bittnerbarni updated this revision to Diff 57172.
http://reviews.llvm.org/D20196
Files:
clang-tidy/performance/InefficientStringAdditionCheck.cpp
docs/ReleaseNotes.rst
docs/clang-tidy/checks/performance-inefficient-string-addition.rst
test/clang-tidy/performance-inefficient-string-addition.cpp
Index: test/clang-tidy/performance-inefficient-string-addition.cpp
===================================================================
--- test/clang-tidy/performance-inefficient-string-addition.cpp
+++ test/clang-tidy/performance-inefficient-string-addition.cpp
@@ -1,4 +1,4 @@
-// RUN: %check_clang_tidy %s performance-inefficient-string-addition %t -- -- -std=c++11
+// RUN: %check_clang_tidy %s performance-inefficient-string-addition %t
namespace std {
template <typename T>
@@ -24,11 +24,11 @@
f(mystr1 + mystr2 + mystr1);
// CHECK-MESSAGES: :[[@LINE-1]]:23: warning: Inefficient string concatenation
mystr1 = mystr1 + mystr2;
- // CHECK-MESSAGES: :[[@LINE-1]]:2: warning: Ineff
+ // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: Ineff
mystr1 = mystr2 + mystr2 + mystr2;
- // CHECK-MESSAGES: :[[@LINE-1]]:27: warning: Ineff
+ // CHECK-MESSAGES: :[[@LINE-1]]:30: warning: Ineff
mystr1 = mystr2 + mystr1;
- // CHECK-MESSAGES: :[[@LINE-1]]:2: warning: Ineff
+ // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: Ineff
mywstr1 = mywstr2 + mywstr1;
// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: Ineff
mywstr1 = mywstr2 + mywstr2 + mywstr2;
@@ -41,4 +41,4 @@
mystr1 = g(mystr1);
}
return 0;
-}
\ No newline at end of file
+}
Index: docs/clang-tidy/checks/performance-inefficient-string-addition.rst
===================================================================
--- docs/clang-tidy/checks/performance-inefficient-string-addition.rst
+++ docs/clang-tidy/checks/performance-inefficient-string-addition.rst
@@ -1,24 +1,22 @@
.. title:: clang-tidy - performance-inefficient-string-addition
performance-inefficient-string-addition
-=====================================
+=======================================
The problem
-------------------
+-----------
This check is to warn about the performance overhead arising from concatenating strings, using the operator+, for instance:
.. code:: c++
-
- std::string a = "Foo", b = "Bar";
+ std::string a("Foo"), b("Bar");
a = a + b;
-Instead of this structure you should use **operator+=** or std::string's (std::basic_string) class member function **append**. For instance:
+Instead of this structure you should use `operator+=` or std::string's (std::basic_string) class member function `append`. For instance:
.. code:: c++
-
- std::string a = "Foo", b = "Baz";
+ std::string a("Foo"), b("Baz");
for(int i = 0; i < 20000; ++i)
{
a = a + "Bar" + b;
@@ -28,7 +26,7 @@
.. code:: c++
- std::string a = "Foo", b = "Baz";
+ std::string a("Foo"), b("Baz");
for(int i = 0; i < 20000; ++i)
{
a.append("Bar").append(b);
@@ -39,19 +37,19 @@
.. code:: c++
void f(const std::string&){}
- std::string a = "Foo", b = "Baz";
+ std::string a("Foo"), b("Baz");
void g()
{
- f(a+"Bar"+b);
+ f(a + "Bar" + b);
}
In a slightly more efficient way like:
.. code:: c++
void f(const std::string&){}
- std::string a = "Foo", b = "Baz";
+ std::string a("Foo"), b("Baz");
void g()
{
f(std::string(a).append("Bar").append(b));
- }
\ No newline at end of file
+ }
Index: docs/ReleaseNotes.rst
===================================================================
--- docs/ReleaseNotes.rst
+++ docs/ReleaseNotes.rst
@@ -184,6 +184,12 @@
Warns about range-based loop with a loop variable of const ref type where the
type of the variable does not match the one returned by the iterator.
+- New `performance-inefficient-string-addition
+ <http://clang.llvm.org/extra/clang-tidy/checks/performance-inefficient-string-addition.html>`_ check
+
+ This check is to warn about the performance overhead arising from concatenating
+ strings, using the operator+, instead of operator+=.
+
- New `performance-unnecessary-value-param
<http://clang.llvm.org/extra/clang-tidy/checks/performance-unnecessary-value-param.html>`_ check
Index: clang-tidy/performance/InefficientStringAdditionCheck.cpp
===================================================================
--- clang-tidy/performance/InefficientStringAdditionCheck.cpp
+++ clang-tidy/performance/InefficientStringAdditionCheck.cpp
@@ -28,22 +28,22 @@
IsStrictMode(Options.get("isStrictMode", 0)) {}
void InefficientStringAdditionCheck::registerMatchers(MatchFinder *Finder) {
- auto BasicStringType = hasType(cxxRecordDecl(hasName("::std::basic_string")));
+ const auto BasicStringType = hasType(cxxRecordDecl(hasName("::std::basic_string")));
- auto BasicStringPlusOperator =
+ const auto BasicStringPlusOperator =
cxxOperatorCallExpr(hasAnyArgument(ignoringImpCasts(declRefExpr(BasicStringType))),
hasOverloadedOperatorName("+"));
- auto PlusOperatorMatcher =
+ const auto PlusOperatorMatcher =
cxxBindTemporaryExpr(
hasDescendant(
cxxOperatorCallExpr(hasDescendant(BasicStringPlusOperator),
hasAnyArgument(ignoringImpCasts(declRefExpr(BasicStringType))),
hasOverloadedOperatorName("+"))
.bind("plusOperator")))
.bind("whole-rhs");
- auto AssingOperator = cxxOperatorCallExpr(
+ const auto AssingOperator = cxxOperatorCallExpr(
hasOverloadedOperatorName("="),hasDescendant(BasicStringPlusOperator),
allOf(hasArgument(
0, allOf(declRefExpr(BasicStringType),
@@ -53,25 +53,24 @@
1, stmt(hasDescendant(declRefExpr(hasDeclaration(decl(
equalsBoundNode("lhsStrT")))) /*.bind("rhs-self")*/)))));
- auto DescendantAssignMatcher = hasDescendant(AssingOperator);
+ const auto DescendantAssignMatcher = hasDescendant(AssingOperator);
if (IsStrictMode == 0) {
- auto SurroundLoopMatcher =
+ const auto SurroundLoopMatcher =
anyOf(hasAncestor(cxxForRangeStmt()), hasAncestor(whileStmt()),
hasAncestor(forStmt()));
- auto WholeMatcher =
+ const auto WholeMatcher =
exprWithCleanups(SurroundLoopMatcher, DescendantAssignMatcher);
Finder->addMatcher(WholeMatcher, this);
Finder->addMatcher(exprWithCleanups(SurroundLoopMatcher,
hasDescendant(PlusOperatorMatcher),
unless(WholeMatcher)),
this);
} else {
- auto WholeMatcher = exprWithCleanups(DescendantAssignMatcher);
+ const auto WholeMatcher = exprWithCleanups(DescendantAssignMatcher);
Finder->addMatcher(WholeMatcher, this);
-
Finder->addMatcher(exprWithCleanups(hasDescendant(PlusOperatorMatcher),
unless(WholeMatcher)),
this);
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