Class: WikiWah::Subst

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

Overview

Subst handles text-transformation using a series of regular-expression substitutions. It encapsulates a number of “patterns”, and associated blocks. Each block is invoked with a MatchData object when it’s associated pattern matches, and is expected to return a replacement string.

The difference between using Subst and applying a series of gsub’s is that replacement values are protected from subsequent transformations.

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Subst

Returns a new instance of Subst.



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# File 'lib/wikiwah/subst.rb', line 15

def initialize
  @transforms = []
end

Instance Method Details

#add_transformation(regexp, &proc) ⇒ Object 



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# File 'lib/wikiwah/subst.rb', line 19

def add_transformation(regexp, &proc)
  @transforms << [regexp, proc]
end

#transform(s) ⇒ Object 



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# File 'lib/wikiwah/subst.rb', line 23

def transform(s)
  s = s.dup
  store = []
  @transforms.each do |transform|
    (regexp, proc) = *transform
    s.gsub!(regexp) {
      store << proc.call($~)
      "\001#{store.size - 1}\002"
    }
  end
  s.gsub!(/\001(\d+)\002/) {
    store[$1.to_i]
  }
  s
end