Use the vendored parser to drive autocomplete. #388
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cristianoc
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First step: find the parsetree expression for the item to be completed.
cristianoc
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<div x=Outer.Inner. name="" /> parses as x=Outer.Inner.name
Sometimes "Foo. " is followed by "bar" and the parser's behaviour is to parse as "Foo.bar". This gets back the intended path "Foo."
Complete with anything in scope including open modules and pervasives.
When completing `x=`, if the following contains `name=...`, then the parser interprets it as `x=name`. Now detect that the cursor is after the label `x` but before `name`, and don;t interpret the situation as label completion.
Use symbol "_" like in other places in the parser.
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More fine grained error recovery from parsing longidents. E.g. Foo. gives Foo._ instead of a default expression which erases info on what's parser already. From: rescript-lang/rescript-vscode#388
cristianoc
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More fine grained error recovery from parsing longidents. E.g. Foo. gives Foo._ instead of a default expression which erases info on what's parser already. From: rescript-lang/rescript-vscode#388
cristianoc
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to rescript-lang/syntax
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Apr 22, 2022
More fine grained error recovery from parsing longidents. E.g. Foo. gives Foo._ instead of a default expression which erases info on what's parser already. From: rescript-lang/rescript-vscode#388
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The vendored parser has a recovery mechanism where parsing continues past an error. This makes it suitable to support autocomplete, which is triggered on incomplete code which would normally not parse.
This replaces the previous hand-crafted mini-parser used specifically for autocomplete, which would start from the cursor position, and try to parse backwards figuring out the context the cursor happens to be in.
The new mechanism starts from the current position and the parse tree produced by the parser. For example,
List.gets parsed asList._where the dummy identifier_is inserted by the recovery mechanism.If the cursor position is immediately after
., the mechanism finds the relevant node in the parse tree which represents expressionList._, and uses that information for autocomplete.One of the benefits of this new approach is that relying on the actual parser gives a better handling of corner cases (e.g. support for template literals inside strings comes for free), and avoids the maintenance burden of supporting/extending the ad-hoc parser.
Another benefit is that the parser provides contextual information, which can be used to decide whether e.g. the current context is a value context or type context, or variant context, or field name context. So that
let x = List.mwill complete values fromList, whilelet f : Js.Promise.will complete types from moduleJs.Promise.