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//===--- UseStartsEndsWithCheck.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 "UseStartsEndsWithCheck.h"
#include "../utils/ASTUtils.h"
#include "../utils/Matchers.h"
#include "clang/ASTMatchers/ASTMatchers.h"
#include "clang/Lex/Lexer.h"
#include <string>
using namespace clang::ast_matchers;
namespace clang::tidy::modernize {
static bool isNegativeComparison(const Expr *ComparisonExpr) {
if (const auto *Op = llvm::dyn_cast<BinaryOperator>(ComparisonExpr))
return Op->getOpcode() == BO_NE;
if (const auto *Op = llvm::dyn_cast<CXXOperatorCallExpr>(ComparisonExpr))
return Op->getOperator() == OO_ExclaimEqual;
if (const auto *Op =
llvm::dyn_cast<CXXRewrittenBinaryOperator>(ComparisonExpr))
return Op->getOperator() == BO_NE;
return false;
}
namespace {
struct NotLengthExprForStringNode {
NotLengthExprForStringNode(std::string ID, DynTypedNode Node,
ASTContext *Context)
: ID(std::move(ID)), Node(std::move(Node)), Context(Context) {}
bool operator()(const internal::BoundNodesMap &Nodes) const {
// Match a string literal and an integer size or strlen() call.
if (const auto *StringLiteralNode = Nodes.getNodeAs<StringLiteral>(ID)) {
if (const auto *IntegerLiteralSizeNode = Node.get<IntegerLiteral>()) {
return StringLiteralNode->getLength() !=
IntegerLiteralSizeNode->getValue().getZExtValue();
}
if (const auto *StrlenNode = Node.get<CallExpr>()) {
if (StrlenNode->getDirectCallee()->getName() != "strlen" ||
StrlenNode->getNumArgs() != 1) {
return true;
}
if (const auto *StrlenArgNode = dyn_cast<StringLiteral>(
StrlenNode->getArg(0)->IgnoreParenImpCasts())) {
return StrlenArgNode->getLength() != StringLiteralNode->getLength();
}
}
}
// Match a string variable and a call to length() or size().
if (const auto *ExprNode = Nodes.getNodeAs<Expr>(ID)) {
if (const auto *MemberCallNode = Node.get<CXXMemberCallExpr>()) {
const CXXMethodDecl *MethodDeclNode = MemberCallNode->getMethodDecl();
const StringRef Name = MethodDeclNode->getName();
if (!MethodDeclNode->isConst() || MethodDeclNode->getNumParams() != 0 ||
(Name != "size" && Name != "length")) {
return true;
}
if (const auto *OnNode =
dyn_cast<Expr>(MemberCallNode->getImplicitObjectArgument())) {
return !utils::areStatementsIdentical(OnNode->IgnoreParenImpCasts(),
ExprNode->IgnoreParenImpCasts(),
*Context);
}
}
}
return true;
}
private:
std::string ID;
DynTypedNode Node;
ASTContext *Context;
};
AST_MATCHER_P(Expr, lengthExprForStringNode, std::string, ID) {
return Builder->removeBindings(NotLengthExprForStringNode(
ID, DynTypedNode::create(Node), &(Finder->getASTContext())));
}
} // namespace
UseStartsEndsWithCheck::UseStartsEndsWithCheck(StringRef Name,
ClangTidyContext *Context)
: ClangTidyCheck(Name, Context) {}
void UseStartsEndsWithCheck::registerMatchers(MatchFinder *Finder) {
const auto ZeroLiteral = integerLiteral(equals(0));
const auto ClassTypeWithMethod = [](const StringRef MethodBoundName,
const auto... Methods) {
return cxxRecordDecl(anyOf(
hasMethod(cxxMethodDecl(isConst(), parameterCountIs(1),
returns(booleanType()), hasAnyName(Methods))
.bind(MethodBoundName))...));
};
const auto OnClassWithStartsWithFunction =
ClassTypeWithMethod("starts_with_fun", "starts_with", "startsWith",
"startswith", "StartsWith");
const auto OnClassWithEndsWithFunction = ClassTypeWithMethod(
"ends_with_fun", "ends_with", "endsWith", "endswith", "EndsWith");
// Case 1: X.find(Y, [0], [LEN(Y)]) [!=]= 0 -> starts_with.
const auto FindExpr = cxxMemberCallExpr(
callee(
cxxMethodDecl(hasName("find"), ofClass(OnClassWithStartsWithFunction))
.bind("find_fun")),
hasArgument(0, expr().bind("needle")),
anyOf(
// Detect the expression: X.find(Y);
argumentCountIs(1),
// Detect the expression: X.find(Y, 0);
allOf(argumentCountIs(2), hasArgument(1, ZeroLiteral)),
// Detect the expression: X.find(Y, 0, LEN(Y));
allOf(argumentCountIs(3), hasArgument(1, ZeroLiteral),
hasArgument(2, lengthExprForStringNode("needle")))));
// Case 2: X.rfind(Y, 0, [LEN(Y)]) [!=]= 0 -> starts_with.
const auto RFindExpr = cxxMemberCallExpr(
callee(cxxMethodDecl(hasName("rfind"),
ofClass(OnClassWithStartsWithFunction))
.bind("find_fun")),
hasArgument(0, expr().bind("needle")),
anyOf(
// Detect the expression: X.rfind(Y, 0);
allOf(argumentCountIs(2), hasArgument(1, ZeroLiteral)),
// Detect the expression: X.rfind(Y, 0, LEN(Y));
allOf(argumentCountIs(3), hasArgument(1, ZeroLiteral),
hasArgument(2, lengthExprForStringNode("needle")))));
// Case 3: X.compare(0, LEN(Y), Y) [!=]= 0 -> starts_with.
const auto CompareExpr = cxxMemberCallExpr(
argumentCountIs(3), hasArgument(0, ZeroLiteral),
callee(cxxMethodDecl(hasName("compare"),
ofClass(OnClassWithStartsWithFunction))
.bind("find_fun")),
hasArgument(2, expr().bind("needle")),
hasArgument(1, lengthExprForStringNode("needle")));
// Case 4: X.compare(LEN(X) - LEN(Y), LEN(Y), Y) [!=]= 0 -> ends_with.
const auto CompareEndsWithExpr = cxxMemberCallExpr(
argumentCountIs(3),
callee(cxxMethodDecl(hasName("compare"),
ofClass(OnClassWithEndsWithFunction))
.bind("find_fun")),
on(expr().bind("haystack")), hasArgument(2, expr().bind("needle")),
hasArgument(1, lengthExprForStringNode("needle")),
hasArgument(0,
binaryOperator(hasOperatorName("-"),
hasLHS(lengthExprForStringNode("haystack")),
hasRHS(lengthExprForStringNode("needle")))));
// All cases comparing to 0.
Finder->addMatcher(
binaryOperator(
matchers::isEqualityOperator(),
hasOperands(cxxMemberCallExpr(anyOf(FindExpr, RFindExpr, CompareExpr,
CompareEndsWithExpr))
.bind("find_expr"),
ZeroLiteral))
.bind("expr"),
this);
// Case 5: X.rfind(Y) [!=]= LEN(X) - LEN(Y) -> ends_with.
Finder->addMatcher(
binaryOperator(
matchers::isEqualityOperator(),
hasOperands(
cxxMemberCallExpr(
anyOf(
argumentCountIs(1),
allOf(argumentCountIs(2),
hasArgument(
1,
anyOf(declRefExpr(to(varDecl(hasName("npos")))),
memberExpr(member(hasName("npos"))))))),
callee(cxxMethodDecl(hasName("rfind"),
ofClass(OnClassWithEndsWithFunction))
.bind("find_fun")),
on(expr().bind("haystack")),
hasArgument(0, expr().bind("needle")))
.bind("find_expr"),
binaryOperator(hasOperatorName("-"),
hasLHS(lengthExprForStringNode("haystack")),
hasRHS(lengthExprForStringNode("needle")))))
.bind("expr"),
this);
// Case 6: X.substr(0, LEN(Y)) [!=]= Y -> starts_with.
Finder->addMatcher(
binaryOperation(
hasAnyOperatorName("==", "!="),
hasOperands(
expr().bind("needle"),
cxxMemberCallExpr(
argumentCountIs(2), hasArgument(0, ZeroLiteral),
hasArgument(1, lengthExprForStringNode("needle")),
callee(cxxMethodDecl(hasName("substr"),
ofClass(OnClassWithStartsWithFunction))
.bind("find_fun")))
.bind("find_expr")))
.bind("expr"),
this);
}
void UseStartsEndsWithCheck::check(const MatchFinder::MatchResult &Result) {
const auto *ComparisonExpr = Result.Nodes.getNodeAs<Expr>("expr");
const auto *FindExpr = Result.Nodes.getNodeAs<CXXMemberCallExpr>("find_expr");
const auto *FindFun = Result.Nodes.getNodeAs<CXXMethodDecl>("find_fun");
const auto *SearchExpr = Result.Nodes.getNodeAs<Expr>("needle");
const auto *StartsWithFunction =
Result.Nodes.getNodeAs<CXXMethodDecl>("starts_with_fun");
const auto *EndsWithFunction =
Result.Nodes.getNodeAs<CXXMethodDecl>("ends_with_fun");
assert(bool(StartsWithFunction) != bool(EndsWithFunction));
const CXXMethodDecl *ReplacementFunction =
StartsWithFunction ? StartsWithFunction : EndsWithFunction;
if (ComparisonExpr->getBeginLoc().isMacroID() ||
FindExpr->getBeginLoc().isMacroID())
return;
// Make sure FindExpr->getArg(0) can be used to make a range in the FitItHint.
if (FindExpr->getNumArgs() == 0)
return;
// Retrieve the source text of the search expression.
const auto SearchExprText = Lexer::getSourceText(
CharSourceRange::getTokenRange(SearchExpr->getSourceRange()),
*Result.SourceManager, Result.Context->getLangOpts());
auto Diagnostic = diag(FindExpr->getExprLoc(), "use %0 instead of %1")
<< ReplacementFunction->getName() << FindFun->getName();
// Remove everything before the function call.
Diagnostic << FixItHint::CreateRemoval(CharSourceRange::getCharRange(
ComparisonExpr->getBeginLoc(), FindExpr->getBeginLoc()));
// Rename the function to `starts_with` or `ends_with`.
Diagnostic << FixItHint::CreateReplacement(FindExpr->getExprLoc(),
ReplacementFunction->getName());
// Replace arguments and everything after the function call.
Diagnostic << FixItHint::CreateReplacement(
CharSourceRange::getTokenRange(FindExpr->getArg(0)->getBeginLoc(),
ComparisonExpr->getEndLoc()),
(SearchExprText + ")").str());
// Add negation if necessary.
if (isNegativeComparison(ComparisonExpr))
Diagnostic << FixItHint::CreateInsertion(FindExpr->getBeginLoc(), "!");
}
} // namespace clang::tidy::modernize
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