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//===--- FasterStrsplitDelimiterCheck.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 "FasterStrsplitDelimiterCheck.h"
#include "clang/AST/ASTContext.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
#include "clang/Tooling/FixIt.h"
#include <optional>
using namespace clang::ast_matchers;
namespace clang::tidy::abseil {
namespace {
AST_MATCHER(StringLiteral, lengthIsOne) { return Node.getLength() == 1; }
std::optional<std::string> makeCharacterLiteral(const StringLiteral *Literal,
const ASTContext &Context) {
assert(Literal->getLength() == 1 &&
"Only single character string should be matched");
assert(Literal->getCharByteWidth() == 1 &&
"StrSplit doesn't support wide char");
std::string Result = clang::tooling::fixit::getText(*Literal, Context).str();
bool IsRawStringLiteral = StringRef(Result).startswith(R"(R")");
// Since raw string literal might contain unescaped non-printable characters,
// we normalize them using `StringLiteral::outputString`.
if (IsRawStringLiteral) {
Result.clear();
llvm::raw_string_ostream Stream(Result);
Literal->outputString(Stream);
}
// Special case: If the string contains a single quote, we just need to return
// a character of the single quote. This is a special case because we need to
// escape it in the character literal.
if (Result == R"("'")")
return std::string(R"('\'')");
// Now replace the " with '.
std::string::size_type Pos = Result.find_first_of('"');
if (Pos == Result.npos)
return std::nullopt;
Result[Pos] = '\'';
Pos = Result.find_last_of('"');
if (Pos == Result.npos)
return std::nullopt;
Result[Pos] = '\'';
return Result;
}
} // anonymous namespace
void FasterStrsplitDelimiterCheck::registerMatchers(MatchFinder *Finder) {
// Binds to one character string literals.
const auto SingleChar =
expr(ignoringParenCasts(stringLiteral(lengthIsOne()).bind("Literal")));
// Binds to a string_view (either absl or std) that was passed by value and
// constructed from string literal.
auto StringViewArg = ignoringElidableConstructorCall(ignoringImpCasts(
cxxConstructExpr(hasType(recordDecl(hasName("::absl::string_view"))),
hasArgument(0, ignoringParenImpCasts(SingleChar)))));
// Need to ignore the elidable constructor as otherwise there is no match for
// c++14 and earlier.
auto ByAnyCharArg =
expr(has(ignoringElidableConstructorCall(
ignoringParenCasts(cxxBindTemporaryExpr(has(cxxConstructExpr(
hasType(recordDecl(hasName("::absl::ByAnyChar"))),
hasArgument(0, StringViewArg))))))))
.bind("ByAnyChar");
// Find uses of absl::StrSplit(..., "x") and absl::StrSplit(...,
// absl::ByAnyChar("x")) to transform them into absl::StrSplit(..., 'x').
Finder->addMatcher(
traverse(TK_AsIs,
callExpr(callee(functionDecl(hasName("::absl::StrSplit"))),
hasArgument(1, anyOf(ByAnyCharArg, SingleChar)),
unless(isInTemplateInstantiation()))
.bind("StrSplit")),
this);
// Find uses of absl::MaxSplits("x", N) and
// absl::MaxSplits(absl::ByAnyChar("x"), N) to transform them into
// absl::MaxSplits('x', N).
Finder->addMatcher(
traverse(TK_AsIs,
callExpr(callee(functionDecl(hasName("::absl::MaxSplits"))),
hasArgument(0, anyOf(ByAnyCharArg,
ignoringParenCasts(SingleChar))),
unless(isInTemplateInstantiation()))),
this);
}
void FasterStrsplitDelimiterCheck::check(
const MatchFinder::MatchResult &Result) {
const auto *Literal = Result.Nodes.getNodeAs<StringLiteral>("Literal");
if (Literal->getBeginLoc().isMacroID() || Literal->getEndLoc().isMacroID())
return;
std::optional<std::string> Replacement =
makeCharacterLiteral(Literal, *Result.Context);
if (!Replacement)
return;
SourceRange Range = Literal->getSourceRange();
if (const auto *ByAnyChar = Result.Nodes.getNodeAs<Expr>("ByAnyChar"))
Range = ByAnyChar->getSourceRange();
diag(
Literal->getBeginLoc(),
"%select{absl::StrSplit()|absl::MaxSplits()}0 called with a string "
"literal "
"consisting of a single character; consider using the character overload")
<< (Result.Nodes.getNodeAs<CallExpr>("StrSplit") ? 0 : 1)
<< FixItHint::CreateReplacement(CharSourceRange::getTokenRange(Range),
*Replacement);
}
} // namespace clang::tidy::abseil
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