QmlDesigner: Add common path to SourcePathView

Change-Id: I685a35a70ad597ac5b0a57f39dcc5037a7489d1a
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>

src/plugins/qmldesigner/libs/designercore/sourcepathstorage/sourcepathview.h

@@ -6,6 +6,7 @@
 #include <utils/smallstringview.h>
 
 #include <algorithm>
+#include <ranges>
 #include <vector>
 
 namespace QmlDesigner {
@@ -60,13 +61,28 @@ public:
                       std::size_t(std::ptrdiff_t(size()) - m_slashIndex - std::ptrdiff_t(1)));
     }
 
-    static
-    std::ptrdiff_t lastSlashIndex(Utils::SmallStringView filePath)
+    static constexpr std::tuple<std::string_view, std::string_view, std::string_view> commonPath(
+        std::string_view first, std::string_view second)
     {
-        auto foundReverse = std::find(filePath.rbegin(), filePath.rend(), separator);
+        auto [firstSplit, secondSplit] = std::ranges::mismatch(first, second);
+
+        firstSplit = std::ranges::find(std::make_reverse_iterator(firstSplit),
+                                       std::make_reverse_iterator(first.begin()),
+                                       separator)
+                         .base();
+
+        secondSplit = std::ranges::next(second.begin(),
+                                        std::ranges::distance(first.begin(), firstSplit));
+
+        return {{first.begin(), firstSplit}, {firstSplit, first.end()}, {secondSplit, second.end()}};
+    }
+
+    static constexpr std::ptrdiff_t lastSlashIndex(Utils::SmallStringView filePath)
+    {
+        auto foundReverse = std::ranges::find(filePath.rbegin(), filePath.rend(), separator);
         auto found = foundReverse.base();
 
-        auto distance = std::distance(filePath.begin(), found);
+        auto distance = std::ranges::distance(filePath.begin(), found);
 
         return distance - 1;
     }

tests/unit/tests/unittests/sourcepathstorage/sourcepathview-test.cpp

@@ -98,4 +98,62 @@ TEST(SourcePathView, file_name_for_file_name_only)
     ASSERT_THAT(filePath.name(), "file.h");
 }
 
+TEST(SourcePathView, common_path_for_same_path)
+{
+    std::string_view input{"/foo/"};
+
+    auto matched = QmlDesigner::SourcePathView::commonPath(input, input);
+
+    ASSERT_THAT(matched, FieldsAre("/foo/", IsEmpty(), IsEmpty()));
+}
+
+TEST(SourcePathView, common_path)
+{
+    std::string_view input1{"/foo/bar"};
+    std::string_view input2{"/foo/hoo"};
+
+    auto matched = QmlDesigner::SourcePathView::commonPath(input1, input2);
+
+    ASSERT_THAT(matched, FieldsAre("/foo/", "bar", "hoo"));
+}
+
+TEST(SourcePathView, common_path_last_is_sub_path)
+{
+    std::string_view input1{"/foo/bar"};
+    std::string_view input2{"/foo/"};
+
+    auto matched = QmlDesigner::SourcePathView::commonPath(input1, input2);
+
+    ASSERT_THAT(matched, FieldsAre("/foo/", "bar", IsEmpty()));
+}
+
+TEST(SourcePathView, common_path_first_is_sub_path)
+{
+    std::string_view input1{"/foo/"};
+    std::string_view input2{"/foo/bar"};
+
+    auto matched = QmlDesigner::SourcePathView::commonPath(input1, input2);
+
+    ASSERT_THAT(matched, FieldsAre("/foo/", IsEmpty(), "bar"));
+}
+
+TEST(SourcePathView, common_path_last_is_file)
+{
+    std::string_view input1{"/foo/bar"};
+    std::string_view input2{"/foo"};
+
+    auto matched = QmlDesigner::SourcePathView::commonPath(input1, input2);
+
+    ASSERT_THAT(matched, FieldsAre("/", "foo/bar", "foo"));
+}
+
+TEST(SourcePathView, common_path_first_is_file)
+{
+    std::string_view input1{"/foo"};
+    std::string_view input2{"/foo/bar"};
+
+    auto matched = QmlDesigner::SourcePathView::commonPath(input1, input2);
+
+    ASSERT_THAT(matched, FieldsAre("/", "foo", "foo/bar"));
+}
 }