1 //===--- ShrinkToFitCheck.cpp - clang-tidy---------------------------------===//
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
9 #include "ShrinkToFitCheck.h"
10 #include "clang/AST/ASTContext.h"
11 #include "clang/ASTMatchers/ASTMatchFinder.h"
12 #include "clang/Lex/Lexer.h"
13 #include "llvm/ADT/StringRef.h"
14
15 using namespace clang::ast_matchers;
16
17 namespace clang::tidy::modernize {
18
registerMatchers(MatchFinder * Finder)19 void ShrinkToFitCheck::registerMatchers(MatchFinder *Finder) {
20 // Swap as a function need not to be considered, because rvalue can not
21 // be bound to a non-const reference.
22 const auto ShrinkableExpr = mapAnyOf(memberExpr, declRefExpr);
23 const auto Shrinkable =
24 ShrinkableExpr.with(hasDeclaration(valueDecl().bind("ContainerDecl")));
25 const auto BoundShrinkable = ShrinkableExpr.with(
26 hasDeclaration(valueDecl(equalsBoundNode("ContainerDecl"))));
27
28 Finder->addMatcher(
29 cxxMemberCallExpr(
30 callee(cxxMethodDecl(hasName("swap"))),
31 hasArgument(
32 0, anyOf(Shrinkable, unaryOperator(hasUnaryOperand(Shrinkable)))),
33 on(cxxConstructExpr(hasArgument(
34 0,
35 expr(anyOf(BoundShrinkable,
36 unaryOperator(hasUnaryOperand(BoundShrinkable))),
37 hasType(hasCanonicalType(hasDeclaration(namedDecl(hasAnyName(
38 "std::basic_string", "std::deque", "std::vector"))))))
39 .bind("ContainerToShrink")))))
40 .bind("CopyAndSwapTrick"),
41 this);
42 }
43
check(const MatchFinder::MatchResult & Result)44 void ShrinkToFitCheck::check(const MatchFinder::MatchResult &Result) {
45 const auto *MemberCall =
46 Result.Nodes.getNodeAs<CXXMemberCallExpr>("CopyAndSwapTrick");
47 const auto *Container = Result.Nodes.getNodeAs<Expr>("ContainerToShrink");
48 FixItHint Hint;
49
50 if (!MemberCall->getBeginLoc().isMacroID()) {
51 const LangOptions &Opts = getLangOpts();
52 std::string ReplacementText;
53 if (const auto *UnaryOp = llvm::dyn_cast<UnaryOperator>(Container)) {
54 ReplacementText = std::string(
55 Lexer::getSourceText(CharSourceRange::getTokenRange(
56 UnaryOp->getSubExpr()->getSourceRange()),
57 *Result.SourceManager, Opts));
58 ReplacementText += "->shrink_to_fit()";
59 } else {
60 ReplacementText = std::string(Lexer::getSourceText(
61 CharSourceRange::getTokenRange(Container->getSourceRange()),
62 *Result.SourceManager, Opts));
63 ReplacementText += ".shrink_to_fit()";
64 }
65
66 Hint = FixItHint::CreateReplacement(MemberCall->getSourceRange(),
67 ReplacementText);
68 }
69
70 diag(MemberCall->getBeginLoc(), "the shrink_to_fit method should be used "
71 "to reduce the capacity of a shrinkable "
72 "container")
73 << Hint;
74 }
75
76 } // namespace clang::tidy::modernize
77