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.



30
31
32
33
# File 'lib/web/htmlparser/sgml-parser.rb', line 30

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

Instance Method Details

#closeObject



61
62
63
# File 'lib/web/htmlparser/sgml-parser.rb', line 61

def close
  goahead(true)
end

#feed(data) ⇒ Object



56
57
58
59
# File 'lib/web/htmlparser/sgml-parser.rb', line 56

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

#finish_endtag(tag) ⇒ Object



242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
# 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



224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
# 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



65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
# 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



295
296
297
298
299
300
301
302
# 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



317
318
# File 'lib/web/htmlparser/sgml-parser.rb', line 317

def handle_comment(data)
end

#handle_data(data) ⇒ Object



314
315
# File 'lib/web/htmlparser/sgml-parser.rb', line 314

def handle_data(data)
end

#handle_endtag(tag, method) ⇒ Object



284
285
286
# File 'lib/web/htmlparser/sgml-parser.rb', line 284

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

#handle_entityref(name) ⇒ Object



304
305
306
307
308
309
310
311
312
# 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



320
321
# File 'lib/web/htmlparser/sgml-parser.rb', line 320

def handle_special(data)
end

#handle_starttag(tag, method, attrs) ⇒ Object



280
281
282
# File 'lib/web/htmlparser/sgml-parser.rb', line 280

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

#has_context(gi) ⇒ Object



43
44
45
# File 'lib/web/htmlparser/sgml-parser.rb', line 43

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

#parse_comment(i) ⇒ Object



160
161
162
163
164
165
166
167
168
169
170
171
172
# 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



212
213
214
215
216
217
218
219
220
221
222
# 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



271
272
273
274
275
276
277
278
# 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



174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
# 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



288
289
290
291
292
293
# 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

#resetObject



35
36
37
38
39
40
41
# File 'lib/web/htmlparser/sgml-parser.rb', line 35

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

#setliteral(*args) ⇒ Object



52
53
54
# File 'lib/web/htmlparser/sgml-parser.rb', line 52

def setliteral(*args)
  @literal = true
end

#setnomoretagsObject



47
48
49
50
# File 'lib/web/htmlparser/sgml-parser.rb', line 47

def setnomoretags
  @nomoretags = true
  @literal = true
end

#unknown_charref(ref) ⇒ Object



327
328
# File 'lib/web/htmlparser/sgml-parser.rb', line 327

def unknown_charref(ref)
end

#unknown_endtag(tag) ⇒ Object



325
326
# File 'lib/web/htmlparser/sgml-parser.rb', line 325

def unknown_endtag(tag)
end

#unknown_entityref(ref) ⇒ Object



329
330
# File 'lib/web/htmlparser/sgml-parser.rb', line 329

def unknown_entityref(ref)
end

#unknown_starttag(tag, attrs) ⇒ Object



323
324
# File 'lib/web/htmlparser/sgml-parser.rb', line 323

def unknown_starttag(tag, attrs)
end