Module: WhittakerTech::Midas::Coin::Bidi

Included in:
WhittakerTech::Midas::Coin
Defined in:
app/models/whittaker_tech/midas/coin/bidi.rb

Overview

Bidi provides Unicode bidirectional-text isolation helpers so that currency strings render correctly when embedded in mixed LTR/RTL sentences.

Background

In HTML, the Unicode Bidirectional Algorithm can reorder numeric and symbol characters in ways that produce confusing output when currency strings appear inside an RTL sentence (e.g. Arabic or Hebrew UI). Wrapping currency text in Unicode isolation marks prevents the algorithm from treating it as part of the surrounding paragraph direction.

Isolation marks used

Constants:

  • LRI (U+2066): Left-to-Right Isolate
  • RLI (U+2067): Right-to-Left Isolate
  • PDI (U+2069): Pop Directional Isolate (close)

Direction configuration

Currency direction defaults to :ltr for all currencies. Override per currency in an initializer:

WhittakerTech::Midas.currency_directions['ILS'] = :rtl
WhittakerTech::Midas.currency_directions['AED'] = :rtl

See also: WhittakerTech::Midas.currency_direction_for

Since:

  • 0.1.0

Constant Summary collapse

LRI =

Unicode Left-to-Right Isolate mark (U+2066)

Since:

  • 0.1.0

"\u2066"
RLI =

Unicode Right-to-Left Isolate mark (U+2067)

Since:

  • 0.1.0

"\u2067"
PDI =

Unicode Pop Directional Isolate mark — closes an isolation span (U+2069)

Since:

  • 0.1.0

"\u2069"

Instance Method Summary collapse

Instance Method Details

#bidi_currency_dir(currency_code) ⇒ Symbol

Resolves the configured display direction for a currency code.

Reads from WhittakerTech::Midas.currency_directions. Defaults to :ltr for any currency not explicitly configured.

Parameters:

  • currency_code (String) —

    ISO 4217 currency code

Returns:

  • (Symbol) —

    :ltr or :rtl

Since:

  • 0.1.0



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# File 'app/models/whittaker_tech/midas/coin/bidi.rb', line 84

def bidi_currency_dir(currency_code)
  WhittakerTech::Midas.currency_direction_for(currency_code)
end

#bidi_isolate(text, dir:) ⇒ String

Wraps text in a Unicode directional-isolate span.

Examples:

bidi_isolate('$29.99', dir: :ltr)  # => "\u2066$29.99\u2069"
bidi_isolate('29.99',  dir: nil)   # => "29.99"

Parameters:

  • text (String, nil) —

    the text to isolate; nil returns ""

  • dir (Symbol, nil) —

    :ltr, :rtl, or nil (no wrapping)

Returns:

  • (String)

Raises:

  • (ArgumentError) —

    if dir is not :ltr, :rtl, or nil

Since:

  • 0.1.0



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# File 'app/models/whittaker_tech/midas/coin/bidi.rb', line 52

def bidi_isolate(text, dir:)
  return '' if text.nil?

  s = text.to_s
  return s if dir.nil?

  case dir
  when :ltr then "#{LRI}#{s}#{PDI}"
  when :rtl then "#{RLI}#{s}#{PDI}"
  else
    raise ArgumentError, "Unknown bidi dir: #{dir.inspect}"
  end
end

#bidi_isolate_number(text) ⇒ String

Wraps a number string with LTR isolation.

Numbers are always rendered LTR. This prevents the bidi algorithm from reordering digit sequences when they appear in an RTL context.

Parameters:

  • text (String, Integer, BigDecimal) —

    the numeric value to isolate

Returns:

  • (String)

Since:

  • 0.1.0



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# File 'app/models/whittaker_tech/midas/coin/bidi.rb', line 73

def bidi_isolate_number(text)
  bidi_isolate(text, dir: :ltr)
end