Module: TUITD::ANSIParser

Defined in:
lib/tui_td/ansi_parser.rb

Overview

Parses raw terminal output (ANSI escape sequences + text) into a structured state representation.

Handles:

  • SGR (Select Graphic Rendition) — colors, bold, italic, underline

  • Cursor movement (CUU, CUD, CUF, CUB, CUP)

  • Erase (ED, EL)

  • Line feed, carriage return, backspace, tab

Output: [[{char, fg, bg, bold, italic, underline]], cursor: col, size: cols}

Constant Summary collapse

SGR_COLORS = 
{
  0  => :reset,
  1  => :bold,
  3  => :italic,
  4  => :underline,
  5  => :blink,
  7  => :reverse,
  22 => :normal,
  23 => :no_italic,
  24 => :no_underline,
  30 => :black,
  31 => :red,
  32 => :green,
  33 => :yellow,
  34 => :blue,
  35 => :magenta,
  36 => :cyan,
  37 => :white,
  38 => :xterm_fg,  # 38;5;N or 38;2;R;G;B
  39 => :default_fg,
  40 => :bg_black,
  41 => :bg_red,
  42 => :bg_green,
  43 => :bg_yellow,
  44 => :bg_blue,
  45 => :bg_magenta,
  46 => :bg_cyan,
  47 => :bg_white,
  48 => :xterm_bg,  # 48;5;N or 48;2;R;G;B
  49 => :default_bg,
  90 => :bright_black,
  91 => :bright_red,
  92 => :bright_green,
  93 => :bright_yellow,
  94 => :bright_blue,
  95 => :bright_magenta,
  96 => :bright_cyan,
  97 => :bright_white,
  100 => :bg_bright_black,
  101 => :bg_bright_red,
  102 => :bg_bright_green,
  103 => :bg_bright_yellow,
  104 => :bg_bright_blue,
  105 => :bg_bright_magenta,
  106 => :bg_bright_cyan,
  107 => :bg_bright_white,
}.freeze
SGR_16_TO_NAME = 
{
  0  => "black",
  1  => "red",
  2  => "green",
  3  => "yellow",
  4  => "blue",
  5  => "magenta",
  6  => "cyan",
  7  => "white",
  8  => "bright_black",
  9  => "bright_red",
  10 => "bright_green",
  11 => "bright_yellow",
  12 => "bright_blue",
  13 => "bright_magenta",
  14 => "bright_cyan",
  15 => "bright_white",
}.freeze

Class Method Summary collapse

Class Method Details

._apply_csi(seq, cursor, attrs, grid, rows, cols) ⇒ Object 



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# File 'lib/tui_td/ansi_parser.rb', line 214

def self._apply_csi(seq, cursor, attrs, grid, rows, cols)
  # Strip leading escape char if present
  cleaned = seq.sub(/^\e/, "")
  match = cleaned.match(/^\[([\d;]*)([A-HJ-KP-SX@`fhmnR])$/)
  return unless match

  params = match[1].split(";").map(&:to_i)
  command = match[2]

  case command
  when "m"
    _apply_sgr(params, attrs)
  when "A" # CUU — Cursor Up
    n = params[0] || 1
    n = 1 if n == 0
    cursor[:row] = [cursor[:row] - n, 0].max
  when "B" # CUD — Cursor Down
    n = params[0] || 1
    n = 1 if n == 0
    cursor[:row] = [cursor[:row] + n, rows - 1].min
  when "C" # CUF — Cursor Forward
    n = params[0] || 1
    n = 1 if n == 0
    cursor[:col] = [cursor[:col] + n, cols - 1].min
  when "D" # CUB — Cursor Back
    n = params[0] || 1
    n = 1 if n == 0
    cursor[:col] = [cursor[:col] - n, 0].max
  when "H", "f" # CUP — Cursor Position
    r = (params[0] || 1) - 1
    c = (params[1] || 1) - 1
    cursor[:row] = r.clamp(0, rows - 1)
    cursor[:col] = c.clamp(0, cols - 1)
  when "J" # ED — Erase in Display
    case params[0]
    when nil, 0
      _erase_down(cursor, grid, rows, cols)
    when 1
      _erase_up(cursor, grid, cols)
    when 2, 3
      _erase_all(grid, rows, cols)
      cursor[:row] = 0
      cursor[:col] = 0
    end
  when "K" # EL — Erase in Line
    case params[0]
    when nil, 0
      _erase_line_right(cursor, grid, cols)
    when 1
      _erase_line_left(cursor, grid, cols)
    when 2
      _erase_line(cursor, grid, cols)
    end
  when "X" # Erase Characters
    n = params[0] || 1
    n.times do |i|
      next unless cursor[:row] < rows && cursor[:col] + i < cols
      grid[cursor[:row]][cursor[:col] + i][:char] = " "
    end
  when "n" # DSR — Device Status Report request
    # \e[6n = request cursor position → caller must respond with \e[row;colR
    return params[0] == 6
  when "R" # DSR response (from terminal side) or CPR — ignore
    nil
  end
end

._apply_sgr(params, attrs) ⇒ Object 



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# File 'lib/tui_td/ansi_parser.rb', line 281

def self._apply_sgr(params, attrs)
  return attrs.merge!(fg: "default", bg: "default", bold: false, italic: false, underline: false) if params.empty? || params == [0]

  i = 0
  while i < params.length
    p = params[i]
    case p
    when 0
      attrs.merge!(fg: "default", bg: "default", bold: false, italic: false, underline: false)
    when 1
      attrs[:bold] = true
    when 3
      attrs[:italic] = true
    when 4
      attrs[:underline] = true
    when 22
      attrs[:bold] = false
    when 23
      attrs[:italic] = false
    when 24
      attrs[:underline] = false
    when 7
      # Reverse — swap fg and bg
      attrs[:fg], attrs[:bg] = attrs[:bg], attrs[:fg]
    when 27
      attrs[:fg], attrs[:bg] = attrs[:bg], attrs[:fg]
    when 30..37
      attrs[:fg] = SGR_16_TO_NAME[p - 30] || "color#{p - 30}"
    when 38
      # Extended foreground
      if params[i + 1] == 5
        color = params[i + 2]
        attrs[:fg] = "color#{color}"
        i += 2
      elsif params[i + 1] == 2
        r, g, b = params[i + 2], params[i + 3], params[i + 4]
        attrs[:fg] = format("#%02x%02x%02x", r, g, b)
        i += 4
      end
    when 39
      attrs[:fg] = "default"
    when 40..47
      attrs[:bg] = SGR_16_TO_NAME[p - 40] || "bg_color#{p - 40}"
    when 48
      # Extended background
      if params[i + 1] == 5
        color = params[i + 2]
        attrs[:bg] = "color#{color}"
        i += 2
      elsif params[i + 1] == 2
        r, g, b = params[i + 2], params[i + 3], params[i + 4]
        attrs[:bg] = format("#%02x%02x%02x", r, g, b)
        i += 4
      end
    when 49
      attrs[:bg] = "default"
    when 90..97
      attrs[:fg] = "bright_#{SGR_16_TO_NAME[p - 90] || "color#{p - 90 + 8}"}"
    when 100..107
      attrs[:bg] = "bright_#{SGR_16_TO_NAME[p - 100] || "color#{p - 100 + 8}"}"
    end
    i += 1
  end
end

._color_code(name, prefix) ⇒ Object 



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# File 'lib/tui_td/ansi_parser.rb', line 395

def self._color_code(name, prefix)
  case name
  when "default" then nil
  when /^(bright_)?(.+)$/
    base_name = $2
    index = SGR_16_TO_NAME.key(base_name)
    index += 8 if $1 && index && index < 8
    index ? "#{prefix};5;#{index}" : nil
  when /^#([0-9a-fA-F]{6})$/
    r = $1[0..1].to_i(16)
    g = $1[2..3].to_i(16)
    b = $1[4..5].to_i(16)
    "#{prefix};2;#{r};#{g};#{b}"
  else
    nil
  end
end

._erase_all(grid, rows, cols) ⇒ Object 



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# File 'lib/tui_td/ansi_parser.rb', line 372

def self._erase_all(grid, rows, cols)
  rows.times do |ri|
    cols.times { |ci| grid[ri][ci][:char] = " " }
  end
end

._erase_down(cursor, grid, rows, cols) ⇒ Object 



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# File 'lib/tui_td/ansi_parser.rb', line 346

def self._erase_down(cursor, grid, rows, cols)
  r = cursor[:row]
  c = cursor[:col]

  # Erase from cursor to end of line
  (c...cols).each { |ci| grid[r][ci][:char] = " " if r < rows }

  # Erase remaining lines
  ((r + 1)...rows).each do |ri|
    cols.times { |ci| grid[ri][ci][:char] = " " }
  end
end

._erase_line(cursor, grid, cols) ⇒ Object 



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# File 'lib/tui_td/ansi_parser.rb', line 390

def self._erase_line(cursor, grid, cols)
  r = cursor[:row]
  cols.times { |ci| grid[r][ci][:char] = " " if r < grid.length }
end

._erase_line_left(cursor, grid, cols) ⇒ Object 



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# File 'lib/tui_td/ansi_parser.rb', line 384

def self._erase_line_left(cursor, grid, cols)
  r = cursor[:row]
  c = cursor[:col]
  (0..c).each { |ci| grid[r][ci][:char] = " " if r < grid.length }
end

._erase_line_right(cursor, grid, cols) ⇒ Object 



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# File 'lib/tui_td/ansi_parser.rb', line 378

def self._erase_line_right(cursor, grid, cols)
  r = cursor[:row]
  c = cursor[:col]
  (c...cols).each { |ci| grid[r][ci][:char] = " " if r < grid.length }
end

._erase_up(cursor, grid, cols) ⇒ Object 



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# File 'lib/tui_td/ansi_parser.rb', line 359

def self._erase_up(cursor, grid, cols)
  r = cursor[:row]
  c = cursor[:col]

  # Erase lines above cursor
  (0...r).each do |ri|
    cols.times { |ci| grid[ri][ci][:char] = " " }
  end

  # Erase from start of line to cursor
  (0..c).each { |ci| grid[r][ci][:char] = " " }
end

._utf8_char_at(str, i) ⇒ Object

Extract a single UTF-8 character at position i in a binary string. Returns [char_string, byte_length] or nil if the byte is not printable/valid.



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# File 'lib/tui_td/ansi_parser.rb', line 415

def self._utf8_char_at(str, i)
  byte = str.getbyte(i)
  return nil unless byte

  if byte < 0x80
    # Single-byte ASCII
    return nil unless byte >= 0x20  # only printable, skip control chars
    return [byte.chr, 1]
  end

  # Multi-byte UTF-8
  len = if byte & 0xE0 == 0xC0
          2
  elsif byte & 0xF0 == 0xE0
          3
  elsif byte & 0xF8 == 0xF0
          4
  else
          return nil  # continuation byte or invalid — let main loop advance
  end
  return nil if i + len > str.bytesize

  bytes = str.byteslice(i, len)
  char = bytes.dup.force_encoding("UTF-8")
  return nil unless char.valid_encoding?

  [char, len]
rescue StandardError
  nil
end

.build_frame(state) ⇒ Object

Rebuild ANSI output from a state hash (for rendering/screenshot)



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# File 'lib/tui_td/ansi_parser.rb', line 174

def self.build_frame(state)
  rows = state.dig(:size, :rows) || state["size"]["rows"]
  cols = state.dig(:size, :cols) || state["size"]["cols"]
  grid = state[:rows] || state["rows"]
  cursor = state[:cursor] || state["cursor"]

  out = +""
  out << "\e[0m"
  out << "\e[2J\e[H"

  grid.each_with_index do |row, ri|
    row.each_with_index do |cell, ci|
      char = cell[:char] || cell["char"] || " "
      fg = cell[:fg] || cell["fg"] || "default"
      bg = cell[:bg] || cell["bg"] || "default"
      bold = cell[:bold] || cell["bold"] || false
      italic = cell[:italic] || cell["italic"] || false
      underline = cell[:underline] || cell["underline"] || false

      codes = []
      codes << "1" if bold
      codes << "3" if italic
      codes << "4" if underline

      fg_code = _color_code(fg, "38")
      bg_code = _color_code(bg, "48")

      codes << fg_code if fg_code
      codes << bg_code if bg_code

      out << "\e[#{codes.join(";")}m" unless codes.empty?
      out << char
    end
    out << "\n" if ri < rows - 1
  end

  out << "\e[0m"
  out
end

.parse(raw, rows = 40, cols = 120) ⇒ Object

Parse raw terminal output into a structured state Hash



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# File 'lib/tui_td/ansi_parser.rb', line 84

def self.parse(raw, rows = 40, cols = 120)
  grid = Array.new(rows) do
    Array.new(cols) do
      { char: " ", fg: "default", bg: "default", bold: false, italic: false, underline: false }
    end
  end

  cursor = { row: 0, col: 0 }
  attrs = { fg: "default", bg: "default", bold: false, italic: false, underline: false }
  saved_cursor = nil
  scroll_region = nil
  pending_dsr = false

  # Strip everything before the last full clear (if any)
  # to avoid accumulated garbage
  processed = raw

  i = 0
  while i < processed.length
    if processed[i] == "\e" && processed[i + 1] == "["
      # Find end of CSI sequence
      j = i + 2
      j += 1 while j < processed.length && !processed[j].match?(/[A-HJ-KP-SX@`fmnR]/)
      seq = processed[i..j]

      dsr = _apply_csi(seq, cursor, attrs, grid, rows, cols)
      pending_dsr ||= dsr

      i = j + 1
    elsif processed[i] == "\n" || processed[i] == "\r\n"
      cursor[:row] += 1
      cursor[:col] = 0
      i += processed[i..i + 1] == "\r\n" ? 2 : 1
    elsif processed[i] == "\r"
      cursor[:col] = 0
      i += 1
    elsif processed[i] == "\t"
      cursor[:col] = ((cursor[:col] / 8) + 1) * 8
      cursor[:col] = cols - 1 if cursor[:col] >= cols
      i += 1
    elsif processed[i] == "\b"
      cursor[:col] -= 1 if cursor[:col] > 0
      i += 1
    elsif processed[i] == "\a"
      # Bell — ignore
      i += 1
    elsif processed[i] == "\e"
      # Skip escape sequences:
      #   CSI: \e[... (already handled above)
      #   ISO 2022 charset: \e( B  \e) 0  etc. (3 chars total)
      #   Other: just the ESC
      if processed[i + 1] && processed[i + 1].match?(/[()*+\-.\/]/)
        i += 3
      else
        i += 1
      end
    elsif (char, char_len = _utf8_char_at(processed, i))
      # Printable character (including multi-byte UTF-8)
      if cursor[:row] < rows && cursor[:col] < cols
        cell = grid[cursor[:row]][cursor[:col]]
        cell[:char] = char
        cell.merge!(attrs)
        cursor[:col] += 1
        cursor[:col] = cols - 1 if cursor[:col] >= cols
      end
      i += char_len
    else
      i += 1
    end

    # Handle scrolling
    if cursor[:row] >= rows
      scroll_lines = cursor[:row] - rows + 1
      grid.shift(scroll_lines)
      scroll_lines.times do
        grid << Array.new(cols) { { char: " ", fg: "default", bg: "default", bold: false, italic: false, underline: false } }
      end
      cursor[:row] = rows - 1
    end
  end

  {
    size: { rows: rows, cols: cols },
    cursor: cursor,
    rows: grid,
    pending_dsr: pending_dsr,
  }
end