Add cut applet

src/cmd/cut/mod.rs

@@ -0,0 +1,285 @@
+use super::Cmd;
+use clap::{parser::ValuesRef, Arg, ArgAction, ArgGroup, Command};
+use std::{
+    error::Error,
+    fs::File,
+    io::{self, BufRead, BufReader, BufWriter, Write},
+    ops::{Range, RangeFrom, RangeTo},
+    usize, vec,
+};
+
+#[derive(Debug, Default)]
+pub struct Cut;
+
+impl Cmd for Cut {
+    fn cli(&self) -> clap::Command {
+        Command::new("cut")
+            .about("cut out selected fields of each line of a file")
+            .author("Nathan Fisher")
+            .version(env!("CARGO_PKG_VERSION"))
+            .args([
+                Arg::new("bytes")
+                    .short('b')
+                    .long("bytes")
+                    .help("select only these bytes")
+                    .num_args(1)
+                    .allow_hyphen_values(true)
+                    .value_name("LIST")
+                    .value_delimiter(','),
+                Arg::new("characters")
+                    .short('c')
+                    .long("characters")
+                    .help("select only these characters")
+                    .num_args(1)
+                    .allow_hyphen_values(true)
+                    .value_name("LIST")
+                    .value_delimiter(','),
+                Arg::new("fields")
+                    .short('f')
+                    .long("fields")
+                    .help("select only these fields")
+                    .num_args(1)
+                    .allow_hyphen_values(true)
+                    .value_name("LIST")
+                    .value_delimiter(','),
+                Arg::new("delimiter")
+                    .short('d')
+                    .long("delimiter")
+                    .help("use DELIM instead of TAB for field delimiter")
+                    .num_args(1)
+                    .value_name("DELIM"),
+                Arg::new("nosplit").help("ignored").short('n'),
+                Arg::new("suppress")
+                    .short('s')
+                    .long("only-delimited")
+                    .requires("fields")
+                    .action(ArgAction::SetTrue),
+                Arg::new("file").value_name("FILE").num_args(0..),
+            ])
+            .group(
+                ArgGroup::new("flags")
+                    .args(["bytes", "characters", "fields"])
+                    .required(true),
+            )
+    }
+
+    fn run(&self, matches: Option<&clap::ArgMatches>) -> Result<(), Box<dyn Error>> {
+        let Some(matches) = matches else {
+            return Err(Box::new(io::Error::new(io::ErrorKind::Other, "no input")));
+        };
+        let files: Vec<String> = match matches.get_many::<String>("file") {
+            Some(f) => f.cloned().collect(),
+            None => vec!["-".to_string()],
+        };
+        let (ranges, operator) = if let Some(raw_ranges) = matches.get_many::<String>("bytes") {
+            (get_ranges(raw_ranges)?, Operator::Bytes)
+        } else if let Some(raw_ranges) = matches.get_many::<String>("characters") {
+            (get_ranges(raw_ranges)?, Operator::Characters)
+        } else if let Some(raw_ranges) = matches.get_many::<String>("fields") {
+            (get_ranges(raw_ranges)?, Operator::Fields)
+        } else {
+            unreachable!()
+        };
+        for file in files {
+            let reader: Box<dyn BufRead> = if file.as_str() == "-" {
+                Box::new(BufReader::new(io::stdin()))
+            } else {
+                let fd = File::open(&file)?;
+                Box::new(BufReader::new(fd))
+            };
+            for line in reader.lines() {
+                match operator {
+                    Operator::Bytes => print_bytes(&line?, &ranges)?,
+                    Operator::Characters => print_chars(&line?, &ranges)?,
+                    Operator::Fields => print_fields(
+                        &line?,
+                        &ranges,
+                        matches.get_flag("suppress"),
+                        matches.get_one::<String>("delimiter"),
+                    )?,
+                }
+            }
+        }
+        Ok(())
+    }
+
+    fn path(&self) -> Option<crate::Path> {
+        Some(crate::Path::UsrBin)
+    }
+}
+
+enum Operator {
+    Bytes,
+    Characters,
+    Fields,
+}
+
+fn get_ranges(raw_ranges: ValuesRef<String>) -> Result<Vec<ParsedRange>, Box<dyn Error>> {
+    let mut ranges = vec![];
+    for range in raw_ranges {
+        let parsed_range = parse_range(range)?;
+        ranges.push(parsed_range);
+    }
+    Ok(ranges)
+}
+
+fn print_bytes(line: &str, ranges: &[ParsedRange]) -> Result<(), Box<dyn Error>> {
+    let combined_ranges = combine_ranges(ranges, line.len());
+    let mut writer = BufWriter::new(std::io::stdout());
+    for (idx, byte) in line.as_bytes().iter().enumerate() {
+        if combined_ranges.contains(&idx) {
+            write!(writer, "{}", *byte as char)?;
+        }
+    }
+    write!(writer, "\n")?;
+    Ok(())
+}
+
+fn print_chars(line: &str, ranges: &[ParsedRange]) -> Result<(), Box<dyn Error>> {
+    let combined_ranges = combine_ranges(ranges, line.len());
+    let mut writer = BufWriter::new(std::io::stdout());
+    for (idx, ch) in line.chars().enumerate() {
+        if combined_ranges.contains(&idx) {
+            write!(writer, "{}", &ch)?;
+        }
+    }
+    write!(writer, "\n")?;
+    Ok(())
+}
+
+fn print_fields(
+    line: &str,
+    ranges: &[ParsedRange],
+    suppress: bool,
+    delimiter: Option<&String>,
+) -> Result<(), Box<dyn Error>> {
+    let combined_ranges = combine_ranges(ranges, line.len());
+    let mut writer = BufWriter::new(std::io::stdout());
+    let delimiter = match delimiter {
+        Some(d) => d,
+        None => "\t",
+    };
+    if suppress {
+        if !line.contains(delimiter) {
+            return Ok(());
+        }
+    }
+    let fields = line.split(delimiter);
+    for (idx, field) in fields.enumerate() {
+        if combined_ranges.contains(&idx) {
+            write!(writer, "{field}")?;
+        }
+    }
+    write!(writer, "\n")?;
+    Ok(())
+}
+
+enum ParsedRange {
+    Bounded(Range<usize>),
+    LowerBounded(RangeFrom<usize>),
+    UpperBounded(RangeTo<usize>),
+    Single(usize),
+}
+
+impl From<Range<usize>> for ParsedRange {
+    fn from(value: Range<usize>) -> Self {
+        Self::Bounded(value)
+    }
+}
+
+impl From<RangeFrom<usize>> for ParsedRange {
+    fn from(value: RangeFrom<usize>) -> Self {
+        Self::LowerBounded(value)
+    }
+}
+
+impl From<RangeTo<usize>> for ParsedRange {
+    fn from(value: RangeTo<usize>) -> Self {
+        Self::UpperBounded(value)
+    }
+}
+
+impl From<usize> for ParsedRange {
+    fn from(value: usize) -> Self {
+        Self::Single(value)
+    }
+}
+
+fn combine_ranges(ranges: &[ParsedRange], max: usize) -> Vec<usize> {
+    let mut outrange: Vec<usize> = vec![];
+    for range in ranges {
+        match range {
+            ParsedRange::Bounded(r) => {
+                for n in r.start..r.end {
+                    outrange.push(n);
+                }
+            }
+            ParsedRange::LowerBounded(r) => {
+                for n in r.start..=max {
+                    outrange.push(n);
+                }
+            }
+            ParsedRange::UpperBounded(r) => {
+                for n in 0..=r.end {
+                    outrange.push(n);
+                }
+            }
+            ParsedRange::Single(u) => outrange.push(*u),
+        }
+    }
+    outrange.dedup();
+    outrange.sort_unstable();
+    outrange
+}
+
+fn parse_range(range: &str) -> Result<ParsedRange, Box<dyn Error>> {
+    if range.starts_with('-') {
+        if range.len() > 1 {
+            let end: usize = range[1..].parse()?;
+            if end >= 1 {
+                Ok((..end - 1).into())
+            } else {
+                Err(Box::new(io::Error::new(
+                    io::ErrorKind::Other,
+                    "invalid range",
+                )))
+            }
+        } else {
+            Err(Box::new(io::Error::new(
+                io::ErrorKind::Other,
+                "invalid range",
+            )))
+        }
+    } else if range.ends_with('-') {
+        if range.len() > 1 {
+            let start: usize = range[0..range.len()].parse()?;
+            if start >= 1 {
+                Ok((start - 1..).into())
+            } else {
+                Err(Box::new(io::Error::new(
+                    io::ErrorKind::Other,
+                    "invalid range",
+                )))
+            }
+        } else {
+            Err(Box::new(io::Error::new(
+                io::ErrorKind::Other,
+                "invalid range",
+            )))
+        }
+    } else if let Some((start, end)) = range.split_once('-') {
+        let start: usize = start.parse()?;
+        let end: usize = end.parse()?;
+        if start >= 1 && end > start {
+            Ok((start - 1..end).into())
+        } else {
+            Err(Box::new(io::Error::new(
+                io::ErrorKind::Other,
+                "invalid range",
+            )))
+        }
+    } else {
+        let range: usize = range.parse::<usize>()? - 1;
+        Ok(range.into())
+    }
+}

src/cmd/mod.rs

@@ -9,6 +9,7 @@ mod cat;
 mod chmod;
 pub mod clear;
 mod cp;
+pub mod cut;
 mod date;
 mod dd;
 pub mod dirname;
@@ -41,10 +42,10 @@ pub mod yes;
 
 pub use {
     self::hostname::Hostname, base32::Base32, base64::Base64, basename::Basename,
-    bootstrap::Bootstrap, clear::Clear, dirname::Dirname, echo::Echo, factor::Factor, fold::Fold,
-    groups::Groups, head::Head, link::Link, mountpoint::Mountpoint, nologin::Nologin, nproc::Nproc,
-    r#false::False, r#true::True, rev::Rev, shitbox::Shitbox, sleep::Sleep, sync::SYnc,
-    which::Which, whoami::Whoami, yes::Yes,
+    bootstrap::Bootstrap, clear::Clear, cut::Cut, dirname::Dirname, echo::Echo, factor::Factor,
+    fold::Fold, groups::Groups, head::Head, link::Link, mountpoint::Mountpoint, nologin::Nologin,
+    nproc::Nproc, r#false::False, r#true::True, rev::Rev, shitbox::Shitbox, sleep::Sleep,
+    sync::Sync as SyncCmd, which::Which, whoami::Whoami, yes::Yes,
 };
 
 pub trait Cmd: fmt::Debug + Sync {
@@ -61,6 +62,7 @@ pub fn get(name: &str) -> Option<Box<dyn Cmd>> {
         "basename" => Some(Box::new(Basename::default())),
         "bootstrap" => Some(Box::new(Bootstrap::default())),
         "clear" => Some(Box::new(Clear::default())),
+        "cut" => Some(Box::new(Cut::default())),
         "dirname" => Some(Box::new(Dirname::default())),
         "echo" => Some(Box::new(Echo::default())),
         "factor" => Some(Box::new(Factor::default())),
@@ -75,7 +77,7 @@ pub fn get(name: &str) -> Option<Box<dyn Cmd>> {
         "rev" => Some(Box::new(Rev::default())),
         "shitbox" => Some(Box::new(Shitbox::default())),
         "sleep" => Some(Box::new(Sleep::default())),
-        "sync" => Some(Box::new(SYnc::default())),
+        "sync" => Some(Box::new(SyncCmd::default())),
         "true" => Some(Box::new(True::default())),
         "which" => Some(Box::new(Which::default())),
         "whoami" => Some(Box::new(Whoami::default())),
@@ -84,12 +86,13 @@ pub fn get(name: &str) -> Option<Box<dyn Cmd>> {
     }
 }
 
-pub static COMMANDS: [&'static str; 25] = [
+pub static COMMANDS: [&'static str; 26] = [
     "base32",
     "base64",
     "basename",
     "bootstrap",
     "clear",
+    "cut",
     "dirname",
     "echo",
     "false",

src/cmd/sync/mod.rs

@@ -1,11 +1,11 @@
 use super::Cmd;
 use clap::{Arg, ArgAction, Command};
-use std::{error::Error, io, ffi::CString};
+use std::{error::Error, ffi::CString, io};
 
 #[derive(Debug, Default)]
-pub struct SYnc;
+pub struct Sync;
 
-impl Cmd for SYnc {
+impl Cmd for Sync {
     fn cli(&self) -> clap::Command {
         Command::new("sync")
             .about("force completion of pending disk writes (flush cache)")
@@ -66,7 +66,9 @@ impl Cmd for SYnc {
                 }
             }
         } else {
-            unsafe { libc::sync(); }
+            unsafe {
+                libc::sync();
+            }
         }
         Ok(())
     }