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/Stmt.h"
14 #include "clang/Basic/LangOptions.h"
15 #include "clang/Basic/SourceLocation.h"
16 #include "clang/Basic/SourceManager.h"
17 #include "clang/Tooling/Core/Replacement.h"
18 #include "llvm/ADT/StringRef.h"
19 #include "llvm/Support/Casting.h"
20 #include "llvm/Support/Error.h"
21
22 namespace clang {
23 namespace clangd {
24 namespace {
25 /// Swaps the 'then' and 'else' branch of the if statement.
26 /// Before:
27 /// if (foo) { return 10; } else { continue; }
28 /// ^^^^^^^ ^^^^
29 /// After:
30 /// if (foo) { continue; } else { return 10; }
31 class SwapIfBranches : public Tweak {
32 public:
33 const char *id() const final;
34
35 bool prepare(const Selection &Inputs) override;
36 Expected<Effect> apply(const Selection &Inputs) override;
title() const37 std::string title() const override { return "Swap if branches"; }
kind() const38 llvm::StringLiteral kind() const override {
39 return CodeAction::REFACTOR_KIND;
40 }
hidden() const41 bool hidden() const override { return true; }
42
43 private:
44 const IfStmt *If = nullptr;
45 };
46
REGISTER_TWEAK(SwapIfBranches)47 REGISTER_TWEAK(SwapIfBranches)
48
49 bool SwapIfBranches::prepare(const Selection &Inputs) {
50 for (const SelectionTree::Node *N = Inputs.ASTSelection.commonAncestor();
51 N && !If; N = N->Parent) {
52 // Stop once we hit a block, e.g. a lambda in the if condition.
53 if (llvm::isa_and_nonnull<CompoundStmt>(N->ASTNode.get<Stmt>()))
54 return false;
55 If = dyn_cast_or_null<IfStmt>(N->ASTNode.get<Stmt>());
56 }
57 // avoid dealing with single-statement brances, they require careful handling
58 // to avoid changing semantics of the code (i.e. dangling else).
59 return If && isa_and_nonnull<CompoundStmt>(If->getThen()) &&
60 isa_and_nonnull<CompoundStmt>(If->getElse());
61 }
62
apply(const Selection & Inputs)63 Expected<Tweak::Effect> SwapIfBranches::apply(const Selection &Inputs) {
64 auto &Ctx = Inputs.AST->getASTContext();
65 auto &SrcMgr = Inputs.AST->getSourceManager();
66
67 auto ThenRng = toHalfOpenFileRange(SrcMgr, Ctx.getLangOpts(),
68 If->getThen()->getSourceRange());
69 if (!ThenRng)
70 return error("Could not obtain range of the 'then' branch. Macros?");
71 auto ElseRng = toHalfOpenFileRange(SrcMgr, Ctx.getLangOpts(),
72 If->getElse()->getSourceRange());
73 if (!ElseRng)
74 return error("Could not obtain range of the 'else' branch. Macros?");
75
76 auto ThenCode = toSourceCode(SrcMgr, *ThenRng);
77 auto ElseCode = toSourceCode(SrcMgr, *ElseRng);
78
79 tooling::Replacements Result;
80 if (auto Err = Result.add(tooling::Replacement(Ctx.getSourceManager(),
81 ThenRng->getBegin(),
82 ThenCode.size(), ElseCode)))
83 return std::move(Err);
84 if (auto Err = Result.add(tooling::Replacement(Ctx.getSourceManager(),
85 ElseRng->getBegin(),
86 ElseCode.size(), ThenCode)))
87 return std::move(Err);
88 return Effect::mainFileEdit(SrcMgr, std::move(Result));
89 }
90
91 } // namespace
92 } // namespace clangd
93 } // namespace clang
94