问题
Is it possible to control the order of the attribute values in Relax NG? which can be achieved using xs:assert in schema?
XML:
<body>
<h1 class="title">title</h1>
<h2 class="subtitle">subtitle</h2>
<p class="paragraph1">para text 1</p>
<p class="paragraph2">Para text 2</p>
<p class="paragraph3">Para text 2</p>
</body>
The class value should be in order, paragraph1 should always come first and paragraph2 should come after paragraph1. The assert I tried in schema:
<xs:assert test="p[1]/@class = 'paragraph1'
and ((every $i in p[2] satisfies $i/@class = 'paragraph2')
and (every $i in p[3] satisfies $i/@class = 'paragraph3')) "/>
回答1:
A (compact-syntax) RelaxNG grammar to express what the question describes could be written as:
start = element body { h1?, h2?, p.paragraph1?, p.paragraph2?, p.paragraph3? }
h1 = element h1 { text & attribute class { string } }
h2 = element h2 { text & attribute class { string } }
p.paragraph1 = element p { text & attribute class { string "paragraph1" } }
p.paragraph2 = element p { text & attribute class { string "paragraph2" } }
p.paragraph3 = element p { text & attribute class { string "paragraph3" } }
Expressed in the RelaxNG XML syntax:
<grammar xmlns="http://relaxng.org/ns/structure/1.0" datatypeLibrary="">
<start>
<element name="body">
<optional>
<ref name="h1"/>
</optional>
<optional>
<ref name="h2"/>
</optional>
<optional>
<ref name="p.paragraph1"/>
</optional>
<optional>
<ref name="p.paragraph2"/>
</optional>
<optional>
<ref name="p.paragraph3"/>
</optional>
</element>
</start>
<define name="h1">
<element name="h1">
<interleave>
<text/>
<attribute name="class">
<data type="string"/>
</attribute>
</interleave>
</element>
</define>
<define name="h2">
<element name="h2">
<interleave>
<text/>
<attribute name="class">
<data type="string"/>
</attribute>
</interleave>
</element>
</define>
<define name="p.paragraph1">
<element name="p">
<interleave>
<text/>
<attribute name="class">
<value type="string">paragraph1</value>
</attribute>
</interleave>
</element>
</define>
<define name="p.paragraph2">
<element name="p">
<interleave>
<text/>
<attribute name="class">
<value type="string">paragraph2</value>
</attribute>
</interleave>
</element>
</define>
<define name="p.paragraph3">
<element name="p">
<interleave>
<text/>
<attribute name="class">
<value type="string">paragraph3</value>
</attribute>
</interleave>
</element>
</define>
</grammar>
来源:https://stackoverflow.com/questions/44015970/control-attribute-values-order-in-relaxng