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//===--- SwapBinaryOperands.cpp ----------------------------------*- C++-*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "ParsedAST.h"
#include "Protocol.h"
#include "Selection.h"
#include "SourceCode.h"
#include "refactor/Tweak.h"
#include "support/Logger.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/Expr.h"
#include "clang/AST/OperationKinds.h"
#include "clang/AST/Stmt.h"
#include "clang/Basic/LLVM.h"
#include "clang/Basic/SourceLocation.h"
#include "clang/Tooling/Core/Replacement.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/FormatVariadic.h"
#include <string>
#include <utility>
namespace clang {
namespace clangd {
namespace {
/// Check whether it makes logical sense to swap operands to an operator.
/// Assignment or member access operators are rarely swappable
/// while keeping the meaning intact, whereas comparison operators, mathematical
/// operators, etc. are often desired to be swappable for readability, avoiding
/// bugs by assigning to nullptr when comparison was desired, etc.
bool isOpSwappable(const BinaryOperatorKind Opcode) {
switch (Opcode) {
case BinaryOperatorKind::BO_Mul:
case BinaryOperatorKind::BO_Add:
case BinaryOperatorKind::BO_LT:
case BinaryOperatorKind::BO_GT:
case BinaryOperatorKind::BO_LE:
case BinaryOperatorKind::BO_GE:
case BinaryOperatorKind::BO_EQ:
case BinaryOperatorKind::BO_NE:
case BinaryOperatorKind::BO_And:
case BinaryOperatorKind::BO_Xor:
case BinaryOperatorKind::BO_Or:
case BinaryOperatorKind::BO_LAnd:
case BinaryOperatorKind::BO_LOr:
case BinaryOperatorKind::BO_Comma:
return true;
// Noncommutative operators:
case BinaryOperatorKind::BO_Div:
case BinaryOperatorKind::BO_Sub:
case BinaryOperatorKind::BO_Shl:
case BinaryOperatorKind::BO_Shr:
case BinaryOperatorKind::BO_Rem:
// <=> is noncommutative
case BinaryOperatorKind::BO_Cmp:
// Member access:
case BinaryOperatorKind::BO_PtrMemD:
case BinaryOperatorKind::BO_PtrMemI:
// Assignment:
case BinaryOperatorKind::BO_Assign:
case BinaryOperatorKind::BO_MulAssign:
case BinaryOperatorKind::BO_DivAssign:
case BinaryOperatorKind::BO_RemAssign:
case BinaryOperatorKind::BO_AddAssign:
case BinaryOperatorKind::BO_SubAssign:
case BinaryOperatorKind::BO_ShlAssign:
case BinaryOperatorKind::BO_ShrAssign:
case BinaryOperatorKind::BO_AndAssign:
case BinaryOperatorKind::BO_XorAssign:
case BinaryOperatorKind::BO_OrAssign:
return false;
}
return false;
}
/// Some operators are asymmetric and need to be flipped when swapping their
/// operands
/// @param[out] Opcode the opcode to potentially swap
/// If the opcode does not need to be swapped or is not swappable, does nothing
BinaryOperatorKind swapOperator(const BinaryOperatorKind Opcode) {
switch (Opcode) {
case BinaryOperatorKind::BO_LT:
return BinaryOperatorKind::BO_GT;
case BinaryOperatorKind::BO_GT:
return BinaryOperatorKind::BO_LT;
case BinaryOperatorKind::BO_LE:
return BinaryOperatorKind::BO_GE;
case BinaryOperatorKind::BO_GE:
return BinaryOperatorKind::BO_LE;
case BinaryOperatorKind::BO_Mul:
case BinaryOperatorKind::BO_Add:
case BinaryOperatorKind::BO_Cmp:
case BinaryOperatorKind::BO_EQ:
case BinaryOperatorKind::BO_NE:
case BinaryOperatorKind::BO_And:
case BinaryOperatorKind::BO_Xor:
case BinaryOperatorKind::BO_Or:
case BinaryOperatorKind::BO_LAnd:
case BinaryOperatorKind::BO_LOr:
case BinaryOperatorKind::BO_Comma:
case BinaryOperatorKind::BO_Div:
case BinaryOperatorKind::BO_Sub:
case BinaryOperatorKind::BO_Shl:
case BinaryOperatorKind::BO_Shr:
case BinaryOperatorKind::BO_Rem:
case BinaryOperatorKind::BO_PtrMemD:
case BinaryOperatorKind::BO_PtrMemI:
case BinaryOperatorKind::BO_Assign:
case BinaryOperatorKind::BO_MulAssign:
case BinaryOperatorKind::BO_DivAssign:
case BinaryOperatorKind::BO_RemAssign:
case BinaryOperatorKind::BO_AddAssign:
case BinaryOperatorKind::BO_SubAssign:
case BinaryOperatorKind::BO_ShlAssign:
case BinaryOperatorKind::BO_ShrAssign:
case BinaryOperatorKind::BO_AndAssign:
case BinaryOperatorKind::BO_XorAssign:
case BinaryOperatorKind::BO_OrAssign:
return Opcode;
}
llvm_unreachable("Unknown BinaryOperatorKind enum");
}
/// Swaps the operands to a binary operator
/// Before:
/// x != nullptr
/// ^ ^^^^^^^
/// After:
/// nullptr != x
class SwapBinaryOperands : public Tweak {
public:
const char *id() const final;
bool prepare(const Selection &Inputs) override;
Expected<Effect> apply(const Selection &Inputs) override;
std::string title() const override {
return llvm::formatv("Swap operands to {0}",
Op ? Op->getOpcodeStr() : "binary operator");
}
llvm::StringLiteral kind() const override {
return CodeAction::REFACTOR_KIND;
}
bool hidden() const override { return false; }
private:
const BinaryOperator *Op;
};
REGISTER_TWEAK(SwapBinaryOperands)
bool SwapBinaryOperands::prepare(const Selection &Inputs) {
for (const SelectionTree::Node *N = Inputs.ASTSelection.commonAncestor();
N && !Op; N = N->Parent) {
// Stop once we hit a block, e.g. a lambda in one of the operands.
// This makes sure that the selection point is in the 'scope' of the binary
// operator, not from somewhere inside a lambda for example
// (5 < [](){ ^return 1; })
if (llvm::isa_and_nonnull<CompoundStmt>(N->ASTNode.get<Stmt>()))
return false;
Op = dyn_cast_or_null<BinaryOperator>(N->ASTNode.get<Stmt>());
// If we hit upon a nonswappable binary operator, ignore and keep going
if (Op && !isOpSwappable(Op->getOpcode())) {
Op = nullptr;
}
}
return Op != nullptr;
}
Expected<Tweak::Effect> SwapBinaryOperands::apply(const Selection &Inputs) {
const auto &Ctx = Inputs.AST->getASTContext();
const auto &SrcMgr = Inputs.AST->getSourceManager();
const auto LHSRng = toHalfOpenFileRange(SrcMgr, Ctx.getLangOpts(),
Op->getLHS()->getSourceRange());
if (!LHSRng)
return error(
"Could not obtain range of the 'lhs' of the operator. Macros?");
const auto RHSRng = toHalfOpenFileRange(SrcMgr, Ctx.getLangOpts(),
Op->getRHS()->getSourceRange());
if (!RHSRng)
return error(
"Could not obtain range of the 'rhs' of the operator. Macros?");
const auto OpRng =
toHalfOpenFileRange(SrcMgr, Ctx.getLangOpts(), Op->getOperatorLoc());
if (!OpRng)
return error("Could not obtain range of the operator itself. Macros?");
const auto LHSCode = toSourceCode(SrcMgr, *LHSRng);
const auto RHSCode = toSourceCode(SrcMgr, *RHSRng);
const auto OperatorCode = toSourceCode(SrcMgr, *OpRng);
tooling::Replacements Result;
if (auto Err = Result.add(tooling::Replacement(
Ctx.getSourceManager(), LHSRng->getBegin(), LHSCode.size(), RHSCode)))
return std::move(Err);
if (auto Err = Result.add(tooling::Replacement(
Ctx.getSourceManager(), RHSRng->getBegin(), RHSCode.size(), LHSCode)))
return std::move(Err);
const auto SwappedOperator = swapOperator(Op->getOpcode());
if (auto Err = Result.add(tooling::Replacement(
Ctx.getSourceManager(), OpRng->getBegin(), OperatorCode.size(),
Op->getOpcodeStr(SwappedOperator))))
return std::move(Err);
return Effect::mainFileEdit(SrcMgr, std::move(Result));
}
} // namespace
} // namespace clangd
} // namespace clang
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