alacritty/src/term.rs

// Copyright 2016 Joe Wilm, The Alacritty Project Contributors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
//! Exports the `Term` type which is a high-level API for the Grid
use std::ops::{Deref, Range};
use std::ptr;
use std::cmp;

use ansi::{self, Attr, Handler};
use grid::{Grid, ClearRegion};
use index::{Cursor, Column, Line};
use ansi::Color;

/// Iterator that yields cells needing render
///
/// Yields cells that require work to be displayed (that is, not a an empty
/// background cell). Additionally, this manages some state of the grid only
/// relevant for rendering like temporarily changing the cell with the cursor.
///
/// This manages the cursor during a render. The cursor location is inverted to
/// draw it, and reverted after drawing to maintain state.
pub struct RenderableCellsIter<'a> {
    grid: &'a mut Grid<Cell>,
    cursor: &'a Cursor,
    mode: TermMode,
    line: Line,
    column: Column,
}


impl<'a> RenderableCellsIter<'a> {
    /// Create the renderable cells iterator
    ///
    /// The cursor and terminal mode are required for properly displaying the
    /// cursor.
    fn new<'b>(
        grid: &'b mut Grid<Cell>,
        cursor: &'b Cursor,
        mode: TermMode
    ) -> RenderableCellsIter<'b> {
        RenderableCellsIter {
            grid: grid,
            cursor: cursor,
            mode: mode,
            line: Line(0),
            column: Column(0),
        }.initialize()
    }

    fn initialize(self) -> Self {
        if self.cursor_is_visible() {
            self.grid[self.cursor].swap_fg_and_bg();
        }

        self
    }

    /// Check if the cursor should be rendered.
    #[inline]
    fn cursor_is_visible(&self) -> bool {
        self.mode.contains(mode::SHOW_CURSOR) && self.grid.contains(self.cursor)
    }
}

impl<'a> Drop for RenderableCellsIter<'a> {
    /// Resets temporary render state on the grid
    fn drop(&mut self) {
        if self.cursor_is_visible() {
            self.grid[self.cursor].swap_fg_and_bg();
        }
    }
}

pub struct IndexedCell {
    pub line: Line,
    pub column: Column,
    pub inner: Cell
}

impl Deref for IndexedCell {
    type Target = Cell;

    #[inline(always)]
    fn deref(&self) -> &Cell {
        &self.inner
    }
}

impl<'a> Iterator for RenderableCellsIter<'a> {
    type Item = IndexedCell;

    /// Gets the next renderable cell
    ///
    /// Skips empty (background) cells and applies any flags to the cell state
    /// (eg. invert fg and bg colors).
    #[inline(always)]
    fn next(&mut self) -> Option<Self::Item> {
        while self.line < self.grid.num_lines() {
            while self.column < self.grid.num_cols() {
                // Grab current state for this iteration
                let line = self.line;
                let column = self.column;
                let cell = &self.grid[line][column];

                // Update state for next iteration
                self.column += 1;

                // Skip empty cells
                if cell.is_empty() {
                    continue;
                }

                // fg, bg are dependent on INVERSE flag
                let (fg, bg) = if cell.flags.contains(cell::INVERSE) {
                    (&cell.bg, &cell.fg)
                } else {
                    (&cell.fg, &cell.bg)
                };

                return Some(IndexedCell {
                    line: line,
                    column: column,
                    inner: Cell {
                        flags: cell.flags,
                        c: cell.c,
                        fg: *fg,
                        bg: *bg,
                    }
                })
            }

            self.column = Column(0);
            self.line += 1;
        }

        None
    }
}

/// coerce val to be between min and max
#[inline]
fn limit<T: PartialOrd + Ord>(val: T, min: T, max: T) -> T {
    cmp::min(cmp::max(min, val), max)
}

pub mod cell {
    use std::mem;

    use ansi;
    use ::Rgb;

    bitflags! {
        #[derive(Serialize, Deserialize)]
        pub flags Flags: u32 {
            const INVERSE   = 0b00000001,
            const BOLD      = 0b00000010,
            const ITALIC    = 0b00000100,
            const UNDERLINE = 0b00001000,
        }
    }

    #[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
    pub enum Color {
        Rgb(Rgb),
        Ansi(ansi::Color),
    }

    #[derive(Clone, Debug, Serialize, Deserialize, Eq, PartialEq)]
    pub struct Cell {
        pub c: char,
        pub fg: Color,
        pub bg: Color,
        pub flags: Flags,
    }

    impl Cell {
        pub fn bold(&self) -> bool {
            self.flags.contains(BOLD)
        }

        pub fn new(c: char, fg: Color, bg: Color) -> Cell {
            Cell {
                c: c.into(),
                bg: bg,
                fg: fg,
                flags: Flags::empty(),
            }
        }

        #[inline]
        pub fn is_empty(&self) -> bool {
            self.c == ' ' &&
                self.bg == Color::Ansi(ansi::Color::Background) &&
                !self.flags.contains(INVERSE)
        }

        #[inline]
        pub fn reset(&mut self, template: &Cell) {
            // memcpy template to self
            *self = template.clone();
        }

        #[inline]
        pub fn swap_fg_and_bg(&mut self) {
            mem::swap(&mut self.fg, &mut self.bg);
        }
    }

    #[cfg(test)]
    mod tests {
        use super::Color;
        use std::mem;

        // Ensure memory layout is well defined so components like renderer
        // can exploit it.
        //
        // Thankfully, everything is just a u8 for now so no endianness
        // considerations are needed.
        #[test]
        fn color_memory_layout() {
            let rgb_color = Color::Rgb(::Rgb { r: 1, g: 2, b: 3 });
            let ansi_color = Color::Ansi(::ansi::Color::Foreground);

            unsafe {
                // Color::Rgb
                // [discriminant(0), red, green ,blue]
                let bytes: [u8; 4] = mem::transmute_copy(&rgb_color);
                assert_eq!(bytes[0], 0);
                assert_eq!(bytes[1], 1);
                assert_eq!(bytes[2], 2);
                assert_eq!(bytes[3], 3);

                // Color::Ansi
                // [discriminant(1), ansi::Color, 0, 0]
                let bytes: [u8; 4] = mem::transmute_copy(&ansi_color);
                assert_eq!(bytes[0], 1);
                assert_eq!(bytes[1], ::ansi::Color::Foreground as u8);
            }
        }
    }
}

pub use self::cell::Cell;

pub mod mode {
    bitflags! {
        pub flags TermMode: u8 {
            const SHOW_CURSOR         = 0b00000001,
            const APP_CURSOR          = 0b00000010,
            const APP_KEYPAD          = 0b00000100,
            const MOUSE_REPORT_CLICK  = 0b00001000,
            const ANY                 = 0b11111111,
            const NONE                = 0b00000000,
        }
    }

    impl Default for TermMode {
        fn default() -> TermMode {
            SHOW_CURSOR
        }
    }
}

pub use self::mode::TermMode;

pub const TAB_SPACES: usize = 8;

pub struct Term {
    /// The grid
    grid: Grid<Cell>,

    /// Alternate grid
    alt_grid: Grid<Cell>,

    /// Alt is active
    alt: bool,

    /// The cursor
    cursor: Cursor,

    /// Alt cursor
    alt_cursor: Cursor,

    /// Tabstops
    tabs: Vec<bool>,

    /// Mode flags
    mode: TermMode,

    /// Scroll region
    scroll_region: Range<Line>,

    /// Size
    size_info: SizeInfo,

    /// Template cell
    template_cell: Cell,

    /// Empty cell
    empty_cell: Cell,

    pub dirty: bool,
}

/// Terminal size info
#[derive(Debug, Copy, Clone, Serialize, Deserialize)]
pub struct SizeInfo {
    /// Terminal window width
    pub width: f32,

    /// Terminal window height
    pub height: f32,

    /// Width of individual cell
    pub cell_width: f32,

    /// Height of individual cell
    pub cell_height: f32,
}

impl SizeInfo {
    #[inline]
    pub fn lines(&self) -> Line {
        Line((self.height / self.cell_height) as usize)
    }

    #[inline]
    pub fn cols(&self) -> Column {
        Column((self.width / self.cell_width) as usize)
    }
}

impl Term {
    pub fn new(
        size: SizeInfo
    ) -> Term {
        let template = Cell::new(
            ' ',
            cell::Color::Ansi(Color::Foreground),
            cell::Color::Ansi(Color::Background)
        );

        let num_cols = size.cols();
        let num_lines = size.lines();

        let grid = Grid::new(num_lines, num_cols, &template);

        let mut tabs = (Column(0)..grid.num_cols())
            .map(|i| (*i as usize) % TAB_SPACES == 0)
            .collect::<Vec<bool>>();

        tabs[0] = false;

        let alt = grid.clone();
        let scroll_region = Line(0)..grid.num_lines();

        Term {
            dirty: true,
            grid: grid,
            alt_grid: alt,
            alt: false,
            cursor: Cursor::default(),
            alt_cursor: Cursor::default(),
            tabs: tabs,
            mode: Default::default(),
            scroll_region: scroll_region,
            size_info: size,
            template_cell: template.clone(),
            empty_cell: template,
        }
    }

    /// Convert the given pixel values to a grid coordinate
    ///
    /// The mouse coordinates are expected to be relative to the top left. The
    /// line and column returned are also relative to the top left.
    ///
    /// Returns None if the coordinates are outside the screen
    pub fn pixels_to_coords(&self, x: usize, y: usize) -> Option<(Line, Column)> {
        let size = self.size_info();
        if x > size.width as usize || y > size.height as usize {
            return None;
        }

        let col = Column(x / (size.cell_width as usize));
        let line = Line(y / (size.cell_height as usize));

        Some((line, col))
    }

    pub fn grid(&self) -> &Grid<Cell> {
        &self.grid
    }

    pub fn renderable_cells<'a>(&'a mut self) -> RenderableCellsIter<'a> {
        RenderableCellsIter::new(&mut self.grid, &self.cursor, self.mode)
    }

    /// Resize terminal to new dimensions
    pub fn resize(&mut self, width: f32, height: f32) {
        let size = SizeInfo {
            width: width,
            height: height,
            cell_width: self.size_info.cell_width,
            cell_height: self.size_info.cell_height,
        };

        let old_cols = self.size_info.cols();
        let old_lines = self.size_info.lines();
        let num_cols = size.cols();
        let num_lines = size.lines();

        self.size_info = size;

        if old_cols == num_cols && old_lines == num_lines {
            return;
        }

        // Scroll up to keep cursor and as much context as possible in grid. This only runs when the
        // lines decreases.
        self.scroll_region = Line(0)..self.grid.num_lines();

        // Scroll up to keep cursor in terminal
        if self.cursor.line >= num_lines {
            let lines = self.cursor.line - num_lines + 1;
            self.scroll_up(lines);
            self.cursor.line -= lines;
        }

        println!("num_cols, num_lines = {}, {}", num_cols, num_lines);

        // Resize grids to new size
        let template = self.template_cell.clone();
        self.grid.resize(num_lines, num_cols, &template);
        self.alt_grid.resize(num_lines, num_cols, &template);

        // Ensure cursor is in-bounds
        self.cursor.line = limit(self.cursor.line, Line(0), num_lines);
        self.cursor.col = limit(self.cursor.col, Column(0), num_cols);

        // Recreate tabs list
        self.tabs = (Column(0)..self.grid.num_cols()).map(|i| (*i as usize) % TAB_SPACES == 0)
                                                     .collect::<Vec<bool>>();

        self.tabs[0] = false;

        // Make sure bottom of terminal is clear
        let template = self.empty_cell.clone();
        self.grid.clear_region((self.cursor.line).., |c| c.reset(&template));
        self.alt_grid.clear_region((self.cursor.line).., |c| c.reset(&template));

        // Reset scrolling region to new size
        self.scroll_region = Line(0)..self.grid.num_lines();
    }

    #[inline]
    pub fn size_info(&self) -> &SizeInfo {
        &self.size_info
    }

    #[inline]
    pub fn mode(&self) -> &TermMode {
        &self.mode
    }

    pub fn swap_alt(&mut self) {
        self.alt = !self.alt;
        ::std::mem::swap(&mut self.grid, &mut self.alt_grid);
        ::std::mem::swap(&mut self.cursor, &mut self.alt_cursor);

        if self.alt {
            let template = self.empty_cell.clone();
            self.grid.clear(|c| c.reset(&template));
        }
    }

    /// Scroll screen down
    ///
    /// Text moves down; clear at bottom
    #[inline]
    fn scroll_down_relative(&mut self, origin: Line, lines: Line) {
        debug_println!("scroll_down: {}", lines);

        // Copy of cell template; can't have it borrowed when calling clear/scroll
        let template = self.empty_cell.clone();

        // Clear `lines` lines at bottom of area
        {
            let end = self.scroll_region.end;
            let start = end - lines;
            self.grid.clear_region(start..end, |c| c.reset(&template));
        }

        // Scroll between origin and bottom
        {
            let end = self.scroll_region.end;
            let start = origin + lines;
            self.grid.scroll_down(start..end, lines);
        }
    }

    /// Scroll screen up
    ///
    /// Text moves up; clear at top
    #[inline]
    fn scroll_up_relative(&mut self, origin: Line, lines: Line) {
        debug_println!("scroll_up: {}", lines);

        // Copy of cell template; can't have it borrowed when calling clear/scroll
        let template = self.empty_cell.clone();

        // Clear `lines` lines starting from origin to origin + lines
        {
            let start = origin;
            let end = start + lines;
            self.grid.clear_region(start..end, |c| c.reset(&template));
        }

        // Scroll from origin to bottom less number of lines
        {
            let start = origin;
            let end = self.scroll_region.end - lines;
            self.grid.scroll_up(start..end, lines);
        }
    }
}

impl ansi::TermInfo for Term {
    #[inline]
    fn lines(&self) -> Line {
        self.grid.num_lines()
    }

    #[inline]
    fn cols(&self) -> Column {
        self.grid.num_cols()
    }
}

impl ansi::Handler for Term {
    /// A character to be displayed
    #[inline]
    fn input(&mut self, c: char) {
        if self.cursor.col == self.grid.num_cols() {
            debug_println!("wrapping");
            if (self.cursor.line + 1) >= self.scroll_region.end {
                self.linefeed();
            } else {
                self.cursor.line += 1;
            }
            self.cursor.col = Column(0);
        }

        unsafe {
            if ::std::intrinsics::unlikely(self.cursor.line == self.grid.num_lines()) {
                panic!("cursor fell off grid");
            }
        }

        let cell = &mut self.grid[&self.cursor];
        *cell = self.template_cell.clone();
        cell.c = c;
        self.cursor.col += 1;
    }

    #[inline]
    fn goto(&mut self, line: Line, col: Column) {
        debug_println!("goto: line={}, col={}", line, col);
        self.cursor.line = line;
        self.cursor.col = col;
    }

    #[inline]
    fn goto_line(&mut self, line: Line) {
        debug_println!("goto_line: {}", line);
        self.cursor.line = line;
    }

    #[inline]
    fn goto_col(&mut self, col: Column) {
        debug_println!("goto_col: {}", col);
        self.cursor.col = col;
    }

    #[inline]
    fn insert_blank(&mut self, count: Column) {
        // Ensure inserting within terminal bounds
        let count = ::std::cmp::min(count, self.size_info.cols() - self.cursor.col);

        let source = self.cursor.col;
        let destination = self.cursor.col + count;
        let num_cells = (self.size_info.cols() - destination).0;

        let line = self.cursor.line; // borrowck
        let line = &mut self.grid[line];

        unsafe {
            let src = line[source..].as_ptr();
            let dst = line[destination..].as_mut_ptr();

            ptr::copy(src, dst, num_cells);
        }

        // Cells were just moved out towards the end of the line; fill in
        // between source and dest with blanks.
        let template = self.empty_cell.clone();
        for c in &mut line[source..destination] {
            c.reset(&template);
        }
    }

    #[inline]
    fn move_up(&mut self, lines: Line) {
        debug_println!("move_up: {}", lines);
        self.cursor.line -= lines;
    }

    #[inline]
    fn move_down(&mut self, lines: Line) {
        debug_println!("move_down: {}", lines);
        self.cursor.line += lines;
    }

    #[inline]
    fn move_forward(&mut self, cols: Column) {
        debug_println!("move_forward: {}", cols);
        self.cursor.col += cols;
    }

    #[inline]
    fn move_backward(&mut self, cols: Column) {
        debug_println!("move_backward: {}", cols);
        self.cursor.col -= cols;
    }

    #[inline]
    fn identify_terminal(&mut self) {
        err_println!("[unimplemented] identify_terminal");
    }

    #[inline]
    fn move_down_and_cr(&mut self, lines: Line) {
        err_println!("[unimplemented] move_down_and_cr: {}", lines);
    }

    #[inline]
    fn move_up_and_cr(&mut self, lines: Line) {
        err_println!("[unimplemented] move_up_and_cr: {}", lines);
    }

    #[inline]
    fn put_tab(&mut self, mut count: i64) {
        debug_println!("put_tab: {}", count);

        let mut col = self.cursor.col;
        while col < self.grid.num_cols() && count != 0 {
            count -= 1;
            loop {
                if col == self.grid.num_cols() || self.tabs[*col as usize] {
                    break;
                }
                col += 1;
            }
        }

        self.cursor.col = col;
    }

    /// Backspace `count` characters
    #[inline]
    fn backspace(&mut self) {
        debug_println!("backspace");
        if self.cursor.col > Column(0) {
            self.cursor.col -= 1;
        }
    }

    /// Carriage return
    #[inline]
    fn carriage_return(&mut self) {
        debug_println!("carriage_return");
        self.cursor.col = Column(0);
    }

    /// Linefeed
    #[inline]
    fn linefeed(&mut self) {
        debug_println!("linefeed");
        if self.cursor.line + 1 == self.scroll_region.end {
            self.scroll_up(Line(1));
        } else {
            self.cursor.line += 1;
        }
    }

    /// Set current position as a tabstop
    #[inline]
    fn bell(&mut self) {
        debug_println!("bell");
    }

    #[inline]
    fn substitute(&mut self) {
        err_println!("[unimplemented] substitute");
    }

    #[inline]
    fn newline(&mut self) {
        err_println!("[unimplemented] newline");
    }

    #[inline]
    fn set_horizontal_tabstop(&mut self) {
        err_println!("[unimplemented] set_horizontal_tabstop");
    }

    #[inline]
    fn scroll_up(&mut self, lines: Line) {
        let origin = self.scroll_region.start;
        self.scroll_up_relative(origin, lines);
    }

    #[inline]
    fn scroll_down(&mut self, lines: Line) {
        let origin = self.scroll_region.start;
        self.scroll_down_relative(origin, lines);
    }

    #[inline]
    fn insert_blank_lines(&mut self, lines: Line) {
        debug_println!("insert_blank_lines: {}", lines);
        if self.scroll_region.contains(self.cursor.line) {
            let origin = self.cursor.line;
            self.scroll_down_relative(origin, lines);
        }
    }

    #[inline]
    fn delete_lines(&mut self, lines: Line) {
        debug_println!("delete_lines: {}", lines);
        if self.scroll_region.contains(self.cursor.line) {
            let origin = self.cursor.line;
            self.scroll_up_relative(origin, lines);
        }
    }

    #[inline]
    fn erase_chars(&mut self, count: Column) {
        debug_println!("erase_chars: {}", count);
        let start = self.cursor.col;
        let end = start + count;

        let row = &mut self.grid[self.cursor.line];
        let template = self.empty_cell.clone();
        for c in &mut row[start..end] {
            c.reset(&template);
        }
    }

    #[inline]
    fn delete_chars(&mut self, count: Column) {
        // Ensure deleting within terminal bounds
        let count = ::std::cmp::min(count, self.size_info.cols());

        let start = self.cursor.col;
        let end = self.cursor.col + count;
        let n = (self.size_info.cols() - end).0;

        let line = self.cursor.line; // borrowck
        let line = &mut self.grid[line];

        unsafe {
            let src = line[end..].as_ptr();
            let dst = line[start..].as_mut_ptr();

            ptr::copy(src, dst, n);
        }

        // Clear last `count` cells in line. If deleting 1 char, need to delete 1 cell.
        let template = self.empty_cell.clone();
        let end = self.size_info.cols() - count;
        for c in &mut line[end..] {
            c.reset(&template);
        }
    }

    #[inline]
    fn move_backward_tabs(&mut self, count: i64) {
        err_println!("[unimplemented] move_backward_tabs: {}", count);
    }

    #[inline]
    fn move_forward_tabs(&mut self, count: i64) {
        err_println!("[unimplemented] move_forward_tabs: {}", count);
    }

    #[inline]
    fn save_cursor_position(&mut self) {
        err_println!("[unimplemented] save_cursor_position");
    }

    #[inline]
    fn restore_cursor_position(&mut self) {
        err_println!("[unimplemented] restore_cursor_position");
    }

    #[inline]
    fn clear_line(&mut self, mode: ansi::LineClearMode) {
        debug_println!("clear_line: {:?}", mode);
        let template = self.empty_cell.clone();
        match mode {
            ansi::LineClearMode::Right => {
                let row = &mut self.grid[self.cursor.line];
                for cell in &mut row[self.cursor.col..] {
                    cell.reset(&template);
                }
            },
            ansi::LineClearMode::Left => {
                let row = &mut self.grid[self.cursor.line];
                for cell in &mut row[..(self.cursor.col + 1)] {
                    cell.reset(&template);
                }
            },
            ansi::LineClearMode::All => {
                let row = &mut self.grid[self.cursor.line];
                for cell in &mut row[..] {
                    cell.reset(&template);
                }
            },
        }
    }

    #[inline]
    fn clear_screen(&mut self, mode: ansi::ClearMode) {
        debug_println!("clear_screen: {:?}", mode);
        let template = self.empty_cell.clone();
        match mode {
            ansi::ClearMode::Below => {
                for row in &mut self.grid[self.cursor.line..] {
                    for cell in row {
                        cell.reset(&template);
                    }
                }
            },
            ansi::ClearMode::All => {
                self.grid.clear(|c| c.reset(&template));
            },
            _ => {
                panic!("ansi::ClearMode::Above not implemented");
            }
        }
    }

    #[inline]
    fn clear_tabs(&mut self, mode: ansi::TabulationClearMode) {
        err_println!("[unimplemented] clear_tabs: {:?}", mode);
    }

    #[inline]
    fn reset_state(&mut self) {
        err_println!("[unimplemented] reset_state");
    }

    #[inline]
    fn reverse_index(&mut self) {
        debug_println!("reverse_index");
        // if cursor is at the top
        if self.cursor.line == self.scroll_region.start {
            self.scroll_down(Line(1));
        } else {
            self.cursor.line -= 1;
        }
    }

    /// set a terminal attribute
    #[inline]
    fn terminal_attribute(&mut self, attr: Attr) {
        debug_println!("Set Attribute: {:?}", attr);
        match attr {
            Attr::Foreground(named_color) => {
                self.template_cell.fg = cell::Color::Ansi(named_color);
            },
            Attr::Background(named_color) => {
                self.template_cell.bg = cell::Color::Ansi(named_color);
            },
            Attr::ForegroundSpec(rgb) => {
                self.template_cell.fg = cell::Color::Rgb(rgb);
            },
            Attr::BackgroundSpec(rgb) => {
                self.template_cell.bg = cell::Color::Rgb(rgb);
            },
            Attr::Reset => {
                self.template_cell.fg = cell::Color::Ansi(Color::Foreground);
                self.template_cell.bg = cell::Color::Ansi(Color::Background);
                self.template_cell.flags = cell::Flags::empty();
            },
            Attr::Reverse => self.template_cell.flags.insert(cell::INVERSE),
            Attr::CancelReverse => self.template_cell.flags.remove(cell::INVERSE),
            Attr::Bold => self.template_cell.flags.insert(cell::BOLD),
            Attr::CancelBoldDim => self.template_cell.flags.remove(cell::BOLD),
            Attr::Italic => self.template_cell.flags.insert(cell::ITALIC),
            Attr::CancelItalic => self.template_cell.flags.remove(cell::ITALIC),
            Attr::Underscore => self.template_cell.flags.insert(cell::UNDERLINE),
            Attr::CancelUnderline => self.template_cell.flags.remove(cell::UNDERLINE),
            _ => {
                debug_println!("Term got unhandled attr: {:?}", attr);
            }
        }
    }

    #[inline]
    fn set_mode(&mut self, mode: ansi::Mode) {
        debug_println!("set_mode: {:?}", mode);
        match mode {
            ansi::Mode::SwapScreenAndSetRestoreCursor => self.swap_alt(),
            ansi::Mode::ShowCursor => self.mode.insert(mode::SHOW_CURSOR),
            ansi::Mode::CursorKeys => self.mode.insert(mode::APP_CURSOR),
            ansi::Mode::ReportMouseClicks => self.mode.insert(mode::MOUSE_REPORT_CLICK),
            _ => {
                debug_println!(".. ignoring set_mode");
            }
        }
    }

    #[inline]
    fn unset_mode(&mut self,mode: ansi::Mode) {
        debug_println!("unset_mode: {:?}", mode);
        match mode {
            ansi::Mode::SwapScreenAndSetRestoreCursor => self.swap_alt(),
            ansi::Mode::ShowCursor => self.mode.remove(mode::SHOW_CURSOR),
            ansi::Mode::CursorKeys => self.mode.remove(mode::APP_CURSOR),
            ansi::Mode::ReportMouseClicks => self.mode.remove(mode::MOUSE_REPORT_CLICK),
            _ => {
                debug_println!(".. ignoring unset_mode");
            }
        }
    }

    #[inline]
    fn set_scrolling_region(&mut self, region: Range<Line>) {
        debug_println!("set scroll region: {:?}", region);
        self.scroll_region = region;
        self.goto(Line(0), Column(0));
    }

    #[inline]
    fn set_keypad_application_mode(&mut self) {
        debug_println!("set mode::APP_KEYPAD");
        self.mode.insert(mode::APP_KEYPAD);
    }

    #[inline]
    fn unset_keypad_application_mode(&mut self) {
        debug_println!("unset mode::APP_KEYPAD");
        self.mode.remove(mode::APP_KEYPAD);
    }
}

#[cfg(test)]
mod tests {
    extern crate serde_json;
    extern crate test;

    use super::limit;

    use ansi::Color;
    use grid::Grid;
    use index::{Line, Column};
    use term::{cell, Cell};

    /// Check that the grid can be serialized back and forth losslessly
    ///
    /// This test is in the term module as opposed to the grid since we want to
    /// test this property with a T=Cell.
    #[test]
    fn grid_serde() {
        let template = Cell::new(
            ' ',
            cell::Color::Ansi(Color::Foreground),
            cell::Color::Ansi(Color::Background)
        );

        let grid = Grid::new(Line(24), Column(80), &template);
        let serialized = serde_json::to_string(&grid).expect("ser");
        let deserialized = serde_json::from_str::<Grid<Cell>>(&serialized)
                                      .expect("de");

        assert_eq!(deserialized, grid);
    }

    #[test]
    fn limit_works() {
        assert_eq!(limit(5, 1, 10), 5);
        assert_eq!(limit(5, 6, 10), 6);
        assert_eq!(limit(5, 1, 4), 4);
    }
}

#[cfg(test)]
mod bench {
    extern crate test;
    extern crate serde_json as json;

    use std::io::Read;
    use std::fs::File;
    use std::mem;
    use std::path::Path;

    use grid::Grid;

    use super::{SizeInfo, Term};
    use super::cell::Cell;

    fn read_string<P>(path: P) -> String
        where P: AsRef<Path>
    {
        let mut res = String::new();
        File::open(path.as_ref()).unwrap()
            .read_to_string(&mut res).unwrap();

        res
    }

    /// Benchmark for the renderable cells iterator
    ///
    /// The renderable cells iterator yields cells that require work to be displayed (that is, not a
    /// an empty background cell). This benchmark measures how long it takes to process the whole
    /// iterator.
    ///
    /// When this benchmark was first added, it averaged ~78usec on my macbook pro. The total
    /// render time for this grid is anywhere between ~1500 and ~2000usec (measured imprecisely with
    /// the visual meter).
    #[bench]
    fn render_iter(b: &mut test::Bencher) {
        // Need some realistic grid state; using one of the ref files.
        let serialized_grid = read_string(
            concat!(env!("CARGO_MANIFEST_DIR"), "/tests/ref/vim_large_window_scroll/grid.json")
        );
        let serialized_size = read_string(
            concat!(env!("CARGO_MANIFEST_DIR"), "/tests/ref/vim_large_window_scroll/size.json")
        );

        let mut grid: Grid<Cell> = json::from_str(&serialized_grid).unwrap();
        let size: SizeInfo = json::from_str(&serialized_size).unwrap();

        let mut terminal = Term::new(size);
        mem::swap(&mut terminal.grid, &mut grid);

        b.iter(|| {
            let iter = terminal.renderable_cells();
            for cell in iter {
                test::black_box(cell);
            }
        })
    }
}