swift-mirror/stdlib/public/core/FloatingPointParsing.swift.gyb

//===----------------------------------------------------------------------===//
//
// 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 SwiftShims

%{

allFloatBits = [32, 64, 80]

def floatName(bits):
    if bits == 32:
        return 'Float'
    if bits == 64:
        return 'Double'
    if bits == 80:
        return 'Float80'

cFuncSuffix2 = {32: 'f', 64: 'd', 80: 'ld'}

}%

/// Returns `true` iff isspace(u) would return nonzero when the current
/// locale is the C locale.
internal func _isspace_clocale(_ u: UTF16.CodeUnit) -> Bool {
  return "\t\n\u{b}\u{c}\r ".utf16.contains(u)
}

% for bits in allFloatBits:
%   Self = floatName(bits)

% if bits == 80:
#if !os(Windows) && (arch(i386) || arch(x86_64))
% end

//===--- Parsing ----------------------------------------------------------===//
extension ${Self} : LosslessStringConvertible {
  /// Creates a new instance from the given string.
  ///
  /// The string passed as `text` can represent a real number in decimal or
  /// hexadecimal format or special floating-point values for infinity and NaN
  /// ("not a number").
  ///
  /// The given string may begin with a plus or minus sign character (`+` or
  /// `-`). The allowed formats for each of these representations is then as
  /// follows:
  ///
  /// - A *decimal value* contains the significand, a sequence of decimal
  ///   digits that may include a decimal point.
  ///
  ///       let c = ${Self}("-1.0")
  ///       // c == -1.0
  ///
  ///       let d = ${Self}("28.375")
  ///       // d == 28.375
  ///
  ///   A decimal value may also include an exponent following the significand,
  ///   indicating the power of 10 by which the significand should be
  ///   multiplied. If included, the exponent is separated by a single
  ///   character, `e` or `E`, and consists of an optional plus or minus sign
  ///   character and a sequence of decimal digits.
  ///
  ///       let e = ${Self}("2837.5e-2")
  ///       // e == 28.375
  ///
  /// - A *hexadecimal value* contains the significand, either `0X` or `0x`,
  ///   followed by a sequence of hexadecimal digits. The significand may
  ///   include a decimal point.
  ///
  ///       let f = ${Self}("0x1c.6")
  ///       // f == 28.375
  ///
  ///   A hexadecimal value may also include an exponent following the
  ///   significand, indicating the power of 2 by which the significand should
  ///   be multiplied. If included, the exponent is separated by a single
  ///   character, `p` or `P`, and consists of an optional plus or minus sign
  ///   character and a sequence of decimal digits.
  ///
  ///       let g = ${Self}("0x1.c6p4")
  ///       // g == 28.375
  ///
  /// - A value of *infinity* contains one of the strings `"inf"` or
  ///   `"infinity"`, case insensitive.
  ///
  ///       let i = ${Self}("inf")
  ///       // i == ${Self}.infinity
  ///
  ///       let j = ${Self}("-Infinity")
  ///       // j == -${Self}.infinity
  ///
  /// - A value of *NaN* contains the string `"nan"`, case insensitive.
  ///
  ///       let n = ${Self}("-nan")
  ///       // n?.isNaN == true
  ///       // n?.sign == .minus
  ///
  ///   A NaN value may also include a payload in parentheses following the
  ///   `"nan"` keyword. The payload consists of a sequence of decimal digits,
  ///   or the characters `0X` or `0x` followed by a sequence of hexadecimal
  ///   digits. If the payload contains any other characters, it is ignored.
  ///   If the value of the payload is larger than can be stored as the
  ///   payload of a `${Self}.nan`, the least significant bits are used.
  ///
  ///       let p = ${Self}("nan(0x10)")
  ///       // p?.isNaN == true
  ///       // String(p!) == "nan(0x10)"
  ///
  /// Passing any other format or any additional characters as `text` results
  /// in `nil`. For example, the following conversions result in `nil`:
  ///
  ///     ${Self}(" 5.0")      // Includes whitespace
  ///     ${Self}("±2.0")      // Invalid character
  ///     ${Self}("0x1.25e4")  // Incorrect exponent format
  ///
  /// - Parameter text: The input string to convert to a `${Self}` instance. If
  ///   `text` has invalid characters or is in an invalid format, the result
  ///   is `nil`.
  public init?(_ text: String) {
    let u16 = text.utf16
    func parseNTBS(_ chars: UnsafePointer<CChar>) -> (${Self}, Int) {
      var result: ${Self} = 0
      let endPtr = withUnsafeMutablePointer(to: &result) {
        _swift_stdlib_strto${cFuncSuffix2[bits]}_clocale(chars, $0)
      }
      return (result, endPtr == nil ? 0 : endPtr! - chars)
    }

    let (result, n) = text.withCString(parseNTBS)

    if n == 0 || n != u16.count
    || u16.contains(where: { $0 > 127 || _isspace_clocale($0) }) {
      return nil
    }
    self = result
  }
}

% if bits == 80:
#endif
% end

% end