引入nokogiri：元素A和B之間選擇內容

什麼是有引入nokogiri選擇開始和停止元素之間的所有內容（包括開始 - /停止元）的最聰明的方法是什麼？引入nokogiri：元素A和B之間選擇內容

檢查下面的示例代碼來了解我在尋找：

require 'rubygems' 
require 'nokogiri' 

value = Nokogiri::HTML.parse(<<-HTML_END) 
    "<html> 
    <body> 
     <p id='para-1'>A</p> 
     <div class='block' id='X1'> 
     <p class="this">Foo</p> 
     <p id='para-2'>B</p> 
     </div> 
     <p id='para-3'>C</p> 
     <p class="that">Bar</p> 
     <p id='para-4'>D</p> 
     <p id='para-5'>E</p> 
     <div class='block' id='X2'> 
     <p id='para-6'>F</p> 
     </div> 
     <p id='para-7'>F</p> 
     <p id='para-8'>G</p> 
    </body> 
    </html>" 
HTML_END 

parent = value.css('body').first 

# START element 
@start_element = parent.at('p#para-3') 
# STOP element 
@end_element = parent.at('p#para-7')

結果（返回值）應該是這樣：

<p id='para-3'>C</p> 
<p class="that">Bar</p> 
<p id='para-4'>D</p> 
<p id='para-5'>E</p> 
<div class='block' id='X2'> 
    <p id='para-6'>F</p> 
</div> 
<p id='para-7'>F</p>

更新：這是我的目前的解決方案，但我認爲必須有一些更聰明：

@my_content = "" 
@selected_node = true 

def collect_content(_start) 

    if _start == @end_element 
    @my_content << _start.to_html 
    @selected_node = false 
    end 

    if @selected_node == true 
    @my_content << _start.to_html 
    collect_content(_start.next) 
    end 

end 

collect_content(@start_element) 

puts @my_content

來源

2009-05-04 Javier

的一種方式太聰明oneliner它使用遞歸：

def collect_between(first, last) 
    first == last ? [first] : [first, *collect_between(first.next, last)] 
end

迭代求解：

def collect_between(first, last) 
    result = [first] 
    until first == last 
    first = first.next 
    result << first 
    end 
    result 
end

編輯：星號（短）解釋

這就是所謂的摔跤運營商。它「解開」的數組：

array = [3, 2, 1] 
[4, array] # => [4, [3, 2, 1]] 
[4, *array] # => [4, 3, 2, 1] 

some_method(array) # => some_method([3, 2, 1]) 
some_method(*array) # => some_method(3, 2, 1) 

def other_method(*array); array; end 
other_method(1, 2, 3) # => [1, 2, 3]

來源

2009-05-04 16:20:10

感謝您的解決方案，並感謝您的尤伯杯智能遞推的單行！雖然，我不明白什麼是「*」前collect_between的遞歸調用（）代表。你能詳細說明一下嗎？ – Javier 2009-05-06 08:21:50

我已在我的原單回答一個小小的解釋。谷歌周圍「圖示操作」獲取更多:-) – 2009-05-07 19:58:50

# monkeypatches for Nokogiri::NodeSet 
# note: versions of these functions will be in Nokogiri 1.3 
class Nokogiri::XML::NodeSet 
    unless method_defined?(:index) 
    def index(node) 
     each_with_index { |member, j| return j if member == node } 
    end 
    end 

    unless method_defined?(:slice) 
    def slice(start, length) 
     new_set = Nokogiri::XML::NodeSet.new(self.document) 
     length.times { |offset| new_set << self[start + offset] } 
     new_set 
    end 
    end 
end 

# 
# solution #1: picking elements out of node children 
# NOTE that this will also include whitespacy text nodes between the <p> elements. 
# 
possible_matches = parent.children 
start_index = possible_matches.index(@start_element) 
stop_index = possible_matches.index(@end_element) 
answer_1 = possible_matches.slice(start_index, stop_index - start_index + 1) 

# 
# solution #2: picking elements out of a NodeSet 
# this will only include elements, not text nodes. 
# 
possible_matches = value.xpath("//body/*") 
start_index = possible_matches.index(@start_element) 
stop_index = possible_matches.index(@end_element) 
answer_2 = possible_matches.slice(start_index, stop_index - start_index + 1)

來源

2009-05-07 11:09:29

爲了完整起見的XPath僅溶液:)
它建立的兩個集合的交集，啓動元件的下面兄弟姐妹和前述最終元素的兄弟姐妹。

基本上就可以構建一個路口：
$a[count(.|$b) = count($b)] 

了幾分變數分爲可讀性：

@start_element = "//p[@id='para-3']" 
@end_element = "//p[@id='para-7']" 
@set_a = "#@start_element/following-sibling::*" 
@set_b = "#@end_element/preceding-sibling::*" 

@my_content = value.xpath("#@set_a[ count(.|#@set_b) = count(#@set_b) ] 
         | #@start_element | #@end_element")

兄弟姐妹不包括元素本身，所以開始和結束元素必須單獨包含在表達式中。

編輯：簡單的解決方案：

@start_element = "p[@id='para-3']" 
@end_element = "p[@id='para-7']" 
@my_content = value.xpath("//*[preceding-sibling::#@start_element and 
           following-sibling::#@end_element] 
         | //#@start_element | //#@end_element")

來源

2009-09-27 21:06:10

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