Class: EscapeParser

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

Overview

See: invisible-island.net/xterm/ctlseqs/ctlseqs.html#h3-Controls-beginning-with-ESC

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ EscapeParser

Returns a new instance of EscapeParser.



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# File 'lib/escapeparser.rb', line 7

def initialize
  @state = :start
  @str = ""
end

Instance Attribute Details

#state ⇒ Object (readonly)

Returns the value of attribute state.



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# File 'lib/escapeparser.rb', line 5

def state
  @state
end

#str ⇒ Object (readonly)

Returns the value of attribute str.



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# File 'lib/escapeparser.rb', line 5

def str
  @str
end

Instance Method Details

#complete? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/escapeparser.rb', line 70

def complete?; @state == :complete; end

#put(ch) ⇒ Object 



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# File 'lib/escapeparser.rb', line 12

def put(ch)
  # ch is a codepoint, which for OSC/DCS string payloads (e.g. a window
  # title) can be a multibyte UTF-8 character - decode it as UTF-8.
  # Bare Integer#chr only handles 0..255 and raises RangeError on
  # anything larger (e.g. a spinner glyph in claude's title sequence).
  c = ch.chr(Encoding::UTF_8)
  case @state
  when :start
    return false if ch < 32
    @str << c
    case c
    when '['
      @state = :csi
    when ']'
      @state = :oc
    when 'P', 'X', '^', '_'
      # DCS, SOS, PM, APC - string sequences terminated by ST (ESC \) or BEL
      @state = :string
    when /\w|[=>|}~6-9]/
      @state = :complete
    end
  when :csi
    # A C0 control byte inside a CSI is executed immediately and the
    # sequence keeps parsing (per ECMA-48) - it must NOT be folded into
    # the sequence or terminate it. Returning false routes it to Term's
    # handle_control while @esc stays in :csi; ESC (27) restarts the
    # sequence there. (vttest "cursor-control chars inside ESC sequences".)
    return false if ch < 32
    @str << c
    @state = :complete if /[[:alpha:]]|[@]/.match(c)
  when :oc
    if ch == 7 then @state = :complete
    elsif ch < 32 then return false
    else @str << c
    end
  when :string
    if ch == 7
      @state = :complete
    elsif ch == 27
      @state = :string_esc
    elsif ch < 32
      return false
    else
      @str << c
    end
  when :string_esc
    if c == '\\'
      @state = :complete
    else
      @str << 27.chr << c
      @state = :string
    end
  else
    return false
  end
  true
end