Check that ukfedlabel elements appear at most once per entity

Resolves ukf/ukf-meta#42.

mdx/uk/beans.xml

@@ -328,6 +328,8 @@
 
                 <ref bean="checkSchemas"/>
                 <ref bean="CHECK_std"/>
+                <bean id="check_ukfedlabel" parent="XSLValidationStage"
+                    p:XSLResource="classpath:uk/check_ukfedlabel.xsl"/>
                 <ref bean="check_ukreg"/>
                 <ref bean="check_owner"/>
                 <ref bean="check_uk_keydesc_key"/>

mdx/uk/check_ukfedlabel.xsl

@@ -0,0 +1,74 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+
+    check_ukfedlabel.xsl
+
+    Checking ruleset for the ukfedlabel namespace.
+
+-->
+<xsl:stylesheet version="1.0"
+    xmlns:md="urn:oasis:names:tc:SAML:2.0:metadata"
+    xmlns:ukfedlabel="http://ukfederation.org.uk/2006/11/label"
+    xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
+
+    xmlns="urn:oasis:names:tc:SAML:2.0:metadata">
+
+    <!--
+        Common support functions.
+    -->
+    <xsl:import href="../_rules/check_framework.xsl"/>
+
+
+    <!--
+        Check for individual elements appearing more than once in
+        a single entity.
+    -->
+    <xsl:template match="md:EntityDescriptor[count(descendant::ukfedlabel:AccountableUsers)>1]">
+        <xsl:call-template name="error">
+            <xsl:with-param name="m">
+                <xsl:text>entity must not have more than one ukfedlabel:AccountableUsers element</xsl:text>
+            </xsl:with-param>
+        </xsl:call-template>
+    </xsl:template>
+    <xsl:template match="md:EntityDescriptor[count(descendant::ukfedlabel:ExportOptIn)>1]">
+        <xsl:call-template name="error">
+            <xsl:with-param name="m">
+                <xsl:text>entity must not have more than one ukfedlabel:ExportOptIn element</xsl:text>
+            </xsl:with-param>
+        </xsl:call-template>
+    </xsl:template>
+    <xsl:template match="md:EntityDescriptor[count(descendant::ukfedlabel:ExportOptOut)>1]">
+        <xsl:call-template name="error">
+            <xsl:with-param name="m">
+                <xsl:text>entity must not have more than one ukfedlabel:ExportOptOut element</xsl:text>
+            </xsl:with-param>
+        </xsl:call-template>
+    </xsl:template>
+    <xsl:template match="md:EntityDescriptor[count(descendant::ukfedlabel:Software)>1]">
+        <xsl:call-template name="error">
+            <xsl:with-param name="m">
+                <xsl:text>entity must not have more than one ukfedlabel:Software element</xsl:text>
+            </xsl:with-param>
+        </xsl:call-template>
+    </xsl:template>
+    <xsl:template match="md:EntityDescriptor[count(descendant::ukfedlabel:UKFederationMember)>1]">
+        <xsl:call-template name="error">
+            <xsl:with-param name="m">
+                <xsl:text>entity must not have more than one ukfedlabel:UKFederationMember element</xsl:text>
+            </xsl:with-param>
+        </xsl:call-template>
+    </xsl:template>
+
+
+    <!--
+        Check for entities which are both opted in to and opted out from export.
+    -->
+    <xsl:template match="md:EntityDescriptor/md:Extensions[ukfedlabel:ExportOptIn][ukfedlabel:ExportOptOut]">
+        <xsl:call-template name="error">
+            <xsl:with-param name="m">
+                <xsl:text>entity cannot be both opted in to and opted out from export</xsl:text>
+            </xsl:with-param>
+        </xsl:call-template>
+    </xsl:template>
+
+</xsl:stylesheet>

mdx/uk/check_ukreg.xsl

@@ -50,16 +50,4 @@
 		</xsl:call-template>
 	</xsl:template>
 
-
-	<!--
-		Check for entities which are both opted in to and opted out from export.
-	-->
-	<xsl:template match="md:EntityDescriptor/md:Extensions[ukfedlabel:ExportOptIn][ukfedlabel:ExportOptOut]">
-		<xsl:call-template name="error">
-			<xsl:with-param name="m">
-				<xsl:text>entity cannot be both opted in to and opted out from export</xsl:text>
-			</xsl:with-param>
-		</xsl:call-template>
-	</xsl:template>
-
 </xsl:stylesheet>