[Recovery 5/7] Rewrite isStartOfDeclaration to more closely match the parser implementation
#746
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At the moment this doesn’t change anything because all places that call `eat` have previous checks that make sure the parser is currently positioned at the expected token. In the future, this will allow us to start parsing functions that `eat` a token at a different token and this function is responsible for eating all intermediate tokens until the expected one.
Use one of the following alternatives instead: - `expect` (mostly at start of productions) - `consume(if:)` where this paradigm is applicable - `consume(if:followedBy:)` to consume two tokens at once - A new `at(anyIn:)` paradigm that allows the parser to check if it is currently positioned at a known token kind, which can be exhausitively switched. If this is the case, the token can be safely consumed using a handle. - This function might seem overly complicated at the moment but it should allow us to later switch to a similar function that also does recovery.
This makes it easier to call it from other functions and forward the expected token kinds.
# Conflicts: # Sources/SwiftParser/Lookahead.swift # Sources/SwiftParser/TokenConsumer.swift
…overy` and `expect`
… higher-level parser primitives
We aren’t using this anywhere, but it seems like useful functionality in general.
…entation This allows us to share a few token kinds betewen `isStartOfDeclaration` and the actual parser.
If the item is not an expression, we can try skipping more tokens to parse a declaration.
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Depends on #745
Diff of this PR: https://github.com/ahoppen/swift-syntax/compare/ahoppen/ahoppen/ahoppen/40-rawtokenkind-subset..ahoppen/50-rewrite-is-at-start-of