From: "ara.t.howard" <ara.t.howard@...>
Date: 2008-07-31T03:15:22+09:00
Subject: Re: Suggestions for improving a trivial tag parser


On Jul 30, 2008, at 11:28 AM, Gregory Brown wrote:

> Hi folks,
>
> I need to take strings that have embedded <i> and <b> tags and split
> them out into an array.
> Here are some examples:
>
> # No need to ensure valid pairs, just need to break out tags from  
> the text
> #----------------------------------------------------------------------------------------------
>
> describe "Inline style parsing" do
>  it "should return an identical string if inline styles are not  
> detected" do
>    create_pdf
>    @pdf.parse_inline_styles("Hello World").should == "Hello World"
>  end
>
>  it "should return an array of segments when a style is detected" do
>    create_pdf
>    @pdf.parse_inline_styles("Hello <i>Fine</i> World").should ==
>      ["Hello ", "<i>","Fine", "</i>", " World"]
>  end
>
>  it "should create an array of segments when multiple styles are
> detected" do
>    create_pdf
>    @pdf.parse_inline_styles("Hello <i>Fine <b>World</b></i>").should  
> ==
>      ["Hello ", "<i>", "Fine ", "<b>", "World", "</b>", "</i>"]
>  end
> end
>
> ###
>
> I fear my implementation (below) is showing one of my weakest areas in
> Ruby, and probably even has some unforeseen problems.  I'm sure it can
> be done more accurately in less code.  Any kind RubyTalk folks want to
> school me?
>
> ###
>
>      def parse_inline_styles(text) #:nodoc:
>        require "strscan"
>
>        sc = StringScanner.new(text)
>        output = []
>        last_pos = 0
>
>        loop do
>         if sc.scan_until(/<\/?[ib]>/)
>           pre = sc.pre_match[last_pos..-1]
>           output << pre unless pre.empty?
>           output << sc.matched
>           last_pos = sc.pos
>         else
>           output << sc.rest if sc.rest?
>           break output
>         end
>        end
>
>        output.length == 1 ? output.first : output
>      end
>
> ###
>
> Thanks,
> -greg
>




my take:


cfp:~ > cat a.rb
require 'yaml'

strings =
   "Hello World",
   "Hello <i>Fine</i> World",
   "Hello <i>Fine <b>World</b></i>"

def parse_inline_styles string, tags = %w(<i> </i> <b> </b>)
   re = Regexp.new tags.flatten.map{|tag| "(#{ Regexp.escape  
tag })"}.join('|')
   tokens = string.split(re)
   tokens.delete_if{|token| token.empty?}
   ((tokens.size == 1 and tokens.first == string) ? string : tokens)
end

strings.each do |string|
   y string => parse_inline_styles(string)
end







cfp:~ > ruby a.rb
---
Hello World: Hello World
---
Hello <i>Fine</i> World:
- "Hello "
- <i>
- Fine
- </i>
- " World"
---
Hello <i>Fine <b>World</b></i>:
- "Hello "
- <i>
- "Fine "
- <b>
- World
- </b>
- </i>




a @ http://codeforpeople.com/
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better. simply reflect on that.
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