stdlib/public/core/StringInterpolation.swift.gyb

//===--- StringInterpolation.swift.gyb - String Interpolation -*- swift -*-===//
//
// 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
//
//===----------------------------------------------------------------------===//

%{

from SwiftIntTypes import all_integer_types

# Number of bits in the Builtin.Word type
word_bits = int(CMAKE_SIZEOF_VOID_P) * 8

StreamableTypes = [
    'String',
    'Character',
    'UnicodeScalar',
  ]

PrintableTypes = [
    'Bool',
    'Float32',
    'Float64'
  ]

for int_ty in all_integer_types(word_bits):
    PrintableTypes.append(int_ty.stdlib_name)

}%

extension String : _ExpressibleByStringInterpolation {
  /// Creates a new string by concatenating the given interpolations.
  ///
  /// Do not call this initializer directly. It is used by the compiler when
  /// you create a string using string interpolation. Instead, use string
  /// interpolation to create a new string by including values, literals,
  /// variables, or expressions enclosed in parentheses, prefixed by a
  /// backslash (`\(`...`)`).
  ///
  ///     let price = 2
  ///     let number = 3
  ///     let message = "If one cookie costs \(price) dollars, " +
  ///                   "\(number) cookies cost \(price * number) dollars."
  ///     print(message)
  ///     // Prints "If one cookie costs 2 dollars, 3 cookies cost 6 dollars."
  @effects(readonly)
  public init(stringInterpolation strings: String...) {
    self.init()
    for str in strings {
      self += str
    }
  }

  /// Creates a string containing the given expression's textual
  /// representation.
  ///
  /// Do not call this initializer directly. It is used by the compiler when
  /// interpreting string interpolations.
  ///
  /// - SeeAlso: `ExpressibleByStringInterpolation`
  public init<T>(stringInterpolationSegment expr: T) {
    self = String(describing: expr)
  }

% for Type in StreamableTypes:
  /// Creates a string containing the given value's textual representation.
  ///
  /// Do not call this initializer directly. It is used by the compiler when
  /// interpreting string interpolations.
  ///
  /// - SeeAlso: `ExpressibleByStringInterpolation`
  public init(stringInterpolationSegment expr: ${Type}) {
    self = _toStringReadOnlyStreamable(expr)
  }
% end

% for Type in PrintableTypes:
  /// Creates a string containing the given value's textual representation.
  ///
  /// Do not call this initializer directly. It is used by the compiler when
  /// interpreting string interpolations.
  ///
  /// - SeeAlso: `ExpressibleByStringInterpolation`
  public init(stringInterpolationSegment expr: ${Type}) {
    self = _toStringReadOnlyPrintable(expr)
  }
% end
}

// ${'Local Variables'}:
// eval: (read-only-mode 1)
// End: