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//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2023 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
//
//===----------------------------------------------------------------------===//
#if swift(>=6)
@_spi(RawSyntax) internal import SwiftSyntax
#else
@_spi(RawSyntax) import SwiftSyntax
#endif
/// Context in which to check if a name can be used as an identifier.
///
/// - SeeAlso: `Swift.isValidSwiftIdentifier(for:)` extension added by SwiftParser.
public enum IdentifierCheckContext {
/// Check if a name can be used to declare a variable, ie. if it can be used after a `let` or `var` keyword.
///
/// ### Examples
/// - `test` is a valid variable name and `let test: Int` is valid Swift code
/// - `class` is not a valid variable and `let class: Int` is invalid Swift code
case variableName
/// Check if a name can be used as a member access, ie. if it can be used after a `.`.
///
/// ### Examples
/// - `test` is a valid identifier for member access because `myStruct.test` is valid
/// - `class` is a valid identifier for member access because `myStruct.class` is valid, even though `class`
/// needs to be wrapped in backticks when used to declare a variable.
/// - `self` is not a valid identifier for member access because `myStruct.self` does not access a member named
/// `self` on `myStruct` and instead returns `myStruct` itself.
case memberAccess
}
extension String {
/// Checks whether `name` can be used as an identifier in a certain context.
///
/// If the name cannot be used as an identifier in this context, it needs to be escaped.
///
/// For example, `class` is not a valid identifier for a variable name and needs to be be wrapped in backticks
/// to be valid Swift code, like the following.
///
/// ```swift
/// let `class`: String
/// ```
///
/// The context is important here – some names can be used as identifiers in some contexts but not others.
/// For example, `myStruct.class` is valid without adding backticks `class`, but as mentioned above,
/// backticks need to be added when `class` is used as a variable name.
///
/// - SeeAlso: ``SwiftParser/IdentifierCheckContext``
public func isValidSwiftIdentifier(for context: IdentifierCheckContext) -> Bool {
switch context {
case .variableName:
return isValidVariableName(self)
case .memberAccess:
return isValidMemberAccess(self)
}
}
}
private func isValidVariableName(_ name: String) -> Bool {
var parser = Parser("var \(name)")
let decl = DeclSyntax.parse(from: &parser)
guard parser.at(.endOfFile) else {
// We didn't parse the entire name. Probably some garbage left in the name, so not an identifier.
return false
}
guard !decl.hasError && !decl.hasWarning else {
// There were syntax errors in the source code. So not valid.
return false
}
guard let variable = decl.as(VariableDeclSyntax.self) else {
return false
}
guard let identifier = variable.bindings.first?.pattern.as(IdentifierPatternSyntax.self)?.identifier else {
return false
}
guard identifier.rawTokenKind == .identifier else {
// We parsed the name as a keyword, eg. `self`, so not a valid identifier.
return false
}
guard identifier.rawText.count == name.utf8.count else {
// The identifier doesn't cover all the characters in `name`, so we parsed
// some of these characters into trivia or another token.
// Thus, `name` is not a valid identifier.
return false
}
return true
}
private func isValidMemberAccess(_ name: String) -> Bool {
var parser = Parser("t.\(name)")
let expr = ExprSyntax.parse(from: &parser)
guard parser.at(.endOfFile) else {
// We didn't parse the entire name. Probably some garbage left in the name, so not an identifier.
return false
}
guard !expr.hasError && !expr.hasWarning else {
// There were syntax errors in the source code. So not valid.
return false
}
guard let memberAccess = expr.as(MemberAccessExprSyntax.self) else {
return false
}
let identifier = memberAccess.declName.baseName
guard identifier.rawTokenKind == .identifier else {
// We parsed the name as a keyword, eg. `self`, so not a valid identifier.
return false
}
guard identifier.rawText.count == name.utf8.count else {
// The identifier doesn't cover all the characters in `name`, so we parsed
// some of these characters into trivia or another token.
// Thus, `name` is not a valid identifier.
return false
}
return true
}
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