Custom Match Implementation¶

You may create your own custom Match implementation by following steps.

1. Run AutoSetSyntax: Create New Match from the command palette¹.

2. It will create a template like

   Example

   from AutoSetSyntax.plugin import UNFOLDED
   from AutoSetSyntax.plugin import AbstractMatch
   from AutoSetSyntax.plugin import Fold
   from AutoSetSyntax.plugin import MatchableRule
   from AutoSetSyntax.plugin import ViewSnapshot
   
   
   class MyOwnMatch(AbstractMatch):
       """Your custom `Match` must inherit `AbstractMatch` and implement the `test` method."""
   
       def fold(self, rules: tuple[MatchableRule, ...]) -> Fold:
           # Optionally, you can implement `fold` to tell the optimizer that this combinator's
           # parameters and `rules` count already settle the answer, so it needn't be tested on
           # every view: return `Fold(True/False, "why")` for the constant `test` would always
           # return, or `UNFOLDED` when the result still depends on the view.
           # The reason is shown to the user in the dropped-rules report, so phrase it for them,
           # e.g. `Fold(False, 'an "any" with no sub-rule matches nothing')`.
           return UNFOLDED
   
       def test(self, view_snapshot: ViewSnapshot, rules: tuple[MatchableRule, ...]) -> bool:
           # Your job is to implement this function, at least.
           # This function tests `rules` (mix of `ConstraintRule`s and `MatchRule`s).
           return False
   

3. Decide the match name of your Match.

   Say, if your class name is MyOwnMatch, the match name is decided by

   1. Remove Match suffix from the class name. (MyOwnMatch » MyOwn)
   2. Convert it into snake case. (MyOwn » my_own)

   That is, you can use it via "match": "my_own" in a match rule.

4. At least, implement the test method.

5. Save your implementation in Packages/AutoSetSyntax-Custom/matches/. Conventionally, the file name used is the match name, my_own.py.

6. Restart ST and check whether your implementation is loaded via Debug Information.