SyntaxExtensions.swift

//===----------------------------------------------------------------------===//
//
// 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 compiler(>=6)
internal import SwiftBasicFormat
@_spi(Diagnostics) internal import SwiftParser
@_spi(RawSyntax) @_spi(ExperimentalLanguageFeatures) internal import SwiftSyntax
#else
import SwiftBasicFormat
@_spi(Diagnostics) import SwiftParser
@_spi(RawSyntax) @_spi(ExperimentalLanguageFeatures) import SwiftSyntax
#endif

extension UnexpectedNodesSyntax {
  func presentTokens(satisfying isIncluded: (TokenSyntax) -> Bool) -> [TokenSyntax] {
    return self.children(viewMode: .sourceAccurate).compactMap({ $0.as(TokenSyntax.self) }).filter(isIncluded)
  }

  func presentTokens(withKind kind: TokenKind) -> [TokenSyntax] {
    return self.presentTokens(satisfying: { $0.tokenKind == kind })
  }

  /// If this only contains a single item, which is a present token satisfying `condition`, return that token, otherwise return `nil`.
  func onlyPresentToken(where condition: (TokenSyntax) -> Bool) -> TokenSyntax? {
    if self.count == 1,
      let token = self.first?.as(TokenSyntax.self),
      condition(token),
      token.presence == .present
    {
      return token
    } else {
      return nil
    }
  }

  /// If this only contains present tokens satisfying `condition`, return an array containing those tokens, otherwise return `nil`.
  func onlyPresentTokens(satisfying condition: (TokenSyntax) -> Bool) -> [TokenSyntax]? {
    let tokens = presentTokens(satisfying: condition)
    if tokens.count == self.count {
      return tokens
    } else {
      return nil
    }
  }

  /// If this only contains two present tokens, the first satisfying `firstCondition`, and the second satisfying `secondCondition`,
  /// return these tokens as a tuple, otherwise return `nil`.
  func twoPresentTokens(
    firstSatisfying firstCondition: (TokenSyntax) -> Bool,
    secondSatisfying secondCondition: (TokenSyntax) -> Bool
  ) -> (first: TokenSyntax, second: TokenSyntax)? {
    let sourceAccurateChildren = self.children(viewMode: .sourceAccurate).compactMap({ $0.as(TokenSyntax.self) })
    guard sourceAccurateChildren.count == 2 else {
      return nil
    }
    guard firstCondition(sourceAccurateChildren[0]) && secondCondition(sourceAccurateChildren[1]) else {
      return nil
    }
    return (sourceAccurateChildren[0], sourceAccurateChildren[1])
  }
}

extension Syntax {
  func hasParent(_ expectedParent: Syntax) -> Bool {
    var walk = self.parent
    while walk != nil {
      if walk == expectedParent {
        return true
      }
      walk = walk?.parent
    }
    return false
  }
}

extension SyntaxProtocol {
  /// A name that can be used to describe this node's type in diagnostics or `nil` if there is no good name for this node.
  /// If `allowBlockNames` is `false`, ``CodeBlockSyntax`` and ``MemberDeclBlockSyntax`` are not considered to have a good name and will return `nil`.
  func nodeTypeNameForDiagnostics(allowBlockNames: Bool) -> String? {
    let syntax = Syntax(self)
    if !allowBlockNames && (syntax.is(CodeBlockSyntax.self) || syntax.is(MemberBlockSyntax.self)) {
      return nil
    }
    return syntax.kind.nameForDiagnostics
  }

  /// A short description of this node that can be displayed inline in a single line.
  /// If the syntax node (excluding leading and trailing trivia) only spans a
  /// single line and has less than 100 characters (and thus fits into a
  /// diagnostic message), return that.
  /// Otherwise, return a generic message that describes the tokens in this node.
  var shortSingleLineContentDescription: String {
    let contentWithoutTrivia = self.trimmedDescription
    if self.children(viewMode: .sourceAccurate).allSatisfy({ $0.as(TokenSyntax.self)?.tokenKind == .rightBrace }) {
      if self.children(viewMode: .sourceAccurate).count == 1 {
        return "brace"
      } else {
        return "braces"
      }
    } else if let token = Syntax(self).as(UnexpectedNodesSyntax.self)?.onlyPresentTokens(satisfying: {
      $0.tokenKind.isLexerClassifiedKeyword
    })?.only {
      return "'\(token.text)' keyword"
    } else if let token = Syntax(self).as(TokenSyntax.self) {
      return "'\(token.text)' keyword"
    } else if contentWithoutTrivia.contains("\n") || contentWithoutTrivia.count > 100 {
      return "code"
    } else {
      return "code '\(contentWithoutTrivia)'"
    }
  }

  /// Returns `true` if the next token's leading trivia should be made leading trivia
  /// of this mode, when it is switched from being missing to present.
  var shouldBeInsertedAfterNextTokenTrivia: Bool {
    if !self.raw.kind.isMissing,
      let memberDeclItem = self.ancestorOrSelf(mapping: { $0.as(MemberBlockItemSyntax.self) }),
      memberDeclItem.firstToken(viewMode: .all) == self.firstToken(viewMode: .all)
    {
      return true
    } else {
      return false
    }
  }

  /// Returns `true` if the previous token and this node don't need to be separated,
  /// when it is switched from being missing to present.
  var shouldBeInsertedBeforePreviousTokenTrivia: Bool {
    if let previousToken = self.previousToken(viewMode: .fixedUp),
      previousToken.isPresent,
      let firstToken = self.firstToken(viewMode: .all),
      previousToken.trailingTrivia.allSatisfy({ $0.isWhitespace }),
      !BasicFormat().requiresWhitespace(between: previousToken, and: firstToken),
      !BasicFormat().requiresNewline(between: previousToken, and: firstToken)
    {
      return true
    } else {
      return false
    }
  }
}

extension TokenKind {
  var isIdentifier: Bool {
    switch self {
    case .identifier:
      return true
    default:
      return false
    }
  }

  var isDollarIdentifier: Bool {
    switch self {
    case .dollarIdentifier:
      return true
    default:
      return false
    }
  }

  var isIntegerLiteral: Bool {
    switch self {
    case .integerLiteral:
      return true
    default:
      return false
    }
  }

  var isRawStringDelimiter: Bool {
    switch self {
    case .rawStringPoundDelimiter:
      return true
    default:
      return false
    }
  }
}

extension TriviaPiece {
  var isBackslash: Bool {
    switch self {
    case .backslashes: return true
    default: return false
    }
  }
}

extension TokenSyntax {
  var isMissing: Bool {
    return presence == .missing
  }

  var isPresent: Bool {
    return presence == .present
  }
}

extension TypeSpecifierListSyntax {
  var simpleSpecifiers: [TokenSyntax] {
    return self.compactMap { specifier in
      switch specifier {
      case .simpleTypeSpecifier(let specifier): return specifier.specifier
      case .lifetimeTypeSpecifier: return nil
      case .nonisolatedTypeSpecifier: return nil
      #if RESILIENT_LIBRARIES
      @unknown default:
        fatalError()
      #endif
      }
    }
  }
}