Is there a NOT operator in VSCode Keybindings JSON to invert an entire "when" clause?

Question

The "when" clause in VSCode's JSON keybindings editor is very useful, but I can't seem to find a way to reverse it. For instance, if I want an action to only work when the Terminal view is not showing, I would want something like this: "when": "not.terminalViewShowing" or "when.not": "terminalViewShowing"

Is something like this possible and if not, are there any plans to add it?

Answer 1

If the when clause only contains one condition, then you can just invert that single condition with the ! operator. For the current list of operators in when-clauses, see the official docs: https://code.visualstudio.com/api/references/when-clause-contexts#conditional-operators.

If the when clause contains multiple condition joined by logical operators...

See this GitHub issue: Add support for parenthesis in "when" conditions #91473, which was added to VS Code's March 2023 Milestone, and was closed as completed by the context keys: implement a new parser (and a scanner/lexer) for 'when' clauses #174471 pull request. So you can just wrap your when clause with !(...). You can read about the exact syntax and grammar there. Here's a quote of its syntax and grammar in Extended Backus-Naur form:

expression ::= or

or ::= and { '||' and }*

and ::= term { '&&' term }*

term ::=
  | '!' (KEY | 'true' | 'false')
  | primary

primary ::=
  | 'true'
  | 'false'
  | '(' expression ')'
  | KEY '=~' REGEX
  | KEY [ ('==' | '!=' | '<' | '<=' | '>' | '>=' | 'not' 'in' | 'in') value ]

value ::=
  | 'true'
  | 'false'
  | 'in'     
  | KEY
  | SINGLE_QUOTED_STR
  | EMPTY_STR

See also the announcement / discussion issue ticket for the new feature: Upcoming when clause context parser #175540.

^{Fun note: Even before parenthesis support in when clauses got added, you could usually use De Morgan's laws as a workaround to negate when-clauses.}

Answer 2

It is as simple as adding the ! before your terminalViewShowing.

"when": "!terminalViewShowing"

BYW, parentheses are not supported in when clauses, see Add support for parenthesis in "when" conditionshttps://github.com/microsoft/vscode/issues/91473 and https://github.com/microsoft/vscode/issues/147904.

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Update: A PR has just been merged that introduces a new parser for when clauses which does, finally, support parentheses, see context keys: implement a new parser (and a scanner/lexer) for 'when' clauses.