//===----------------------------------------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//

// Generate comparison functions for tuples up to some reasonable arity.

%{

comparableOperators = [
  ('<', 'before'),
  ('<=', 'before or the same as'),
  ('>', 'after'),
  ('>=', 'after or the same as')
]

}%

/// Returns a Boolean value indicating whether the corresponding components of
/// two tuples are equal.
///
/// All arity zero tuples are equal.
///
/// - Parameters:
///   - lhs: An empty tuple.
///   - rhs: An empty tuple.
@inlinable // trivial-implementation
public func ==(lhs: (), rhs: ()) -> Bool {
  return true
}

/// Returns a Boolean value indicating whether any corresponding components of
/// the two tuples are not equal.
///
/// All arity zero tuples are equal.
///
/// - Parameters:
///   - lhs: An empty tuple.
///   - rhs: An empty tuple.
@inlinable // trivial-implementation
public func !=(lhs: (), rhs: ()) -> Bool {
    return false
}

/// Returns a Boolean value indicating whether the first tuple is ordered
/// before the second in a lexicographical ordering.
///
/// An arity zero tuple is never strictly before another arity zero tuple in a
/// lexicographical ordering.
///
/// - Parameters:
///   - lhs: An empty tuple.
///   - rhs: An empty tuple.
@inlinable // trivial-implementation
public func <(lhs: (), rhs: ()) -> Bool {
    return false
}

/// Returns a Boolean value indicating whether the first tuple is ordered
/// before or the same as the second in a lexicographical ordering.
///
/// An arity zero tuple is always before or the same as another arity zero tuple
/// in a lexicographical ordering.
///
/// - Parameters:
///   - lhs: An empty tuple.
///   - rhs: An empty tuple.
@inlinable // trivial-implementation
public func <=(lhs: (), rhs: ()) -> Bool {
    return true
}

/// Returns a Boolean value indicating whether the first tuple is ordered
/// after the second in a lexicographical ordering.
///
/// An arity zero tuple is never strictly after another arity zero tuple in a
/// lexicographical ordering.
///
/// - Parameters:
///   - lhs: An empty tuple.
///   - rhs: An empty tuple.
@inlinable // trivial-implementation
public func >(lhs: (), rhs: ()) -> Bool {
    return false
}

/// Returns a Boolean value indicating whether the first tuple is ordered
/// after or the same as the second in a lexicographical ordering.
///
/// An arity zero tuple is always after or the same as another arity zero tuple
/// in a lexicographical ordering.
///
/// - Parameters:
///   - lhs: An empty tuple.
///   - rhs: An empty tuple.
@inlinable // trivial-implementation
public func >=(lhs: (), rhs: ()) -> Bool {
    return true
}

% for arity in range(2,7):
%   typeParams = [chr(ord("A") + i) for i in range(arity)]
%   tupleT = "({})".format(",".join(typeParams))
%   equatableTypeParams = ", ".join(["{}: Equatable".format(c) for c in typeParams])

%   originalTuple = "(\"a\", {})".format(", ".join(map(str, range(1, arity))))
%   greaterTuple = "(\"a\", {})".format(", ".join(map(str, list(range(1, arity - 1)) + [arity])))

/// Returns a Boolean value indicating whether the corresponding components of
/// two tuples are equal.
///
/// For two tuples to compare as equal, each corresponding pair of components
/// must be equal. The following example compares tuples made up of ${arity}
/// components:
///
///     let a = ${originalTuple}
///     let b = ${originalTuple}
///     print(a == b)
///     // Prints "true"
///
///     let c = ${greaterTuple}
///     print(a == c)
///     // Prints "false"
///
/// - Parameters:
///   - lhs: A tuple of `Equatable` elements.
///   - rhs: Another tuple of elements of the same type as `lhs`.
@inlinable // trivial-implementation
public func == <${equatableTypeParams}>(lhs: ${tupleT}, rhs: ${tupleT}) -> Bool {
  guard lhs.0 == rhs.0 else { return false }
  /*tail*/ return (
    ${", ".join("lhs.{}".format(i) for i in range(1, arity))}
  ) == (
    ${", ".join("rhs.{}".format(i) for i in range(1, arity))}
  )
}

/// Returns a Boolean value indicating whether any corresponding components of
/// the two tuples are not equal.
///
/// For two tuples to compare as equal, each corresponding pair of components
/// must be equal. The following example compares tuples made up of ${arity}
/// components:
///
///     let a = ${originalTuple}
///     let b = ${originalTuple}
///     print(a != b)
///     // Prints "false"
///
///     let c = ${greaterTuple}
///     print(a != c)
///     // Prints "true"
///
/// - Parameters:
///   - lhs: A tuple of `Equatable` elements.
///   - rhs: Another tuple of elements of the same type as `lhs`.
@inlinable // trivial-implementation
public func != <${equatableTypeParams}>(lhs: ${tupleT}, rhs: ${tupleT}) -> Bool {
  guard lhs.0 == rhs.0 else { return true }
  /*tail*/ return (
    ${", ".join("lhs.{}".format(i) for i in range(1, arity))}
  ) != (
    ${", ".join("rhs.{}".format(i) for i in range(1, arity))}
  )
}

%   comparableTypeParams = ", ".join(["{}: Comparable".format(c) for c in typeParams])
%   for op, phrase in comparableOperators:
/// Returns a Boolean value indicating whether the first tuple is ordered
/// ${phrase} the second in a lexicographical ordering.
///
/// Given two tuples `(a1, a2, ..., aN)` and `(b1, b2, ..., bN)`, the first
/// tuple is ${phrase} the second tuple if and only if
/// `a1 ${op.replace('=', '')} b1` or (`a1 == b1` and
/// `(a2, ..., aN) ${op} (b2, ..., bN)`).
///
/// - Parameters:
///   - lhs: A tuple of `Comparable` elements.
///   - rhs: Another tuple of elements of the same type as `lhs`.
@inlinable // trivial-implementation
public func ${op} <${comparableTypeParams}>(lhs: ${tupleT}, rhs: ${tupleT}) -> Bool {
  if lhs.0 != rhs.0 { return lhs.0 ${op} rhs.0 }
  /*tail*/ return (
    ${", ".join("lhs.{}".format(i) for i in range(1, arity))}
  ) ${op} (
    ${", ".join("rhs.{}".format(i) for i in range(1, arity))}
  )
}
%   end
% end

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