From 2ec868181cd4a60a816030eb776b6ed9116c75c7 Mon Sep 17 00:00:00 2001
From: Juri Leino <github@line-o.de>
Date: Fri, 19 Mar 2021 17:20:46 +0100
Subject: [PATCH] feat: pluck-deep handles missing properties

---
 src/content/xbow.xqm   |  6 +++++-
 src/test/xbow-spec.xqm | 21 ++++++++-------------
 2 files changed, 13 insertions(+), 14 deletions(-)

diff --git a/src/content/xbow.xqm b/src/content/xbow.xqm
index a35dec4..a23c55b 100644
--- a/src/content/xbow.xqm
+++ b/src/content/xbow.xqm
@@ -217,7 +217,11 @@ function xbow:pluck-deep ($fields as xs:anyAtomicType*) as item()* {
 
 declare
 function xbow:pluck-deep ($map-or-array-or-node as item(), $fields as xs:anyAtomicType*) as item()* {
-    fold-left($fields, $map-or-array-or-node, xbow:pluck#2)
+    fold-left($fields, $map-or-array-or-node, function ($eventual-item as item()*, $field) {
+        if (exists($eventual-item))
+        then (xbow:pluck($eventual-item, $field))
+        else ()
+    })
 };
 
 (: stats :)
diff --git a/src/test/xbow-spec.xqm b/src/test/xbow-spec.xqm
index 0d99842..c1718d4 100644
--- a/src/test/xbow-spec.xqm
+++ b/src/test/xbow-spec.xqm
@@ -210,22 +210,17 @@ function xbow-spec:array-group-by-even-odd-accessor () {
 declare 
     %test:assertEquals(1)
 function xbow-spec:pluck-deep () {
-    map { 
-        'a': map { 
-            'b': map { 
-                'c': map { 
-                    'd': map { 
-                        'e': map { 
-                            'f': 1 
-                        }
-                    }
-                }
-            }
-        }
-    }
+    map {'a': map {'b': map {'c': map {'d': map {'e': map {'f': 1 }}}}}}
         => xbow:pluck-deep(('a','b','c','d','e','f'))
 };
 
+declare 
+    %test:assertEmpty
+function xbow-spec:pluck-deep-non-existent-field () {
+    map {'a': map {'b': map {'c': map {'d': map {'e': map {'f': 1 }}}}}}
+        => xbow:pluck-deep(('a','b','c', 1, 'd','e','f'))
+};
+
 
 declare 
     %test:assertEquals(9)