TypeSwap

Instantly replace typed text using your own substitution rules — TeXShop-style "key bindings" for VS Code / Cursor.

🇯🇵 日本語版 README はこちら (Japanese README)

TypeSwap watches what you type and replaces it the moment it appears, based on a list of rules you define. It is inspired by the key bindings feature of TeXShop, the macOS TeX editor — but works for any language, not just TeX.

Typical uses:

• Type ¥ on a Japanese keyboard and get \ in your LaTeX source
• Type $ with text selected and get the selection wrapped as $…$, cursor placed at the end
• Type " and get proper TeX quotation marks ``…''
• Convert full-width spaces to half-width spaces as you type

Quick start

Install the extension — it works immediately. These rules are preconfigured:

From	To	Languages	Effect
(full-width space)	(half-width space)	all	fixes accidental full-width spaces
¥	\	TeX/LaTeX	yen sign → backslash
"	``#SEL##INS#''	TeX/LaTeX	TeX-style quotes around the selection
$	$#SEL##INS#$	TeX/LaTeX	wraps the selection in inline math

To customize the rules, run TypeSwap: Edit Replacement Rules (GUI) from the Command Palette (Cmd+Shift+P / Ctrl+Shift+P) — no need to touch settings.json. You can also edit typeswap.rules in settings.json directly if you prefer.

The #SEL# marker — use the selection

If to contains #SEL#, the text selected just before typing is inserted at that position. With no selection, #SEL# simply disappears.

From	To	Action	Result
$	$#SEL#$	select E=mc^2, type $	$E=mc^2$
[	[#SEL#]	select link, type [	[link]

#SEL# may appear multiple times; every occurrence receives the same selected text.

The #INS# marker — place the cursor

If to contains #INS#, the cursor moves to that position after the replacement. The marker itself is removed from the output. Multiple #INS# markers create multiple cursors (multi-cursor mode).

From	To	Cursor after typing
$	$#INS#$	between the two $
[	[#SEL##INS#]	right after the selection, before ]

Combining #SEL# and #INS# gives you snippet-like behavior from plain typing.

Rule properties

Each entry of typeswap.rules supports:

Property	Type	Default	Description
from	string	— (required)	Text to replace. Literal match (no regex). Must be a single character to react to keyboard input.
to	string	— (required)	Replacement text. Empty string deletes the input. May contain #SEL# / #INS#.
replaceOnPaste	boolean	false	Also apply the rule to pasted text.
enabled	boolean	true	Turn the rule off without deleting it.
enabledLanguages	string[]	[]	Language IDs where this rule is active. Empty = follow the global setting.
disabledLanguages	string[]	[]	Language IDs where this rule is inactive. Wins over enabledLanguages.
description	string	—	Free-form note; no effect on behavior.

Language filtering

• typeswap.enabledLanguages (global): language IDs where TypeSwap is active at all. Empty array (default) = all languages. This one is editable directly in the Settings UI.
• Per-rule override: each rule's enabledLanguages / disabledLanguages refine or override the global setting.

Evaluation order (first match wins):

1. Language is in the rule's disabledLanguages → inactive
2. The rule's enabledLanguages is non-empty → active iff the language is listed (overrides the global setting)
3. Otherwise → follow the global typeswap.enabledLanguages

Paste behavior

By default, pasted text is not modified. Set replaceOnPaste: true on a rule to apply it to pasted content too.

How paste is detected: the VS Code API cannot distinguish keystrokes from paste, so any change of two or more characters is treated as paste-like. IME commits (e.g. Japanese input) may therefore also count as "paste".

Notes

• from is a literal string — regular expressions are not supported.
• Rules whose from is longer than one character never trigger on keystrokes, only on paste (with replaceOnPaste: true).
• When several rules match the same change, they are applied in list order.
• A single Undo (Cmd+Z / Ctrl+Z) restores the text exactly as typed.
• In settings.json, a backslash in to must be written as "\\" (JSON escaping).
• The yen sign (¥, U+00A5) and the backslash (\, U+005C) are distinct characters; the ¥ key on Japanese keyboards produces U+00A5, so you can write ¥ literally in from.

License

MIT