clang-tools-extra/clang-tidy/modernize/ShrinkToFitCheck.cpp

   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
  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
  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