clang-tools  5.0.0
InefficientStringConcatenationCheck.cpp
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1 //===--- InefficientStringConcatenationCheck.cpp - clang-tidy--------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
11 #include "clang/AST/ASTContext.h"
12 #include "clang/ASTMatchers/ASTMatchFinder.h"
13 
14 using namespace clang::ast_matchers;
15 
16 namespace clang {
17 namespace tidy {
18 namespace performance {
19 
20 void InefficientStringConcatenationCheck::storeOptions(
22  Options.store(Opts, "StrictMode", StrictMode);
23 }
24 
25 InefficientStringConcatenationCheck::InefficientStringConcatenationCheck(
26  StringRef Name, ClangTidyContext *Context)
27  : ClangTidyCheck(Name, Context),
28  StrictMode(Options.getLocalOrGlobal("StrictMode", 0)) {}
29 
31  MatchFinder *Finder) {
32  if (!getLangOpts().CPlusPlus)
33  return;
34 
35  const auto BasicStringType =
36  hasType(cxxRecordDecl(hasName("::std::basic_string")));
37 
38  const auto BasicStringPlusOperator = cxxOperatorCallExpr(
39  hasOverloadedOperatorName("+"),
40  hasAnyArgument(ignoringImpCasts(declRefExpr(BasicStringType))));
41 
42  const auto PlusOperator =
43  cxxOperatorCallExpr(
44  hasOverloadedOperatorName("+"),
45  hasAnyArgument(ignoringImpCasts(declRefExpr(BasicStringType))),
46  hasDescendant(BasicStringPlusOperator))
47  .bind("plusOperator");
48 
49  const auto AssignOperator = cxxOperatorCallExpr(
50  hasOverloadedOperatorName("="),
51  hasArgument(0, declRefExpr(BasicStringType,
52  hasDeclaration(decl().bind("lhsStrT")))
53  .bind("lhsStr")),
54  hasArgument(1, stmt(hasDescendant(declRefExpr(
55  hasDeclaration(decl(equalsBoundNode("lhsStrT"))))))),
56  hasDescendant(BasicStringPlusOperator));
57 
58  if (StrictMode) {
59  Finder->addMatcher(cxxOperatorCallExpr(anyOf(AssignOperator, PlusOperator)),
60  this);
61  } else {
62  Finder->addMatcher(
63  cxxOperatorCallExpr(anyOf(AssignOperator, PlusOperator),
64  hasAncestor(stmt(anyOf(cxxForRangeStmt(),
65  whileStmt(), forStmt())))),
66  this);
67  }
68 }
69 
71  const MatchFinder::MatchResult &Result) {
72  const auto *LhsStr = Result.Nodes.getNodeAs<DeclRefExpr>("lhsStr");
73  const auto *PlusOperator =
74  Result.Nodes.getNodeAs<CXXOperatorCallExpr>("plusOperator");
75  const auto DiagMsg =
76  "string concatenation results in allocation of unnecessary temporary "
77  "strings; consider using 'operator+=' or 'string::append()' instead";
78 
79  if (LhsStr)
80  diag(LhsStr->getExprLoc(), DiagMsg);
81  else if (PlusOperator)
82  diag(PlusOperator->getExprLoc(), DiagMsg);
83 }
84 
85 } // namespace performance
86 } // namespace tidy
87 } // namespace clang
LangOptions getLangOpts() const
Returns the language options from the context.
Definition: ClangTidy.h:187
StringHandle Name
std::unique_ptr< ast_matchers::MatchFinder > Finder
Definition: ClangTidy.cpp:275
void registerMatchers(ast_matchers::MatchFinder *Finder) override
Override this to register AST matchers with Finder.
Base class for all clang-tidy checks.
Definition: ClangTidy.h:127
std::map< std::string, std::string > OptionMap
ClangTidyContext & Context
Definition: ClangTidy.cpp:87
Every ClangTidyCheck reports errors through a DiagnosticsEngine provided by this context.
void check(const ast_matchers::MatchFinder::MatchResult &Result) override
ClangTidyChecks that register ASTMatchers should do the actual work in here.
DiagnosticBuilder diag(SourceLocation Loc, StringRef Description, DiagnosticIDs::Level Level=DiagnosticIDs::Warning)
Add a diagnostic with the check's name.
Definition: ClangTidy.cpp:416