1 files changed, 36 insertions, 1 deletions
diff --git a/lua/clever_f/direct_preview_planner.lua b/lua/clever_f/direct_preview_planner.lua
index e771b15..6735924 100644
--- a/lua/clever_f/direct_preview_planner.lua
+++ b/lua/clever_f/direct_preview_planner.lua
@@ -149,6 +149,41 @@ function M.case_grouping_settings(settings)
   }
 end
 
+function M.validate_marker_positions(view, positions)
+  require_view(view)
+  if type(positions) ~= "table" then
+    fail("direct preview markers must be a list of positions", 2)
+  end
+
+  local result = {}
+  local seen = {}
+  local item_count = 0
+  for key, position in pairs(positions) do
+    if type(key) ~= "number"
+      or key ~= math.floor(key)
+      or key < 1
+      or key > #positions
+    then
+      fail("direct preview markers must be a list of positions", 2)
+    end
+    position = domain.Position.coerce(position)
+    if not view:is_character_start(position) then
+      fail("direct preview marker must start an editor character", 2)
+    end
+    local identity = tostring(position.line) .. ":" .. tostring(position.byte_column)
+    if seen[identity] then
+      fail("direct preview marker positions must be unique", 2)
+    end
+    seen[identity] = true
+    result[key] = position
+    item_count = item_count + 1
+  end
+  if item_count ~= #positions then
+    fail("direct preview markers must be a list of positions", 2)
+  end
+  return result
+end
+
 function DirectPreviewPlanner:plan(view, origin, descriptor, count, settings)
   local grouping = M.case_grouping_settings(settings)
   local ignore_case = grouping.ignore_case
@@ -181,7 +216,7 @@ function DirectPreviewPlanner:plan(view, origin, descriptor, count, settings)
       positions[#positions + 1] = M.marker_position(descriptor, record.position)
     end
   end
-  return positions
+  return M.validate_marker_positions(view, positions)
 end
 
 function M.new(options)