From: Trans <transfire@...>
Date: 2008-12-31T12:14:11+09:00
Subject: Re: AnsiString (#185)



On Dec 12, 1:06 pm, Matthew Moss <m...@moss.name> wrote:
> It would seem that writing Transfire's desired `ANSIString` class is  
> more difficult that it appears. (Or, perhaps, y'all are busy preparing  
> for the holidays.)

Yep. That's too bad. The holidays have had me occupied as well, and it
is a tricky problem. I was hoping someone brighter than I would come
up with a really clever way of doing it.

Robert's implementation using an array is string and symbol is much
like my first stab at it. In some ways I think maybe it's the better
way to go, although more limited in scope, one can at least wrap ones
head around the implementation without too much trouble. Thanks for
taking a stab at the quiz Robert!

My implementation on the other hand tries to go the full nine-yards
toward drop-in compatibility with the core String class. It's not
complete by any means, but the foundation is in place for doing so,
ie. the #shift_marks method. The downside though is that the algorithm
is somewhat complex and, worse still, time consuming, not to mention
imperfect -- hence my hope someone else might have a brighter idea for
going about this.


  require 'facets/ansicode'
  require 'facets/string'

  # ANSIStrings stores a regular string (@text) and
  # a Hash mapping character index to ansicodes (@marks).
  # For example is we has the string:
  #
  #   "Big Apple"
  #
  # And applied the color red to it, the marks hash would be:
  #
  #   { 0=>[:red] , 9=>[:clear] }
  #
  class ANSIString

    CLR = ANSICode.clear

    attr :text
    attr :marks

    def initialize(text=nil, marks=nil)
      @text  = (text  || '').to_s
      @marks = marks  || []
      yield(self) if block_given?
    end

    def to_s
      s = text.dup
      m = marks.sort do |(a,b)|
        v = b[0] <=> a[0]
        if v == 0
          (b[1] == :clear or b[1] == :reset) ? -1 : 1
        else
          v
        end
      end
      m.each do |(index, code)|
        s.insert(index, ANSICode.__send__(code))
      end
      #s << CLR unless s =~ /#{Regexp.escape(CLR)}$/  # always end
with a clear
      s
    end

    #
    alias_method :to_str, :to_s

    def size ; text.size ; end

    def upcase  ; self.class.new(text.upcase, marks) ; end
    def upcase! ; text.upcase! ; end

    def downcase  ; self.class.new(text.upcase, marks) ; end
    def downcase! ; text.upcase! ; end

    def +(other)
      case other
      when String
        ntext  = text + other.text
        nmarks = marks.dup
        omarks = shift_marks(0, text.size, other.marks)
        omarks.each{ |(i, c)| nmarks << [i,c] }
      else
        ntext  = text + other.to_s
        nmarks = marks.dup
      end
      self.class.new(ntext, nmarks)
    end

    def slice(*args)
      if args.size == 2
        index, len = *args
        endex  = index+len
        new_text  = text[index, len]
        new_marks = []
        marks.each do |(i, v)|
          new_marks << [i, v] if i >= index && i < endex
        end
        self.class.new(new_text, new_marks)
      elsif args.size == 1
        rng = args.first
        case rng
        when Range
          index, endex = rng.begin, rng.end
          new_text  = text[rng]
          new_marks = []
          marks.each do |(i, v)|
            new_marks << [i, v] if i >= index && i < endex
          end
          self.class.new(new_text, new_marks)
        else
          nm = marks.select do |(i,c)|
            marks[0] == rng or ( marks[0] == rng + 1 &&
[:clear, :reset].include?(marks[1]) )
          end
          self.class.new(text[rng,1], nm)
        end
      else
        raise ArgumentError
      end
    end

    alias_method :[], :slice

    # This is more limited than the normal String method.
    # It does not yet support a block, and +replacement+
    # won't substitute for \1, \2, etc.
    #
    # TODO: block support.
    def sub!(pattern, replacement=nil, &block)
      mark_changes = []
      text = @text.sub(pattern) do |s|
        index  = $~.begin(0)
        replacement = block.call(s) if block_given?
        delta  = (replacement.size - s.size)
        mark_changes << [index, delta]
        replacement
      end
      marks = @marks
      mark_changes.each do |index, delta|
        marks = shift_marks(index, delta, marks)
      end
      @text  = text
      @marks = marks
      self
    end

    #
    def sub(pattern,replacement=nil, &block)
      dup.sub!(pattern, replacement, &block)
    end

    #
    def gsub!(pattern, replacement=nil, &block)
      mark_changes   = []
      mark_additions = []
      text = @text.gsub(pattern) do |s|
        index = $~.begin(0)
        replacement = block.call(self.class.new(s)) if block_given?
        if self.class===replacement
          adj_marks = replacement.marks.map{ |(i,c)| [i+index,c] }
          mark_additions.concat(adj_marks)
          replacement = replacement.text
        end
        delta = (replacement.size - s.size)
        mark_changes << [index, delta]
        replacement
      end
      marks = @marks
      mark_changes.each do |(index, delta)|
        marks = shift_marks(index, delta, marks)
      end
      marks.concat(mark_additions)
      @text  = text
      @marks = marks
      self
    end

    #
    def gsub(pattern, replacement=nil, &block)
      dup.gsub!(pattern, replacement, &block)
    end

    #
    def ansi(code)
      m = marks.dup
      m.unshift([0, code])
      m.push([size, :clear])
      self.class.new(text, m)
    end
    alias_method :color, :ansi

    #
    def ansi!(code)
      marks.unshift([0, ansicolor])
      marks.push([size, :clear])
    end
    alias_method :color!, :ansi!

    def red      ; color(:red)      ; end
    def green    ; color(:green)    ; end
    def blue     ; color(:blue)     ; end
    def black    ; color(:black)    ; end
    def magenta  ; color(:magenta)  ; end
    def yellow   ; color(:yellow)   ; end
    def cyan     ; color(:cyan)     ; end

    def bold       ; ansi(:bold)       ; end
    def underline  ; ansi(:underline)  ; end

    def red!     ; color!(:red)     ; end
    def green!   ; color!(:green)   ; end
    def blue!    ; color!(:blue)    ; end
    def black!   ; color!(:black)   ; end
    def magenta! ; color!(:magenta) ; end
    def yellow!  ; color!(:yellow)  ; end
    def cyan!    ; color!(:cyan)    ; end

    def bold!      ; ansi!(:bold)      ; end
    def underline! ; ansi!(:underline) ; end

  private

    #
    def shift_marks(index, delta, marks=nil)
      new_marks = []
      (marks || @marks).each do |(i, c)|
        case i <=> index
        when -1
          new_marks << [i, c]
        when 0, 1
          new_marks << [i+delta, c]
        end
      end
      new_marks
    end

    #
    def shift_marks!(index, delta)
     @marks.replace(shift_marks(index, delta))
    end

  end


Sorry for my late post. I'm only now starting to get settled back into
the routine of things.