Method: UnicodeUtils.each_grapheme

Defined in:
lib/unicode_utils/each_grapheme.rb

.each_grapheme(str) {|grapheme| ... } ⇒ Object

Iterate over the grapheme clusters that make up str. A grapheme cluster is a user perceived character (the basic unit of a writing system for a language) and consists of one or more code points.

This method uses the default Unicode algorithm for extended grapheme clusters.

Returns an enumerator if no block is given.

Examples:

require "unicode_utils/each_grapheme"
UnicodeUtils.each_grapheme("a\r\nb") { |g| p g }

prints:

"a"
"\r\n"
"b"

and

UnicodeUtils.each_grapheme("a\r\nb").count => 3

Yields:

  • (grapheme)
[View source]

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# File 'lib/unicode_utils/each_grapheme.rb', line 35

def each_grapheme(str)
  return enum_for(__method__, str) unless block_given?
  c0 = nil
  c0_prop = nil
  grapheme = String.new.force_encoding(str.encoding)
  str.each_codepoint { |c|
    gbreak = false
    c_prop = GRAPHEME_CLUSTER_BREAK_MAP[c]
    
    ### rules ###
    if c0_prop == 0x0 && c_prop == 0x1
      # don't break CR LF
    elsif c0_prop == 0x0 || c0_prop == 0x1 || c0_prop == 0x2
      # break after controls
      gbreak = true
    elsif c_prop == 0x0 || c_prop == 0x1 || c_prop == 0x2
      # break before controls
      gbreak = true
    elsif c0_prop == 0x6 && (c_prop == 0x6 || c_prop == 0x7 ||
                             c_prop == 0x9 || c_prop == 0xA)
      # don't break hangul syllable
    elsif (c0_prop == 0x9 || c0_prop == 0x7) &&
          (c_prop == 0x7 || c_prop == 0x8)
      # don't break hangul syllable
    elsif (c0_prop == 0xA || c0_prop == 0x8) && c_prop == 0x8
      # don't break hangul syllable
    elsif c0_prop == 0xB && c_prop == 0xB
      # don't break between regional indicator symbols
    elsif c_prop == 0x3
      # don't break before extending characters
    elsif c_prop == 0x5
      # don't break before SpacingMarks
    elsif c0_prop == 0x4
      # don't break after Prepend characters
    else
      # break everywhere
      gbreak = true
    end
    #############

    if gbreak && !grapheme.empty?
      yield grapheme
      grapheme = String.new.force_encoding(str.encoding)
    end
    grapheme << c
    c0 = c
    c0_prop = c_prop
  }
  yield grapheme unless grapheme.empty?
end