# HG changeset patch
# User Mike Becker <universe@uap-core.de>
# Date 1526053216 -7200
# Node ID deb0035635ebdfd60d186f3ac66dd1d91b3a14b5
# Parent  d5d6ab809ad3ce10d2439962a5832ff4b4e9cd55
adds ucx_list_prepend_once() and ucx_list_prepend_once_a()

diff -r d5d6ab809ad3 -r deb0035635eb src/list.c
--- a/src/list.c	Wed May 09 20:15:10 2018 +0200
+++ b/src/list.c	Fri May 11 17:40:16 2018 +0200
@@ -142,6 +142,39 @@
     }
 }
 
+UcxList *ucx_list_prepend_once(UcxList *l, void *data,
+        cmp_func cmpfnc, void *cmpdata) {
+    return ucx_list_prepend_once_a(ucx_default_allocator(), l,
+            data, cmpfnc, cmpdata);
+}
+
+UcxList *ucx_list_prepend_once_a(UcxAllocator *alloc, UcxList *l, void *data,
+        cmp_func cmpfnc, void *cmpdata) {
+
+    UcxList* first = ucx_list_first(l);
+    {
+        UcxList *e = first;
+        while (e) {
+            if (cmpfnc(e->data, data, cmpdata) == 0) {
+                return l;
+            }
+            e = e->next;
+        }
+    }
+    
+    UcxList *nl = ucx_list_append_a(alloc, NULL, data);
+    if (!nl) {
+        return NULL;
+    }
+
+    if (first) {
+        nl->next = first;
+        first->prev = nl;
+    }
+    
+    return nl;
+}
+
 UcxList *ucx_list_prepend(UcxList *l, void *data) {
     return ucx_list_prepend_a(ucx_default_allocator(), l, data);
 }
diff -r d5d6ab809ad3 -r deb0035635eb src/ucx/list.h
--- a/src/ucx/list.h	Wed May 09 20:15:10 2018 +0200
+++ b/src/ucx/list.h	Fri May 11 17:40:16 2018 +0200
@@ -232,8 +232,6 @@
  * Inserts an element at the end of the list, if it is not present in the list,
  * using a UcxAllocator.
  * 
- * See ucx_list_append() for details.
- * 
  * @param allocator the allocator to use
  * @param list the list where to append the data, or <code>NULL</code> to
  * create a new list
@@ -248,6 +246,38 @@
         UcxList *list, void *data, cmp_func cmpfnc, void *cmpdata);
 
 /**
+ * Inserts an element at the beginning of the list, if it is not present
+ * in the list.
+ * 
+ * 
+ * @param list the list where to prepend the data, or <code>NULL</code> to
+ * create a new list
+ * @param data the data to insert
+ * @param cmpfnc the compare function
+ * @param cmpdata additional data for the compare function
+ * @return a pointer to the new list head
+ * @see ucx_list_prepend()
+ */
+UcxList *ucx_list_prepend_once(UcxList *list, void *data,
+        cmp_func cmpfnc, void *cmpdata);
+
+/**
+ * Inserts an element at the beginning of the list, if it is not present in
+ * the list, using a UcxAllocator.
+ * 
+ * @param allocator the allocator to use
+ * @param list the list where to prepend the data, or <code>NULL</code> to
+ * create a new list
+ * @param data the data to insert
+ * @param cmpfnc the compare function
+ * @param cmpdata additional data for the compare function
+ * @return a pointer to the new list head
+ * @see ucx_list_prepend_a()
+ */
+UcxList *ucx_list_prepend_once_a(UcxAllocator *allocator,
+        UcxList *list, void *data, cmp_func cmpfnc, void *cmpdata);
+
+/**
  * Inserts an element at the beginning of the list.
  * 
  * You <i>should</i> overwrite the old list pointer by calling