Class: Muxr::Terminal

Inherits:
Object
  • Object
show all
Defined in:
lib/muxr/terminal.rb

Overview

A minimal VT100/ANSI terminal emulator. It maintains a fixed grid of cells plus a cursor and parser state. Bytes fed from a PTY are interpreted into mutations of the grid which the Renderer then composites into the final frame. The emulator implements enough of the protocol to host typical interactive shells (bash, zsh) and line-oriented programs.

Defined Under Namespace

Classes: Cell

Constant Summary collapse

BOLD = 
1
UNDERLINE = 
2
REVERSE = 
4
DIM = 
8
SCROLLBACK_MAX = 
5000
SYNC_TIMEOUT =

Inner programs (fzf ≥ 0.41, neovim, helix, …) bracket coherent screen updates with ‘e[?2026h … e[?2026l` (DECSET 2026 — “Synchronized Output”). When we see the open, we know more bytes are coming that belong to the same logical frame; rendering before the close shows a half-painted state. SYNC_TIMEOUT is the safety cap so a crashed inner program (which left ?2026h open) cannot wedge the pane indefinitely.

0.2

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(rows: 24, cols: 80) ⇒ Terminal

Returns a new instance of Terminal.



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# File 'lib/muxr/terminal.rb', line 41

def initialize(rows: 24, cols: 80)
  @rows = rows
  @cols = cols
  @buffer = Array.new(rows) { Array.new(cols) { blank_cell } }
  @cursor_row = 0
  @cursor_col = 0
  @saved_cursor = [0, 0]
  @fg = nil
  @bg = nil
  @attrs = 0
  @autowrap_pending = false
  @scroll_top = 0
  @scroll_bottom = rows - 1
  @parser_state = :ground
  @parser_params = +""
  @feed_remainder = +"".b
  @dirty = true
  @scrollback = []
  @view_offset = 0
  @selection_anchor = nil
  @selection_cursor = nil
  @selection_mode = :linear
  @sync_pending = false
  @sync_started_at = nil
end

Instance Attribute Details

#cols ⇒ Object (readonly)

Returns the value of attribute cols.



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# File 'lib/muxr/terminal.rb', line 39

def cols
  @cols
end

#cursor_col ⇒ Object (readonly)

Returns the value of attribute cursor_col.



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# File 'lib/muxr/terminal.rb', line 39

def cursor_col
  @cursor_col
end

#cursor_row ⇒ Object (readonly)

Returns the value of attribute cursor_row.



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# File 'lib/muxr/terminal.rb', line 39

def cursor_row
  @cursor_row
end

#rows ⇒ Object (readonly)

Returns the value of attribute rows.



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# File 'lib/muxr/terminal.rb', line 39

def rows
  @rows
end

#selection_mode ⇒ Object (readonly)

Returns the value of attribute selection_mode.



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# File 'lib/muxr/terminal.rb', line 86

def selection_mode
  @selection_mode
end

#view_offset ⇒ Object (readonly)

Returns the value of attribute view_offset.



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# File 'lib/muxr/terminal.rb', line 39

def view_offset
  @view_offset
end

Instance Method Details

#anchor_selection!(mode: :linear) ⇒ Object

Drop the anchor at the cursor’s current position. ‘mode` controls the selection shape: :linear (character-by-character, reading order) or :block (rectangular).



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# File 'lib/muxr/terminal.rb', line 157

def anchor_selection!(mode: :linear)
  return unless @selection_cursor
  @selection_anchor = @selection_cursor.dup
  @selection_mode = mode
  @dirty = true
end

#cell(r, c) ⇒ Object 



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# File 'lib/muxr/terminal.rb', line 88

def cell(r, c)
  @buffer[r][c]
end

#clear_anchor! ⇒ Object

Drop the anchor but keep the cursor so the user can continue navigating (vim’s behavior when pressing v while already in linear visual mode).



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# File 'lib/muxr/terminal.rb', line 166

def clear_anchor!
  return unless @selection_anchor
  @selection_anchor = nil
  @dirty = true
end

#clear_dirty! ⇒ Object 



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# File 'lib/muxr/terminal.rb', line 368

def clear_dirty!
  @dirty = false
end

#clear_selection ⇒ Object 



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# File 'lib/muxr/terminal.rb', line 306

def clear_selection
  return unless @selection_anchor
  @selection_anchor = nil
  @selection_cursor = nil
  @dirty = true
end

#dirty? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/muxr/terminal.rb', line 364

def dirty?
  @dirty
end

#extract_selection_text ⇒ Object 



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# File 'lib/muxr/terminal.rb', line 327

def extract_selection_text
  return "" unless @selection_anchor
  if @selection_mode == :block
    ar, ac = @selection_anchor
    br, bc = @selection_cursor
    min_r, max_r = ar <= br ? [ar, br] : [br, ar]
    min_c, max_c = ac <= bc ? [ac, bc] : [bc, ac]
    lines = []
    (min_r..max_r).each do |tr|
      row = timeline_row(tr)
      if row.nil? || min_c >= row.length
        lines << ""
        next
      end
      last = [max_c, row.length - 1].min
      chars = (min_c..last).map { |c| row[c]&.char || " " }
      lines << chars.join.rstrip
    end
    return lines.join("\n")
  end
  sr, sc, er, ec = ordered_selection
  lines = []
  (sr..er).each do |tr|
    row = timeline_row(tr)
    if row.nil?
      lines << ""
      next
    end
    first = (tr == sr) ? sc : 0
    last = (tr == er) ? ec : row.length - 1
    last = [last, row.length - 1].min
    chars = (first..last).map { |c| row[c]&.char || " " }
    lines << chars.join.rstrip
  end
  lines.join("\n")
end

#feed(data) ⇒ Object 



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# File 'lib/muxr/terminal.rb', line 398

def feed(data)
  bytes = @feed_remainder + data.b
  @feed_remainder = +"".b
  str = bytes.dup.force_encoding(Encoding::UTF_8)
  unless str.valid_encoding?
    # Find the longest valid UTF-8 prefix and stash the remainder for the
    # next feed call so multi-byte characters don't get garbled across PTY
    # read boundaries.
    raw = bytes.bytes
    while raw.any?
      candidate = raw.pack("C*").force_encoding(Encoding::UTF_8)
      break if candidate.valid_encoding?
      @feed_remainder = ([raw.last] + @feed_remainder.bytes).pack("C*").b
      raw.pop
    end
    str = raw.pack("C*").force_encoding(Encoding::UTF_8)
    # Bail out completely if we couldn't decode anything yet.
    return if str.empty?
  end
  str.each_char { |c| process_char(c) }
  @dirty = true
end

#move_selection_cursor_by(dr, dc) ⇒ Object 



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# File 'lib/muxr/terminal.rb', line 178

def move_selection_cursor_by(dr, dc)
  return unless @selection_cursor
  tr, tc = @selection_cursor
  ntr = (tr + dr).clamp(0, timeline_size - 1)
  ntc = (tc + dc).clamp(0, @cols - 1)
  return if ntr == tr && ntc == tc
  @selection_cursor = [ntr, ntc]
  ensure_selection_cursor_visible
  @dirty = true
end

#place_selection_cursor(r, c) ⇒ Object

Place the moving cursor at a viewport position without dropping an anchor — the user is still navigating, not yet selecting.



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# File 'lib/muxr/terminal.rb', line 146

def place_selection_cursor(r, c)
  tr = timeline_row_for_visible(r).clamp(0, timeline_size - 1)
  tc = c.clamp(0, @cols - 1)
  @selection_cursor = [tr, tc]
  @selection_anchor = nil
  @dirty = true
end

#resize(rows, cols) ⇒ Object 



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# File 'lib/muxr/terminal.rb', line 372

def resize(rows, cols)
  return if rows == @rows && cols == @cols
  new_buf = Array.new(rows) { Array.new(cols) { blank_cell } }
  keep_rows = [rows, @rows].min
  keep_cols = [cols, @cols].min
  src_start = @rows - keep_rows
  keep_rows.times do |i|
    keep_cols.times do |j|
      new_buf[i][j].copy_from(@buffer[src_start + i][j])
    end
  end
  @buffer = new_buf
  @rows = rows
  @cols = cols
  @scroll_top = 0
  @scroll_bottom = rows - 1
  @cursor_row = @cursor_row.clamp(0, rows - 1)
  @cursor_col = @cursor_col.clamp(0, cols - 1)
  @autowrap_pending = false
  # Selection points at timeline rows whose shape can't be remapped
  # meaningfully through a resize, so drop it rather than show a smear.
  @selection_anchor = nil
  @selection_cursor = nil
  @dirty = true
end

#scroll_back(n = 1) ⇒ Object 



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# File 'lib/muxr/terminal.rb', line 116

def scroll_back(n = 1)
  set_view_offset(@view_offset + n)
end

#scroll_forward(n = 1) ⇒ Object 



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# File 'lib/muxr/terminal.rb', line 120

def scroll_forward(n = 1)
  set_view_offset(@view_offset - n)
end

#scroll_to_bottom ⇒ Object 



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# File 'lib/muxr/terminal.rb', line 128

def scroll_to_bottom
  set_view_offset(0)
end

#scroll_to_top ⇒ Object 



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# File 'lib/muxr/terminal.rb', line 124

def scroll_to_top
  set_view_offset(@scrollback.size)
end

#scrollback_size ⇒ Object 



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# File 'lib/muxr/terminal.rb', line 108

def scrollback_size
  @scrollback.size
end

#scrolled_back? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/muxr/terminal.rb', line 112

def scrolled_back?
  @view_offset > 0
end

#selected_at_visible?(r, c) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/muxr/terminal.rb', line 313

def selected_at_visible?(r, c)
  return false unless @selection_anchor
  tr = timeline_row_for_visible(r)
  inside_selection?(tr, c)
end

#selection_active? ⇒ Boolean

———- selection ———-

Selection coordinates are in the combined “timeline”:

0..scrollback.size-1                 → @scrollback rows
scrollback.size..scrollback.size+rows-1 → @buffer rows

so the selection stays anchored to the same text as the user pages through history.

Returns:

  • (Boolean) 


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# File 'lib/muxr/terminal.rb', line 140

def selection_active?
  !@selection_anchor.nil?
end

#selection_cursor_to(tr, tc) ⇒ Object 



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# File 'lib/muxr/terminal.rb', line 189

def selection_cursor_to(tr, tc)
  return unless @selection_cursor
  ntr = tr.clamp(0, timeline_size - 1)
  ntc = tc.clamp(0, @cols - 1)
  @selection_cursor = [ntr, ntc]
  ensure_selection_cursor_visible
  @dirty = true
end

#selection_cursor_to_bottom ⇒ Object 



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# File 'lib/muxr/terminal.rb', line 212

def selection_cursor_to_bottom
  selection_cursor_to(timeline_size - 1, @cols - 1)
end

#selection_cursor_to_first_non_blank ⇒ Object 



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# File 'lib/muxr/terminal.rb', line 216

def selection_cursor_to_first_non_blank
  return unless @selection_cursor
  tr = @selection_cursor[0]
  selection_cursor_to(tr, first_non_blank_col(tr))
end

#selection_cursor_to_line_end ⇒ Object 



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# File 'lib/muxr/terminal.rb', line 203

def selection_cursor_to_line_end
  return unless @selection_cursor
  selection_cursor_to(@selection_cursor[0], @cols - 1)
end

#selection_cursor_to_line_start ⇒ Object 



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# File 'lib/muxr/terminal.rb', line 198

def selection_cursor_to_line_start
  return unless @selection_cursor
  selection_cursor_to(@selection_cursor[0], 0)
end

#selection_cursor_to_top ⇒ Object 



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# File 'lib/muxr/terminal.rb', line 208

def selection_cursor_to_top
  selection_cursor_to(0, 0)
end

#selection_cursor_to_viewport(where) ⇒ Object

Jump to top/middle/bottom of the visible viewport (vim H/M/L), landing on the first non-blank column of the destination line.



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# File 'lib/muxr/terminal.rb', line 224

def selection_cursor_to_viewport(where)
  return unless @selection_cursor
  vr = case where
       when :top    then 0
       when :middle then @rows / 2
       when :bottom then @rows - 1
       end
  return if vr.nil?
  tr = timeline_row_for_visible(vr).clamp(0, timeline_size - 1)
  selection_cursor_to(tr, first_non_blank_col(tr))
end

#selection_cursor_visible ⇒ Object 



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# File 'lib/muxr/terminal.rb', line 319

def selection_cursor_visible
  return nil unless @selection_cursor
  tr, tc = @selection_cursor
  vr = tr - (@scrollback.size - @view_offset)
  return nil unless vr.between?(0, @rows - 1)
  [vr, tc]
end

#selection_cursor_word_backward(big: false) ⇒ Object 



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# File 'lib/muxr/terminal.rb', line 281

def selection_cursor_word_backward(big: false)
  return unless @selection_cursor
  tr, tc = @selection_cursor
  pos = step_backward(tr, tc)
  return unless pos
  tr, tc = pos
  while char_class_at(tr, tc, big: big) == :space
    pos = step_backward(tr, tc)
    unless pos
      selection_cursor_to(tr, tc)
      return
    end
    tr, tc = pos
  end
  cls = char_class_at(tr, tc, big: big)
  loop do
    pos = step_backward(tr, tc)
    if pos.nil? || pos[0] != tr || char_class_at(pos[0], pos[1], big: big) != cls
      selection_cursor_to(tr, tc)
      return
    end
    tr, tc = pos
  end
end

#selection_cursor_word_end(big: false) ⇒ Object 



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# File 'lib/muxr/terminal.rb', line 258

def selection_cursor_word_end(big: false)
  return unless @selection_cursor
  tr, tc = @selection_cursor
  pos = step_forward(tr, tc)
  return unless pos
  tr, tc = pos
  while char_class_at(tr, tc, big: big) == :space
    pos = step_forward(tr, tc)
    break unless pos
    tr, tc = pos
  end
  return if char_class_at(tr, tc, big: big) == :space
  cls = char_class_at(tr, tc, big: big)
  loop do
    pos = step_forward(tr, tc)
    if pos.nil? || pos[0] != tr || char_class_at(pos[0], pos[1], big: big) != cls
      selection_cursor_to(tr, tc)
      return
    end
    tr, tc = pos
  end
end

#selection_cursor_word_forward(big: false) ⇒ Object 



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# File 'lib/muxr/terminal.rb', line 236

def selection_cursor_word_forward(big: false)
  return unless @selection_cursor
  tr, tc = @selection_cursor
  prev_cls = char_class_at(tr, tc, big: big)
  loop do
    nxt = step_forward(tr, tc)
    break unless nxt
    ntr, ntc = nxt
    cur_cls = char_class_at(ntr, ntc, big: big)
    # Row boundaries act as whitespace breaks even when the row is fully
    # packed (no trailing pad) — visually the user sees a new line.
    effective_prev = (ntr != tr) ? :space : prev_cls
    if effective_prev != cur_cls && cur_cls != :space
      selection_cursor_to(ntr, ntc)
      return
    end
    tr, tc = ntr, ntc
    prev_cls = cur_cls
  end
  selection_cursor_to(timeline_size - 1, @cols - 1)
end

#start_selection_at_visible(r, c, mode: :linear) ⇒ Object

Convenience for tests: place cursor at (r,c) AND anchor immediately.



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# File 'lib/muxr/terminal.rb', line 173

def start_selection_at_visible(r, c, mode: :linear)
  place_selection_cursor(r, c)
  anchor_selection!(mode: mode)
end

#sync_deadline ⇒ Object 



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# File 'lib/muxr/terminal.rb', line 81

def sync_deadline
  return nil unless @sync_pending && @sync_started_at
  @sync_started_at + SYNC_TIMEOUT
end

#sync_pending? ⇒ Boolean

True iff the inner program has opened a synchronized-output block (e[?2026h) and not yet closed it, and the safety timeout has not elapsed. The Application uses this to defer rendering so the diff lands on a fully-formed frame instead of a half-painted one.

Returns:

  • (Boolean) 


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# File 'lib/muxr/terminal.rb', line 71

def sync_pending?
  return false unless @sync_pending
  if @sync_started_at && (Process.clock_gettime(Process::CLOCK_MONOTONIC) - @sync_started_at) > SYNC_TIMEOUT
    @sync_pending = false
    @sync_started_at = nil
    return false
  end
  true
end

#visible_cell(r, c) ⇒ Object

Returns the Cell that should be visible at (r, c) given the current scrollback view_offset. When view_offset == 0 this is the live grid. When view_offset > 0, rows in the top of the visible area are sourced from @scrollback instead.



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# File 'lib/muxr/terminal.rb', line 96

def visible_cell(r, c)
  return @buffer[r][c] if @view_offset.zero?
  idx = @scrollback.size - @view_offset + r
  if idx < @scrollback.size
    row = @scrollback[idx]
    return blank_cell if row.nil? || c >= row.length
    row[c]
  else
    @buffer[idx - @scrollback.size][c]
  end
end