Class: Yay::Colourizer

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

Overview

this class adds colour to a stream based on rules that have been generated by a parser

Instance Method Summary collapse

Constructor Details

#initialize(rules, input, output) ⇒ Colourizer

create a colourizer using specified parser rules and input and output streams (usually stdin/stdout)



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# File 'lib/yay/colourizer.rb', line 9

def initialize rules, input, output
  colourize_rules rules
  @input   = input
  @output  = output
  
  # this is the colour we'll use when we haven't already applied a colour
  # we remember the previous choice as we can colourize words within a line
  # that's already been coloured
  @default_end_colour = ColourWheel::end_colour
  @end_colour = @default_end_colour
end

Instance Method Details

#apply_line_rules(line) ⇒ Object

apply all rules that span the entire line



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# File 'lib/yay/colourizer.rb', line 57

def apply_line_rules line
  # track the line_rules end colour so we can return to this after each
  # match
  @line_rules.each { |rule| 
    if line.match(rule[0])
      line = "#{rule[1]}#{line.rstrip}#{@default_end_colour}"
      @end_colour = rule[1]
      # leave loop; only allow one line match per line
      break
    end
  }
  return line
end

#apply_word_rules(line) ⇒ Object

apply all partial rules



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# File 'lib/yay/colourizer.rb', line 72

def apply_word_rules line
  @part_rules.each { |rule|
    line = line.gsub(rule[0], "#{rule[1]}\\0#{@end_colour}")
  }
  return line
end

#colourize_pipe ⇒ Object

create a pipe between the input and output streams, applying colour rules to every line that appears. only an interrupt, end of file or exception will end this process



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# File 'lib/yay/colourizer.rb', line 82

def colourize_pipe
  @end_colour = @default_end_colour
  begin
    @input.each_line { |line|
      line = apply_line_rules(line)
      line = apply_word_rules(line)
      @output.puts line
    }
  rescue Errno::EPIPE
    # ignore the Broken Pipe error that is caused by tools like head
  end
end

#colourize_rules(rules) ⇒ Object

process the rules created by a parser and determine the actual strings we need to emit when we use this colour. this breaks parser rules up in to two categories - line rules and part rules



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# File 'lib/yay/colourizer.rb', line 36

def colourize_rules rules
  @line_rules = []
  @part_rules = []

  rules.each { |rule|

    regex   = rule[0]
    colours = rule[1]
    is_line = rule[2]

    colour_string = ColourWheel::begin_colours(colours)

    if is_line
      @line_rules.unshift [regex, colour_string]
    else
      @part_rules.unshift [regex, colour_string]
    end
  }
end

#line_rules ⇒ Object

get the rules that are applied to a whole line if it contains matching text of the form [[regex, colour_string],..]



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# File 'lib/yay/colourizer.rb', line 23

def line_rules
  @line_rules
end

#part_rules ⇒ Object

get the rules that are applied to matching text of the form [[regex, colour_string],..]



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# File 'lib/yay/colourizer.rb', line 29

def part_rules
  @part_rules
end