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use std::io::{Error, ErrorKind, Result, Write};
const ESCAPE_CODE: &[u8] = "\x1b[L".as_bytes();
const GENERATOR_MAX_CHAR_INDEX: u8 = 7;
macro_rules! write_char {
($writer:ident, $char:expr) => {
$writer.write(&[$char as u8])
};
}
macro_rules! write_digit {
($writer:ident, $num:expr) => {
$writer.write(&[$num + '0' as u8])
};
}
pub trait WriteInto<W>
where
W: Write,
{
fn write_into(self, writer: &mut W) -> Result<usize>;
}
pub enum SpecialCode {
DisplayOn,
DisplayOff,
CursorOn,
CursorOff,
BlinkOn,
BlinkOff,
BacklightOn,
BacklightOff,
FlashBacklight,
SmallFont,
LargeFont,
OneLine,
TwoLines,
ShiftCursorLeft,
ShiftCursorRight,
ShiftDisplayLeft,
ShiftDisplayRight,
KillEndOfLine,
ReinitializeDisplay,
Generator(u8, u64),
GotoXY(Option<u32>, Option<u32>),
}
/// Write a X or Y goto symbol, as required
fn write_goto_xy_sym<T: Write>(writer: &mut T, sym: char, value: Option<u32>) -> Result<usize> {
let mut total = 0;
if let Some(value) = value {
total += write_char!(writer, sym)?;
total += writer.write(value.to_string().as_bytes())?;
}
Ok(total)
}
/// Write both X and/or Y goto symbol, as required
fn write_goto_xy<T: Write>(writer: &mut T, x: Option<u32>, y: Option<u32>) -> Result<usize> {
let mut total = 0;
total += write_goto_xy_sym(writer, 'x', x)?;
total += write_goto_xy_sym(writer, 'y', y)?;
total += write_char!(writer, ';')?;
Ok(total)
}
fn write_generator<T: Write>(writer: &mut T, char_index: u8, value: u64) -> Result<usize> {
if char_index > GENERATOR_MAX_CHAR_INDEX {
return Err(Error::new(
ErrorKind::Other,
format!(
"char index cannot be greater than {}",
GENERATOR_MAX_CHAR_INDEX
),
));
}
let mut total = 0;
total += write_char!(writer, 'G')?;
total += write_digit!(writer, char_index)?;
total += writer.write(format!("{:>016x}", value).as_bytes())?;
total += write_char!(writer, ';')?;
Ok(total)
}
impl<W> WriteInto<W> for SpecialCode
where
W: Write,
{
fn write_into(self, writer: &mut W) -> Result<usize> {
let mut total = 0;
total += writer.write(ESCAPE_CODE)?;
total += match self {
SpecialCode::DisplayOn => write_char!(writer, 'D')?,
SpecialCode::DisplayOff => write_char!(writer, 'd')?,
SpecialCode::CursorOn => write_char!(writer, 'C')?,
SpecialCode::CursorOff => write_char!(writer, 'c')?,
SpecialCode::BlinkOn => write_char!(writer, 'B')?,
SpecialCode::BlinkOff => write_char!(writer, 'b')?,
SpecialCode::BacklightOn => write_char!(writer, '+')?,
SpecialCode::BacklightOff => write_char!(writer, '-')?,
SpecialCode::FlashBacklight => write_char!(writer, '*')?,
SpecialCode::SmallFont => write_char!(writer, 'f')?,
SpecialCode::LargeFont => write_char!(writer, 'F')?,
SpecialCode::OneLine => write_char!(writer, 'n')?,
SpecialCode::TwoLines => write_char!(writer, 'N')?,
SpecialCode::ShiftCursorLeft => write_char!(writer, 'l')?,
SpecialCode::ShiftCursorRight => write_char!(writer, 'r')?,
SpecialCode::ShiftDisplayLeft => write_char!(writer, 'L')?,
SpecialCode::ShiftDisplayRight => write_char!(writer, 'R')?,
SpecialCode::KillEndOfLine => write_char!(writer, 'k')?,
SpecialCode::ReinitializeDisplay => write_char!(writer, 'I')?,
SpecialCode::GotoXY(x, y) => write_goto_xy(writer, x, y)?,
SpecialCode::Generator(c, x) => write_generator(writer, c, x)?,
};
Ok(total)
}
}
#[cfg(test)]
mod tests {
use super::*;
fn assert_code_eq(code: SpecialCode, expected: &str) {
use std::io::Cursor;
let mut buf = Cursor::new(Vec::new());
let count = code.write_into(&mut buf).unwrap();
let expected = expected.as_bytes();
assert_eq!(count, expected.len());
assert_eq!(&buf.get_ref()[0..count], expected);
}
#[test]
fn simple_codes() {
assert_code_eq(SpecialCode::DisplayOff.into(), "\x1b[Ld");
assert_code_eq(SpecialCode::DisplayOn.into(), "\x1b[LD");
}
#[test]
fn special_code_goto_xy() {
assert_code_eq(SpecialCode::GotoXY(None, None), "\x1b[L;");
assert_code_eq(SpecialCode::GotoXY(Some(42), None), "\x1b[Lx42;");
assert_code_eq(SpecialCode::GotoXY(None, Some(42)), "\x1b[Ly42;");
assert_code_eq(SpecialCode::GotoXY(Some(42), Some(32)), "\x1b[Lx42y32;");
}
#[test]
fn special_code_gen() {
assert_code_eq(
SpecialCode::Generator(7, 0xdeadbeefdecacafe),
"\x1b[LG7deadbeefdecacafe;",
);
assert_code_eq(SpecialCode::Generator(7, 0xff), "\x1b[LG700000000000000ff;");
}
}
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