InefficientStringConcatenationCheck.cpp
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//===--- InefficientStringConcatenationCheck.cpp - clang-tidy--------------===//
//
// 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 "InefficientStringConcatenationCheck.h"
#include "clang/AST/ASTContext.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
using namespace clang::ast_matchers;
namespace clang {
namespace tidy {
namespace performance {
void InefficientStringConcatenationCheck::storeOptions(
ClangTidyOptions::OptionMap &Opts) {
Options.store(Opts, "StrictMode", StrictMode);
}
InefficientStringConcatenationCheck::InefficientStringConcatenationCheck(
StringRef Name, ClangTidyContext *Context)
: ClangTidyCheck(Name, Context),
StrictMode(Options.getLocalOrGlobal("StrictMode", false)) {}
void InefficientStringConcatenationCheck::registerMatchers(
MatchFinder *Finder) {
const auto BasicStringType =
hasType(qualType(hasUnqualifiedDesugaredType(recordType(
hasDeclaration(cxxRecordDecl(hasName("::std::basic_string")))))));
const auto BasicStringPlusOperator = cxxOperatorCallExpr(
hasOverloadedOperatorName("+"),
hasAnyArgument(ignoringImpCasts(declRefExpr(BasicStringType))));
const auto PlusOperator =
cxxOperatorCallExpr(
hasOverloadedOperatorName("+"),
hasAnyArgument(ignoringImpCasts(declRefExpr(BasicStringType))),
hasDescendant(BasicStringPlusOperator))
.bind("plusOperator");
const auto AssignOperator = cxxOperatorCallExpr(
hasOverloadedOperatorName("="),
hasArgument(0, declRefExpr(BasicStringType,
hasDeclaration(decl().bind("lhsStrT")))
.bind("lhsStr")),
hasArgument(1, stmt(hasDescendant(declRefExpr(
hasDeclaration(decl(equalsBoundNode("lhsStrT"))))))),
hasDescendant(BasicStringPlusOperator));
if (StrictMode) {
Finder->addMatcher(cxxOperatorCallExpr(anyOf(AssignOperator, PlusOperator)),
this);
} else {
Finder->addMatcher(
cxxOperatorCallExpr(anyOf(AssignOperator, PlusOperator),
hasAncestor(stmt(anyOf(cxxForRangeStmt(),
whileStmt(), forStmt())))),
this);
}
}
void InefficientStringConcatenationCheck::check(
const MatchFinder::MatchResult &Result) {
const auto *LhsStr = Result.Nodes.getNodeAs<DeclRefExpr>("lhsStr");
const auto *PlusOperator =
Result.Nodes.getNodeAs<CXXOperatorCallExpr>("plusOperator");
const auto DiagMsg =
"string concatenation results in allocation of unnecessary temporary "
"strings; consider using 'operator+=' or 'string::append()' instead";
if (LhsStr)
diag(LhsStr->getExprLoc(), DiagMsg);
else if (PlusOperator)
diag(PlusOperator->getExprLoc(), DiagMsg);
}
} // namespace performance
} // namespace tidy
} // namespace clang