references: fix merge key order for edge case where target is the last element

re #484

Author: biojppm

changelog/current.md

@@ -1,7 +1,8 @@
 
-## Fixes
+### Fixes
 
 - Fix [#400](https://github.com/biojppm/rapidyaml/issues/400) ([PR#506](https://github.com/biojppm/rapidyaml/pull/506)): clear anchors after resolving.
+- Fix [#484](https://github.com/biojppm/rapidyaml/issues/484) ([PR#506](https://github.com/biojppm/rapidyaml/pull/506)): fix merge key order for last element to be overriden.
 - [PR#503](https://github.com/biojppm/rapidyaml/pull/503): ensure parse error on `a: b: c` and similar cases containing nested maps opening on the same line.
 - [PR#502](https://github.com/biojppm/rapidyaml/pull/502): fix parse errors or missing tags:
   - missing tags in empty documents:

src/c4/yml/tree.cpp

@@ -1014,11 +1014,13 @@ id_type Tree::duplicate_children_no_rep(Tree const *src, id_type node, id_type p
             }
             else  // yes, there is a repetition
             {
-                if(after_pos != NONE && dstnode_dup_pos < after_pos)
+                if(after_pos != NONE && dstnode_dup_pos <= after_pos)
                 {
                     // the dst duplicate is located before the node which will be inserted,
                     // and will be overridden by the duplicate. So replace it.
                     _c4dbgpf("duplicate_no_dstnode_dup: replace {}/{} with {}/{}", parent, dstnode_dup, node, i);
+                    if(prev == dstnode_dup)
+                        prev = prev_sibling(dstnode_dup);
                     remove(dstnode_dup);
                     prev = duplicate(src, i, parent, prev);
                 }

test/test_anchor.cpp

@@ -730,6 +730,84 @@ a5: &a5
     }
 }
 
+TEST(simple_anchor, issue_484_0)
+{
+    csubstr yaml = R"(
+base_1: &base_1
+  a: 10
+  b: 10
+base_2: &base_2
+  b: 20
+k1:
+  !!merge <<: *base_1
+  !!merge <<: *base_2
+k2:
+  !!merge <<: *base_2
+  !!merge <<: *base_1
+)";
+    Tree t = parse_in_arena(yaml);
+    EXPECT_EQ(t["k1"][0].val(), "*base_1");
+    EXPECT_EQ(t["k1"][1].val(), "*base_2");
+    EXPECT_EQ(t["k2"][0].val(), "*base_2");
+    EXPECT_EQ(t["k2"][1].val(), "*base_1");
+    t.resolve();
+    EXPECT_EQ(t["k1"]["a"].val(), "10");
+    EXPECT_EQ(t["k1"]["b"].val(), "20");
+    EXPECT_EQ(t["k2"]["a"].val(), "10");
+    EXPECT_EQ(t["k2"]["b"].val(), "10");
+    EXPECT_EQ(emitrs_yaml<std::string>(t), R"(base_1:
+  a: 10
+  b: 10
+base_2:
+  b: 20
+k1:
+  a: 10
+  b: 20
+k2:
+  a: 10
+  b: 10
+)");
+}
+
+TEST(simple_anchor, issue_484_1)
+{
+    csubstr yaml = R"(
+base_1: &base_1
+  a: 10
+  b: 10
+base_2: &base_2
+  a: 30
+k1:
+  <<: *base_1
+  <<: *base_2
+k2:
+  <<: *base_2
+  <<: *base_1
+)";
+    Tree t = parse_in_arena(yaml);
+    EXPECT_EQ(t["k1"][0].val(), "*base_1");
+    EXPECT_EQ(t["k1"][1].val(), "*base_2");
+    EXPECT_EQ(t["k2"][0].val(), "*base_2");
+    EXPECT_EQ(t["k2"][1].val(), "*base_1");
+    t.resolve();
+    EXPECT_EQ(t["k1"]["a"].val(), "30");
+    EXPECT_EQ(t["k1"]["b"].val(), "10");
+    EXPECT_EQ(t["k2"]["a"].val(), "10");
+    EXPECT_EQ(t["k2"]["b"].val(), "10");
+    EXPECT_EQ(emitrs_yaml<std::string>(t), R"(base_1:
+  a: 10
+  b: 10
+base_2:
+  a: 30
+k1:
+  b: 10
+  a: 30
+k2:
+  a: 10
+  b: 10
+)");
+}
+
 
 //-----------------------------------------------------------------------------
 //-----------------------------------------------------------------------------
@@ -1529,6 +1607,28 @@ N(MB, L{
   })
 );
 
+ADD_CASE_TO_GROUP("github 484, resolved", RESOLVE_REFS,
+R"(
+base_1: &base_1
+  a: 10
+  b: 10
+base_2: &base_2
+  b: 20
+k1:
+  !!merge <<: *base_1
+  !!merge <<: *base_2
+k2:
+  !!merge <<: *base_2
+  !!merge <<: *base_1
+)",
+N(MB, L{
+      N(KP|MB, "base_1", L{N(KP|VP, "a", "10"), N(KP|VP, "b", "10")}),
+      N(KP|MB, "base_2", L{/*                 */N(KP|VP, "b", "20")}),
+      N(KP|MB, "k1", L{N(KP|VP, "a", "10"), N(KP|VP, "b", "20")}),
+      N(KP|MB, "k2", L{N(KP|VP, "a", "10"), N(KP|VP, "b", "10")}),
+  })
+);
+
 }
 
 

test/test_merge.cpp

@@ -63,12 +63,23 @@ TEST(merge, basic)
     test_merge(
         {
             "{a: 0, b: 1}",
-            "{a: 1, c: 20}"
+            "{a: 1,     c: 20}"
         },
         "{a: 1, b: 1, c: 20}"
     );
 }
 
+TEST(merge, basic_inv)
+{
+    test_merge(
+        {
+            "{a: 1,     c: 20}",
+            "{a: 0, b: 1}"
+        },
+        "{a: 0, c: 20, b: 1}"
+    );
+}
+
 TEST(merge, dst_scalar_keeps_style)
 {
     Tree dst = parse_in_arena("a: b");