Question

我试图以Hpricot / Nokogiri类型的方式解析，而不是评估，修改ERB文件。我试图解析的文件包含混合了使用ERB生成的动态内容的HTML片段（标准的rails视图文件）我正在寻找一个不仅会解析周围内容的库，就像Hpricot或Nokogiri那样，但也会对待它ERB符号，＆lt;％，＆lt;％=等，就好像它们是html / xml标签一样。

理想情况下，我会回到类似DOM的结构，其中＆lt;％，＆lt;％= etc符号将作为自己的节点类型包含在内。

我知道可以使用正则表达式一起破解某些东西，但我正在寻找一些更可靠的东西，因为我正在开发一个工具，我需要在一个非常大的视图代码库上运行，其中包含html内容和erb内容很重要。

例如，内容如：

blah blah blah
<div>My Great Text <%= my_dynamic_expression %></div>

将返回一个树结构，如：

root
 - text_node (blah blah blah)
 - element (div)
    - text_node (My Great Text )
        - erb_node (<%=)

Answer 1

我最终通过使用RLex，http://raa.ruby-lang.org/project/ruby-lex/，带有以下语法的lex的ruby版本来解决这个问题：

%{

#define NUM 257

#define OPTOK 258
#define IDENT 259
#define OPETOK 260
#define CLSTOK 261
#define CLTOK 262
#define FLOAT 263
#define FIXNUM 264
#define WORD 265
#define STRING_DOUBLE_QUOTE 266
#define STRING_SINGLE_QUOTE 267

#define TAG_START 268
#define TAG_END 269
#define TAG_SELF_CONTAINED 270
#define ERB_BLOCK_START 271
#define ERB_BLOCK_END 272
#define ERB_STRING_START 273
#define ERB_STRING_END 274
#define TAG_NO_TEXT_START 275
#define TAG_NO_TEXT_END 276
#define WHITE_SPACE 277
%}

digit   [0-9]
blank   [ ]
letter  [A-Za-z]
name1   [A-Za-z_]
name2   [A-Za-z_0-9]
valid_tag_character [A-Za-z0-9"'=@_():/ ] 
ignore_tags style|script
%%

{blank}+"\n"                  { return [ WHITE_SPACE, yytext ] } 
"\n"{blank}+                  { return [ WHITE_SPACE, yytext ] } 
{blank}+"\n"{blank}+                  { return [ WHITE_SPACE, yytext ] } 

"\r"                  { return [ WHITE_SPACE, yytext ] } 
"\n"            { return[ yytext[0], yytext[0..0] ] };
"\t"            { return[ yytext[0], yytext[0..0] ] };

^{blank}+       { return [ WHITE_SPACE, yytext ] }

{blank}+$       { return [ WHITE_SPACE, yytext ] };

""   { return [ TAG_NO_TEXT_START, yytext ] }
""  { return [ TAG_NO_TEXT_END, yytext ] }
""                   { return [ TAG_SELF_CONTAINED, yytext ] }
""  { return [ TAG_SELF_CONTAINED, yytext ] }
""    { return [ TAG_START, yytext ] }
""   { return [ TAG_END, yytext ] }

""  { return [ ERB_BLOCK_END, yytext ] }
""  { return [ ERB_STRING_END, yytext ] }


{letter}+       { return [ WORD, yytext ] }


\".*\"          { return [ STRING_DOUBLE_QUOTE, yytext ] }
'.*'                    { return [ STRING_SINGLE_QUOTE, yytext ] }
.           { return [ yytext[0], yytext[0..0] ] }

%%

这不是一个完整的语法，但出于我的目的，查找和重新发送文本，它的工作原理。我将这个语法与这一小段代码结合起来：

    text_handler = MakeYourOwnCallbackHandler.new

    l = Erblex.new
    l.yyin = File.open(file_name, "r")

    loop do
      a,v = l.yylex
      break if a == 0

      if( a < WORD )
        text_handler.character( v.to_s, a )
      else
        case a
        when WORD
          text_handler.text( v.to_s )
        when TAG_START
          text_handler.start_tag( v.to_s )
        when TAG_END
          text_handler.end_tag( v.to_s )
        when WHITESPACE
          text_handler.white_space( v.to_s )
        when ERB_BLOCK_START
          text_handler.erb_block_start( v.to_s )
        when ERB_BLOCK_END
          text_handler.erb_block_end( v.to_s )      
        when ERB_STRING_START
          text_handler.erb_string_start( v.to_s )
        when ERB_STRING_END
          self.text_handler.erb_string_end( v.to_s )
        when TAG_NO_TEXT_START
          text_handler.ignorable_tag_start( v.to_s )
        when TAG_NO_TEXT_END
          text_handler.ignorable_tag_end( v.to_s )
        when STRING_DOUBLE_QUOTE
          text_handler.string_double_quote( v.to_s )
        when STRING_SINGLE_QUOTE
          text_handler.string_single_quote( v.to_s )
        when TAG_SELF_CONTAINED
          text_handler.tag_self_contained( v.to_s )
        end
      end  
    end

Answer 2

我最近遇到了类似的问题。我采用的方法是编写一个小脚本（erblint.rb）执行字符串替换以将ERB标记（<% %>和<%= %>）转换为XML标记，然后使用Nokogiri进行解析。

请参阅以下代码以了解我的意思：

#!/usr/bin/env ruby
require 'rubygems'
require 'nokogiri'

# This is a simple program that reads in a Ruby ERB file, and parses
# it as an XHTML file. Specifically, it makes a decent attempt at
# converting the ERB tags (<% %> and <%= %>) to XML tags (<erb-disp/>
# and <erb-eval/> respectively.
#
# Once the document has been parsed, it will be validated and any
# error messages will be displayed.
#
# More complex option and error handling is left as an exercise to the user.

abort 'Usage: erb.rb <filename>' if ARGV.empty?

filename = ARGV[0]

begin
  doc = ""
  File.open(filename) do |file|
    puts "\n*** Parsing #{filename} ***\n\n"
    file.read(nil, s = "")

    # Substitute the standard ERB tags to convert them to XML tags
    #   <%= ... %> for <erb-disp> ... </erb-disp>
    #   <% ... %>  for <erb-eval> ... </erb-eval>
    #
    # Note that this won't work for more complex expressions such as:
    #   <a href=<% @some_object.generate_url -%> >link text</a>
    # Of course, this is not great style, anyway...
    s.gsub!(/<%=(.+?)%>/m, '<erb-disp>\1</erb-disp>')
    s.gsub!(/<%(.+?)%>/m, '<erb-eval>\1</erb-eval>')
    doc = Nokogiri::XML(s) do |config|
      # put more config options here if required
      # config.strict
    end
  end

  puts doc.to_xhtml(:indent => 2, :encoding => 'UTF-8')
  puts "Huzzah, no errors!" if doc.errors.empty?

  # Otherwise, print each error message
  doc.errors.each { |e| puts "Error at line #{e.line}: #{e}" }
rescue
  puts "Oops! Cannot open #{filename}"
end

我已将此作为Github上的要点发布：https://gist.github.com/787145

用于解析ERB文件的库

2 个答案: