Module: TailwindMerge::ParseClassName

Included in:
Merger
Defined in:
lib/tailwind_merge/parse_class_name.rb

Constant Summary collapse

IMPORTANT_MODIFIER = 
"!"
EMPTY_MODIFIERS = 
[].freeze
MODIFIER_SEPARATOR = 
":"
MODIFIER_SEPARATOR_LENGTH = 
MODIFIER_SEPARATOR.length
MODIFIER_SEPARATOR_BYTE = 
MODIFIER_SEPARATOR.ord
POSTFIX_SEPARATOR_BYTE = 
"/".ord
OPEN_BRACKET_BYTE = 
"[".ord
CLOSE_BRACKET_BYTE = 
"]".ord
OPEN_PAREN_BYTE = 
"(".ord
CLOSE_PAREN_BYTE = 
")".ord

Instance Method Summary collapse

Instance Method Details

#parse_class_name(class_name, prefix: nil) ⇒ Object

Parse class name into parts.

Inspired by splitAtTopLevelOnly used in Tailwind CSS

See Also:



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# File 'lib/tailwind_merge/parse_class_name.rb', line 25

def parse_class_name(class_name, prefix: nil)
  unless prefix.nil?
    full_prefix = "#{prefix}#{MODIFIER_SEPARATOR}"
    if class_name.start_with?(full_prefix)
      return parse_class_name(class_name[full_prefix.length..])
    else
      return TailwindClass.new(
        is_external: true,
        modifiers: EMPTY_MODIFIERS,
        has_important_modifier: false,
        base_class_name: class_name,
        maybe_postfix_modifier_position: nil,
      )
    end
  end

  # Stays nil until the first modifier separator, so the common no-modifier
  # class (`px-2`, `block`) never allocates an array.
  modifiers = nil

  bracket_depth = 0
  paren_depth = 0
  modifier_start = 0
  postfix_modifier_position = nil

  # Byte-wise scan: all separators are ASCII, so byte positions are safe
  # for multibyte class names (UTF-8 continuation bytes never match ASCII).
  # Positions produced here (including maybe_postfix_modifier_position)
  # are byte offsets and must be consumed with String#byteslice.
  index = 0
  size = class_name.bytesize
  while index < size
    byte = class_name.getbyte(index)

    if bracket_depth.zero? && paren_depth.zero?
      if byte == MODIFIER_SEPARATOR_BYTE
        (modifiers ||= []) << class_name.byteslice(modifier_start, index - modifier_start)
        modifier_start = index + MODIFIER_SEPARATOR_LENGTH
        index += 1
        next
      elsif byte == POSTFIX_SEPARATOR_BYTE
        postfix_modifier_position = index
        index += 1
        next
      end
    end

    case byte
    when OPEN_BRACKET_BYTE then bracket_depth += 1
    when CLOSE_BRACKET_BYTE then bracket_depth -= 1
    when OPEN_PAREN_BYTE then paren_depth += 1
    when CLOSE_PAREN_BYTE then paren_depth -= 1
    end

    index += 1
  end

  base_class_name_with_important_modifier = modifiers ? class_name.byteslice(modifier_start, size - modifier_start) : class_name

  base_class_name, has_important_modifier = strip_important_modifier(base_class_name_with_important_modifier)

  maybe_postfix_modifier_position = if postfix_modifier_position && postfix_modifier_position > modifier_start
    postfix_modifier_position - modifier_start
  end

  TailwindClass.new(
    is_external: false,
    modifiers: modifiers || EMPTY_MODIFIERS,
    has_important_modifier:,
    base_class_name: base_class_name,
    maybe_postfix_modifier_position:,
  )
end

#strip_important_modifier(base_class_name) ⇒ Object 



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# File 'lib/tailwind_merge/parse_class_name.rb', line 99

def strip_important_modifier(base_class_name)
  if base_class_name.end_with?(IMPORTANT_MODIFIER)
    return [base_class_name[0...-IMPORTANT_MODIFIER.length], true]
  end

  # In Tailwind CSS v3 the important modifier was at the start of the base class name. This is still supported for legacy reasons.
  # @see https://github.com/dcastil/tailwind-merge/issues/513#issuecomment-2614029864
  if base_class_name.start_with?(IMPORTANT_MODIFIER)
    return [base_class_name[1..], true]
  end

  [base_class_name, false]
end