bootstack.CodeEditor#

class bootstack.CodeEditor(value='', *, textsignal=None, language=None, theme='auto', light_theme='default', dark_theme='monokai', read_only=False, wrap=False, tab_width=4, insert_spaces=True, auto_indent=True, show_line_numbers=True, show_indent_guides=False, height=20, scrollbars='both', font='code', show_border=True, accent='primary', extensions=None, parent=None, **kwargs)#

Bases: PublicWidgetBase

A full-featured code editor with line numbers, bracket matching, and syntax highlighting.

Not Field-wrapped — use TextArea for labeled form inputs.

Parameters:

  • value (str) – Initial text content.

  • textsignal (Signal[str] | None) – Reactive Signal[str] bound to the editor content.

  • language (str | None) – Pygments lexer name for syntax highlighting (e.g. 'python', 'json', 'sql'). Any Pygments lexer name works; unknown names fall back to plain text. None disables highlighting. See the full list at https://pygments.org/languages/.

  • theme (str) – Pygments color scheme. 'auto' (default) switches between light_theme and dark_theme when the bootstack theme changes. Pass an explicit Pygments style name (e.g. 'monokai', 'dracula') to pin the scheme. See the full list at https://pygments.org/styles/.

  • light_theme (str) – Pygments style used when theme='auto' and the active bootstack theme is light. Default 'default'.

  • dark_theme (str) – Pygments style used when theme='auto' and the active bootstack theme is dark. Default 'monokai'.

  • read_only (bool) – If True, content is visible but not editable.

  • wrap (bool) – If True, long lines wrap. Default False (horizontal scroll).

  • tab_width (int) – Number of spaces per tab stop. Default 4.

  • insert_spaces (bool) – If True, Tab inserts spaces instead of a tab character.

  • auto_indent (bool) – If True, Return replicates the current line’s indentation.

  • show_line_numbers (bool) – If True (default), shows a line-number gutter.

  • show_indent_guides (bool) – If True, draws subtle vertical guide marks at each indent stop.

  • height (int) – Visible row count. Default 20.

  • scrollbars (Literal['both', 'auto', 'vertical', 'none']) – Scrollbar visibility. Default 'both'. Horizontal scrolling requires wrap=False.

  • font (str) – Semantic font token for the editor. Default 'code' (the monospace token). See Typography.

  • show_border (bool) – If True (default), styles the editor frame as a themed border with a focus ring.

  • accent (AccentToken | str) – Accent token applied to the focus border. Default 'primary'.

  • extensions (list[EditFilter] | None) – Additional EditFilter instances to install on top of the built-in set.

  • parent (Any) – Override the context-stack parent.

  • **kwargs (Any) – Layout placement options applied by the parent container — fill, expand, anchor, margin, row, column, sticky. See Layout & Spacing.

property is_attached: bool#

Whether the widget is currently placed in its layout.

True while the widget occupies space in its parent; False after detach (or before it has ever been placed). A detached widget keeps its state and can be returned to the layout with attach.

property is_dirty: bool#

True if content has changed since the last mark_saved() call.

property language: str | None#

Active syntax highlighting language, or None if disabled.

property read_only: bool#

Whether the editor content is visible but not editable.

property schedule: Schedule#

Scheduler tied to this widget’s lifetime.

All jobs are automatically cancelled when the widget is destroyed. First access creates the Schedule instance; subsequent accesses return the same instance.

Usage:

self.schedule.delay(500, callback)
self.schedule.every(1000, tick)
job = self.schedule.idle(refresh)
job.cancel()
property signal: Signal[str] | None#

The reactive Signal bound to this editor, or None.

property text: str#

The current display text. Same as value for a code editor (no formatting layer). Read-only — assign to value to change it.

property theme: str#

Active Pygments color scheme, or 'auto' if tracking the bootstack theme.

property value: str#

Full text content (trailing newline stripped).

attach(**kwargs)#

Return a detached widget to its layout, optionally moving it.

With no arguments, restores the widget to exactly where detach took it from. Any layout kwargs accepted by the original placement (e.g. fill, expand, anchor, sticky, margin) override the stored options. For stacked widgets, index= sets the position among the currently attached siblings (or pass an explicit before=/after= sibling); without one, the snapshotted position is used.

Calling attach on a widget that is already attached moves it (the kwargs are re-applied). Fires on_attach.

Parameters:

**kwargs (Any) – Layout placement options to override for this placement.

Raises:

ParentResolutionError – If the widget was never placed in a layout.

clear()#

Clear all text content.

destroy()#

Destroy the widget and release the resources it holds.

Removes the widget from its parent, destroys its children, and cancels any pending or repeating jobs on its schedule. After this the widget must not be used again. Destroying a container destroys everything inside it.

detach()#

Remove the widget from its layout without destroying it.

The widget stops occupying space but keeps its state, children, and event bindings, ready to be returned with attach. The current position is snapshotted so a plain attach() restores it exactly — for stacked siblings this is the index among the currently attached siblings, so detaching other siblings first shifts that index.

Calling detach on a widget that is already detached, or one that was never placed in a layout, does nothing. Fires on_detach.

emit(event, *, data=None)#

Fire a named event on this widget, as if it produced the event itself.

This is how a composite widget surfaces high-level activity to its listeners, and the generic counterpart to the on_*() shorthands for firing events that have no dedicated method.

Parameters:

  • event (str) – The event name, unprefixed — the same name you pass to on() or an on_<event>() shorthand (e.g. 'change', 'select').

  • data (Any) – The payload delivered to handlers. For a data-carrying event, pass the matching payload dataclass from bootstack.events — the same object an on_<event>() handler receives. Leave as None for native events (click, hover, focus, …), which carry no payload.

Example

widget.emit("change", data=bs.events.ChangeEvent(value=new_value))
focus()#

Move keyboard focus to the editor.

get_clipboard()#

Return the current text contents of the system clipboard.

Returns:

The clipboard text, or an empty string when the clipboard is empty or holds non-text data.

Return type:

str

goto_line(n)#

Move the cursor to the start of line n and scroll it into view.

Parameters:

n (int) – 1-indexed line number.

Hide the find/replace bar.

insert(index, text)#

Insert text at index.

index is a text position: 'end' for the end of the content, or a 'line.column' string such as '1.0' (line 1, column 0).

Parameters:

  • index (str) – Target text position, e.g. 'end' or '1.0'.

  • text (str) – Text to insert.

install(f)#

Install a custom filter extension.

Parameters:

f (EditFilter) – The EditFilter to add.

mark_saved()#

Mark the current state as the saved baseline (clears is_dirty).

on(event: str) → Stream#
on(event: str, handler: Callable[[Event], Any]) → Subscription

Register a callback for an event by name.

A generic, string-keyed escape hatch — prefer the typed on_* shorthands (e.g. on_change), which carry the precise payload type. Called with no handler, returns a composable Stream; with a handler, binds it and returns a Subscription.

Parameters:

  • event (str) – Event name (for example 'change' or 'focus').

  • handler (Callable[[Event], Any] | None) – Called with the event payload. Omit to get a composable Stream instead.

Returns:

A cancellable Subscription when a handler is given, otherwise a Stream.

Return type:

Stream | Subscription

on_attach(handler=None)#

Register a callback fired when the widget enters the layout.

Fires each time the widget becomes visible in its parent — on initial placement and on every attach. Pair it with on_detach to keep per-visibility resources (timers, observers) tied to the widget’s presence on screen. The handler receives a curated Event.

Parameters:

handler (Callable[[Event], Any] | None) – Called when the widget is attached. Omit to get a composable Stream.

Returns:

A cancellable Subscription when a handler is given, otherwise a Stream.

Return type:

Stream | Subscription

on_blur() → Stream#
on_blur(handler: Callable[[Event], Any]) → Subscription

Register a callback fired when the editor loses focus.

Parameters:

handler (Callable[[Event], Any] | None) – Called with an Event. Omit to get a composable Stream instead.

Returns:

A cancellable Subscription when a handler is given, otherwise a Stream.

Return type:

Stream | Subscription

on_change() → Stream#
on_change(handler: Callable[[ChangeEvent], Any]) → Subscription

Register a callback fired on every edit.

Parameters:

handler (Callable[[ChangeEvent], Any] | None) – Called with a ChangeEvent whose value is the editor text. Omit to get a composable Stream.

Returns:

A cancellable Subscription when a handler is given, otherwise a Stream.

Return type:

Stream | Subscription

on_cursor_move() → Stream#
on_cursor_move(handler: Callable[[Event], Any]) → Subscription

Register a callback fired when the cursor position changes.

Parameters:

handler (Callable[[Event], Any] | None) – Called with an Event. Omit to get a composable Stream instead.

Returns:

A cancellable Subscription when a handler is given, otherwise a Stream.

Return type:

Stream | Subscription

on_destroy(handler=None)#

Register a callback fired when the widget is destroyed.

Fires once, as the widget is torn down — the place to release resources the widget owns that aren’t cleaned up automatically (file handles, observers, external subscriptions). The handler receives a curated Event.

Parameters:

handler (Callable[[Event], Any] | None) – Called as the widget is destroyed. Omit to get a composable Stream.

Returns:

A cancellable Subscription when a handler is given, otherwise a Stream.

Return type:

Stream | Subscription

on_detach(handler=None)#

Register a callback fired when the widget leaves the layout.

Fires each time the widget stops occupying space in its parent — on detach and when an ancestor hides it. Pair it with on_attach to release per-visibility resources. The handler receives a curated Event.

Parameters:

handler (Callable[[Event], Any] | None) – Called when the widget is detached. Omit to get a composable Stream.

Returns:

A cancellable Subscription when a handler is given, otherwise a Stream.

Return type:

Stream | Subscription

on_focus() → Stream#
on_focus(handler: Callable[[Event], Any]) → Subscription

Register a callback fired when the editor gains focus.

Parameters:

handler (Callable[[Event], Any] | None) – Called with an Event. Omit to get a composable Stream instead.

Returns:

A cancellable Subscription when a handler is given, otherwise a Stream.

Return type:

Stream | Subscription

on_input() → Stream#
on_input(handler: Callable[[InputEvent], Any]) → Subscription

Register a callback fired on every edit, before commit.

Parameters:

handler (Callable[[InputEvent], Any] | None) – Called with an InputEvent whose text is the current content. Omit to get a composable Stream.

Returns:

A cancellable Subscription when a handler is given, otherwise a Stream.

Return type:

Stream | Subscription

on_modified() → Stream#
on_modified(handler: Callable[[TextModifiedEvent], Any]) → Subscription

Register a callback fired when is_dirty changes.

Parameters:

handler (Callable[[TextModifiedEvent], Any] | None) – Called with a TextModifiedEvent. Omit to get a composable Stream instead.

Returns:

A cancellable Subscription when a handler is given, otherwise a Stream.

Return type:

Stream | Subscription

on_redo() → Stream#
on_redo(handler: Callable[[InputEvent], Any]) → Subscription

Register a callback fired after a redo operation.

Parameters:

handler (Callable[[InputEvent], Any] | None) – Called with an InputEvent. Omit to get a composable Stream instead.

Returns:

A cancellable Subscription when a handler is given, otherwise a Stream.

Return type:

Stream | Subscription

on_undo() → Stream#
on_undo(handler: Callable[[InputEvent], Any]) → Subscription

Register a callback fired after an undo operation.

Parameters:

handler (Callable[[InputEvent], Any] | None) – Called with an InputEvent. Omit to get a composable Stream instead.

Returns:

A cancellable Subscription when a handler is given, otherwise a Stream.

Return type:

Stream | Subscription

redo()#

Redo the last undone edit.

select_all()#

Select all text content.

set_clipboard(text)#

Replace the system clipboard contents with text.

Parameters:

text (str) – The text to place on the clipboard.

show_replace()#

Show the find/replace bar with the replace row visible.

Show the find bar and focus the search input.

undo()#

Undo the last edit.

undo_block()#

Context manager that groups edits into a single undo step.

Usage:

with editor.undo_block():
    editor.insert("1.0", "# header\n")
    editor.value = new_content
uninstall(f)#

Remove a previously installed filter extension.

Parameters:

f (EditFilter) – The EditFilter to remove.