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Checking terminal capabilities on each operation #45

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Checking terminal capabilities on each operation #45

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99 changes: 22 additions & 77 deletions src/core/driver.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,8 +1,7 @@
// Temporary fix before certain constants are used.
#![allow(dead_code)]

use std::io::{Error, ErrorKind};

use term::Error;
use term::terminfo::TermInfo;
use term::terminfo::parm;
use term::terminfo::parm::{Param, Variables};
Expand Down Expand Up @@ -48,31 +47,11 @@ const REVERSE: &'static str = "rev";
const SETFG: &'static str = "setaf";
const SETBG: &'static str = "setab";

// Array of terminal capabilities. Used as an iterator to test for functionality.
//
// At the moment all functionality is required, however in the future we should implement optional
// functionality checks so the absence of underlining or reverse video doesn't cause initialization
// to fail.
//
// TODO: Optional functionality testing.
const CAPABILITIES: &'static [&'static str] = &[ENTER_CA,
EXIT_CA,
SHOW_CURSOR,
HIDE_CURSOR,
SET_CURSOR,
CLEAR,
RESET,
UNDERLINE,
BOLD,
REVERSE,
SETFG,
SETBG];

// Driver capabilities are an enum instead of string constants (there are string constants private
// to the module however, those are only used for naming convenience and disambiguation)
// to take advantage of compile-time type-checking instead of hoping invalid strings aren't passed.
// This allows us to guarantee that driver accesses will succeed. In addition, using an enum means
// Driver doesn't need hard-coded methods for each capability we want to use.
// In addition, using an enum means Driver doesn't need hard-coded methods for each capability we
// want to use.
pub enum DevFn {
EnterCa,
ExitCa,
Expand Down Expand Up @@ -113,67 +92,33 @@ pub struct Driver {
tinfo: TermInfo,
}

// Validates and returns a reference to the terminfo database.
//
// If this function returns Ok(..), the contained terminfo database is guaranteed to have the
// functionality found in CAPABILITIES.
//
// If this function returns Err(..), the terminfo database did not contain all the required
// functionality; the error returned will provide more specific detail.
fn get_tinfo() -> Result<TermInfo, Error> {
let tinfo = TermInfo::from_env().unwrap_or({
TermInfo {
names: Default::default(),
bools: Default::default(),
numbers: Default::default(),
strings: Default::default(),
}
});

for capname in CAPABILITIES {
if !tinfo.strings.contains_key(*capname) {
return Err(Error::new(ErrorKind::NotFound,
format!("terminal missing capability: '{}'", capname)));
}
}
Ok(tinfo)
}

impl Driver {
// Creates a new `Driver`
//
// If successful, the terminfo database is guaranteed to contain all capabilities we support.
pub fn new() -> Result<Driver, Error> {
let tinfo = try!(get_tinfo());
let tinfo = try!(TermInfo::from_env());
Ok(Driver { tinfo: tinfo })
}

// Returns the device specific escape sequence for the given `DevFn`.
//
// get() will not return an error, and (in theory) should never panic. The `DevFn` enum
// restricts possible inputs to a subset that will not fail when passed to `parm::expand()`.
// This can be verified by examining the source of the `parm::expand()` function in the `term`
// crate.
//
// Furthermore, the pre-flight checks on initialization of `Driver` ensure that every
// capability is present, thus the call to `Hashmap::get()` should never fail.
pub fn get(&self, dfn: DevFn) -> Vec<u8> {
// Returns the device specific escape sequence for the given `DevFn`, or None if the terminal
// lacks the capability to perform the specified function.
pub fn get(&self, dfn: DevFn) -> Option<Vec<u8>> {
let capname = dfn.as_str();
let cap = self.tinfo.strings.get(capname).unwrap();
self.tinfo.strings.get(capname).map(|cap| {

match dfn {
DevFn::SetFg(attr) |
DevFn::SetBg(attr) => {
let params = &[Param::Number(attr as i32)];
let mut vars = Variables::new();
parm::expand(cap, params, &mut vars).unwrap()
}
DevFn::SetCursor(x, y) => {
let params = &[Param::Number(y as i32), Param::Number(x as i32)];
let mut vars = Variables::new();
parm::expand(cap, params, &mut vars).unwrap()
match dfn {
DevFn::SetFg(attr) |
DevFn::SetBg(attr) => {
let params = &[Param::Number(attr as i32)];
let mut vars = Variables::new();
parm::expand(cap, params, &mut vars).unwrap()
}
DevFn::SetCursor(x, y) => {
let params = &[Param::Number(y as i32), Param::Number(x as i32)];
let mut vars = Variables::new();
parm::expand(cap, params, &mut vars).unwrap()
}
_ => cap.clone(),
}
_ => cap.clone(),
}
})
}
}
39 changes: 23 additions & 16 deletions src/core/terminal.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -160,10 +160,10 @@ impl Terminal {
};

// Switch to alternate screen buffer. Writes the control code to the output buffer.
try!(terminal.outbuffer.write_all(&terminal.driver.get(DevFn::EnterCa)));
try!(terminal.outbuffer_write_devfn(DevFn::EnterCa));

// Hide cursor. Writes the control code to the output buffer.
try!(terminal.outbuffer.write_all(&terminal.driver.get(DevFn::HideCursor)));
try!(terminal.outbuffer_write_devfn(DevFn::HideCursor));

// Resize the buffers to the size of the underlying terminals. Using the given cell as a
// blank.
Expand All @@ -173,6 +173,13 @@ impl Terminal {
Ok(terminal)
}

fn outbuffer_write_devfn(&mut self, devfn: DevFn) -> Result<(), Error> {
match self.driver.get(devfn) {
None => Ok(()),
Some(seq) => self.outbuffer.write_all(&seq)
}
}

/// Swaps buffers to display the current backbuffer.
///
/// # Examples
Expand Down Expand Up @@ -414,7 +421,7 @@ impl Terminal {
/// ```
pub fn set_cursor(&mut self, x: usize, y: usize) -> Result<(), Error> {
if self.cursor.pos().is_none() {
try!(self.outbuffer.write_all(&self.driver.get(DevFn::ShowCursor)));
try!(self.outbuffer_write_devfn(DevFn::ShowCursor));
}
self.cursor.set_pos(Some((x, y)));
try!(self.send_cursor());
Expand All @@ -434,7 +441,7 @@ impl Terminal {
/// ```
pub fn hide_cursor(&mut self) -> Result<(), Error> {
if self.cursor.pos().is_some() {
try!(self.outbuffer.write_all(&self.driver.get(DevFn::HideCursor)));
try!(self.outbuffer_write_devfn(DevFn::HideCursor));
}
Ok(())
}
Expand Down Expand Up @@ -478,7 +485,7 @@ impl Terminal {

fn send_cursor(&mut self) -> Result<(), Error> {
if let Some((cx, cy)) = self.cursor.pos() {
try!(self.outbuffer.write_all(&self.driver.get(DevFn::SetCursor(cx, cy))));
try!(self.outbuffer_write_devfn(DevFn::SetCursor(cx, cy)));
}
Ok(())
}
Expand All @@ -493,7 +500,7 @@ impl Terminal {
}

fn send_clear(&mut self) -> Result<(), Error> {
try!(self.outbuffer.write_all(&self.driver.get(DevFn::Clear)));
try!(self.outbuffer_write_devfn(DevFn::Clear));
try!(self.send_cursor());
try!(self.flush());
self.cursor.invalidate_last_pos();
Expand All @@ -503,14 +510,14 @@ impl Terminal {
fn send_style(&mut self, cell: Cell) -> Result<(), Error> {
if cell.fg() != self.laststyle.fg() || cell.bg() != self.laststyle.bg() ||
cell.attrs() != self.laststyle.attrs() {
try!(self.outbuffer.write_all(&self.driver.get(DevFn::Reset)));
try!(self.outbuffer_write_devfn(DevFn::Reset));

match cell.attrs() {
Attr::Bold => try!(self.outbuffer.write_all(&self.driver.get(DevFn::Bold))),
Attr::Bold => try!(self.outbuffer_write_devfn(DevFn::Bold)),
Attr::Underline => {
try!(self.outbuffer.write_all(&self.driver.get(DevFn::Underline)))
try!(self.outbuffer_write_devfn(DevFn::Underline))
}
Attr::Reverse => try!(self.outbuffer.write_all(&self.driver.get(DevFn::Reverse))),
Attr::Reverse => try!(self.outbuffer_write_devfn(DevFn::Reverse)),
_ => {}
}

Expand All @@ -524,13 +531,13 @@ impl Terminal {
match fgcol {
Color::Default => {}
fgc @ _ => {
try!(self.outbuffer.write_all(&self.driver.get(DevFn::SetFg(fgc.as_byte()))));
try!(self.outbuffer_write_devfn(DevFn::SetFg(fgc.as_byte())));
}
}
match bgcol {
Color::Default => {}
bgc @ _ => {
try!(self.outbuffer.write_all(&self.driver.get(DevFn::SetBg(bgc.as_byte()))));
try!(self.outbuffer_write_devfn(DevFn::SetBg(bgc.as_byte())));
}
}
Ok(())
Expand Down Expand Up @@ -688,10 +695,10 @@ impl IndexMut<Pos> for Terminal {

impl Drop for Terminal {
fn drop(&mut self) {
self.outbuffer.write_all(&self.driver.get(DevFn::ShowCursor)).unwrap();
self.outbuffer.write_all(&self.driver.get(DevFn::Reset)).unwrap();
self.outbuffer.write_all(&self.driver.get(DevFn::Clear)).unwrap();
self.outbuffer.write_all(&self.driver.get(DevFn::ExitCa)).unwrap();
self.outbuffer_write_devfn(DevFn::ShowCursor).unwrap();
self.outbuffer_write_devfn(DevFn::Reset).unwrap();
self.outbuffer_write_devfn(DevFn::Clear).unwrap();
self.outbuffer_write_devfn(DevFn::ExitCa).unwrap();
self.flush().unwrap();
self.termctl.reset().unwrap();
SIGWINCH_STATUS.store(false, Ordering::SeqCst);
Expand Down