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//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2024 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
import SwiftSyntax
/// Scope that introduces generic parameter names and directs
/// futher lookup to its `WithGenericParametersScopeSyntax`
/// parent scope's parent scope (i.e. on return, bypasses names
/// introduced by its parent).
protocol GenericParameterScopeSyntax: ScopeSyntax {}
@_spi(Experimental) extension GenericParameterScopeSyntax {
/// Returns names matching lookup and bypasses
/// `WithGenericParametersScopeSyntax` parent scope in futher lookup.
///
/// ### Example
/// ```swift
/// let a = 23
/// func foo<A>(a: A) {
/// a // <-- start lookup here
/// }
/// ```
/// When starting lookup at the `a` reference,
/// lookup first visits the code block scope associated
/// with the function's body. Then, it's forwarded to the
/// function declaration scope and then to generic parameter
/// scope (`WithGenericParametersScopeSyntax`).
/// Then, to ensure there is no infinite cycle,
/// this method passes lookup to function scope's parent scope
/// (in this case: file scope).
@_spi(Experimental) public func lookup(
_ identifier: Identifier?,
at lookUpPosition: AbsolutePosition,
with config: LookupConfig
) -> [LookupResult] {
return defaultLookupImplementation(
identifier,
at: lookUpPosition,
with: config,
propagateToParent: false
)
+ lookupBypassingParentResults(
identifier,
at: lookUpPosition,
with: config
)
}
/// Bypasses names introduced by `WithGenericParametersScopeSyntax` parent scope.
///
/// ### Example
/// ```swift
/// let a = 23
/// func foo<A>(a: A) {
/// a // <-- start lookup here
/// }
/// ```
/// When starting lookup at the `a` reference,
/// lookup first visits the code block scope associated
/// with the function's body. Then, it's forwarded to the
/// function declaration scope and then to generic parameter
/// scope (`WithGenericParametersScopeSyntax`).
/// Then, to ensure there is no infinite cycle,
/// we use this method instead of the standard `lookupInParent`
/// to pass lookup to the function scope's parent scope (in this case: file scope)
/// and effectively bypass names already looked up before.
private func lookupBypassingParentResults(
_ identifier: Identifier?,
at lookUpPosition: AbsolutePosition,
with config: LookupConfig
) -> [LookupResult] {
guard let parentScope else { return [] }
if let parentScope = Syntax(parentScope).asProtocol(SyntaxProtocol.self)
as? WithGenericParametersScopeSyntax
{
return parentScope.returningLookupFromGenericParameterScope(identifier, at: lookUpPosition, with: config)
} else {
return lookupInParent(identifier, at: lookUpPosition, with: config)
}
}
}
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