From 33788871a9bc9cc9a4464dd24da17ef93d2b7732 Mon Sep 17 00:00:00 2001
From: Mike Gerwitz <gerwitzm@lovullo.com>
Date: Wed, 26 Nov 2014 15:35:35 -0500
Subject: [PATCH] f:make-ref, f:is-ref, and f:QName added

---
 src/apply.xsl       |  76 ++++++++++++++++++++-
 test/apply-test.xsl |  44 +++++++++---
 test/apply.xspec    | 161 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 271 insertions(+), 10 deletions(-)

diff --git a/src/apply.xsl b/src/apply.xsl
index 5a2b704..f7130b5 100644
--- a/src/apply.xsl
+++ b/src/apply.xsl
@@ -1,4 +1,4 @@
-<?xml version="1.0" encoding="ISO-8859-1"?>
+<?xml version="1.0" encoding="utf-8"?>
 <!--
   Dynamic function application
 
@@ -195,4 +195,78 @@
   </message>
 </template>
 
+
+<!--
+  Create a reference to dynamic function @var{name} with arity
+  @var{arity}
+
+  This function @emph{does not} verify that the function @var{name}
+  exists, nor does it verify that the provided @var{arity} is valid
+  for it.  Further, the returned function reference will work
+  @emph{only with dynamic functions}—that is, an application template
+  is needed.  See @file{transform/apply-gen.xsl} for more information
+  and examples.
+-->
+<function name="f:make-ref" as="element( f:ref )">
+  <param name="name"  as="xs:QName" />
+  <param name="arity" as="xs:integer" />
+
+  <variable name="ns"
+            select="namespace-uri-from-QName( $name )" />
+
+  <f:ref arity="{$arity}">
+    <element name="{$name}"
+             namespace="{$ns}" />
+  </f:ref>
+</function>
+
+
+<!--
+  Determines whether @var{fnref} represents a valid dynamic function
+  reference
+
+  This can be used to determine if @var{fnref} is valid as input to
+  other functions, some of which may produce an error if called with
+  an invalid dynamic function reference.
+
+  @i{Implementation details:} To be valid, @var{fnref} must:
+
+  @enumerate
+  @item Be an element of type @code{f:ref};
+  @item Have a numeric @code{@arity}; and
+  @item Have a child target function node.
+  @enumerate
+-->
+<function name="f:is-ref" as="xs:boolean">
+  <param name="fnref" as="item()*" />
+
+  <variable name="ref" select="$fnref[ 1 ]" />
+
+  <!-- for @arity check: note that NaN != NaN -->
+  <sequence select="$ref instance of element( f:ref )
+                    and number( $ref/@arity ) = number( $ref/@arity )
+                    and exists( $ref/*[ 1 ] )" />
+</function>
+
+
+<!--
+  Retrieve the QName of the target dynamic function
+
+  Usually, this would match precisely the QName of the target
+  function.
+
+  @i{Implementation details:} This actually represents the QName of
+  the @emph{application template}, which could differ from the target
+  function name.  One reason this may be the case is to provide a
+  function alias.
+-->
+<function name="f:QName" as="xs:QName?">
+  <param name="fnref" as="element( f:ref )" />
+
+  <variable name="target" as="element()?"
+            select="$fnref/element()[ 1 ]" />
+
+  <sequence select="node-name( $target )" />
+</function>
+
 </stylesheet>
diff --git a/test/apply-test.xsl b/test/apply-test.xsl
index 5327deb..010de9c 100644
--- a/test/apply-test.xsl
+++ b/test/apply-test.xsl
@@ -28,13 +28,25 @@
   <import href="../src/apply.xsl" />
 
 
-  <template mode="f:apply" match="f:ref[ foo:fn0 ]">
+  <!-- catch errors (otherwise, we'd terminate) -->
+  <template mode="f:apply"
+            match="*"
+            priority="2">
+    <foo:unknown-dyn-fun />
+  </template>
+
+
+  <template mode="f:apply"
+            match="f:ref[ foo:fn0 ]"
+            priority="5">
     <!-- return something to show that we were called properly -->
     <foo:applied n="0" />
   </template>
 
 
-  <template mode="f:apply" match="f:ref[ foo:fn1 ]">
+  <template mode="f:apply"
+            match="f:ref[ foo:fn1 ]"
+            priority="5">
     <param name="arg1" />
 
     <foo:applied n="1" />
@@ -42,7 +54,9 @@
   </template>
 
 
-  <template mode="f:apply" match="f:ref[ foo:fn2 ]">
+  <template mode="f:apply"
+            match="f:ref[ foo:fn2 ]"
+            priority="5">
     <param name="arg1" />
     <param name="arg2" />
 
@@ -51,7 +65,9 @@
   </template>
 
 
-  <template mode="f:apply" match="f:ref[ foo:fn3 ]">
+  <template mode="f:apply"
+            match="f:ref[ foo:fn3 ]"
+            priority="5">
     <param name="arg1" />
     <param name="arg2" />
     <param name="arg3" />
@@ -61,7 +77,9 @@
   </template>
 
 
-  <template mode="f:apply" match="f:ref[ foo:fn4 ]">
+  <template mode="f:apply"
+            match="f:ref[ foo:fn4 ]"
+            priority="5">
     <param name="arg1" />
     <param name="arg2" />
     <param name="arg3" />
@@ -72,7 +90,9 @@
   </template>
 
 
-  <template mode="f:apply" match="f:ref[ foo:fn5 ]">
+  <template mode="f:apply"
+            match="f:ref[ foo:fn5 ]"
+            priority="5">
     <param name="arg1" />
     <param name="arg2" />
     <param name="arg3" />
@@ -85,7 +105,9 @@
   </template>
 
 
-  <template mode="f:apply" match="f:ref[ foo:fn6 ]">
+  <template mode="f:apply"
+            match="f:ref[ foo:fn6 ]"
+            priority="5">
     <param name="arg1" />
     <param name="arg2" />
     <param name="arg3" />
@@ -99,7 +121,9 @@
   </template>
 
 
-  <template mode="f:apply" match="f:ref[ foo:fn7 ]">
+  <template mode="f:apply"
+            match="f:ref[ foo:fn7 ]"
+            priority="5">
     <param name="arg1" />
     <param name="arg2" />
     <param name="arg3" />
@@ -114,7 +138,9 @@
   </template>
 
 
-  <template mode="f:apply" match="f:ref[ foo:fn8 ]">
+  <template mode="f:apply"
+            match="f:ref[ foo:fn8 ]"
+            priority="5">
     <param name="arg1" />
     <param name="arg2" />
     <param name="arg3" />
diff --git a/test/apply.xspec b/test/apply.xspec
index 4ccce28..662c5d5 100644
--- a/test/apply.xspec
+++ b/test/apply.xspec
@@ -26,6 +26,9 @@
              xmlns:foo="http://www.lovullo.com/_junk"
              stylesheet="apply-test.xsl">
 
+  <variable name="foo-uri"
+            select="namespace-uri-for-prefix( 'foo', $args )" />
+
   <variable name="args">
     <foo:args>
       <foo:arg1 />
@@ -222,4 +225,162 @@
       </scenario>
     </scenario>
   </scenario>
+
+
+  <scenario label="f:make-ref constructor">
+    <scenario label="when called with a function QName and arity">
+      <variable name="qname"
+                select="QName( $foo-uri, 'reftest' )" />
+      <variable name="arity"
+                select="2" />
+
+      <call function="f:make-ref">
+        <param name="name"  select="$qname" />
+        <param name="arity" select="$arity" />
+      </call>
+
+      <expect label="produces a dynamic function reference"
+              test="f:is-ref( $x:result )" />
+
+      <expect label="produces provided reference arity"
+              test="f:arity( $x:result ) = $arity" />
+
+      <expect label="produces reference to expected QName"
+              test="f:QName( $x:result ) = $qname" />
+    </scenario>
+
+
+    <scenario label="produces a valid dynamic function reference">
+      <call function="f:apply">
+        <param name="fnref"
+               select="f:make-ref( QName( $foo-uri, 'fn1' ),
+                                   1 )" />
+        <param name="arg1"
+               select="$args/foo:arg1" />
+      </call>
+
+      <expect label="that can be applied using f:apply"
+              test="$x:result[ 1 ] = foo:applied[ @n = 1 ]
+                    and $x:result[ 2 ] is $args/foo:arg1" />
+    </scenario>
+  </scenario>
+
+
+  <scenario label="f:is-ref predicate">
+    <scenario label="given a valid dynamic function reference">
+      <call function="f:is-ref">
+        <param name="fnref"
+               select="f:make-ref( QName( $foo-uri, 'foo' ), 0 )" />
+      </call>
+
+      <expect label="returns true()"
+              select="true()" />
+    </scenario>
+
+
+    <scenario label="given an invalid dynamic function reference">
+      <call function="f:is-ref">
+        <param name="fnref">
+          <foo:bar />
+        </param>
+      </call>
+
+      <expect label="returns false()"
+              select="false()" />
+    </scenario>
+
+
+    <scenario label="given a dynamic function reference without arity">
+      <call function="f:is-ref">
+        <param name="fnref">
+          <f:ref>
+            <foo:bar />
+          </f:ref>
+        </param>
+      </call>
+
+      <expect label="returns false()"
+              select="false()" />
+    </scenario>
+
+
+    <scenario label="given a dynamic function reference without
+                     integral arity">
+      <call function="f:is-ref">
+        <param name="fnref">
+          <f:ref arity="moo">
+            <foo:bar />
+          </f:ref>
+        </param>
+      </call>
+
+      <expect label="returns false()"
+              select="false()" />
+    </scenario>
+
+
+    <scenario label="given a dynamic function reference without target
+                     node">
+      <call function="f:is-ref">
+        <param name="fnref">
+          <f:ref arity="0" />
+        </param>
+      </call>
+
+      <expect label="returns false()"
+              select="false()" />
+    </scenario>
+
+
+    <scenario label="given an empty sequence">
+      <call function="f:is-ref">
+        <param name="fnref" select="()" />
+      </call>
+
+      <expect label="returns false()"
+              select="false()" />
+    </scenario>
+
+
+    <scenario label="given a non-element">
+      <call function="f:is-ref">
+        <param name="fnref" select="5" />
+      </call>
+
+      <expect label="returns false()"
+              select="false()" />
+    </scenario>
+  </scenario>
+
+
+  <scenario label="f:QName accessor">
+    <scenario label="given a valid dynamic function reference">
+      <variable name="foo-qname"
+                select="QName( $foo-uri, 'foo' )" />
+
+      <call function="f:QName">
+        <param name="fnref"
+               select="f:make-ref( $foo-qname, 0 )" />
+      </call>
+
+      <expect label="returns QName"
+              test="$x:result instance of xs:QName" />
+
+      <expect label="returns QName of target dynamic function"
+              select="$foo-qname" />
+    </scenario>
+
+
+    <scenario label="given a dynamic function reference with no target
+                     node">
+      <call function="f:QName">
+        <param name="fnref">
+          <f:ref arity="5" />
+        </param>
+      </call>
+
+      <expect label="returns empty sequence"
+              select="()" />
+    </scenario>
+  </scenario>
 </description>