Module: Echoes::SvgWalker

Defined in:
lib/echoes/svg_walker.rb

Overview

Minimal SVG element scanner. Yields one event per element to the block (or returns an Enumerator):

[:open,        tag, {attr => value, …}]
[:close,       tag, {}]
[:self_close,  tag, {attr => value, …}]

Skips comments, processing instructions (‘<?xml…?>`), DOCTYPE declarations, and CDATA sections. Text content between tags is ignored (the fast-path SVG renderer doesn’t render text — any SVG that uses <text> is rejected before we walk it).

Stops yielding on malformed input (no matching ‘>`, unbalanced comment, etc.). The caller treats early termination as “can’t render — bail to WKWebView.”

Constant Summary collapse

TAG_NAME_RE = 
/[a-zA-Z][\w:.-]*/
CLOSE_TAG_RE =

‘G` anchors the match to the scan offset passed to Regexp#match, so we can reuse the same regex from any position. `A` would only match at string-position 0, which is wrong once we’re past the first tag.

/\G<\/(#{TAG_NAME_RE})\s*>/m
OPEN_TAG_RE = 
/\G<(#{TAG_NAME_RE})([^>]*)>/m
ATTR_RE = 
/(#{TAG_NAME_RE})\s*=\s*(?:"([^"]*)"|'([^']*)')/

Class Method Summary collapse

Class Method Details

.events(bytes) ⇒ Object 



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# File 'lib/echoes/svg_walker.rb', line 31

def events(bytes)
  return enum_for(:events, bytes) unless block_given?
  return if bytes.nil?

  s = bytes.b
  pos = 0
  len = s.length
  while pos < len
    lt = s.index('<', pos)
    break unless lt
    pos = lt

    # Comment: <!-- … -->
    if s[pos, 4] == '<!--'
      close = s.index('-->', pos + 4)
      break unless close
      pos = close + 3
      next
    end

    # CDATA: <![CDATA[ … ]]>
    if s[pos, 9] == '<![CDATA['
      close = s.index(']]>', pos + 9)
      break unless close
      pos = close + 3
      next
    end

    # Other declarations: <!DOCTYPE …>, <!ENTITY …>, etc.
    if s[pos, 2] == '<!'
      close = s.index('>', pos + 2)
      break unless close
      pos = close + 1
      next
    end

    # Processing instruction: <?xml …?>
    if s[pos, 2] == '<?'
      close = s.index('?>', pos + 2)
      break unless close
      pos = close + 2
      next
    end

    # Closing tag: </tag>
    if s[pos, 2] == '</'
      m = CLOSE_TAG_RE.match(s, pos)
      break unless m && m.begin(0) == pos
      yield [:close, m[1], {}]
      pos = m.end(0)
      next
    end

    # Opening or self-closing tag.
    m = OPEN_TAG_RE.match(s, pos)
    break unless m && m.begin(0) == pos
    tag = m[1]
    body = m[2]
    if body.rstrip.end_with?('/')
      attrs_str = body.rstrip.chomp('/')
      yield [:self_close, tag, parse_attrs(attrs_str)]
    else
      yield [:open, tag, parse_attrs(body)]
    end
    pos = m.end(0)
  end
end

.parse_attrs(str) ⇒ Object 



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# File 'lib/echoes/svg_walker.rb', line 99

def parse_attrs(str)
  out = {}
  str.scan(ATTR_RE) do |name, dq, sq|
    out[name] = dq || sq || ''
  end
  out
end