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//===- examples/Tooling/RemoveCStrCalls.cpp - Redundant c_str call removal ===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements a tool that prints replacements that remove redundant
// calls of c_str() on strings.
//
// Usage:
// remove-cstr-calls <cmake-output-dir> <file1> <file2> ...
//
// Where <cmake-output-dir> is a CMake build directory in which a file named
// compile_commands.json exists (enable -DCMAKE_EXPORT_COMPILE_COMMANDS in
// CMake to get this output).
//
// <file1> ... specify the paths of files in the CMake source tree. This path
// is looked up in the compile command database. If the path of a file is
// absolute, it needs to point into CMake's source tree. If the path is
// relative, the current working directory needs to be in the CMake source
// tree and the file must be in a subdirectory of the current working
// directory. "./" prefixes in the relative files will be automatically
// removed, but the rest of a relative path must be a suffix of a path in
// the compile command line database.
//
// For example, to use remove-cstr-calls on all files in a subtree of the
// source tree, use:
//
// /path/in/subtree $ find . -name '*.cpp'|
// xargs remove-cstr-calls /path/to/source
//
//===----------------------------------------------------------------------===//
#include "clang/Basic/SourceManager.h"
#include "clang/Frontend/FrontendActions.h"
#include "clang/Lex/Lexer.h"
#include "clang/Tooling/ASTMatchers.h"
#include "clang/Tooling/Tooling.h"
#include "llvm/ADT/OwningPtr.h"
#include "llvm/ADT/Twine.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Support/system_error.h"
using namespace clang::tooling::match;
// FIXME: Pull out helper methods in here into more fitting places.
// Returns the text that makes up 'node' in the source.
// Returns an empty string if the text cannot be found.
template <typename T>
std::string GetText(const clang::SourceManager &SourceManager, const T &Node) {
clang::SourceLocation StartSpellingLocatino =
SourceManager.getSpellingLoc(Node.getLocStart());
clang::SourceLocation EndSpellingLocation =
SourceManager.getSpellingLoc(Node.getLocEnd());
if (!StartSpellingLocatino.isValid() || !EndSpellingLocation.isValid()) {
return std::string();
}
bool Invalid = true;
const char *Text =
SourceManager.getCharacterData(StartSpellingLocatino, &Invalid);
if (Invalid) {
return std::string();
}
std::pair<clang::FileID, unsigned> Start =
SourceManager.getDecomposedLoc(StartSpellingLocatino);
std::pair<clang::FileID, unsigned> End =
SourceManager.getDecomposedLoc(clang::Lexer::getLocForEndOfToken(
EndSpellingLocation, 0, SourceManager, clang::LangOptions()));
if (Start.first != End.first) {
// Start and end are in different files.
return std::string();
}
if (End.second < Start.second) {
// Shuffling text with macros may cause this.
return std::string();
}
return std::string(Text, End.second - Start.second);
}
// Returns the position of the spelling location of a node inside a file.
// The format is:
// "<start_line>:<start_column>:<end_line>:<end_column>"
template <typename T1>
void PrintPosition(
llvm::raw_ostream &OS,
const clang::SourceManager &SourceManager, const T1 &Node) {
clang::SourceLocation StartSpellingLocation =
SourceManager.getSpellingLoc(Node.getLocStart());
clang::SourceLocation EndSpellingLocation =
SourceManager.getSpellingLoc(Node.getLocEnd());
clang::PresumedLoc Start =
SourceManager.getPresumedLoc(StartSpellingLocation);
clang::SourceLocation EndToken = clang::Lexer::getLocForEndOfToken(
EndSpellingLocation, 1, SourceManager, clang::LangOptions());
clang::PresumedLoc End = SourceManager.getPresumedLoc(EndToken);
OS << Start.getLine() << ":" << Start.getColumn() << ":"
<< End.getLine() << ":" << End.getColumn();
}
class ReportPosition : public clang::tooling::MatchFinder::MatchCallback {
public:
virtual void Run(const clang::tooling::MatchFinder::MatchResult &Result) {
llvm::outs() << "Found!\n";
}
};
// Return true if expr needs to be put in parens when it is an
// argument of a prefix unary operator, e.g. when it is a binary or
// ternary operator syntactically.
bool NeedParensAfterUnaryOperator(const clang::Expr &ExprNode) {
if (llvm::dyn_cast<clang::BinaryOperator>(&ExprNode) ||
llvm::dyn_cast<clang::ConditionalOperator>(&ExprNode)) {
return true;
}
if (const clang::CXXOperatorCallExpr *op =
llvm::dyn_cast<clang::CXXOperatorCallExpr>(&ExprNode)) {
return op->getNumArgs() == 2 &&
op->getOperator() != clang::OO_PlusPlus &&
op->getOperator() != clang::OO_MinusMinus &&
op->getOperator() != clang::OO_Call &&
op->getOperator() != clang::OO_Subscript;
}
return false;
}
// Format a pointer to an expression: prefix with '*' but simplify
// when it already begins with '&'. Return empty string on failure.
std::string FormatDereference(const clang::SourceManager &SourceManager,
const clang::Expr &ExprNode) {
if (const clang::UnaryOperator *Op =
llvm::dyn_cast<clang::UnaryOperator>(&ExprNode)) {
if (Op->getOpcode() == clang::UO_AddrOf) {
// Strip leading '&'.
return GetText(SourceManager, *Op->getSubExpr()->IgnoreParens());
}
}
const std::string Text = GetText(SourceManager, ExprNode);
if (Text.empty()) return std::string();
// Add leading '*'.
if (NeedParensAfterUnaryOperator(ExprNode)) {
return std::string("*(") + Text + ")";
}
return std::string("*") + Text;
}
class FixCStrCall : public clang::tooling::MatchFinder::MatchCallback {
public:
virtual void Run(const clang::tooling::MatchFinder::MatchResult &Result) {
const clang::CallExpr *Call =
Result.Nodes.GetStmtAs<clang::CallExpr>("call");
const clang::Expr *Arg =
Result.Nodes.GetStmtAs<clang::Expr>("arg");
const bool Arrow =
Result.Nodes.GetStmtAs<clang::MemberExpr>("member")->isArrow();
// Replace the "call" node with the "arg" node, prefixed with '*'
// if the call was using '->' rather than '.'.
const std::string ArgText = Arrow ?
FormatDereference(*Result.SourceManager, *Arg) :
GetText(*Result.SourceManager, *Arg);
if (ArgText.empty()) return;
llvm::outs() <<
Result.SourceManager->getBufferName(Call->getLocStart(), NULL) << ":";
PrintPosition(llvm::outs(), *Result.SourceManager, *Call);
llvm::outs() << ":" << ArgText << "\n";
}
};
const char *StringConstructor =
"::std::basic_string<char, std::char_traits<char>, std::allocator<char> >"
"::basic_string";
const char *StringCStrMethod =
"::std::basic_string<char, std::char_traits<char>, std::allocator<char> >"
"::c_str";
int main(int argc, char **argv) {
clang::tooling::ClangTool Tool(argc, argv);
clang::tooling::MatchFinder finder;
finder.AddMatcher(
ConstructorCall(
HasDeclaration(Method(HasName(StringConstructor))),
ArgumentCountIs(2),
// The first argument must have the form x.c_str() or p->c_str()
// where the method is string::c_str(). We can use the copy
// constructor of string instead (or the compiler might share
// the string object).
HasArgument(
0,
Id("call", Call(
Callee(Id("member", MemberExpression())),
Callee(Method(HasName(StringCStrMethod))),
On(Id("arg", Expression()))))),
// The second argument is the alloc object which must not be
// present explicitly.
HasArgument(
1,
DefaultArgument())), new FixCStrCall);
finder.AddMatcher(
ConstructorCall(
// Implicit constructors of these classes are overloaded
// wrt. string types and they internally make a StringRef
// referring to the argument. Passing a string directly to
// them is preferred to passing a char pointer.
HasDeclaration(Method(AnyOf(
HasName("::llvm::StringRef::StringRef"),
HasName("::llvm::Twine::Twine")))),
ArgumentCountIs(1),
// The only argument must have the form x.c_str() or p->c_str()
// where the method is string::c_str(). StringRef also has
// a constructor from string which is more efficient (avoids
// strlen), so we can construct StringRef from the string
// directly.
HasArgument(
0,
Id("call", Call(
Callee(Id("member", MemberExpression())),
Callee(Method(HasName(StringCStrMethod))),
On(Id("arg", Expression())))))),
new FixCStrCall);
return Tool.Run(finder.NewFrontendActionFactory());
}
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