From 189eb0cdd6429f46453b1282cc540d2b3654fb8f Mon Sep 17 00:00:00 2001
From: Mike Gerwitz <gerwitzm@lovullo.com>
Date: Mon, 1 Dec 2014 01:20:29 -0500
Subject: [PATCH] Partial applications now defined in terms of ref mutators

---
 src/apply/partial.xsl       | 69 +++++++++++--------------------------
 test/apply/partial-test.xsl |  6 ++--
 test/apply/partial.xspec    | 49 +++++++++++++-------------
 3 files changed, 47 insertions(+), 77 deletions(-)

diff --git a/src/apply/partial.xsl b/src/apply/partial.xsl
index 98700be..e078163 100644
--- a/src/apply/partial.xsl
+++ b/src/apply/partial.xsl
@@ -55,57 +55,32 @@
   <param name="fnref" as="item()+" />
   <param name="args"  as="item()*" />
 
-  <!-- perform type check here, not above, since we can be passed a
-       sequence (e.g.a  partially applied function) -->
-  <variable name="ref"
-            as="element(f:ref)"
-            select="$fnref[ 1 ]" />
-
-  <variable name="argout" as="item()*">
-    <!-- include any previously applied arguments (if we're partially
-         applying a partial application) -->
-    <sequence select="remove( $fnref, 1 )" />
-
-    <!-- nested sequences are implicitly flattened, so we're not
-         returning a sub-sequence here -->
-    <sequence select="$args" />
-  </variable>
-
   <!-- note that, if FNREF is partially applied, then this arity
        represents the arity of the partially applied function, _not_
        the target function -->
   <variable name="arity" as="xs:integer"
-            select="f:arity( $ref )" />
+            select="f:arity( $fnref )" />
 
   <variable name="argn" as="xs:integer"
             select="count( $args )" />
 
   <choose>
-    <when test="$argn eq $arity">
-      <sequence select="_f:apply-partial( $ref, $argout )" />
-    </when>
-
     <when test="$argn gt $arity">
       <apply-templates mode="f:partial-arity-error-hook"
-                       select="$ref">
-        <with-param name="args"  select="$argout" />
-        <with-param name="arity" select="$arity" />
-        <with-param name="argn"  select="count( $argout )" />
+                       select="$fnref">
+        <with-param name="fnref" select="$fnref" />
+        <with-param name="args"  select="$args" />
       </apply-templates>
     </when>
 
     <otherwise>
-      <f:ref>
-        <sequence select="$ref/@*" />
+      <variable name="new-ref"
+                select="f:push-args( $fnref, $args )" />
 
-        <!-- the arity of the new partial application -->
-        <attribute name="arity"
-                   select="$arity - $argn" />
-
-        <sequence select="$ref/*" />
-      </f:ref>
-
-      <sequence select="$argout" />
+      <sequence select="if ( $argn eq $arity ) then
+                          _f:apply-partial( $new-ref )
+                        else
+                          $new-ref" />
     </otherwise>
   </choose>
 </function>
@@ -149,24 +124,18 @@
           match="f:ref"
           priority="1">
   <param name="args"  as="item()*" />
-  <param name="arity" as="xs:decimal" />
 
-  <variable name="ref" as="element(f:ref)"
-            select="." />
+  <variable name="arity" as="xs:integer"
+            select="f:arity(.)" />
   <variable name="argn" as="xs:decimal"
             select="count( $args )" />
-  <variable name="fn"
-            select="$ref/*[1]" />
-  <variable name="fname"
-            select="concat( '{', namespace-uri( $fn ), '}',
-                    $fn/local-name() )" />
 
   <sequence
       select="error(
-                QName( namespace-uri-for-prefix( 'f', $ref ),
+                QName( namespace-uri-for-prefix( 'f', . ),
                        'err:PARTIAL_PARAM_OVERFLOW' ),
                 concat( 'Attempted partial application of ',
-                        $fname, '#', $arity, ' with ',
+                        'function of arity ', $arity, ' with ',
                         $argn, ' arguments' ) )" />
 </template>
 
@@ -183,14 +152,16 @@
   are supported}.  This should be enough.
 -->
 <function name="_f:apply-partial">
-  <param name="fnref" as="element(f:ref)" />
-  <param name="args"  as="item()*" />
+  <param name="fnref" as="item()+" />
 
-  <variable name="fn" as="element()"
+  <variable name="args"
+            select="f:args( $fnref )" />
+
+  <variable name="desc" as="element( f:ref )"
             select="$fnref[ 1 ]" />
 
   <!-- just as `f:apply', we support up to 8 arguments -->
-  <apply-templates select="$fn" mode="f:apply">
+  <apply-templates select="$desc" mode="f:apply">
     <with-param name="arg1" select="$args[ 1 ]" />
     <with-param name="arg2" select="$args[ 2 ]" />
     <with-param name="arg3" select="$args[ 3 ]" />
diff --git a/test/apply/partial-test.xsl b/test/apply/partial-test.xsl
index 99dfadd..bdb0422 100644
--- a/test/apply/partial-test.xsl
+++ b/test/apply/partial-test.xsl
@@ -41,8 +41,10 @@
   <template mode="f:partial-arity-error-hook"
             match="f:ref"
             priority="5">
-    <param name="args" as="item()*" />
-    <param name="arity" as="xs:decimal" />
+    <param name="args"  as="item()*" />
+
+    <variable name="arity"
+              select="f:arity(.)" />
 
     <foo:partial-error arity="{$arity}" />
 
diff --git a/test/apply/partial.xspec b/test/apply/partial.xspec
index 33e3743..aca7643 100644
--- a/test/apply/partial.xspec
+++ b/test/apply/partial.xspec
@@ -52,8 +52,7 @@
       </call>
 
       <expect label="returns reference to original target"
-              test="f:QName( $x:result[ 1 ] )
-                      = f:QName( $fnref )" />
+              test="f:QName( $x:result) = f:QName( $fnref )" />
 
       <expect label="returns nothing else"
               test="count( $x:result ) = 1" />
@@ -68,14 +67,12 @@
 
       <expect label="returns target reference as first item in
                      sequence"
-              test="f:QName( $fnref )
-                      = f:QName( $x:result[ 1 ] )" />
+              test="f:QName( $fnref ) = f:QName( $x:result )" />
 
-      <!-- FIXME: this breaks the abstraction; use opaque
-           introspection -->
+      <variable name="rargs" select="f:args( $x:result )" />
       <expect label="returns each argument, ordered"
-              test="$x:result[ 2 ] is $args/foo:a
-                    and $x:result[ 3 ] is $args/foo:b" />
+              test="$rargs[ 1 ] is $args/foo:a
+                    and $rargs[ 2 ] is $args/foo:b" />
     </scenario>
 
 
@@ -92,10 +89,11 @@
               test="$x:result[ 1 ]
                     and $x:result[ 1 ] = foo:ternary-applied" />
 
+      <variable name="rargs" select="f:args( $x:result )" />
       <expect label="applies target function with arguments, by reference"
-              test="$x:result[ 2 ] is $args/foo:a
-                    and $x:result[ 3 ] is $args/foo:b
-                    and $x:result[ 4 ] is $args/foo:c" />
+              test="$rargs[ 1 ] is $args/foo:a
+                    and $rargs[ 2 ] is $args/foo:b
+                    and $rargs[ 3 ] is $args/foo:c" />
     </scenario>
 
 
@@ -107,18 +105,17 @@
         <param name="args"  select="$args/foo:b" />
       </call>
 
-      <expect label="returns target reference as first item in
-                     sequence"
-              test="f:QName( $fnref )
-                      = f:QName( $x:result[ 1 ] )" />
+      <expect label="retains target reference"
+              test="f:QName( $fnref ) = f:QName( $x:result )" />
 
       <expect label="returns arguments from both partial applications"
-              test="count( $x:result ) = 3" />
+              test="count( f:args( $x:result ) ) = 2" />
 
+      <variable name="rargs" select="f:args( $x:result )" />
       <expect label="arguments are ordered with previous applications
                      first in sequence"
-              test="$x:result[ 2 ] is $args/foo:a
-                    and $x:result[ 3 ] is $args/foo:b" />
+              test="$rargs[ 1 ] is $args/foo:a
+                    and $rargs[ 2 ] is $args/foo:b" />
     </scenario>
 
 
@@ -193,9 +190,9 @@
                 test="$x:result[ 1 ] = foo:applied[ @n = 3 ]" />
 
         <expect label="applies target function with arguments, by reference"
-                test="$x:result[ 2 ] is $args/foo:a
-                      and $x:result[ 3 ] is $args/foo:b
-                      and $x:result[ 4 ] is $args/foo:c" />
+                test="$x:result[ 2 ] = $args/foo:a
+                      and $x:result[ 3 ] = $args/foo:b
+                      and $x:result[ 4 ] = $args/foo:c" />
       </scenario>
 
 
@@ -442,8 +439,7 @@
       <expect label="provides source dynamic function reference"
               test="$x:result[ 2 ] is $fnref" />
 
-      <expect label="provides arity of target (root of all partial
-                     applications) function"
+      <expect label="provides arity of ref"
               test="$x:result[ 1 ]/@arity = 3" />
 
       <expect label="provides each argument of partial application
@@ -465,10 +461,11 @@
                                     $args/foo:d" />
       </call>
 
-      <expect label="produces error with all arguments"
+      <expect label="produces error with arguments of final
+                     application"
               test="exists( foo:partial-error )
-                    and $x:result[ 3 ] is $args/foo:a
-                    and $x:result[ 6 ] is $args/foo:d" />
+                    and $x:result[ 3 ] is $args/foo:c
+                    and $x:result[ 4 ] is $args/foo:d" />
     </scenario>
   </scenario>
 </description>