tools/SwiftSyntax/Trivia.swift.gyb

%{
  # -*- mode: Swift -*-
  from gyb_syntax_support.Trivia import TRIVIAS
  # Ignore the following admonition it applies to the resulting .swift file only
}%
//// Automatically Generated From Trivia.swift.gyb.
//// Do Not Edit Directly!
//===------------------- Trivia.swift - Source Trivia Enum ----------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2017 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 Foundation

/// A contiguous stretch of a single kind of trivia. The constituent part of
/// a `Trivia` collection.
///
/// For example, four spaces would be represented by
/// `.spaces(4)`
///
/// In general, you should deal with the actual Trivia collection instead
/// of individual pieces whenever possible.
public enum TriviaPiece: Codable {
  enum CodingKeys: CodingKey {
    case kind, value
  }
  public init(from decoder: Decoder) throws {
    let container = try decoder.container(keyedBy: CodingKeys.self)
    let kind = try container.decode(String.self, forKey: .kind)
    switch kind {
% for trivia in TRIVIAS:
    case "${trivia.name}":
%   if trivia.is_collection():
      let value = try container.decode(Int.self, forKey: .value)
      self = .${trivia.lower_name}s(value)
%   else:
      let value = try container.decode(String.self, forKey: .value)
      self = .${trivia.lower_name}(value)
%   end
% end
    default:
      let context =
        DecodingError.Context(codingPath: [CodingKeys.kind],
                              debugDescription: "invalid TriviaPiece kind \(kind)")
      throw DecodingError.valueNotFound(String.self, context)
    }
  }

  public func encode(to encoder: Encoder) throws {
    var container = encoder.container(keyedBy: CodingKeys.self)
    switch self {
% for trivia in TRIVIAS:
%   if trivia.is_collection():
    case .${trivia.lower_name}s(let count):
      try container.encode("${trivia.name}", forKey: .kind)
      try container.encode(count, forKey: .value)
%   else:
    case .${trivia.lower_name}(let text):
      try container.encode("${trivia.name}", forKey: .kind)
      try container.encode(text, forKey: .value)
%   end
% end
    }
  }

% for trivia in TRIVIAS:
    /// ${trivia.comment}
%   if trivia.is_collection():
    case ${trivia.lower_name}s(Int)
%   else:
    case ${trivia.lower_name}(String)
%   end
% end
}

extension TriviaPiece: TextOutputStreamable {
  /// Prints the provided trivia as they would be written in a source file.
  ///
  /// - Parameter stream: The stream to which to print the trivia.
  public func write<Target>(to target: inout Target)
    where Target: TextOutputStream {
    func printRepeated(_ character: String, count: Int) {
      for _ in 0..<count { target.write(character) }
    }
    switch self {
% for trivia in TRIVIAS:
%   if trivia.is_collection():
%   joined = ''.join(trivia.swift_characters)
    case let .${trivia.lower_name}s(count):
      printRepeated("${joined}", count: count)
%   else:
    case let .${trivia.lower_name}(text):
      target.write(text)
%   end
% end
    }
  }

  /// Computes the information from this trivia to inform the source locations
  /// of the associated tokens.
  /// Specifically, walks through the trivia and keeps track of every newline
  /// to give a number of how many newlines and UTF8 characters appear in the
  /// trivia, along with the UTF8 offset of the last column.
  func characterSizes() -> (lines: Int, lastColumn: Int, utf8Length: Int) {
    func calculateTextSizes(_ text: String) ->
        (lines: Int, lastColumn: Int, utf8Length: Int) {
      var lines = 0
      var col = 0
      var total = 0
      var prevChar: UInt8? = nil
      // TODO: CR + LF should be regarded as one newline
      for char in text.utf8 {
        total += 1
        switch char {
        case 0x0a:
          if prevChar == 0x0d {
            /* ASCII CR LF */
            assert(col == 0)
          } else {
            /* ASCII newline */
            col = 0
            lines += 1
          }
        /* ASCII carriage-return */
        case 0x0d:
          col = 0
          lines += 1

        default:
          col += 1
        }
        prevChar = char
      }
      return (lines: lines, lastColumn: col, utf8Length: total)
    }
    switch self {
% for trivia in TRIVIAS:
%   if trivia.is_new_line:
    case let .${trivia.lower_name}s(n):
      return (lines: n, lastColumn: 0, utf8Length: n * ${trivia.characters_len()})
%   elif trivia.is_collection():
    case let .${trivia.lower_name}s(n):
      return (lines: 0, lastColumn: n, utf8Length: n * ${trivia.characters_len()})
%   else:
    case let .${trivia.lower_name}(text):
      return calculateTextSizes(text)
%   end
% end
    }
  }
}

/// A collection of leading or trailing trivia. This is the main data structure
/// for thinking about trivia.
public struct Trivia: Codable {
  let pieces: [TriviaPiece]

  /// Creates Trivia with the provided underlying pieces.
  public init(pieces: [TriviaPiece]) {
    self.pieces = pieces
  }

  public init(from decoder: Decoder) throws {
    var container = try decoder.unkeyedContainer()
    var pieces = [TriviaPiece]()
    while let piece = try container.decodeIfPresent(TriviaPiece.self) {
      pieces.append(piece)
    }
    self.pieces = pieces
  }

  public func encode(to encoder: Encoder) throws {
    var container = encoder.unkeyedContainer()
    for piece in pieces {
      try container.encode(piece)
    }
  }

  /// Creates Trivia with no pieces.
  public static var zero: Trivia {
    return Trivia(pieces: [])
  }

  /// Creates a new `Trivia` by appending the provided `TriviaPiece` to the end.
  public func appending(_ piece: TriviaPiece) -> Trivia {
    var copy = pieces
    copy.append(piece)
    return Trivia(pieces: copy)
  }

% for trivia in TRIVIAS:
%   if trivia.is_collection():
%   joined = ''.join(trivia.swift_characters)
    /// Return a piece of trivia for some number of '${joined}' characters.
    public static func ${trivia.lower_name}s(_ count: Int) -> Trivia {
      return [.${trivia.lower_name}s(count)]
    }
%   else:
    /// Return a piece of trivia for ${trivia.name}.
    public static func ${trivia.lower_name}(_ text: String) -> Trivia {
      return [.${trivia.lower_name}(text)]
    }
%   end
% end

  /// Computes the total sizes and offsets of all pieces in this Trivia.
  func characterSizes() -> (lines: Int, lastColumn: Int, utf8Length: Int) {
    var lines = 0
    var lastColumn = 0
    var length = 0
    for piece in pieces {
      let (ln, col, len) = piece.characterSizes()
      lines += ln
      lastColumn = col
      length += len
    }
    return (lines: lines, lastColumn: lastColumn, utf8Length: length)
  }
}

/// Conformance for Trivia to the Collection protocol.
extension Trivia: Collection {
  public var startIndex: Int {
    return pieces.startIndex
  }

  public var endIndex: Int {
    return pieces.endIndex
  }

  public func index(after i: Int) -> Int {
    return pieces.index(after: i)
  }

  public subscript(_ index: Int) -> TriviaPiece {
    return pieces[index]
  }

  /// Get the byteSize of this trivia
  public var byteSize: Int {
    let pos = UTF8Position()
    for piece in pieces {
      piece.accumulateAbsolutePosition(pos)
    }
    return pos.byteOffset
  }
}


extension Trivia: ExpressibleByArrayLiteral {
  /// Creates Trivia from the provided pieces.
  public init(arrayLiteral elements: TriviaPiece...) {
    self.pieces = elements
  }
}

/// Concatenates two collections of `Trivia` into one collection.
public func +(lhs: Trivia, rhs: Trivia) -> Trivia {
  return Trivia(pieces: lhs.pieces + rhs.pieces)
}

extension TriviaPiece {
  func accumulateAbsolutePosition(_ pos: AbsolutePosition) {
    switch self {
% for trivia in TRIVIAS:
%   if trivia.is_new_line:
    case let .${trivia.lower_name}s(count):
      pos.add(lines: count, size: ${trivia.characters_len()})
%   elif trivia.is_collection():
    case let .${trivia.lower_name}s(count):
      pos.add(columns: count)
%   else:
    case let .${trivia.lower_name}(text):
      pos.add(text: text)
%   end
% end
  }
  }
}