include/swift/AST/TrailingCallArguments.h

//===--- TrailingCallArguments.h - Trailing Call Arguments ------*- C++ -*-===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
//  This file defines the TrailingCallArguments template, which is used
//  to tail-allocate the names and source locations of argument labels in a
//  call.
//
//===----------------------------------------------------------------------===//

#ifndef SWIFT_AST_TRAILINGCALLARGUMENTS_H
#define SWIFT_AST_TRAILINGCALLARGUMENTS_H

#include "swift/AST/Identifier.h"
#include "swift/Basic/SourceLoc.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/Support/TrailingObjects.h"

namespace swift {

/// Helper class to capture trailing call argument labels and related
/// information, for expression nodes that involve argument labels, trailing
/// closures, etc.
template<typename Derived>
class TrailingCallArguments
    : private llvm::TrailingObjects<Derived, Identifier, SourceLoc> {
  // We need to friend TrailingObjects twice here to work around an MSVC bug.
  // If we have two functions of the same name with the parameter
  // typename TrailingObjectsIdentifier::template OverloadToken<T> where T is
  // different for each function, then MSVC reports a "member function already
  // defined or declared" error, which is incorrect.
  using TrailingObjectsIdentifier = llvm::TrailingObjects<Derived, Identifier>;
  friend TrailingObjectsIdentifier;

  using TrailingObjects = llvm::TrailingObjects<Derived, Identifier, SourceLoc>;
  friend TrailingObjects;

  Derived &asDerived() {
    return *static_cast<Derived *>(this);
  }

  const Derived &asDerived() const {
    return *static_cast<const Derived *>(this);
  }

  size_t numTrailingObjects(
      typename TrailingObjectsIdentifier::template OverloadToken<Identifier>)
      const {
    return asDerived().getNumArguments();
  }

  size_t numTrailingObjects(
      typename TrailingObjectsIdentifier::template OverloadToken<SourceLoc>)
      const {
    return asDerived().hasArgumentLabelLocs() ? asDerived().getNumArguments()
                                              : 0;
  }

  /// Retrieve the buffer containing the argument labels.
  MutableArrayRef<Identifier> getArgumentLabelsBuffer() {
    return { this->template getTrailingObjects<Identifier>(),
             asDerived().getNumArguments() };
  }

  /// Retrieve the buffer containing the argument label locations.
  MutableArrayRef<SourceLoc> getArgumentLabelLocsBuffer() {
    if (!asDerived().hasArgumentLabelLocs())
      return { };

    return { this->template getTrailingObjects<SourceLoc>(),
             asDerived().getNumArguments() };
  }

protected:
  /// Determine the total size to allocate.
  static size_t totalSizeToAlloc(ArrayRef<Identifier> argLabels,
                                 ArrayRef<SourceLoc> argLabelLocs) {
    return TrailingObjects::template totalSizeToAlloc<Identifier, SourceLoc>(
        argLabels.size(), argLabelLocs.size());
  }

  /// Initialize the actual call arguments.
  void initializeCallArguments(ArrayRef<Identifier> argLabels,
                               ArrayRef<SourceLoc> argLabelLocs) {
    if (!argLabels.empty()) {
      std::uninitialized_copy(argLabels.begin(), argLabels.end(),
                              this->template getTrailingObjects<Identifier>());
    }

    if (!argLabelLocs.empty())
      std::uninitialized_copy(argLabelLocs.begin(), argLabelLocs.end(),
                              this->template getTrailingObjects<SourceLoc>());
  }

public:
  /// Retrieve the argument labels provided at the call site.
  ArrayRef<Identifier> getArgumentLabels() const {
    return { this->template getTrailingObjects<Identifier>(),
             asDerived().getNumArguments() };
  }

  /// Retrieve the buffer containing the argument label locations.
  ArrayRef<SourceLoc> getArgumentLabelLocs() const {
    if (!asDerived().hasArgumentLabelLocs())
      return { };

    return { this->template getTrailingObjects<SourceLoc>(),
             asDerived().getNumArguments() };
  }

  /// Retrieve the location of the ith argument label.
  SourceLoc getArgumentLabelLoc(unsigned i) const {
    auto locs = getArgumentLabelLocs();
    return i < locs.size() ? locs[i] : SourceLoc();
  }
};

} // end namespace swift

#endif // SWIFT_AST_TRAILINGCALLARGUMENTS_H