Class: SGMLParser

Inherits:
Object show all
Defined in:
lib/web/htmlparser/sgml-parser.rb

Overview

A parser for SGML, using the derived class as static DTD.

Direct Known Subclasses

HTML::StackingParser, HTMLParser

Constant Summary collapse

Interesting =

Regular expressions used for parsing:

/[&<]/
Incomplete = 
Regexp.compile('&([a-zA-Z][a-zA-Z0-9]*|#[0-9]*)?|' +
'<([a-zA-Z][^<>]*|/([a-zA-Z][^<>]*)?|' +
'![^<>]*)?')
Entityref = 
/&([a-zA-Z][-.a-zA-Z0-9]*)[^-.a-zA-Z0-9]/
Charref = 
/&#([0-9]+)[^0-9]/
Starttagopen = 
/<[>a-zA-Z]/
Endtagopen = 
/<\/[<>a-zA-Z]/
Endbracket = 
/[<>]/
Special = 
/<![^<>]*>/
Commentopen = 
/<!--/
Commentclose = 
/--[ \t\n]*>/
Tagfind = 
/[a-zA-Z][a-zA-Z0-9.-]*/
Attrfind = 
Regexp.compile('[\s,]*([a-zA-Z_][a-zA-Z_0-9.-]*)' +
'(\s*=\s*' +
"('[^']*'" +
'|"[^"]*"' +
'|[-~a-zA-Z0-9,./:+*%?!()_#=]*))?')
Entitydefs = 
{'lt'=>'<', 'gt'=>'>', 'amp'=>'&', 'quot'=>'"', 'apos'=>'\''}

Instance Method Summary collapse

Constructor Details

#initialize(verbose = false) ⇒ SGMLParser

Returns a new instance of SGMLParser.



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# File 'lib/web/htmlparser/sgml-parser.rb', line 30

def initialize(verbose=false)
  @verbose = verbose
  reset
end

Instance Method Details

#close ⇒ Object 



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# File 'lib/web/htmlparser/sgml-parser.rb', line 61

def close
  goahead(true)
end

#feed(data) ⇒ Object 



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# File 'lib/web/htmlparser/sgml-parser.rb', line 56

def feed(data)
  @rawdata << data
  goahead(false)
end

#finish_endtag(tag) ⇒ Object 



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# File 'lib/web/htmlparser/sgml-parser.rb', line 242

def finish_endtag(tag)
  if tag == ''
    found = @stack.length - 1
    if found < 0
      unknown_endtag(tag)
      return
    end
  else
    unless @stack.include? tag
      method = 'end_' + tag
      unless self.respond_to?(method)
        unknown_endtag(tag)
      end
      return
    end
    found = @stack.index(tag) #or @stack.length
  end
  while @stack.length > found
    tag = @stack[-1]
    method = 'end_' + tag
    if respond_to?(method)
      handle_endtag(tag, method)
    else
      unknown_endtag(tag)
    end
    @stack.pop
  end
end

#finish_starttag(tag, attrs) ⇒ Object 



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# File 'lib/web/htmlparser/sgml-parser.rb', line 224

def finish_starttag(tag, attrs)
  method = 'start_' + tag
  if self.respond_to?(method)
    @stack << tag
    handle_starttag(tag, method, attrs)
    return 1
  else
    method = 'do_' + tag
    if self.respond_to?(method)
      handle_starttag(tag, method, attrs)
      return 0
    else
      unknown_starttag(tag, attrs)
      return -1
    end
  end
end

#goahead(_end) ⇒ Object 



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# File 'lib/web/htmlparser/sgml-parser.rb', line 65

def goahead(_end)
  rawdata = @rawdata
  i = 0
  n = rawdata.length
  while i < n
    if @nomoretags
      handle_data(rawdata[i..(n-1)])
      i = n
      break
    end
    j = rawdata.index(Interesting, i)
    j = n unless j
    if i < j
      handle_data(rawdata[i..(j-1)])
    end
    i = j
    break if (i == n)
    if rawdata[i] == ?< #
      if rawdata.index(Starttagopen, i) == i
        if @literal
          handle_data(rawdata[i, 1])
          i += 1
          next
        end
        k = parse_starttag(i)
        break unless k
        i = k
        next
      end
      if rawdata.index(Endtagopen, i) == i
        k = parse_endtag(i)
        break unless k
        i = k
        @literal = false
        next
      end
      if rawdata.index(Commentopen, i) == i
        if @literal
          handle_data(rawdata[i,1])
          i += 1
          next
        end
        k = parse_comment(i)
        break unless k
        i += k
        next
      end
      if rawdata.index(Special, i) == i
        if @literal
          handle_data(rawdata[i, 1])
          i += 1
          next
        end
        k = parse_special(i)
        break unless k
        i += k
        next
      end
    elsif rawdata[i] == ?& #
      if rawdata.index(Charref, i) == i
        i += $&.length
        handle_charref($1)
        i -= 1 unless rawdata[i-1] == ?;
        next
      end
      if rawdata.index(Entityref, i) == i
        i += $&.length
        handle_entityref($1)
        i -= 1 unless rawdata[i-1] == ?;
        next
      end
    else
      raise RuntimeError, 'neither < nor & ??'
    end
    # We get here only if incomplete matches but
    # nothing else
    match = rawdata.index(Incomplete, i)
    unless match == i
      handle_data(rawdata[i, 1])
      i += 1
      next
    end
    j = match + $&.length
    break if j == n # Really incomplete
    handle_data(rawdata[i..(j-1)])
    i = j
  end
  # end while
  if _end and i < n
    handle_data(@rawdata[i..(n-1)])
    i = n
  end
  @rawdata = rawdata[i..-1]
end

#handle_charref(name) ⇒ Object 



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# File 'lib/web/htmlparser/sgml-parser.rb', line 295

def handle_charref(name)
  n = Integer(name)
  if !(0 <= n && n <= 255)
    unknown_charref(name)
    return
  end
  handle_data(n.chr)
end

#handle_comment(data) ⇒ Object 



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# File 'lib/web/htmlparser/sgml-parser.rb', line 317

def handle_comment(data)
end

#handle_data(data) ⇒ Object 



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# File 'lib/web/htmlparser/sgml-parser.rb', line 314

def handle_data(data)
end

#handle_endtag(tag, method) ⇒ Object 



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# File 'lib/web/htmlparser/sgml-parser.rb', line 284

def handle_endtag(tag, method)
  self.send(method)
end

#handle_entityref(name) ⇒ Object 



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# File 'lib/web/htmlparser/sgml-parser.rb', line 304

def handle_entityref(name)
  table = Entitydefs
  if table.include?(name)
    handle_data(table[name])
  else
    unknown_entityref(name)
    return
  end
end

#handle_special(data) ⇒ Object 



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# File 'lib/web/htmlparser/sgml-parser.rb', line 320

def handle_special(data)
end

#handle_starttag(tag, method, attrs) ⇒ Object 



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# File 'lib/web/htmlparser/sgml-parser.rb', line 280

def handle_starttag(tag, method, attrs)
  self.send(method, attrs)
end

#has_context(gi) ⇒ Object 



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# File 'lib/web/htmlparser/sgml-parser.rb', line 43

def has_context(gi)
  @stack.include? gi
end

#parse_comment(i) ⇒ Object 



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# File 'lib/web/htmlparser/sgml-parser.rb', line 160

def parse_comment(i)
  rawdata = @rawdata
  if rawdata[i, 4] != '<!--'
    raise RuntimeError, 'unexpected call to handle_comment'
  end
  match = rawdata.index(Commentclose, i)
  return nil unless match
  matched_length = $&.length
  j = match
  handle_comment(rawdata[i+4..(j-1)])
  j = match + matched_length
  return j-i
end

#parse_endtag(i) ⇒ Object 



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# File 'lib/web/htmlparser/sgml-parser.rb', line 212

def parse_endtag(i)
  rawdata = @rawdata
  j = rawdata.index(Endbracket, i + 1)
  return nil unless j
  tag = (rawdata[i+2..j-1].strip).downcase
  if rawdata[j] == ?> #
    j += 1
  end
  finish_endtag(tag)
  return j
end

#parse_special(i) ⇒ Object 



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# File 'lib/web/htmlparser/sgml-parser.rb', line 271

def parse_special(i)
  rawdata = @rawdata
  match = rawdata.index(Endbracket, i+1)
  return nil unless match
  matched_length = $&.length
  handle_special(rawdata[i+1..(match-1)])
  return match - i + matched_length
end

#parse_starttag(i) ⇒ Object 



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# File 'lib/web/htmlparser/sgml-parser.rb', line 174

def parse_starttag(i)
  rawdata = @rawdata
  j = rawdata.index(Endbracket, i + 1)
  return nil unless j
  attrs = []
  if rawdata[i+1] == ?> #
    # SGML shorthand: <> == <last open tag seen>
    k = j
    tag = @lasttag
  else
    match = rawdata.index(Tagfind, i + 1)
    unless match
      raise RuntimeError, 'unexpected call to parse_starttag'
    end
    k = i + 1 + ($&.length)
    tag = $&.downcase
    @lasttag = tag
  end
  while k < j
    break unless rawdata.index(Attrfind, k)
    matched_length = $&.length
    attrname, rest, attrvalue = $1, $2, $3
    if not rest
      attrvalue = '' # was: = attrname
    elsif (attrvalue[0] == ?' && attrvalue[-1] == ?') or
        (attrvalue[0] == ?" && attrvalue[-1] == ?")
      attrvalue = attrvalue[1..-2]
    end
    attrs << [attrname.downcase, attrvalue]
    k += matched_length
  end
  if rawdata[j] == ?> #
    j += 1
  end
  finish_starttag(tag, attrs)
  return j
end

#report_unbalanced(tag) ⇒ Object 



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# File 'lib/web/htmlparser/sgml-parser.rb', line 288

def report_unbalanced(tag)
  if @verbose
    print '*** Unbalanced </' + tag + '>', "\n"
    print '*** Stack:', self.stack, "\n"
  end
end

#reset ⇒ Object 



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# File 'lib/web/htmlparser/sgml-parser.rb', line 35

def reset
  @rawdata = ''
  @stack = []
  @lasttag = '???'
  @nomoretags = false
  @literal = false
end

#setliteral(*args) ⇒ Object 



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# File 'lib/web/htmlparser/sgml-parser.rb', line 52

def setliteral(*args)
  @literal = true
end

#setnomoretags ⇒ Object 



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# File 'lib/web/htmlparser/sgml-parser.rb', line 47

def setnomoretags
  @nomoretags = true
  @literal = true
end

#unknown_charref(ref) ⇒ Object 



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# File 'lib/web/htmlparser/sgml-parser.rb', line 327

def unknown_charref(ref)
end

#unknown_endtag(tag) ⇒ Object 



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# File 'lib/web/htmlparser/sgml-parser.rb', line 325

def unknown_endtag(tag)
end

#unknown_entityref(ref) ⇒ Object 



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# File 'lib/web/htmlparser/sgml-parser.rb', line 329

def unknown_entityref(ref)
end

#unknown_starttag(tag, attrs) ⇒ Object 



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# File 'lib/web/htmlparser/sgml-parser.rb', line 323

def unknown_starttag(tag, attrs)
end