From 975dfdffa9db39f620a9521ba89d372b0519fadb Mon Sep 17 00:00:00 2001
From: Bob Swift <bswift@rsds.ca>
Date: Thu, 13 Jan 2022 23:58:35 -0700
Subject: [PATCH] PICARD-2382: Add option to keep duplicates in `$copymerge()`
 function. (#2020)

---
 picard/script/functions.py |  8 +++++---
 test/test_script.py        | 21 +++++++++++++++++++++
 2 files changed, 26 insertions(+), 3 deletions(-)

diff --git a/picard/script/functions.py b/picard/script/functions.py
index 091a1a023..a8587c73d 100644
--- a/picard/script/functions.py
+++ b/picard/script/functions.py
@@ -492,20 +492,22 @@ def func_copy(parser, new, old):
 
 
 @script_function(documentation=N_(
-    """`$copymerge(new,old)`
+    """`$copymerge(new,old[,keep_duplicates])`
 
 Merges metadata from variable `old` into `new`, removing duplicates and
     appending to the end, so retaining the original ordering. Like `$copy`, this
     will also copy multi-valued variables without flattening them.
 
+If `keep_duplicates` is set, then the duplicates will not be removed from the result.
+
 _Since Picard 1.0_"""
 ))
-def func_copymerge(parser, new, old):
+def func_copymerge(parser, new, old, keep_duplicates=False):
     new = normalize_tagname(new)
     old = normalize_tagname(old)
     newvals = parser.context.getall(new)
     oldvals = parser.context.getall(old)
-    parser.context[new] = uniqify(newvals + oldvals)
+    parser.context[new] = newvals + oldvals if keep_duplicates else uniqify(newvals + oldvals)
     return ""
 
 
diff --git a/test/test_script.py b/test/test_script.py
index e640ec4fb..736194d59 100644
--- a/test/test_script.py
+++ b/test/test_script.py
@@ -700,6 +700,27 @@ class ScriptParserTest(PicardTestCase):
         context["source"] = "sourceval"
         self._eval_and_check_copymerge(context, ["targetval", "sourceval"])
 
+    def test_cmd_copymerge_empty_keepdupes(self):
+        context = Metadata()
+        context["target"] = ["tag1", "tag2", "tag1"]
+        context["source"] = ["tag2", "tag3", "tag2"]
+        self.parser.eval("$copymerge(target,source,)", context)
+        self.assertEqual(self.parser.context.getall("target"), ["tag1", "tag2", "tag3"])
+
+    def test_cmd_copymerge_keepdupes(self):
+        context = Metadata()
+        context["target"] = ["tag1", "tag2", "tag1"]
+        context["source"] = ["tag2", "tag3", "tag2"]
+        self.parser.eval("$copymerge(target,source,keep)", context)
+        self.assertEqual(self.parser.context.getall("target"), ["tag1", "tag2", "tag1", "tag2", "tag3", "tag2"])
+
+    def test_cmd_copymerge_nonlist_keepdupes(self):
+        context = Metadata()
+        context["target"] = "targetval"
+        context["source"] = "targetval"
+        self.parser.eval("$copymerge(target,source,keep)", context)
+        self.assertEqual(self.parser.context.getall("target"), ["targetval", "targetval"])
+
     def test_cmd_eq_any(self):
         self.assertScriptResultEquals("$eq_any(abc,def,ghi,jkl)", "")
         self.assertScriptResultEquals("$eq_any(abc,def,ghi,jkl,abc)", "1")