fix: truncate output text (#67)

README.md

@@ -171,6 +171,7 @@ variable, their values, and a brief description.
 | `g:molten_output_win_style`                   | (`false`) \| `"minimal"`                                    | Value passed to the `style` option in `:h nvim_open_win()` |
 | `g:molten_save_path`                          | (`stdpath("data").."/molten"`) \| any path to a folder      | Where to save/load data with `:MoltenSave` and `:MoltenLoad` |
 | `g:molten_use_border_highlights`              | `true` \| (`false`)                                         | When true, uses different highlights for output border depending on the state of the cell (running, done, error). see [highlights](#highlights) |
+| `g:molten_limit_output_chars`                 | (`1000000`) \| int                                          | Limit on the number of chars in an output. If you're lagging your editor with too much output text, decrease it |
 | `g:molten_virt_lines_off_by_1`                | `true` \| (`false`)                                         | Allows the output window to cover exactly one line of the regular buffer when `output_virt_lines` is true, also effects `virt_text_output`. (useful for running code in a markdown file where that covered line will just be \`\`\`) |
 | `g:molten_virt_text_output`                   | `true` \| (`false`)                                         | When true, show output as virtual text below the cell. When true, output window doesn't open automatically on run. Effected by `virt_lines_off_by_1` |
 | `g:molten_virt_text_max_lines`                | (`12`) \| int                                               | Max height of the virtual text |

rplugin/python3/molten/options.py

@@ -35,6 +35,7 @@ class MoltenOptions:
     copy_output: bool
     enter_output_behavior: str
     image_provider: str
+    limit_output_chars: int
     output_crop_border: bool
     output_show_more: bool
     output_virt_lines: bool
@@ -68,6 +69,7 @@ def __init__(self, nvim: Nvim):
             ("molten_output_virt_lines", False),
             ("molten_output_win_border", [ "", "━", "", "" ]),
             ("molten_output_win_cover_gutter", True),
+            ("molten_limit_output_chars", 1000000),
             ("molten_output_win_hide_on_leave", True),
             ("molten_output_win_max_height", 999999),
             ("molten_output_win_max_width", 999999),

rplugin/python3/molten/outputbuffer.py

@@ -147,6 +147,11 @@ def build_output_text(self, shape, buf: int, virtual: bool) -> Tuple[List[str],
                 lineno += chunktext.count("\n")
                 virtual_lines += virt_lines
 
+            limit = self.options.limit_output_chars
+            if limit and len(lines_str) > limit:
+                lines_str = lines_str[:limit]
+                lines_str += f"\n...truncated to {limit} chars\n"
+
             lines = handle_progress_bars(lines_str)
             lineno = len(lines) + virtual_lines
         else: