Class: String

Inherits:
Object show all
Defined in:
lib/wdd-ruby-ext/string.rb

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.lcs(s1, s2) ⇒ Object

Finds the longest commong substring betweent the two supplied strings



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# File 'lib/wdd-ruby-ext/string.rb', line 4

def self.lcs(s1, s2)
  num=Array.new(s1.size){Array.new(s2.size)}
  len,ans=0

  longest_substr = ""
  substr = ""
  s1.scan(/./).each_with_index do |l1,i |
    s2.scan(/./).each_with_index do |l2,j |

      unless l1==l2
        num[i][j]=[0,""]
      else
        if (i==0 || j==0)
          num[i][j]=[1,l1] 
        else
          num[i][j] = [1 + num[i-1][j-1][0], num[i-1][j-1][1] +l1]
        end
        if num[i][j][0] > len
          len = ans = num[i][j][0] 
          longest_substr = num[i][j][1]
        end
      end
    end
  end
  longest_substr
end

Instance Method Details

#mgpsub(key_value_pairs = [].freeze) ⇒ Object

Performs multiple gsub operations in a single pass. key_value_pairs is an array of [key,value] pairs where each key is a regular expression and the value is the value to substitute when that regexp is matched.

Unlike mgsub, this method allows parenthesized subsections of the match string from the regexp to be embedded in the replace string. The normal variables are available in the replacement string.

eg.

>> “this is that”.mgpsub( [ [/(that)/, ‘really $1!’], [/this/, ‘that’] ] )

> that is really that!“



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# File 'lib/wdd-ruby-ext/string.rb', line 54

def mgpsub(key_value_pairs=[].freeze)
  regexp_fragments = key_value_pairs.collect { |k,v| k }
  gsub(Regexp.union(*regexp_fragments)) do |match|
    replacement_term = key_value_pairs.detect{|k,v| k=~match}[1]
    vars = ["$1", "$2", "$3", "$4", "$5", "$6", "$7", "$8", "$9", "$`", "$&", "$'"]
    vars.each do |var|
      replacement_term.gsub!( Regexp.compile("\\"+var), eval(var)||'' )
    end
    replacement_term
  end
end

#mgsub(key_value_pairs = [].freeze) ⇒ Object

Performs multiple gsub operations in a single pass. key_value_pairs is an array of [key,value] pairs where each key is a regular expression and the value is the value to substitute when that regexp is matched.



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# File 'lib/wdd-ruby-ext/string.rb', line 34

def mgsub(key_value_pairs=[].freeze)
  regexp_fragments = key_value_pairs.collect { |k,v| k }
  gsub(Regexp.union(*regexp_fragments)) do |match|
    key_value_pairs.detect{|k,v| k =~ match}[1]
  end
end

#trim_to_word(max_length) ⇒ Object

trims the string to the nearest word boundary ensuring that the resulting length is less than max_length



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# File 'lib/wdd-ruby-ext/string.rb', line 67

def trim_to_word( max_length )
  string = self
  if string.length > max_length
    string = string[0..max_length-4]
    while string[-1,1] =~ /[\w]/ && string.length > 1
      string = string[0..string.length-2]
    end
    string += "..."
  end
  string
end