg(OsStr::from_bytes(&[invalid_utf8]))
+            .arg(OsStr::from_bytes(&[non_utf8_byte]))
             .arg("non-unicode_1.bin")
             .arg("non-unicode_2.bin")
             .succeeds()
             .stdout_only_fixture("non-unicode_sep.expected");
+
+        new_ucmd!()
+            .arg("-t")
+            .arg(OsStr::from_bytes(&[non_utf8_byte, non_utf8_byte]))
+            .arg("non-unicode_1.bin")
+            .arg("non-unicode_2.bin")
+            .fails()
+            .stderr_is("join: non-UTF-8 multi-byte tab\n");
     }
 
     #[cfg(windows)]
@@ -462,6 +489,16 @@ fn non_unicode() {
     }
 }
 
+#[test]
+fn multibyte_sep() {
+    new_ucmd!()
+        .arg("-t§")
+        .arg("multibyte_sep_1.txt")
+        .arg("multibyte_sep_2.txt")
+        .succeeds()
+        .stdout_only_fixture("multibyte_sep.expected");
+}
+
 #[test]
 fn null_field_separators() {
     new_ucmd!()

tests/fixtures/join/contiguous_separators.txt

@@ -0,0 +1 @@
+ a  ,,,b

tests/fixtures/join/multibyte_sep.expected

@@ -0,0 +1 @@
+a§b§c

tests/fixtures/join/multibyte_sep_1.txt

@@ -0,0 +1 @@
+a§b

tests/fixtures/join/multibyte_sep_2.txt

@@ -0,0 +1 @@
+a§c