Extract out AST-collecting-walker to a separate function + abstract class #1154
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…lass and use it for range aggregation
| namespace FSharp.Compiler | ||
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| module Syntax = | ||
| open FSharp.Compiler.Syntax | ||
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| type SyntaxCollectorBase = | ||
| new: unit -> SyntaxCollectorBase | ||
| abstract WalkSynModuleOrNamespace: SynModuleOrNamespace -> unit | ||
| abstract WalkAttribute: SynAttribute -> unit | ||
| abstract WalkSynModuleDecl: SynModuleDecl -> unit | ||
| abstract WalkExpr: SynExpr -> unit | ||
| abstract WalkTypar: SynTypar -> unit | ||
| abstract WalkTyparDecl: SynTyparDecl -> unit | ||
| abstract WalkTypeConstraint: SynTypeConstraint -> unit | ||
| abstract WalkType: SynType -> unit | ||
| abstract WalkMemberSig: SynMemberSig -> unit | ||
| abstract WalkPat: SynPat -> unit | ||
| abstract WalkValTyparDecls: SynValTyparDecls -> unit | ||
| abstract WalkBinding: SynBinding -> unit | ||
| abstract WalkSimplePat: SynSimplePat -> unit | ||
| abstract WalkInterfaceImpl: SynInterfaceImpl -> unit | ||
| abstract WalkClause: SynMatchClause -> unit | ||
| abstract WalkInterpolatedStringPart: SynInterpolatedStringPart -> unit | ||
| abstract WalkMeasure: SynMeasure -> unit | ||
| abstract WalkComponentInfo: SynComponentInfo -> unit | ||
| abstract WalkTypeDefnSigRepr: SynTypeDefnSigRepr -> unit | ||
| abstract WalkUnionCaseType: SynUnionCaseKind -> unit | ||
| abstract WalkEnumCase: SynEnumCase -> unit | ||
| abstract WalkField: SynField -> unit | ||
| abstract WalkTypeDefnSimple: SynTypeDefnSimpleRepr -> unit | ||
| abstract WalkValSig: SynValSig -> unit | ||
| abstract WalkMember: SynMemberDefn -> unit | ||
| abstract WalkUnionCase: SynUnionCase -> unit | ||
| abstract WalkTypeDefnRepr: SynTypeDefnRepr -> unit | ||
| abstract WalkTypeDefn: SynTypeDefn -> unit | ||
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| val walkAst: walker: SyntaxCollectorBase -> input: ParsedInput -> unit |
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This is the bit that I would contribute upstream at some point (maybe the Active Patterns as well but they aren't strictly necessary).
| module FoldingRange = | ||
| open FSharp.Compiler.Syntax | ||
| open FSharp.Compiler.Text | ||
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| val getRangesAtPosition: input: ParsedInput -> r: Position -> Range list | ||
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| module Completion = | ||
| open FSharp.Compiler.Syntax | ||
| open FSharp.Compiler.Text |
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Look at these nice, compact modules with no extraneous information in them.
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| loop [] pats | ||
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| type SyntaxCollectorBase() = |
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To make this type I looked at every walkX member in the walker function from the previous version and made a WalkX member on this type. The walker function handles going 'deeper' into the structure, so the member overrides that users write here should be strictly focused on looking at this particular syntax node, not doing traversal themselves.
| abstract WalkTypeDefn: SynTypeDefn -> unit | ||
| default _.WalkTypeDefn s = () | ||
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| let walkAst (walker: SyntaxCollectorBase) (input: ParsedInput) : unit = |
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The implementation here is the same as before, but with all of the addIfInside calls replace with calls to walker.WalkX as appropriate.
| if (Range.rangeContainsPos m pos) then | ||
| ranges.Add m | ||
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| override _.WalkSynModuleOrNamespace m = addIfInside m.Range |
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because we pulled out all of the noise of walking the tree, these individual node decision become really easy to reason about. Many AST nodes provide a helpful Range member so that we don't have to unpack too many of the nodes.
| let getRangesAtPosition input (r: Position) : Range list = | ||
| let walker = new RangeCollectorWalker(r) | ||
| walkAst walker input | ||
| walker.Ranges |> Seq.toList |
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And now the method becomes more understandable.
…lass (ionide#1154) * extract out AST-collecting-walker to a separate function + abstract class and use it for range aggregation * better factoring of the syntax-walking code
WHAT
🤖 Generated by Copilot at c7037be
Refactored the code for finding folding ranges in F# files. Moved the logic to a new
FoldingRangemodule and used a custom syntax walker to collect the ranges. Split theUntypedAstUtils.fsifile intoSyntax.fsandUntypedAstUtils.fsfor better modularity.🤖 Generated by Copilot at c7037be
🔧📦📑
WHY
I logged an issue at dotnet/fsharp a while ago to pull out this walker from UntypedAstUtils into a reusable component because I thought it would be helpful. This walker gives the opportunity to do an action at every node which is helpful for 'collecting' style operations, like folding ranges and the soon-to-be-implemented nested language support.
This PR is the infrastructure for that - it pulls out the collecting walker into an abstract class for the caller to override, and a walking function that the walker is passed to - very much like the existing position-finding walker. It then uses that walker to reimplement the folding-range detection, which now is very simple to understand.
HOW
🤖 Generated by Copilot at c7037be
UntypedAstUtils.fsifile into two files:Syntax.fsandUntypedAstUtils.fs(link)