experiment: Sparse file support

examples/simple.rs

@@ -1,6 +1,6 @@
 use std::io;
 
-use hexyl::{BorderStyle, PrinterBuilder};
+use hexyl::{BorderStyle, Input, PrinterBuilder};
 
 fn main() {
  let input = vec![
@@ -20,5 +20,7 @@ fn main() {
  .num_panels(2)
  .group_size(1)
  .build();
- printer.print_all(&input[..]).unwrap();
+ printer
+ .print_all(Input::Generic(Box::new(io::Cursor::new(input))))
+ .unwrap();
 }

src/bin/hexyl.rs

@@ -17,7 +17,7 @@ use thiserror::Error as ThisError;
 
 use terminal_size::terminal_size;
 
-use hexyl::{Base, BorderStyle, Endianness, Input, PrinterBuilder};
+use hexyl::{Base, BorderStyle, CharacterTable, Endianness, Input, PrinterBuilder};
 
 const DEFAULT_BLOCK_SIZE: i64 = 512;
 
@@ -209,6 +209,18 @@ fn run() -> Result<()> {
  .hide(true)
  .help("An alias for '--endianness=little'."),
  )
+ .arg(
+ Arg::new("character-table")
+ .long("character-table")
+ .value_name("FORMAT")
+ .value_parser(["codepage-437", "ascii-only"])
+ .default_value("ascii-only")
+ .help(
+ "The character table that should be used. 'ascii-only' \
+ will show dots for non-ASCII characters, and 'codepage-437' \
+ will use Code page 437 for those characters."
+ ),
+ )
  .arg(
  Arg::new("base")
  .short('b')
@@ -306,7 +318,7 @@ fn run() -> Result<()> {
  .into())
  };
 
- let mut reader = if let Some(length) = matches
+ let reader = if let Some(length) = matches
  .get_one::<String>("length")
  .or_else(|| matches.get_one::<String>("bytes"))
  .or_else(|| matches.get_one::<String>("count"))
@@ -318,9 +330,11 @@ fn run() -> Result<()> {
  })
  .transpose()?
  {
- Box::new(reader.take(length))
+ Input::Generic(Box::new(reader.take(length)))
+ } else if let Input::File(_) = reader {
+ reader
  } else {
- reader.into_inner()
+ Input::Generic(reader.into_inner())
  };
 
  let show_color = match matches.get_one::<String>("color").map(String::as_ref) {
@@ -466,6 +480,17 @@ fn run() -> Result<()> {
  ("big", _) => Endianness::Big,
  _ => unreachable!(),
  };
+
+ let character_table = match matches
+ .get_one::<String>("character-table")
+ .unwrap()
+ .as_ref()
+ {
+ "ascii-only" => CharacterTable::AsciiOnly,
+ "codepage-437" => CharacterTable::CP437,
+ _ => unreachable!(),
+ };
+
  let stdout = io::stdout();
  let mut stdout_lock = BufWriter::new(stdout.lock());
 
@@ -479,9 +504,10 @@ fn run() -> Result<()> {
  .group_size(group_size)
  .with_base(base)
  .endianness(endianness)
+ .character_table(character_table)
  .build();
  printer.display_offset(skip_offset + display_offset);
- printer.print_all(&mut reader).map_err(|e| anyhow!(e))?;
+ printer.print_all(reader).map_err(|e| anyhow!(e))?;
 
  Ok(())
 }

src/input.rs

@@ -5,13 +5,15 @@ use std::io::{self, copy, sink, Read, Seek, SeekFrom};
 pub enum Input<'a> {
  File(fs::File),
  Stdin(io::StdinLock<'a>),
+ Generic(Box<dyn Read>),
 }
 
 impl<'a> Read for Input<'a> {
  fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
  match *self {
  Input::File(ref mut file) => file.read(buf),
  Input::Stdin(ref mut stdin) => stdin.read(buf),
+ Input::Generic(ref mut reader) => reader.read(buf),
  }
  }
 }
@@ -51,6 +53,11 @@ impl<'a> Seek for Input<'a> {
  pos,
  "STDIN only supports seeking forward with a relative offset",
  ),
+ Input::Generic(ref mut reader) => try_skip(
+ reader,
+ pos,
+ "This reader only supports seeking forward with a relative offset",
+ ),
  }
  }
 }
@@ -60,6 +67,7 @@ impl<'a> Input<'a> {
  match self {
  Input::File(file) => Box::new(file),
  Input::Stdin(stdin) => Box::new(stdin),
+ Input::Generic(reader) => reader,
  }
  }
 }