Patterns have an unusual parse tree, but now the matching should
at least be a bit easier to follow.
The TODO regarding not being able to pass down context to handle
var/let is still relevant, and can't be solved in the mapping alone.
Adds a test case 'Switch with labeled case pattern arguments' covering:
- case .implicit(isAcknowledged: false) — labeled bool literal
- case .thread(threadRowId: _, let rowId) — labeled wildcard + binding
The current output contains type errors: pattern_element::key is being
produced as name_expr instead of identifier. These will be fixed in the
following commit.
The switch_entry rule was capturing switch_pattern wrapper nodes instead of
drilling into them to extract the actual pattern nodes. This caused patterns
from switch cases to be lost during desugaring.
Changed the pattern match from:
(switch_entry pattern: (switch_pattern)* @pats ...)
to:
(switch_entry pattern: (switch_pattern pattern: @pats)* ...)
This now correctly extracts the pattern field from each switch_pattern node,
ensuring that patterns from cases like 'case 1:' and 'case .circle(let r):'
are preserved in the switch_case AST nodes.
Updated control-flow.txt corpus outputs to reflect the new behavior.
Same as in the preceding commit, these items do not make sense as
separate fields on the parent node, so we materialise (or create new)
intermediate nodes to group them together.
The field representation would have made it difficult to figure out
which parameters correspond to which default values and attributes, so
instead we now encapsulate these in a new `function_parameter` node.
Introduces (by making it named) a `block` node, and conversely makes
`statements` anonymous. This enables us to sensibly distinguish between
the "then" and "else" branch of an `if_statement`, which we were not
able to previously.
The output is not so interesting as the mapping removes most nodes from the current test file.
I added a name_expr.swift test so at least one NameExpr makes it through.
ast_types.yml additions:
- tuple_pattern { element*: pattern } in the pattern supertype.
- sequence_condition { stmt*: stmt, condition: condition } in the
condition supertype.
swift.rs:
- Map Swift tuple destructuring (e.g. `let (a, b) = pair`) to the new
tuple_pattern instead of synthesizing an apply_pattern.
- if-let / guard-let: explicitly match the value_binding_pattern
(the `let` keyword) and bind the source expression as the next
condition child, so `let` no longer leaks into the output.
