Module: CSS::Urange

Extended by:
Urange
Included in:
Urange
Defined in:
lib/css/urange.rb

Overview

Parser for CSS <urange> tokens, e.g. ‘U+0-7F`, `U+26`, `U+10??`. drafts.csswg.org/css-syntax/#urange-syntax

Operates on the source string rather than a token stream because the tokenizer destructively normalizes shapes like ‘U+0` (the `+` is absorbed into a number-token whose sign is lost on serialization). Sticking with the source preserves the exact form.

Constant Summary collapse

URANGE_RE = 
/\Au\+([0-9a-f?]{1,6})(?:-([0-9a-f]{1,6}))?\z/i.freeze
WILDCARD_RE = 
/\A[0-9a-f]*\?+\z/i.freeze
MAX_CODEPOINT = 
0x10FFFF

Instance Method Summary collapse

Instance Method Details

#parse(input) ⇒ Object

Raises:



17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
 
# File 'lib/css/urange.rb', line 17

def parse(input)
  s = input.to_s.strip
  m = URANGE_RE.match(s)

  raise ParseError, "invalid urange: #{input.inspect}" unless m

  start_str, end_str = m[1], m[2]

  first, last =
    if end_str
      raise ParseError, 'wildcards are not allowed in range form' if start_str.include?('?')

      [start_str.to_i(16), end_str.to_i(16)]
    elsif start_str.include?('?')
      raise ParseError, 'wildcards must be trailing' unless start_str.match?(WILDCARD_RE)

      [start_str.tr('?', '0').to_i(16), start_str.tr('?', 'f').to_i(16)]
    else
      n = start_str.to_i(16)
      [n, n]
    end

  raise ParseError, "codepoint out of range: U+#{format('%X', last)}" if last > MAX_CODEPOINT
  raise ParseError, "urange start must be <= end (U+#{format('%X', first)} > U+#{format('%X', last)})" if first > last

  Nodes::UnicodeRange.new(first:, last:)
end