new html2text converter

git-svn-id: svn+ssh://svn.gna.org/svn/feed2imap/trunk/feed2imap@36 f70e237a-67f3-0310-a06c-d2b8a7116972

3 files changed, 462 insertions, 13 deletions

diff --git a/lib/feed2imap/html2text-parser.rb b/lib/feed2imap/html2text-parser.rb
new file mode 100644
index 0000000..a6bf400
--- /dev/null
+++ b/lib/feed2imap/html2text-parser.rb
@@ -0,0 +1,97 @@
+=begin
+Feed2Imap - RSS/Atom Aggregator uploading to an IMAP Server
+Copyright (c) 2005 Lucas Nussbaum <lucas@lucas-nussbaum.net>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program; if not, write to the Free Software
+Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+=end
+
+require 'feed2imap/sgml-parser.rb'
+
+# this class provides a simple SGML parser that removes HTML tags
+class HTML2TextParser < SGMLParser
+
+  attr_reader :savedata
+
+  def initialize(verbose = false)
+    @savedata = ''
+    @pre = false
+    @href = nil
+    @links = []
+    super(verbose)
+  end
+
+  def handle_data(data)
+    # let's remove all CR
+    data.gsub!(/\n/, '') if not @pre
+ 
+    @savedata << data
+  end
+
+  def unknown_starttag(tag, attrs)
+    case tag
+    when 'p'
+      @savedata << "\n\n"
+    when 'br'
+      @savedata << "\n"
+    when 'b'
+      @savedata << '*'
+    when 'u'
+      @savedata << '_'
+    when 'i'
+      @savedata << '/'
+    when 'pre'
+      @savedata << "\n\n"
+      @pre = true
+    when 'a'
+      # find href in args
+      @href = nil
+      attrs.each do |a|
+        if a[0] == 'href'
+          @href = a[1]
+        end
+      end
+      @links << @href.gsub(/^("|'|)(.*)("|')$/,'\2')
+    end
+  end
+
+  def close
+    super
+    if @links.length > 0
+      @savedata << "\n\n"
+      @links.each_index do |i|
+        @savedata << "[#{i+1}] #{@links[i]}\n"
+      end
+    end
+  end
+
+  def unknown_endtag(tag)
+    case tag
+    when 'b'
+      @savedata << '*'
+    when 'u'
+      @savedata << '_'
+    when 'i'
+      @savedata << '/'
+    when 'pre'
+      @savedata << "\n\n"
+      @pre = false
+    when 'a'
+      if @href
+        @savedata << "[#{@links.length}]"
+        @href = nil
+      end
+    end
+  end
+end
diff --git a/lib/feed2imap/sgml-parser.rb b/lib/feed2imap/sgml-parser.rb
new file mode 100644
index 0000000..c692f52
--- /dev/null
+++ b/lib/feed2imap/sgml-parser.rb
@@ -0,0 +1,333 @@
+# A parser for SGML, using the derived class as static DTD.
+# from http://raa.ruby-lang.org/project/html-parser
+
+class SGMLParser
+
+  # Regular expressions used for parsing:
+  Interesting = /[&<]/
+  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'=>'\''}
+
+  def initialize(verbose=false)
+    @verbose = verbose
+    reset
+  end
+
+  def reset
+    @rawdata = ''
+    @stack = []
+    @lasttag = '???'
+    @nomoretags = false
+    @literal = false
+  end
+
+  def has_context(gi)
+    @stack.include? gi
+  end
+
+  def setnomoretags
+    @nomoretags = true
+    @literal = true
+  end
+
+  def setliteral(*args)
+    @literal = true
+  end
+
+  def feed(data)
+    @rawdata << data
+    goahead(false)
+  end
+
+  def close
+    goahead(true)
+  end
+
+  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
+
+  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 = $&.length
+    j = match
+    handle_comment(rawdata[i+4..(j-1)])
+    j = match + matched_length
+    return j-i
+  end
+
+  def parse_starttag(i)
+    rawdata = @rawdata
+    j = rawdata.index(Endbracket, i + 1)
+    return nil unless j
+    attrs = []
+    if rawdata[i+1] == ?> #
+      # SGML shorthand: <> == <last open tag seen>
+      k = j
+      tag = @lasttag
+    else
+      match = rawdata.index(Tagfind, i + 1)
+      unless match
+        raise RuntimeError, 'unexpected call to parse_starttag'
+      end
+      k = i + 1 + ($&.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[-1,1] == ?")
+        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
+
+  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
+
+  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
+
+  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
+
+  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
+
+  def handle_starttag(tag, method, attrs)
+    self.send(method, attrs)
+  end
+
+  def handle_endtag(tag, method)
+    self.send(method)
+  end
+
+  def report_unbalanced(tag)
+    if @verbose
+      print '*** Unbalanced </' + tag + '>', "\n"
+      print '*** Stack:', self.stack, "\n"
+    end
+  end
+
+  def handle_charref(name)
+    n = Integer(name)
+    if !(0 <= n && n <= 255)
+      unknown_charref(name)
+      return
+    end
+    handle_data(n.chr)
+  end
+
+  def handle_entityref(name)
+    table = Entitydefs
+    if table.include?(name)
+      handle_data(table[name])
+    else
+      unknown_entityref(name)
+      return
+    end
+  end
+
+  def handle_data(data)
+  end
+
+  def handle_comment(data)
+  end
+
+  def handle_special(data)
+  end
+
+  def unknown_starttag(tag, attrs)
+  end
+  def unknown_endtag(tag)
+  end
+  def unknown_charref(ref)
+  end
+  def unknown_entityref(ref)
+  end
+
+end
diff --git a/lib/feed2imap/textconverters.rb b/lib/feed2imap/textconverters.rb
index be63173..ba3813a 100644
--- a/lib/feed2imap/textconverters.rb
+++ b/lib/feed2imap/textconverters.rb
@@ -18,6 +18,7 @@ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 =end
 
 require 'uri' # for URI::regexp
+require 'feed2imap/html2text-parser'
 
 # This class provides various converters
 class String
@@ -41,19 +42,37 @@ class String
 
   # Convert an HTML text to plain text
   def html2text
-    text = self.clone
-    # let's remove all CR
-    text.gsub!(/\n/, '')
-    # convert <p> and <br>
-    text.gsub!(/\s*<\/p>\s*/, '')
-    text.gsub!(/\s*<p(\s[^>]*)?>\s*/, "\n\n")
-    text.gsub!(/\s*<br(\s*)\/?(\s*)>\s*/, "\n")
-    # remove other tags
-    text.gsub!(/<[^>]*>/, '')
-    # remove leading and trailing whilespace
-    text.gsub!(/\A\s*/m, '')
-    text.gsub!(/\s*\Z/m, '')
-    text
+    if false
+      text = self.clone
+      # let's remove all CR
+      text.gsub!(/\n/, '')
+      # convert <p> and <br>
+      text.gsub!(/\s*<\/p>\s*/, '')
+      text.gsub!(/\s*<p(\s[^>]*)?>\s*/, "\n\n")
+      text.gsub!(/\s*<br(\s*)\/?(\s*)>\s*/, "\n")
+      # remove other tags
+      text.gsub!(/<[^>]*>/, '')
+      # remove leading and trailing whilespace
+      text.gsub!(/\A\s*/m, '')
+      text.gsub!(/\s*\Z/m, '')
+      text
+    else
+      text = self.clone
+      # parse HTML
+      p = HTML2TextParser::new(true)
+      p.feed(text)
+      p.close
+      text = p.savedata
+      # remove leading and trailing whilespace
+      text.gsub!(/\A\s*/m, '')
+      text.gsub!(/\s*\Z/m, '')
+      # remove whitespace around \n
+      text.gsub!(/ *\n/m, "\n")
+      text.gsub!(/\n */m, "\n")
+      # and duplicates \n
+      text.gsub!(/\n\n+/m, "\n\n")
+      text
+    end
   end
 
   # Remove white space around the text