blocks|key|2683054|text|我同意FiveO的观点，即这是一个重复问题，但是同样，您也会问规范foo和bar/foo之间的区别以及选择哪一个。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2683055|本质上，除非在xsl:template声明中指定优先级，否则匹配的顺序取决于5.5模板规则的冲突解决+for+XSLT1.0、6.4模板规则的冲突解决用于XSLT2.0和6.4模板规则的冲突解决中的规则。这些是您所要求的正式定义。|2683056|然而，基本规则非常简单:匹配越具体，优先级越高。但是，在多个谓词或更深的路径之间，优先级没有差别。|2683057|如果两个模板具有相同的优先级，那么在XSLT1.0和2.0中，处理器可以恢复(按声明顺序取最后一个)或发出错误信号。在3.0中，您可以使用<xsl:mode+on-multiple-match="xxx"+/>设置此行为声明性。|2683058|NodeTest+(即您的match="level2")获得默认优先级-0.5，如果它有子轴说明符(即match="level1/level2")，则获得默认优先级0。更高的优先级优先，这就是为什么bar/foo将匹配foo，只要它有一个父bar。否则，它将与foo匹配。|2683059|这些规则的基础在XSLT版本之间没有改变，它们只是被扩展到允许新的允许语法的规范。|2683060|更多信息在关联问题中。|2683061|基于注释的更新：|BOLD|2683062|您会问这是如何实现的。我只能代表我们的XSLT3.0处理器，Exselt，并用一般的行来解释它，因为由于许多微妙和优化的原因，实际的过程是相当复杂的。|2683063|处理以初始模式的初始上下文节点开始。|unordered-list-item|2683064|处理器保存所有模式的散列，并将所有联合拆分为单独的匹配模板。|2683065|每种模式都有一个按优先级排序的模式列表。|2683066|在访问一个节点(此处为初始上下文节点)时，处理器将遍历所有模式，并找到匹配的第一个模式。|2683067|它通过向后比较路径(类似于规范中解释路径的方式)来做到这一点，如下所示：**节点的路径称为注释*最右边的子轴步骤是根据节点的NameTest或KindTest+(参见XPath规范中的生成)*执行的，如果匹配，则匹配下一个(向左)子轴步骤，等等**如果完整路径匹配，则谓词(如果有)将在当前节点中计算，这将在以后完成，因为它是一个更复杂的进程，可能需要处理器离开当前节点，这是相对昂贵的。|2683068|如果所有匹配，则执行匹配的模板，将当前节点设置为模板的上下文节点。|2683069|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/q/1531664/583513|1|http://www.w3.org/TR/xslt/#conflict|2|http://www.w3.org/TR/xslt20/#conflict|3|http://www.w3.org/TR/xslt-30/#conflict|4|5|http://exselt.net/^0|X|3|11|7|H|4|0|0|7|C|12|C|1|1R|C|2|2D|C|3|0|0|1X|10|0|D|E|Z|4|1F|L|2A|1|2R|7|31|3|3C|3|3M|3|0|0|5|4|4|0|5|3|0|G|K|5|0|0|0|0|0|1Q|8|1Z|8|0|0^^$0|@$1|2|3|4|5|6|7|1Q|8|@$9|1R|A|1S|B|C]|$9|1T|A|1U|B|C]]|D|@$9|1V|A|1W|1|1X]]|E|$]]|$1|F|3|G|5|6|7|1Y|8|@$9|1Z|A|20|B|C]]|D|@$9|21|A|22|1|23]|$9|24|A|25|1|26]|$9|27|A|28|1|29]]|E|$]]|$1|H|3|I|5|6|7|2A|8|@]|D|@]|E|$]]|$1|J|3|K|5|6|7|2B|8|@$9|2C|A|2D|B|C]]|D|@]|E|$]]|$1|L|3|M|5|6|7|2E|8|@$9|2F|A|2G|B|C]|$9|2H|A|2I|B|C]|$9|2J|A|2K|B|C]|$9|2L|A|2M|B|C]|$9|2N|A|2O|B|C]|$9|2P|A|2Q|B|C]|$9|2R|A|2S|B|C]|$9|2T|A|2U|B|C]]|D|@]|E|$]]|$1|N|3|O|5|6|7|2V|8|@]|D|@]|E|$]]|$1|P|3|Q|5|6|7|2W|8|@]|D|@$9|2X|A|2Y|1|2Z]]|E|$]]|$1|R|3|S|5|6|7|30|8|@$9|31|A|32|B|T]]|D|@]|E|$]]|$1|U|3|V|5|6|7|33|8|@]|D|@$9|34|A|35|1|36]]|E|$]]|$1|W|3|X|5|Y|7|37|8|@]|D|@]|E|$]]|$1|Z|3|10|5|Y|7|38|8|@]|D|@]|E|$]]|$1|11|3|12|5|Y|7|39|8|@]|D|@]|E|$]]|$1|13|3|14|5|Y|7|3A|8|@]|D|@]|E|$]]|$1|15|3|16|5|Y|7|3B|8|@$9|3C|A|3D|B|C]|$9|3E|A|3F|B|C]]|D|@]|E|$]]|$1|17|3|18|5|Y|7|3G|8|@]|D|@]|E|$]]|$1|19|3|-4|5|6|7|3H|8|@]|D|@]|E|$]]]|1A|$1B|$5|1C|1D|1E|E|$1F|1G]]|1H|$5|1C|1D|1E|E|$1F|1I]]|1J|$5|1C|1D|1E|E|$1F|1K]]|1L|$5|1C|1D|1E|E|$1F|1M]]|1N|$5|1C|1D|1E|E|$1F|1G]]|1O|$5|1C|1D|1E|E|$1F|1P]]]]

I agree with FiveO that this is a <a href="https://stackoverflow.com/q/1531664/583513">duplicate question</a>, but then again, you also ask specification what the difference is between <code>foo</code> and <code>bar/foo</code> and which one is selected.

Essentially, unless you specify a priority on the <code>xsl:template</code> declaration, the order in which things are matched is determined by the rules in <a href="http://www.w3.org/TR/xslt/#conflict" rel="nofollow noreferrer">5.5 Conflict Resolution for Template Rules</a> for XSLT 1.0, <a href="http://www.w3.org/TR/xslt20/#conflict" rel="nofollow noreferrer">6.4 Conflict Resolution for Template Rules</a> for XSLT 2.0 and <a href="http://www.w3.org/TR/xslt-30/#conflict" rel="nofollow noreferrer">6.4 Conflict Resolution for Template Rules</a>. These are the formal definitions you asked for. 

However, the basic rule is quite simple: the more specific a match, the higher the priority. Except that there is no difference in priority between multiple predicates or deeper paths.

If two templates match that have the same priority, in XSLT 1.0 and 2.0 the processor can either recover (take the last one in declaration order) or signal the error. In 3.0 you can set this behavior declarative with <code>&lt;xsl:mode on-multiple-match="xxx" /&gt;</code>. 

A NodeTest (which is your <code>match="level2"</code>) gets default priority <code>-0.5</code> and if it has a child axis specifier (which is your <code>match="level1/level2"</code>) it gets default priority <code>0</code>. Higher priority goes first, which is why <code>bar/foo</code> will match <code>foo</code>, provided it has a parent <code>bar</code>. Otherwise it will match <code>foo</code>.

The basics of these rules have not changed between XSLT versions, they have just been expanded to allow specification of new allowed syntax.

More information is in the <a href="https://stackoverflow.com/q/1531664/583513">linked question</a>.

Update, based on comment: 
You ask how this is implemented. I can only speak for <a href="http://exselt.net" rel="nofollow noreferrer">our XSLT 3.0 processor, Exselt</a>, and explain it in general lines, because the actual process is rather involved because of many subtleties and optimizations.

<ul>
<li>Processing starts with the initial context node with the initial mode</li>
<li>Processor keeps a hash of all modes and splits all unions into separate matching templates</li>
<li>Each mode has a list of patterns that are ordered by priority</li>
<li>Upon visiting a node (here the initial context node), the processor goes over all patterns and finds the first that matches</li>
<li>It does this by compare the path backwards (similar to how it is explained in the spec), as follows:
** The path to a node is known as an annotation
** The rightmost child axis step is taken and matched to the current node based on its <code>NameTest</code> or <code>KindTest</code> (see productions of these in the XPath spec)
** Only if it matches, the next (to the left) child axis step is matched, and so on
** If the full path matches, the predicate, if any is evaluated against the current node, this is done later, because it is a more involved process and may require the processor to move away from the current node, which is relatively costly.</li>
<li>If all matches, the matched template is executed with the current node set to the context node of the template.</li>
</ul>

For example, consider the following XML:

<pre><code>&lt;root&gt;
 &lt;level1&gt;
 &lt;!--S--&gt;
 &lt;level2&gt;bingo!&lt;/level2&gt;
 &lt;/level1&gt;
&lt;/root&gt;
</code></pre>

And assume we have two templates: <code>match="level2"</code> and <code>match="level1/level2"</code>.

When parser reaches the <code>level2</code> node, how exactly does it determine that current node is matched by both templates, and that it must choose second template because it is more specific? What is formal definition of a "more specific" template?

How does XSLT processor find matching templates?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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例如，考虑以下XML：<root> <level1>  <level2>bingo!</level2> </level1></root>假设我们有两个模板：match="level2"和match="level1/level2"。当解析器到达level2节点时，它...

问XSLT处理器如何找到匹配的模板？
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