clang-tools  14.0.0git
SwapIfBranches.cpp
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1 //===--- SwapIfBranches.cpp --------------------------------------*- C++-*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 #include "ParsedAST.h"
9 #include "SourceCode.h"
10 #include "refactor/Tweak.h"
11 #include "support/Logger.h"
12 #include "clang/AST/ASTContext.h"
13 #include "clang/AST/RecursiveASTVisitor.h"
14 #include "clang/AST/Stmt.h"
15 #include "clang/Basic/LangOptions.h"
16 #include "clang/Basic/SourceLocation.h"
17 #include "clang/Basic/SourceManager.h"
18 #include "clang/Lex/Lexer.h"
19 #include "clang/Tooling/Core/Replacement.h"
20 #include "llvm/ADT/None.h"
21 #include "llvm/ADT/Optional.h"
22 #include "llvm/ADT/StringRef.h"
23 #include "llvm/Support/Casting.h"
24 #include "llvm/Support/Error.h"
25 
26 namespace clang {
27 namespace clangd {
28 namespace {
29 /// Swaps the 'then' and 'else' branch of the if statement.
30 /// Before:
31 /// if (foo) { return 10; } else { continue; }
32 /// ^^^^^^^ ^^^^
33 /// After:
34 /// if (foo) { continue; } else { return 10; }
35 class SwapIfBranches : public Tweak {
36 public:
37  const char *id() const override final;
38 
39  bool prepare(const Selection &Inputs) override;
40  Expected<Effect> apply(const Selection &Inputs) override;
41  std::string title() const override { return "Swap if branches"; }
42  llvm::StringLiteral kind() const override {
44  }
45  bool hidden() const override { return true; }
46 
47 private:
48  const IfStmt *If = nullptr;
49 };
50 
51 REGISTER_TWEAK(SwapIfBranches)
52 
53 bool SwapIfBranches::prepare(const Selection &Inputs) {
54  for (const SelectionTree::Node *N = Inputs.ASTSelection.commonAncestor();
55  N && !If; N = N->Parent) {
56  // Stop once we hit a block, e.g. a lambda in the if condition.
57  if (llvm::isa_and_nonnull<CompoundStmt>(N->ASTNode.get<Stmt>()))
58  return false;
59  If = dyn_cast_or_null<IfStmt>(N->ASTNode.get<Stmt>());
60  }
61  // avoid dealing with single-statement brances, they require careful handling
62  // to avoid changing semantics of the code (i.e. dangling else).
63  return If && isa_and_nonnull<CompoundStmt>(If->getThen()) &&
64  isa_and_nonnull<CompoundStmt>(If->getElse());
65 }
66 
67 Expected<Tweak::Effect> SwapIfBranches::apply(const Selection &Inputs) {
68  auto &Ctx = Inputs.AST->getASTContext();
69  auto &SrcMgr = Inputs.AST->getSourceManager();
70 
71  auto ThenRng = toHalfOpenFileRange(SrcMgr, Ctx.getLangOpts(),
72  If->getThen()->getSourceRange());
73  if (!ThenRng)
74  return error("Could not obtain range of the 'then' branch. Macros?");
75  auto ElseRng = toHalfOpenFileRange(SrcMgr, Ctx.getLangOpts(),
76  If->getElse()->getSourceRange());
77  if (!ElseRng)
78  return error("Could not obtain range of the 'else' branch. Macros?");
79 
80  auto ThenCode = toSourceCode(SrcMgr, *ThenRng);
81  auto ElseCode = toSourceCode(SrcMgr, *ElseRng);
82 
83  tooling::Replacements Result;
84  if (auto Err = Result.add(tooling::Replacement(Ctx.getSourceManager(),
85  ThenRng->getBegin(),
86  ThenCode.size(), ElseCode)))
87  return std::move(Err);
88  if (auto Err = Result.add(tooling::Replacement(Ctx.getSourceManager(),
89  ElseRng->getBegin(),
90  ElseCode.size(), ThenCode)))
91  return std::move(Err);
92  return Effect::mainFileEdit(SrcMgr, std::move(Result));
93 }
94 
95 } // namespace
96 } // namespace clangd
97 } // namespace clang
clang::clangd::toHalfOpenFileRange
llvm::Optional< SourceRange > toHalfOpenFileRange(const SourceManager &SM, const LangOptions &LangOpts, SourceRange R)
Turns a token range into a half-open range and checks its correctness.
Definition: SourceCode.cpp:424
Expected
std::vector< const char * > Expected
Definition: PrintASTTests.cpp:27
clang::clangd::error
llvm::Error error(std::error_code EC, const char *Fmt, Ts &&... Vals)
Definition: Logger.h:80
Ctx
Context Ctx
Definition: TUScheduler.cpp:454
Inputs
ParseInputs Inputs
Definition: TUScheduler.cpp:451
Tweak.h
Logger.h
SourceCode.h
clang
===– Representation.cpp - ClangDoc Representation --------—*- C++ -*-===//
Definition: ApplyReplacements.h:27
clang::clangd::CodeAction::REFACTOR_KIND
const static llvm::StringLiteral REFACTOR_KIND
Definition: Protocol.h:980
clang::clangd::toSourceCode
llvm::StringRef toSourceCode(const SourceManager &SM, SourceRange R)
Returns the source code covered by the source range.
Definition: SourceCode.cpp:446
REGISTER_TWEAK
#define REGISTER_TWEAK(Subclass)
Definition: Tweak.h:132
ParsedAST.h