From e79db92d8d1ec067e629247b32a8d674ffceb4e7 Mon Sep 17 00:00:00 2001
From: Christopher Lam <christopher.lck@gmail.com>
Date: Mon, 22 Feb 2021 18:17:02 +0800
Subject: [PATCH] [Split.c] xaccSplitListGetUniqueTransactionsReversed

Same as xaccSplitListGetUniqueTransactions but doesn't reverse the
list prior to returning. To be used by gnc-tree-model-split-reg.c

Several optimizations

* doesn't call g_list_find and g_list_append for every iteration
* uses g_hash_table to cache list of txns already added instead of g_list_find
* does not reverse the result, thereby returning a reversed list.
---
 libgnucash/engine/Split.c | 23 +++++++++++++++++------
 libgnucash/engine/Split.h |  1 +
 2 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/libgnucash/engine/Split.c b/libgnucash/engine/Split.c
index 4f74b37094..5b3ecd6a37 100644
--- a/libgnucash/engine/Split.c
+++ b/libgnucash/engine/Split.c
@@ -893,21 +893,32 @@ xaccSplitEqual(const Split *sa, const Split *sb,
  * xaccSplitListGetUniqueTransactions
  ********************************************************************/
 GList *
-xaccSplitListGetUniqueTransactions(const GList *splits)
+xaccSplitListGetUniqueTransactionsReversed (const GList *splits)
 {
-    const GList *snode;
+    GHashTable *txn_hash = g_hash_table_new (NULL, NULL);
     GList *transList = NULL;
+    const GList *snode;
 
-    for(snode = splits; snode; snode = snode->next)
+    for (snode = splits; snode; snode = snode->next)
     {
         Transaction *trans = xaccSplitGetParent((Split *)(snode->data));
 
-        GList *item = g_list_find (transList, trans);
-        if (item == NULL)
-            transList = g_list_append (transList, trans);
+        if (g_hash_table_contains (txn_hash, trans))
+            continue;
+
+        g_hash_table_insert (txn_hash, trans, NULL);
+        transList = g_list_prepend (transList, trans);
     }
+    g_hash_table_destroy (txn_hash);
     return transList;
 }
+
+GList *
+xaccSplitListGetUniqueTransactions(const GList *splits)
+{
+    return g_list_reverse (xaccSplitListGetUniqueTransactionsReversed (splits));
+}
+
 /*################## Added for Reg2 #################*/
 
 
diff --git a/libgnucash/engine/Split.h b/libgnucash/engine/Split.h
index 7f2e2025f8..fffc8409cc 100644
--- a/libgnucash/engine/Split.h
+++ b/libgnucash/engine/Split.h
@@ -359,6 +359,7 @@ Split      * xaccSplitLookup (const GncGUID *guid, QofBook *book);
 
 /*################## Added for Reg2 #################*/
 /* Get a GList of unique transactions containing the given list of Splits. */
+GList *xaccSplitListGetUniqueTransactionsReversed (const GList *splits);
 GList *xaccSplitListGetUniqueTransactions(const GList *splits);
 /*################## Added for Reg2 #################*/
 /** Add a peer split to this split's lot-split list.