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Fix RangeError: decoration positions exceeding document length
Three fixes for "Position N is out of range for changeset" errors:
1. js_top_worker: clamp output_at loc to input length — the ";;"
appended for parsing made pos_cnum extend past the original source
2. x-ocaml/editor: clamp decoration positions against CM document
length (Text.length) not OCaml String.length — they differ for
non-ASCII text (UTF-16 vs bytes). Also combine doc replacement +
decoration clear into a single transaction in set_source, and
read actual CM doc in build_range_set
3. jsoo-code-mirror/decoration: defensive safe_map that catches
JS RangeError in RangeSet.map and returns empty
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
+40
-13
+40
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src/editor.ml
+40
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src/editor.ml
···
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in
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Jv.call deco_facet "from" [| field |] |> Code_mirror.Extension.of_jv)
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let source_of_state s =
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String.concat "\n" @@ Array.to_list @@ Array.map Jstr.to_string
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@@ Code_mirror.Text.to_jstr_array
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@@ Code_mirror.Editor.State.doc s
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+
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let source t = source_of_state @@ Code_mirror.Editor.View.state t.view
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let build_range_set cm =
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let open Code_mirror.Decoration in
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let doc = cm.current_doc in
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(* Use the CM document length (in UTF-16 code units) for clamping, not
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String.length which counts bytes — they differ for non-ASCII text. *)
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let cm_len =
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Code_mirror.Text.length
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(Code_mirror.Editor.State.doc
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(Code_mirror.Editor.View.state cm.view))
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in
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let ranges =
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Array.of_list
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@@ List.map (fun (at, msg) ->
···
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@@ List.map (fun (at, msg) ->
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let at = min at (String.length doc) in
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let at = find_line_ends at doc in
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let at = min at (max 0 (String.length doc - 1)) in
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let at = min at (max 0 (cm_len - 1)) in
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(at, msg))
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@@ List.concat
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@@ List.map (fun (loc, lst) -> List.map (fun m -> (loc, m)) lst)
···
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refresh_lines x;
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refresh_messages x;
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refresh_merlin x
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-
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let source_of_state s =
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String.concat "\n" @@ Array.to_list @@ Array.map Jstr.to_string
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@@ Code_mirror.Text.to_jstr_array
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@@ Code_mirror.Editor.State.doc s
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-
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let source t = source_of_state @@ Code_mirror.Editor.View.state t.view
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let prefix_length a b =
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let rec go i =
···
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let add_message t loc msg = set_messages t ((loc, msg) :: t.messages)
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let set_source t doc =
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Code_mirror.Editor.View.set_doc t.view (Jstr.of_string doc);
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(* Read back from CodeMirror to get the canonical form — the raw
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string may differ (e.g., HTML entity decoding, line ending
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normalization) from what CodeMirror stores internally. *)
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(* Clear decorations AND replace the document in a single transaction
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so CodeMirror never sees stale decoration positions. *)
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let state = Code_mirror.Editor.View.state t.view in
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let doc_len =
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Code_mirror.Text.length (Code_mirror.Editor.State.doc state)
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in
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t.messages <- [];
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let changes =
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Jv.obj
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[| ("from", Jv.of_int 0);
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("to", Jv.of_int doc_len);
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("insert", Jv.of_jstr (Jstr.of_string doc)) |]
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in
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let effect =
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Code_mirror.State_effect.of_ set_messages_effect
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(Code_mirror.Decoration.Range_set.to_jv
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(Code_mirror.Decoration.Range_set.empty))
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in
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let txn =
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Jv.obj [| ("changes", changes); ("effects", effect) |]
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|> Code_mirror.Editor.View.Transaction.of_jv
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in
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Code_mirror.Editor.View.dispatch t.view txn;
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(* Read back canonical form *)
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let canonical = source t in
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set_current_doc t canonical
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t.current_doc <- canonical