确定两个 Nokogiri 节点是否等效

Question

想象一下，您有代表以下两个文档中的 元素的 Nokogiri 节点：

<r xmlns:x="foo"><a foo="bar" jim="jam" x:oh="no"><x:b>Hello</x:b></a></r>
<r xmlns:i="foo"><a jim="jam" i:oh="no" foo="bar"><i:b>Hello</i:b></a></r>

从 DOM 的角度来看，这两个节点是等效的。我想有效地检测到这一点，但是 Nokogiri::XML::Node#== 只是检查对象相等性。由于 Nokogiri 1.5.0 尚不支持规范化，因此我不能只序列化节点并比较字符串。

比较两个节点以确保它们的名称、属性和内容在规范上等效的最快方法是什么？

答案可能依赖于仅在 Ruby 1.9.2+ 中提供的功能。

如果需要，

ORIG1 = "<a>
  <a1><a1a/><a1b/><a1c/></a1>
  <a2><a2a/><a2b foo='bar' jim='jam'/><a2c/></a2>
  <a3><a3a/><a3b/><a3c>foo</a3c></a3>
</a>"
ORIG2 = "<a>
  <a1><a1a/><a1b/><a1c/></a1>
  <a2><a2a/><a2b jim='jam' foo='bar'/><a2c/></a2>
  <a3><a3a/><a3b/><a3c>foo</a3c></a3>
</a>"
NOTEXT = "<a>
  <a1><a1a/><a1b/><a1c/></a1>
  <a2><a2a/><a2b foo='bar' jim='jam'/><a2c/></a2>
  <a3><a3a/><a3b/><a3c/></a3>
</a>"
EXTRATEXT1 = "<a>
  <a1><a1a/><a1b/><a1c/></a1>
  <a2><a2a/><a2b foo='bar' jim='jam'/><a2c/></a2>
  <a3><a3a/><a3b/><a3c>foobar</a3c></a3>
</a>"
EXTRATEXT2 = "<a>
  <a1><a1a/><a1b/><a1c/></a1>
  <a2><a2a/><a2b foo='bar' jim='jam'/><a2c/></a2>
  <a3><a3a/><a3b>hi</a3b><a3c>foo</a3c></a3>
</a>"
MISSINGNODE = "<a>
  <a1><a1a/><a1b/><a1c/></a1>
  <a2><a2a/><a2b foo='bar' jim='jam'/><a2c/></a2>
  <a3><a3a/><a3b/></a3>
</a>"
EXTRANODE = "<a>
  <a1><a1a/><a1b/><a1c/></a1>
  <a2><a2a/><a2b foo='bar' jim='jam'/><a2c/></a2>
  <a3><a3a/><a3b/><a3c>foo</a3c><a3d/></a3>
</a>"
SWAPNODE = "<a>
  <a1><a1a/><a1b/><a1c/></a1>
  <a2><a2a/><a2b foo='bar' jim='jam'/><a2c/></a2>
  <a3><a3x/><a3b/><a3c>foo</a3c></a3>
</a>"
MISSINGATTRIB = "<a>
  <a1><a1a/><a1b/><a1c/></a1>
  <a2><a2a/><a2b jim='jam'/><a2c/></a2>
  <a3><a3a/><a3b/><a3c>foo</a3c></a3>
</a>"
EXTRAATTRIB1 = "<a>
  <a1><a1a/><a1b/><a1c/></a1>
  <a2><a2a/><a2b foo='bar' jim='jam' kits='meow'/><a2c/></a2>
  <a3><a3a/><a3b/><a3c>foo</a3c></a3>
</a>"
EXTRAATTRIB2 = "<a>
  <a1><a1a/><a1b/><a1c kits='meow'/></a1>
  <a2><a2a/><a2b foo='bar' jim='jam'/><a2c/></a2>
  <a3><a3a/><a3b/><a3c>foo</a3c></a3>
</a>"
SWAPATTRIB1 = "<a>
  <a1><a1a/><a1b/><a1c/></a1>
  <a2><a2a/><a2b foo='bar' jim='zzz'/><a2c/></a2>
  <a3><a3a/><a3b/><a3c>foo</a3c></a3>
</a>"
SWAPATTRIB2 = "<a>
  <a1><a1a/><a1b/><a1c/></a1>
  <a2><a2a/><a2b foo='bar' zzz='jam'/><a2c/></a2>
  <a3><a3a/><a3b/><a3c>foo</a3c></a3>
</a>"
NAMESPACE1 = "<a xmlns:x='foo'>
  <a1><a1a/><a1b/><a1c/></a1>
  <a2><a2a/><a2b foo='bar' jim='jam'/><a2c/></a2>
  <a3><x:a3a/><a3b/><a3c>foo</a3c></a3>
</a>"
NAMESPACE1B = "<a xmlns:z='foo'>
  <a1><a1a/><a1b/><a1c/></a1>
  <a2><a2a/><a2b foo='bar' jim='jam'/><a2c/></a2>
  <a3><z:a3a/><a3b/><a3c>foo</a3c></a3>
</a>"
NAMESPACE1C = "<a xmlns:x='bar'>
  <a1><a1a/><a1b/><a1c/></a1>
  <a2><a2a/><a2b foo='bar' jim='jam'/><a2c/></a2>
  <a3><x:a3a/><a3b/><a3c>foo</a3c></a3>
</a>"
NAMESPACE2 = "<a xmlns:x='foo'>
  <a1><a1a/><a1b/><a1c/></a1>
  <a2><a2a/><a2b foo='bar' x:jim='jam'/><a2c/></a2>
  <a3><a3a/><a3b/><a3c>foo</a3c></a3>
</a>"
NAMESPACE2B= "<a xmlns:z='foo'>
  <a1><a1a/><a1b/><a1c/></a1>
  <a2><a2a/><a2b foo='bar' z:jim='jam'/><a2c/></a2>
  <a3><a3a/><a3b/><a3c>foo</a3c></a3>
</a>"
NAMESPACE2C= "<a xmlns:x='bar'>
  <a1><a1a/><a1b/><a1c/></a1>
  <a2><a2a/><a2b foo='bar' x:jim='jam'/><a2c/></a2>
  <a3><a3a/><a3b/><a3c>foo</a3c></a3>
</a>"


require 'nokogiri'
require 'minitest/autorun'
class NodeEquivalence < MiniTest::Unit::TestCase
  def setup
    @o1 = Nokogiri::XML(ORIG1,&:noblanks).root
  end
  def test_equivalence
    o2 = Nokogiri::XML(ORIG2,&:noblanks).root
    assert @o1 =~ o2, "Equivalent nodes should be equivalent"
    assert o2 =~ @o1, "Equivalent nodes should be equivalent"
  end
  def test_textnodes
    no_text = Nokogiri::XML(NOTEXT,&:noblanks).root
    extra1  = Nokogiri::XML(EXTRATEXT1,&:noblanks).root
    extra2  = Nokogiri::XML(EXTRATEXT2,&:noblanks).root
    refute @o1 =~ no_text, "Notice missing text node child"
    refute no_text =~ @o1, "Notice missing text node child"
    refute @o1 =~ extra1,  "Notice different text in text node"
    refute extra1 =~ @o1,  "Notice different text in text node"
    refute @o1 =~ extra2,  "Notice extra text node"
    refute extra2 =~ @o1,  "Notice extra text node"
  end
  def test_nodes
    missing = Nokogiri::XML(MISSINGNODE,&:noblanks).root
    extra   = Nokogiri::XML(EXTRANODE,&:noblanks).root
    changed = Nokogiri::XML(SWAPNODE,&:noblanks).root
    refute @o1 =~ missing, "Notice missing node"
    refute missing =~ @o1, "Notice missing node"
    refute @o1 =~ extra,   "Notice extra node"
    refute extra =~ @o1,   "Notice extra node"
    refute @o1 =~ changed, "Notice renamed node"
    refute changed =~ @o1, "Notice renamed node"
  end
  def test_attributes
    missing = Nokogiri::XML(MISSINGATTRIB,&:noblanks).root
    extra1  = Nokogiri::XML(EXTRAATTRIB1,&:noblanks).root
    extra2  = Nokogiri::XML(EXTRAATTRIB2,&:noblanks).root
    swap1   = Nokogiri::XML(SWAPATTRIB1,&:noblanks).root
    swap2   = Nokogiri::XML(SWAPATTRIB2,&:noblanks).root
    refute @o1 =~ missing, "Notice missing attribute"
    refute missing =~ @o1, "Notice missing attribute"
    refute @o1 =~ extra1,  "Notice extra attribute"
    refute extra1 =~ @o1,  "Notice extra attribute"
    refute @o1 =~ extra2,  "Notice new attribute"
    refute extra2 =~ @o1,  "Notice new attribute"
    refute @o1 =~ swap1,   "Notice changed attribute value"
    refute swap1 =~ @o1,   "Notice changed attribute value"
    refute @o1 =~ swap2,   "Notice changed attribute name"
    refute swap2 =~ @o1,   "Notice changed attribute name"
  end
  def test_namespaces
    ns1  = Nokogiri::XML(NAMESPACE1,&:noblanks).root
    ns2  = Nokogiri::XML(NAMESPACE2,&:noblanks).root
    ns1b = Nokogiri::XML(NAMESPACE1B,&:noblanks).root
    ns2b = Nokogiri::XML(NAMESPACE2B,&:noblanks).root
    ns1c = Nokogiri::XML(NAMESPACE1C,&:noblanks).root
    ns2c = Nokogiri::XML(NAMESPACE2C,&:noblanks).root
    refute @o1 =~ ns1,  "Notice added node namespace"
    refute ns1 =~ @o1,  "Notice removed node namespace"
    refute @o1 =~ ns2,  "Notice added attribute namespace"
    refute ns2 =~ @o1,  "Notice removed attribute namespace"
    assert ns1 =~ ns1b, "Different namespace names on nodes don't matter"
    assert ns2 =~ ns2b, "Different namespace names on attributes don't matter"
    refute ns1 =~ ns1c, "Notice different namespace hrefs on nodes"
    refute ns2 =~ ns2c, "Notice different namespace hrefs on attributes"
  end
end

Answer 1

这是我当前的实现。它notnow命名空间感知：

class Nokogiri::XML::Node
  # Return true if this node is content-equivalent to other, false otherwise
  def =~(other)
    return true if self == other
    return false unless name == other.name
    stype = node_type; otype = other.node_type
    return false unless stype == otype
    sa = attributes; oa = other.attributes
    return false unless sa.length == oa.length
    sa = sa.sort.map{ |n,a| [n,a.value,a.namespace && a.namespace.href] }
    oa = oa.sort.map{ |n,a| [n,a.value,a.namespace && a.namespace.href] }
    return false unless sa == oa
    skids = children; okids = other.children
    return false unless skids.length == okids.length
    return false if stype == TEXT_NODE && (content != other.content)
    sns = namespace; ons = other.namespace
    return false if !sns ^ !ons
    return false if sns && (sns.href != ons.href)
    skids.to_enum.with_index.all?{ |ski,i| ski =~ okids[i] }
  end
end

这是我的基准代码（使用上面测试用例中的常量）：

require 'benchmark'
Benchmark.bm(10) do |x|
  N = 1000
  NODES = [
    ORIG1, ORIG2, NOTEXT, EXTRATEXT1, EXTRATEXT2,
    MISSINGNODE, EXTRANODE, SWAPNODE,
    MISSINGATTRIB, EXTRAATTRIB1, EXTRAATTRIB2, SWAPATTRIB1, SWAPATTRIB2,
    NAMESPACE1, NAMESPACE2
  ].map{ |xml| Nokogiri::XML(xml,&:noblanks).root }
  MAIN = NODES.shift
  x.report("Phrogz"){ N.times{
    NODES.each{ |other| MAIN =~ other }
  }}
end